Excerpt

## List of Contents

**Dedication**

**Acknowledgement**

**Abstract**

**List of Content Abbreviations List of Tables List of Figures**

**Chapter 1: Introduction**

1.1 General

**Chapter 2: Literature Review**

2.1 Literature review

2.2 Motivation

2.3 Objectives

**Chapter 3: Materials and Methodology**

3.1 Materials Collection

3.1.1 Sponge gourd

3.1.2 Coir

3.1.3 Jute

3.1.4 Epoxy resin and Hardener

3.1.5 Caustic Soda (NaOH)

3.2 Fiber preparation

3.3 Taguchi Method

3.4 Composite Fabrication Procedure

**Chapter 4: Results and Discussion**

4.1 Impact Strength

4.1.1 Taguchi Analysis for Impact Strength

4.1.2 Confirmation Test for Impact Strength

4.2 Brinell Hardness

4.2.1 Taguchi Analysis for Brinell Hardness

4.2.2 Confirmation Test for Brinell Hardness

4.3 Tensile Strength

4.3.1 Taguchi Analysis for Tensile Strength

4.3.2 Confirmation Test for Tensile Strength

4.4 Flexural Strength

4.4.1 Taguchi Analysis for Flexural Strength

4.4.2 Confirmation Test for Flexural Strength

4.5 Optimal factor combinations for different maximum mechanical properties

4.6 ANOVA (Analysis of variance)

4.6.1 ANOVA for Impact Strength

4.6.2 ANOVA for Brinell Hardness

4.6.3 ANOVA for Tensile Strength

4.6.4 ANOVA for Flexural Strength

4.7 Contour Plot

4.7.1 Contour plot for Impact strength

4.7.2 Contour plot for Brinell hardness

4.7.3 Contour plot for Tensile strength

4.7.4 Contour plot for Flexural strength

4.8 Regression Analysis

4.8.1 Regression analysis for Impact strength

4.8.2 Regression analysis for Brinell hardness

4.8.3 Regression analysis for Tensile strength

4.8.4 Regression analysis for Flexural strength

4.9 Comparison with other NFC's

**Chapter 5: Conclusion**

**Chapter 6: Recommendation**

6.1 Recommendation for potential application

6.2 Scope for future research

**References**

**List of Research Publications out of this thesis work**

**Brief Biography of Author**

## Abbreviations

Abbildung in dieser Leseprobe nicht enthalten

## List of Tables

**Chapter 3**

Table 3.1: Chemical compositions of sponge gourd, coir, and jute fibers

Table 3.2:Levels of control factors used in the experiment

Table 3.3: DOE using L9 orthogonal array

**Chapter 4**

Table 4.1:Impact strength of different experiment

Table 4.2: Response table for mean of impact strength at various levels of input 21 parameters

Table 4.3:Brinell hardness of different experiment

Table 4.4: Response table for mean of brinell hardness at various levels of input 25 parameters

Table 4.5:Response table for mean of tensile strength at various levels of input 28 parameters

Table 4.6: Response table for mean of tensile strength at various levels of input 29 parameters

Table 4.7:Response table for mean of flexural strength at various levels of input 32 parameters

Table 4.8: Response table for mean of flexural strength at various levels of input 33 parameters

Table 4.9: Optimal combinations of four control factors for different mechanical property

Table 4.10: ANOVA analysis for Impact strength at 95% Confidence Level

Table 4.11: ANOVA analysis for Brinell hardness at 95% Confidence Level

Table 4.12: ANOVA analysis for Tensile strength at 95% Confidence Level

Table 4.13: ANOVA analysis for Flexural strength at 95% Confidence Level

Table 4.14: Comparison of different mechanical properties with other NFC's

## List of Figures

**Chapter 3**

Fig. 3.1: Sponge gourd fruit

Fig. 3.2: Ripe sponge gourd without exocarp

Fig. 3.3: Coconut Coir Husk

Fig. 3.4: Tossa and white jute fiber

Fig. 3.5: Epoxy Resin and Hardener

Fig. 3.6: Photographic image of Sodium hydroxide flake

Fig. 3.7: Shredder machine

Fig. 3.8: Photographic image of chemically treated short fibers (a) Sponge gourd, (b) 13 Coir, and (c) Jute

Fig. 3.9: Complete sequential process for fabrication (a) Measuring mass of Epoxy resin 17 (b) Measuring mass of Hardener (c) Taking appropriate proportion of Epoxy and Hardener (d) Mixing Epoxy and Hardener (e) Measuring mass of fibers (f) Mixing resin and fibers in appropriate proportion (g) Pouring of mixer on the mold (h) Applying pressure on mold (i) Curing by exposure to normal atmosphere (j) Marking on specimen (k) Cutting by a Jig saw machine (l) Specimens for different tests.

**Chapter 4**

Fig. 4.1: Specimen for impact strength

Fig. 4.2: HSM55 Pendulum Impact Tester (300 J)

Fig. 4.3: Comparison of impact strength of different experiments

Fig. 4.4: Main effect plots for mean values of impact strength

Fig. 4.5: Specimen for brinell hardness

Fig. 4.6: Brinell Hardness Tester (HSM51)

Fig. 4.7: Comparison of Brinell hardness of different experiments

Fig. 4.8: Main effect plots for mean values of Brinell hardness

Fig. 4.9: Specimen for tensile strength

Fig. 4.10: Universal Testing Machine (WANCE HUT A106)

Fig. 4.11: Comparison of tensile strength of different experiments

Fig. 4.12: Main effect plots for mean values tensile strength

Fig. 4.13: Specimen for flexural strength

Fig. 4.14: Flexural Testing Machine

Fig. 4.15: Comparison of flexural strength of different experiments

Fig. 4.16: Main effect plots for mean values of flexural strength

Fig. 4.17: Contour plots of impact strength

Fig. 4.18: Contour plots of brinell hardness

Fig. 4.19: Contour plots of tensile strength

Fig. 4.20: Contour plots of flexural strength

Fig. 4.21: Comparison between experimental and predicted impact strength values

Fig. 4.22: Comparison between experimental and predicted brinell hardness values

Fig. 4.23: Comparison between experimental and predicted tensile strength values

Fig. 4.24: Comparison between experimental and predicted flexural strength values

## Dedicated To

MY BELOVED PARENTS, ELDER BROTHER, AND MY WIFE WHO SUPPORTED ALWAYS TO MAKE ME SUCCESSFUL

## Acknowledgments

In the name of Allah, the most Merciful and Beneficent Alhamdulillah, all praises to Allah, the creator, the giver of life, the owner of all, the lord of majesty and generosity, the bestower of honors, the fast, the last, the ever-living, for giving me blessing, opportunity, willpower, strength, courage, and endurance in completing this thesis. My modest gratitude to the holy prophet Muhammad (peace be upon him) whose way of life has been continuous guidance for me.

It gives me immense pleasure to express my deep sense of gratitude to my supervisor Prof. Dr. Md. Nurul Islam for his invaluable guidance, motivation, constant inspiration, and above all for his ever-co-operating attitude that enabled me in bringing up this thesis in the present form. I have been lucky to have a supervisor who supported me in all situations specially to complete all formal procedures mandatory for the accomplishment of this thesis work.

I am grateful to Prof. Dr. Md. Shamim Akhter, Associate Prof. Md. Wahedul Islam, Department of Mechanical Engineering, Rajshahi University of Engineering & Technology, and Assistant Prof. Dr. Md. Rafiquzzaman, Department of Industrial Engineering and Management, Khulna University of Engineering & Technology for being helpful and generous. I also appreciate the encouragement from faculty members of the Mechanical Engineering Department of Rajshahi University of Engineering & Technology (RUET) and Bangladesh Army University of Science and Technology (BAUST).

I greatly appreciate and convey my heartfelt thanks to my colleagues Md. Hasan Ali and Md. Abubakar Siddique, Lecturer, Department of Industrial and Production Engineering; Md. Washim Akram, Lecturer, Department of Mechanical Engineering, Bangladesh Army University of Science and Technology (BAUST); Assistant Prof. Dr. Md. Shafiul Ferdous, Department of Mechanical Engineering, Khulna University of Engineering & Technology (KUET) for helping during fabrication and priceless assistance on the way of my journey.

Furthermore, I would like to record my sincere thanks to Tazbiul Mahmud Aranno, Teaching Assistant; Md. Abu Sufian, Md. Ajgor Ali, Md. Rofiqul Islam, Md. Ashiqur Rahaman, Md. Nahimul Islam, Assistant Technical Officer;Md. Imran Hossain, Lab Assistant; Md. Al Emran Hossain Shuvo, Student, BAUST; Md. Saiful Islam, Assistant Chief Technical Officer, Metallurgy Lab, RUET for their cordial cooperation during this research. Iam thankful to the Electrical and Mechanical Engineering (EME) Centre and School, Saidpur Cantonment.

Finally, I must express my very profound gratitude to my parents Dr. Md. Abu Yusuf and Dr. Most. Saleha Khatun, my elder brother Dr. Sk. Salahuddin Yusuf, and to my wife Shamsun Nahar Nasrin for providing me with unfailing support and continuous encouragement throughout my years of study and through the process of researching and writing this thesis. This accomplishment would not have been possible without them.

The evolution of human civilization is based on interest in research for new things. Natural fiber reinforced polymer matrix composites has got a considerable interest in the exploration of new light weight bio-degradable durable materials that can be used in different applications. Fiber-reinforced composites got considerable attention in numerous applications because of the good properties and superior advantages of natural fiber over synthetic fibers in term of its relatively low weight, low cost, good relative mechanical properties, electrical resistance, corrosion resistance, renewable resources, being abundant, flexibility during processing, biodegradability, and minimal health hazards. The properties of natural fiber composites to a large extent influenced by the type of fibers, treatment method, types of hardener and resin, and fabrication method. This paper presents a study of mechanical behaviour of sponge gourd, coir, and jute fibers reinforced thermosetting resin based composites. Natural fibers were treated with 5% NaOH solution by volume and hand lay-up technique was used to fabricate these composites. The Wt% (weight percentage) ratio of resin and hardener, Wt% of resin & hardener in composite, Wt% ratio of sponge gourd & jute, and Wt% ratio of sponge gourd & coir are considered as control factors which were optimized using Taguchi L9 orthogonal design of experiments. The optimal control factors combinations for different maximum mechanical strengths were found out and the predicted optimal values, obtained from Taguchi analysis, were confirmed by validation experiments. Maximum impact strength, brinell hardness, tensile strength, and flexural strength of this composite were found 111.92 kJ/m2, 71.62, 29.92 MPa, and 137.321MPa respectively. The percentage of contribution of four control factors on different mechanical properties was investigated by Analysis of Variance (ANOVA). Contour plots are very helpful to explore the combined influences of different control factors on output characteristics. At last, the regression equation represents a mathematical model that relates control factors with different mechanical properties.

## Chapter I

## INTRODUCTION

### 1.1 General

At present, the focus of researcher's attention is centered to the improvement of natural fiber reinforced composite (NFC) to meet the demand of new era utilizing the superior advantages of natural fibers over artificial ones. Natural fiber reinforced composites (NFC) are gaining wider consideration in current years in various applications including structural, automobile, roof and wall panel, container, protective vest, etc. As a fabricated material, the characteristics of NFC can be controlled to meet certain demands. Wider variation in properties and characteristics is a major challenge to work with NFC. Different parameters such as the category of fibers, ecological condition where the plant fibers are grown, and fiber treatment methods influence the characteristics of NFC to a large extent. Natural fiber composites, with their exclusive and wide range of variability in characteristics, can alter the use of synthetic fiber composites in the way of searching new alternative engineered material 1. Natural fiber reinforced composite is a composite material that contains a polymer matrix (resin and hardener) embedded with high- strength natural fibers such as coir, jute, sponge gourd, sisal, banana, kenaf, cotton, hemp, etc. In a new engineered composite, natural fibers have been accepted as good potential reinforcements 2.

Natural fibers are not synthetic or manmade and are collected from various animal and plant resources. Fiber-reinforced composites got considerable attention in numerous applications because of the improved characteristics and superior advantages of natural fiber over artificial fibers in term of its high durability, electrical resistance, corrosion resistance, comparatively low weight, little cost, renewable resources, being abundant, good comparative mechanical properties such as flexural, impact, and tensile strength, good surface quality, flexibility during processing, biodegradability, and negligible health threats. The plants, from which natural fibers are collected, can be categorized into bast fibers (jute, hemp, kenaf), seed fibers (cotton, sponge gourd, coir), leaf fibers (banana, sisal, agave, pineapple), grass and reed fibers (wheat, corn, rice), and core fibers (jute, hemp, kenaf) as well as all other kinds (wood and roots) 3.

The focus area of NFC researchers is to use different natural fibers as a reinforcement agent in the matrix of composites. The largest portion of strength is provided by fibers that are bonded by resin matrix. Matrix of resin is utilized to bind and protect the fibers from the atmosphere as fibers by themselves cannot carry the total load and they are biodegradable 1. Depending on types of intermolecular bonding, the polymer matrix can be categorized into thermosetting and thermoplastics. Advanced resistance to degradation and improved interfacial bonding between polymer matrix and natural fibers helps to preserve their chemical and mechanical characteristics. Thermoset polymers, as a matrix, are widely used for fabricating different NFC materials 4. Thermosets polymer can be defined as highly cross-linked structure polymers. This structure provides some exclusive advantages such as higher tensile and flexural strength, water resistance, flexibility of fabrication. It can be cured using only heat, or heat and pressure, and/or light irradiation. 3. The strength and interfacial adhesion to the composites are improved by addition of hardener in resin. Without addition of hardener to a correct proportion, epoxies do not achieve proper mechanical and chemical characteristics. The curing process of composites is speeded up by hardener additives that serve as a catalytic agent.

The superior advantage of thermoset polymers is that they have shown a very low viscosity and can easily be used with fibers at low pressures. The thermosetting polymer can be used with different composite processing methods such as vacuum infusion, vacuum bagging, hand lay-up, resin transfer, compression molding. Improved mechanical properties have been observed in different NFC with a thermoset matrix. Epoxy resins, one of the thermosetting resins, have good mechanical strength, improved chemical properties, electrical and corrosion resistance, excellent thermal and dimensional stability, and bettercomposite surfaces 4.

Fiber-reinforced (short fibers and continuous), particle reinforced (large-particle and dispersion- strengthened), and structural (sandwich and laminates) are three basic categories of composites. Among those fiber-reinforced composites have shown high strength and advanced properties. Fibers of coir, sponge gourd, and jute are naturally available, easy to process, and inexpensive in Bangladesh. The collected fibers are treated with 5% NaOH for 24 hours and then dried at the open atmosphere in sunlight. The composites are made-up by hand layup method. Epoxy resin is used as a matrix material where sponge gourd, coir, and jute fibers are taken as reinforcement agents.

The focus of present work is the fabrication and characterization of sponge gourd, coir, and jute fibers reinforced thermosetting resin-based composites polymer by using hand layout technique. The blending of short fibers of jute, sponge gourd, and epoxy resin with hardener at different weight ratios will be used to fabricate composite. Taguchi method with a three-factor four-level orthogonal array is used to design the experiments that was applied to the fabrication process for selection of the optimal combination of control factors value for attaining the desired properties. A validation test was performed by using this optimum combination. Analysis of Variance (ANOVA) is helpful to discover the percentage of contribution of control factors on different mechanical properties of this composite. The contour plot involves two control factors at a time, reveals the maximum or minimum expected response of these factors regarding different mechanical behavior.

Regression analysis provides a mathematical model that establishes a relationship between mechanical properties with control factors. Linear regression, endeavors to show the relationship between two or more factors by fitting a linear equation to experiential data, is used in this analysis. Different conditions such as weight percentage ratio of resin and hardener, the weight percentage of resin and hardener in composite, the weight percentage ratio of sponge gourd and jute, weight percentage ratio of sponge gourd and coir are varied in different samples. In the fabrication process, all those combinations are ensured according to the rules of the Taguchi method which refers to a statistical method. Now a day, its applications have increased especially in the field of engineering. It proposed extending each experiment with an " orthogonal array". In this study, the L9 orthogonal array is used. The mechanical properties such as impact, tensile, and flexural strength, and brinell hardness of these composites were investigated. The comparison of physical properties will help to explore the optimum combination of the composite.

## Chapter II

## LITERATURE REVIEW

### 2.1 Literature review

Natural fiber reinforced composites (NFC) can be defined as material where one or more types of natural fibers are reinforced in natural/ artificial resin. Natural/ bio-resin are formulated from different natural resources that are bio-degradable and environment friendly. Both natural and artificial resin are classified as thermosetting or thermoplastic type. NFCs have been used in diverse applications including structural, automobile, roof and wall panel, container, protective vest, etc 5. But, most of the thermoset resins based NFC are used in infrastructural purposes 6. Now a days, the usage of NFC has been observed in different biomedical applications including bone and tissue restoration and rebuilding 7. Numerous researches have been accomplished to explore the characteristics of natural fiber composites.

Sponge gourd-epoxy based NFCs have been fabricated by the hand lay-up method. Both chemically treated and untreated Sponge gourd fibers for 12 hrs and 24 hrs in different fiber loading (5%, 10%, 15%, 20%, and 25%) was used. Tensile and flexural strength are varied from 35-75 MPa and 40-85 MPa respectively with different percentages of fiber reinforcement 8. Another epoxy resin-based chemically treated sponge gourd-glass fiber natural composite was fabricated. Sponge gourd fibers were treated with 2% NaOH solution by volume for 1 hr. Maximum tensile strength 17.97 MPa was tested for composite with sponge gourd fiber (5 gms) and glass fiber (15 gms) and maximum flexural strength 106.67 MPa was found for composite with luffa fiber (15gms) and glass fiber(5 gms) 9.

An experiment was conducted by Taimur-Al-Mobarak et al., in Bangladesh, using raw and chemically modified sponge gourd fiber and polylactic acid based composites. 5% and 10% NaOH, acetic anhydride, and benzoyl chloride solutions by weight were used to treat fibers chemically. Melt compounding technique was used as the fabrication method. Compressive strength treated fiber reinforced composites was observed 7.61-10.06 MPa that was 10% - 35% larger than raw one 10. Another experiment was conducted by Valcineide O.A. Tanobe et al., in Brazil, using chemically treated short fiber-polymer composite as well as mat-polyester composites. Fibers were treated in 2% NaOH by volume for different periods 10, 60 and 90 min. For short fiber composites, tensile strength varied within 16-19 MPa. But tensile strength (22 MPa) was improved while mats of fiber were used as reinforcement 11. Viviane A. Escocio et al. studied the structural and mechanical properties of agro-residue of sponge gourd and high density polyethylene (HDPE) composites. HDPE was collected from natural resources and blending of sponge gourd scrap was used at different weight percentages (10, 20, 30 and 40%). The flexural, tensile, and impact strength of these composites with different compositions are 28.4-35.8 MPa, 19.2-20.8 MPa, and 25.5-34.7 J/m respectively 12. The surface investigation appears that the chemical treatments helps to remove the superficial surface layer and expose the inner fibrillar structure of fibers. So, the surface area of the fiber is increased that promotes a secondary increment on the mechanical properties. The best flexural property was observed for chemical treatment with 5% NaOH by volume 13.

Both thermosetting and thermoplastic resins can be used in coir fiber reinforced composite. Interfacial adhesion of fiber to the matrix resin has a large contribution to the mechanical property of the composites. Attractive interfacial adhesion is observed in coir fiber under dry conditions. The interfacial adhesion properties of coir fiber reinforced polyester composites were tested with different aging solutions 14. Alkali treatment and fiber length of coir have shown a considerable effect on the performance of coir-epoxy composites. Improved impact strength (27 kJ/m2) was found for the increased length of alkali treated coir fiber. Alkali (8% by volume) treated coir fiber (30 mm) had revealed better results 15. Polypropylenes based coir fiber reinforced composites were made-up with different weight percentages by Nadir Ayrilmis et al. for automotive interior applications. Mechanical, physical, and inflammability characteristics of these composite panels were tested. Coir fiber, at four different weight percentages, was used with the polypropylene powder and a coupling agent, 3 wt % maleic anhydrides grafted polypropylene (MAPP) powder. The flexural strength, the tensile strength, and the hardness of the composites improved with the increment of weight percentages of the coir fiber up to 60%. The tensile and flexural strengths of these composites were found 13.2-17.8 N/mm2 and 24.3-30.6 N/mm2 respectively 16.

Fairuz I. Romli et al. 17 also explored the consequence of fiber loading on the tensile property of epoxy based coir fiber reinforced composite. The conventional hand lay-up technique is used for fabricating the composites. Maximum tensile strength (8.25 MPa) was found for 15% fiber loading with 48 hours curing. MD. Zyaoul Haque et al. 18 investigated the mechanical properties of epoxy based coir and glass fiber reinforced composites where the maximum flexural and tensile strength was found for the composite with 10% fiber loading by weight. Vineet Kumar Bhaga et al. tested the physical and mechanical behavior of a hybrid composite made of sponge gourd and coir fiber strengthened epoxy resin. Maximum hardness and flexural strength of 30.55 Hv and 60.13 MPa respectively were found for composites with 25% fiber content by weight at a length of 30mm. With an increment of fiber length, the value of tensile modulus rises irrespective of fiber loading. The maximum impact strength of 31.74 kJ/m2 was observed at 35 mm fiber length and 25% fiber loading by weight 19. Another epoxy resin based sisal and coir natural fibers composite was fabricated by Girisha.C et al. Washed and dried sisal fibers and coir were treated with 10% NaOH solution. Tensile and flexural strengths are 39 MPa and 47 MPa respectively for 20 wt% fibers reinforcement 20.

Ajith Gopinatha et al. investigated two types of jute fiber reinforced composites made of epoxy and polyester resins ASTM standards. The mechanical properties of both NFC were tested and compared. The tensile property for jute-epoxy and jute-polyester NFC was observed 12.46 MPa and 9.23 MPa respectively. The 5% NaOH, by volume, treatment showed better result than 10% NaOH treatment 21. P. Prabaharan Grcaeraj et al. studied the tensile behavior of jute fiber strengthened hybrid polymer matrix composites. The maximum tensile strength of alkali-treated jute fiber reinforced hybrid polyester resin matrix composites was tested 70,662 kN/m2 22. M. R. Sanjay et al. studied the mechanical performance of jute and e-glass fiber strengthened epoxy hybrid NFC. The addition of synthetic glass fiber in jute fiber composites enhances the mechanical properties 23. The compression molding technique was used to fabricate polypropylene matrix based short jute fiber reinforced composite. Mechanical properties such as tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus, impact strength, and hardness of the composites were found 32 N/mm2, 850 N/mm2, 12%, 38 N/mm2, 1685 N/mm2, 18,000 J/m2, and 96 shore-A respectively 24.

M. J. Miah et al. fabricated an NFC, consists of jute fiber (10-30%) and low density polyethylene, by compression molding. Chemical treatment of the jute fibers showed a significant improvement in the mechanical properties of the composites 25. Another jute fiber reinforced m-TMI-grafted- polypropylene matrix based NFC was investigated by Pankaj K. Aggarwal et al. The variation of fiber percentages and coupling agent shows larger contribution on mechanical properties of the composites 26.

Thermosetting epoxy resin based bidirectional jute fiber mat strengthen NFC was developed by Vivek Mishra et al. Hand lay-up method was used for fabrication and fiber loading varied from zero to 48% by weight. Improvement of mechanical properties was explored with the increment in fiber loading. The maximum tensile strength, tensile modulus, and impact strength were found 110 MPa, 4.45 GPa, and 4.875 J respectively 27. Jute-coir fiber and polypropylene based hybrid polymer composites were tested by Salma Siddika et al. Hot press machine was used for composite fabrication. Fibers were taken at different weight percentages (5, 10, 15, 20%) where jute and coir were used at an equal ratio. Different mechanical properties such as young's and flexural modulus, flexural strength, impact strength, and hardness of these composites were improved with an increment on weight percentages of fiber 28. Md. Rafiquzzaman et al. investigated a hybrid polymer composite where jute and glass fiber was used as natural and synthetic fiber respectively and as polymer matrix epoxy resin and hardener were used. The hand lay-up method was used for fabrication where the maximum flexural, tensile, and impact strength were found 107.89 MPa, 89.56 MPa, and 265.87 J/m2 for composite with 10% jute and 30% glass fiber by weight 29. In a study, the film stacking method was used to produce jute and polypropylene (PP) based NFC. Here, jute fiber was treated with sodium hydroxide (NaOH) and Maleic anhydride-grafted polypropylene (MPP) to improve mechanical properties. Maximum tensile, impact, and flexural were found to be 42.2 MPa, 65 kJ/m2, and 59.0 MPa respectively 30.

Among numerous optimization methods, Design of experiment (DOE) formulated by the Taguchi technique has shown better performance for optimizing various control factors or process parameters. This technique is very suitable for researchers to explore the effects of process parameters on output characteristics and to find out an optimal combination of process parameters for improved output results. A complete factorial experimental design with all probable combinations of process parameters will require a large number of experiments that involved with extended cost and time. But Taguchi technique reduces experimentation time and cost by introducing an orthogonal array of different process parameters. Taguchi has discovered a new technique of conducting the design of experiments that are founded on distinct guidelines. Orthogonal arrays, formulated by the Taguchi method, specify the way of conducting the minimum number of experiments which could provide the comprehensive data of all the process parameters whose variation can show contribution on output characteristics.

Dr. Genichi Taguchi developed the Taguchi method in the 1950s. It is widely been used by engineers and researchers to enhance the quality of product and process performance. This method is largely used to develop DOE in several fields of engineering and science such as crop and product development in agriculture, management and business study, environmental research, and different other sectors like statistics, biotechnology, chemistry, human health and medication, and manufacturing process 31. Taguchi method was used to develop DOE by various researchers for optimizing different input parameters involved in mechanical behavior, production and machining methods [32-39]. P. Prabaharan Grcaeraj et al. studied the tensile property of jute fiber strengthened polymer composites. DOE was developed by the Taguchi method. The effect of different control factors was explored and the best combinations of these control factors were recommended by using the Taguchi method. 32. In another study, the Taguchi method was used to determine the influences of different process parameters like concentrations and sorts of chemical foaming agent, melt flow index on density of HDPE and wood flour, mechanical performance of wood flour and HDPE composite foams 33. Fei et al. 34 applied the Taguchi technique for the optimization of control factors related to the manufacturing process for the plastic injection molding process. This method was also applied for manufacturing PVC/acrylonitrile- butadiene rubber (NBR)/organoclay nanocomposites by Esmizadeh et al. for improvement of quality and performance, and cost reduction 35. Sailesh and Shanjeevi 36 fabricated a hybrid composite using bamboo, banana and glass fiber. The Taguchi method was used in this study for predicting the combination of optimum process parameters for maximum hardness property. Vankantia and Gantab 37 worked on the improvement of drilling operation on glass fiber strengthened polymer composites. DOE was done using the Taguchi method considering different process parameters such as feed, cutting speed, chisel edge width, and point angle. Taguchi method was found very helpful for determining the combinations of optimum values of various parameters to reduce the torque and thrust force and to improve the quality of the drilled hole. Both the Taguchi method and Analysis of Variance (ANOVA) were used to explore the effects of different parameters on wear behavior of cutting tools, to find out the optimal combination of the cutting parameter, and to determine the percentages of the contribution of each parameter 38. Different injection molding parameters are optimized to improve the mechanical performance of recycled plastic parts using the Taguchi technique by Mehat and Kamaruddin 39.

### 2.2 Motivation

The concern in developing NFC as a replacement of artificial composite material has increased meaningfully to find out low cost and upgraded material that can be used in different applications. Sponge-gourds, coir, and jute are easily available and widely used throughout the world. Sponge gourd, jute, and coir are easily available and low cost natural fibers. The scientific data concerning mechanical characteristics of sponge gourd, coir, and jute fiber reinforced thermosetting resin based composites are not available. This area being investigated has a knowledge gap that needs to be filled. In this work, chemically treated short fibers of jute, coir, and sponge gourd will be used with thermosetting epoxy resin and hardener to fabricate natural composites. Characterization of the composites with respect to impact strength, brinell hardness, tensile strength, and flexural strength was performed. This research will make a way to find a low cost natural composite.

### 2.3 Objectives

The specific objectives of this thesis work are mentioned as follows:

I. To fabricate epoxy resin based sponge gourd, coir and jute fiber reinforced composites.

II. To investigate the mechanical performances like impact strength, brinell hardness, tensile strength, and flexural strength.

III. To understand the effect of different control factors on output characteristics of this composite by using the Taguchi method and to explore the optimal combination of control factors for each mechanical property.

IV. To find out the percentage of contributions of control factors on mechanical properties by ANOVA and to find out mathematical models for different mechanical properties by Regression analysis.

## Chapter III

## MATERIALS AND METHODOLOGY

### 3.1 Materials Collection

In this work, natural fibers (sponge gourd, coir, and jute) were used for reinforcement in the composite. Sponge gourd, coir, and jute are easily available in Bangladesh. Coir and jute fibers are collected from the local market of Saidpur, Nilphamari, Bangladesh. Sponge gourds are collected from New Market, Dhaka, Bangladesh. Caustic Soda (NaOH) is used for the treatment of natural fibers. Caustic Soda is collected from a Chemical store of Rajshahi. Thermoset polymers are widely used to fabricate NFC. Epoxy resins, one of the thermosetting resins, have outstanding mechanical and chemical characteristics, thermal and corrosion resistance. The epoxy resin (Araldite AW 106) and hardener (Hardener HV 953 IN) were used as the matrix of this composite. The hardener is applied to provide more strength and enhance the interfacial adhesion. Both epoxy resin and hardener were collected from the local market of Khulna.

#### 3.1.1 Sponge gourd

Sponge gourd is a fruit of *Luffa cylindrica.* The size of this fruit is around 0.3 meters long which is similar to a cucumber in shape and size. The young fruit of sponge gourd is largely used as a vegetable. But completely ripened fruit is utilized to produce scrubbing bath sponges due to its strongly fibrous morphology. As a result, it is also recognized as sponge gourd. This strong fiber of this fruit is very suitable for reinforcement in NFC. It requires lots of heat and water to grow. 40. Now a days, Sponge gourd fibers are used in different natural or hybrid composites fabrication [8-13]. Fully ripened sponge gourd fruits were used to collect fiber. Young sponge gourd fruit and ripe sponge gourd without exocarp are shown in figures 3.1 and 3.2 respectively.

#### 3.1.2 Coir

Coir is a fruit fiber. Coir fiber is collected from the husk of the coconut fruit. It is located between the husk and the outer shell of the coconut. It is a type of fruit fiber. White coir fiber and brown coir fiber are two general categories of coir fiber. Having low lignin content, the white coir fibers, collected from young coconuts, showed smoother and more flexible properties than brown coir. But brown coir fibers are collected matured coconuts that contain a high amount of lignin contents 43. Coconut coir husks with brown coir fibers are presented in figure 3.3. In this work, brown coir fibers were used. High lignin content increases the lifespan of coir fiber considerably compared to natural fibers of other types. Biodegradable coir fiber is abundant in nature and showed upgraded resistance to degradation in salty environment and excellent interfacial adhesion 44. Coir fibers have been used with both thermosetting and thermoplastic resin for producing NFC or hybrid composites by different researchers [14-20].

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.1: Sponge gourd fruit 41.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.2: Ripe sponge gourd without exocrap 42.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.3: Coconut Coir Husk 45.

#### 3.1.3 Jute

Jute fiber is called Golden fiber that is naturally available fiber and easy to cultivate. It is a cash crop in Bangladesh. Our local farmers widely produce this eco-friendly jute fiber. Jute fiber is a type of bast fiber that contains mainly lignin and cellulose (lignocellulose). It is a long, flexible, glossyfiber thatis used to produce strong threads, cloth, bag, etc. Two typesofjute are cultivated in Bangladesh. They are Tossa jute (*Corchorus olitorius*), and White jute (*Corchorus capsularis*) 46. Tossa and white jute fibers are displayed in figure 3.4. A wide variety of NFC has been developed by using jute fibers with different types of resins [21-30]. White jute fibers are used in this research.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.4: Tossaand white jute fibers 47.

Table 3.1: Chemical compositions of sponge gourd, coir, and jutefibers 3.

Abbildung in dieser Leseprobe nicht enthalten

#### 3.1.4 Epoxy resin and Hardener

Strength, durability, electrical and chemical resistance of a composite material largely depends on types and chemical composition of epoxy resin. Resin as a laminating material can improve adhesive characteristics, hold the fibers in place and provide resistance to water degradation. In this research, epoxy resin Araldite AW 106 was applied as the polymer matrix material. Hardener (HV 953 IN /ADH 160 and Methyl Ethyl Peroxide) 48, was used to provide more strength and increase the interfacial bond to the composites. Both are displayed in figure 3.5. This epoxy adhesive is a multipurpose, viscous material and it is very easy to apply. The resin iscolorless, the hardener is light yellow, and the mixer of resin and hardener is pale yellow. The specific gravity of AW 106 and HV 953 IN is 1.15 and 0.95 respectively. The viscosity of epoxy and hardener is 500,000 cP and 35,000 cP respectively. Epoxy resin and hardeners are stored at room temperature. To prevent contamination, the containers should keep closed. Epoxy resin and hardener with proper storage should remain usable for many years.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.5: Epoxy resin (AW 106) and hardener (HV 953 IN).

#### 3.1.5 Caustic Soda (NaOH)

NaOH is the formula of Sodium hydroxide. The solid form of NaOH is called caustic soda that is a white substance with crystalline structure (flakes). It is a strong caustic base and hygroscopic in nature. It absorbs moisture and soluble in water. Sodium hydroxide is used in paper industry, soap, detergents, cleaner and sodium salts production, pH regulation, organic synthesis, in food and beverage industry, petroleum industry, etc 49. Flakes of NaOH is presented in figure 3.6.

Abbildung in dieser Leseprobe nicht enthalten

### 3.2 Fiber preparation

At first, collected sponge gourd, coir, and jute fibers were cleaned properly and cut into small pieces by a shredder machine. The Shredder machine is presented in figure 3.7. The size of short fibers is within 20 mm to 25 mm. A caustic solution was made which contains 5% NaOH by volume. Then, the fibers were immersed in this solution and stirred properly. Fibers are treated with NaOH solution for 24 hours. Then fibers were cleaned by distilled water and dried atSunlight in the open atmosphere. Chemically treated dried fibers were then stored properly. Chemically treated short fibers of sponge gourd, coir, and jute are presented in figure 3.8.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.7: Shredder machine 50.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 3.8: Photographic image of chemically treated short fibers (a) Sponge gourd, (b) Coir,

### 3.3 Taguchi Method

The Taguchi method is an excellent combination of both statistical and mathematical techniques. It is popular as a proficient and powerful tool for the optimization of control factors or process parameters. It provides a well-organized tactic for the execution of experiments to explore the optimal experimental settings of selected process parameters. Time and cost involved with performing experiments are minimized by reducing the number of experimental runs essential to satisfy the design objectives. Orthogonal arrays (OA) and signal-to-noise (S/N) ratio are the major tools of this method 51. Experiments founded on the Taguchi technique were conducted as per the precisely designed OA in which process parameters were considered as input parameters 52. The experimental result analysis uses the S/N ratio to aid in the determination of the best process or product design 53.

Orthogonal Arrays provide a set of well-adjusted combination of least numbers of experiments. Signal-to-Noise ratios (S/N) are log functions of desired output that is related to the objective functions for optimization technique essential in data analysis and prediction of optimum results with respect to recommended input parameters level value. The S/N ratio depends on the characteristics of the product/process to be optimized. The larger is better, nominal is best, and the smaller is better are three basic categories of S/N ratio. Once all of the S/N ratios have been calculated for each run of an experiment, the Taguchi method provides a graphical approach to analyze the data. In the graphical approach, the S/N ratios and average responses are plotted for each factor against each of its levels. The objective function described in this investigation is the maximization of mechanical properties. So, the S/N ratios were calculated using the “larger is better” approach. These characteristics can be calculated using the expression shown in equation (3.1).

Abbildung in dieser Leseprobe nicht enthalten

Where yi is the ith value of the response variable 51.

Before choosing an OA, the minimum number of experiments to be performed is to be decided based on the formula below,

N Taguchi = 1+ NV (L - 1) (3.2)

Where N Taguchi is the number of experiments to be conducted, NV is the number of control factors, L is umber of levels 53. In this work, NV = 4 and L = 3. So,

N Taguchi = 1+ 4 (3-1) = 9

Hence at least 9 experiments must be conducted. Based on this calculation, an OA is to be selected which has at least 9 experimental runs. Taguchi's experimental design of experiments suggests L9 OA, where 9 experiments are satisfactory to optimize the parameters. Once the orthogonal array is selected, the experiments are selected as per the level combinations. An important step in the design of experiments is the selection of control factors. Four factors i.e., weight percentage ratio of resin and hardener (A), weight percentage of resin and hardener in composite (B), weight percentage ratio of sponge gourd and jute (C), and weight percentage ratio of sponge gourd and coir (D), each at three levels is considered in this study. The influence of four factors was analyzed using L9 (34) orthogonal design. The levels of control factors are shown in Table 3.2.

Table 3.2: Levels of control factors used in the experiment.

Abbildung in dieser Leseprobe nicht enthalten

Table 3.3 DOE using L9 orthogonal array.

Abbildung in dieser Leseprobe nicht enthalten

Table 3.3 shows the Taguchi (L9) orthogonal array. In Table 3.3, each column stands for a test parameter and a row provides a test condition which is the combination of parameter levels. A full factorial experiment with four parameters with three levels needs 34 = 81 experiments, whereas it decreases to 9 experiments only, on using the Taguchi OA. The experimental results or outputs obtained from the tests were converted into the S/N ratio. The S/N ratios serve as the objective functions for optimization and help in the analysis of data and optimum results prediction 54.

### 3.4 Composite Fabrication Procedure

The hand lay-up process, a simple and easy technique for manufacturing composites, is used to fabricate composite. The hand lay-up process is a composites fabrication technique where a mixture of fibers and resins are poured into a mold of desired size and shape to produce a solid object. The primary significance of the hand lay-up technique is its simple and cheap equipment's with reduced complexity and times. The complete sequential fabrication process is shown in Figure 3.9.

i. First, mold was cleaned;

ii. The dimension of the mold was 275 x 155 x 5 mm3 which was made from mild steel plate;

iii. Then, parachute cloth was placed on the mold surface for easy removal of composite;

iv. The mass of resin, hardener, and chemically treated fibers were measured;

v. The resin was mixed with the hardener properly at a certain proportion according to the composition of different samples. For example; in sample 7, the proportion of epoxy resin and hardener was 1:1 and weight percentage of epoxy resin and hardener in composite was 91%;

vi. The fibers were mixed properly at appropriate proportions with the epoxy and hardener mixer. For example; in sample 7, the weight percentage of fibers in composites were 9% and weight percentage ratio of Sponge gourd, Jute, and Coir fibers were 3:1:3 (Sponge gourd = 42.857%, Jute = 14.286%, and Coir = 42.857 %);

vii. After mixing, the mixer of epoxy resin with natural fibers was then poured into the mold;

viii. To spread the resin properly throughout the fibers and to reduce void in the fiber structure, hand roller and brush was used;

ix. Finally, upper casing of mold was placed and 2 kg load was applied over the upper casing to remove any air gap in between the fibers and resin.

x. Then, it was kept for 24 hours to solidify;

xi. After the composite material get hardened entirely, the composite material was removed from the mold and rough edges are neatly cut;

xii. Then NFC samples were cured by exposure to normal atmosphere;

xiii. The dimensions of the different specimen were marked on the top surface of the composite by using a permanent marker pen;

xiv. The fabricated NFC's were cut using a Jig saw machine to obtain the specimens for different mechanical testing.

Abbildung in dieser Leseprobe nicht enthalten

## Chapter IV

## Results and Discussion

This chapter presents the mechanical behavior of the sponge gourd, coir, and jute fiber reinforced epoxy composites. Taguchi experimental design of experiments suggests L9 orthogonal array, where 9 experiments are sufficient to optimize the parameters. So, 9 experiments were performed three times as per the level combinations. The effect of different control factors on various properties of composites is discussed. From Taguchi analysis, optimal combinations of four control factors for different mechanical properties were achieved. Predicted values of different mechanical properties at optimal conditions were calculated using the Taguchi method and these values were compared with new experimental results. The percentage of contribution of four factors on different mechanical properties was investigated by Analysis of Variance (ANOVA). Contour plots are very helpful to explore the combined influences of different control factors on output characteristics. The regression equation represents a mathematical model that relates control factors with different mechanical properties.

### 4.1 Impact Strength

Impact strength is the capability of the material to withstand a suddenly applied load. The impact test determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's toughness. It is one of the most important strength characteristics of a metal. Charpy V- notch test is a standardized high strain-rate test which determines the amount of energy absorbed by a material during fracture. The test specimens were tested according to the ASTM A370 standard in which the dimension of each specimen is 55 mm x 10 mm x 5 mm. Figure 4.1 shows the impact strength test specimen. HSM55 Pendulum Impact Tester (300 J), shown in figure 4.2, was used to measure impact strength.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.1: Specimen for impact strength.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.2: HSM55 Pendulum Impact Tester (300 J).

Table 4.1 Impact strength of different experiment.

Abbildung in dieser Leseprobe nicht enthalten

Table 4.1 shows the design of the experiment by using Taguchi L9 orthogonal array with the impact strength values of these composites. Experiment no. 6 gives the maximum impact strength value (89.361 kJ/m2), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.25, 85, 0.33 and 1.00 respectively. On the other hand, experiment no. 9 reveals the minimum impact strength value (34.820 kJ/m2), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.00, 85, 1.00 and 0.33 respectively. The impact strength results of various experiments are compared in figure 4.3.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.3: Comparison of impact strength of different experiments.

#### 4.1.1 Taguchi Analysis for Impact Strength

The “larger is better” approach is used in this method as the maximization of mechanical strength is a prime goal of thesis work. The response table for mean of impact strength at various levels of input parameters is shown in table 4.2 for the impact strength of the natural composites. From table 4.2 and figure 4.4, it is seen that the variations of wt % ratio of sponge gourd & coir showed very little effect on impact property. The large variation comes from wt% ratio of resin and hardener. So at a first glance, it may be predicted that wt% ratio of resin and hardener would be the main factor for improvement of impact strength. The highest response was found from 1.25 wt% ratio of resin and hardener in the composite that was somewhat desired for high impact strength. Very poor results are obtained in the case of 1.00 wt% ratio of resin and hardener. Wt% ratio of sponge gourd and coir is another much better option that affects the impact strength of the composites. But it should be kept in mind that 0.33 ratio should be avoided. It was clearly seen from the graph that; the wt% ratio of sponge gourd & coir must be maintained very close to 1.00 for higher impact strength of the natural composite. Wt% of resin and hardener is the third important option for the improvement of impact strength. But it should be kept in mind that, 91 wt% of resin and hardener should be avoided. As the ratio decreases, that is, relative reduction of resin and hardener in the composite, much better results can be obtained. The result is higher incremental for 85 wt% of resin and hardener.

Table 4.2: Response table for mean of impact strength at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.4: Main effect plots for mean values of impact strength.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.1.2 Confirmation Test for Impact Strength

A confirmation test is a crucial step and is highly suggested by Taguchi to verify the experimental results. The optimal combination of parameters is A(1.25), B(85), C(3.00), D(1.00) has been obtained from the Taguchi experimental design. The predicted maximum impact strength is given by the following equation:

Impact Strength (Predicted) = A(1.25) + B(85) + C(3.00) + D(1.00) - 3Y

= 71.92 + 66.11 + 69.82 +69.75 - 3(52.33)

= 120.61 kJ/m2.

Where A, B, C, and D are the average mean values of impact strength at their optimum levels respectively, and Y is the overall mean.

The optimal factor combination for maximum impact strength is A(1.25), B(85), C(3.00), D(1.00) did not correspond to any experiment in the orthogonal array. So, a new experiment was performed to verify the predicted value of impact strength, found from the Taguchi method, on three samples. Impact Strength (Experimental) = 111.92J/m2.

Percentage of error (%) = 7.21.

### 4.2 Brinell Hardness

Material hardness is the property of the material which enables it to resist plastic deformation. It is the resistance of a material to localized deformation. The term can apply to deformation from indentation, scratching, cutting or bending. The usual type of hardness test is where a pointed or rounded indenter is pressed into a surface of the material under a substantially static load. The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material testpiece. The test specimens were tested according to the ASTM E10-18 standards in which the dimension of each specimen is 35 mm x 35 mm x 5 mm. Figure 4.5 shows the brinell test specimen. Brinell hardness tester (HSM51), shown in figure 4.6, was used to measure brinell hardness. Brinell hardness is determined by the following equation,

Abbildung in dieser Leseprobe nicht enthalten

Here, P = Applied load, kg

D = Diameter of the indenter, mm

d = Mean diameter of the indentation, mm.

Table 4.3 shows the design of the experiment by using Taguchi L9 orthogonal array with Brinell hardness values of these composites. Experiment no. 7 gives the maximum Brinell hardness value (67.337), where the combination is Wt% ratio of resin & hardener:1, Wt% of resin & hardener in composite: 91%, Wt% ratio of sponge gourd & jute: 3, and Wt% ratio of sponge gourd & coir: 1. On the other hand, experiment no. 3 reveals the minimum hardness value (39.010), where Wt% ratio of resin & hardener, Wt% of resin & hardener in composite, Wt% ratio of sponge gourd & jute, and Wt% ratio of sponge gourd & coir are 1.50, 85, 3.00 and 3.00 respectively. Figure 4.7 reveals the graph indicating Brinell hardness values corresponding to the experiment number.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.5: Specimen for brinell hardness.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.6: Brinell Hardness Tester (HSM51).

Abbildung in dieser Leseprobe nicht enthalten

Table 4.3 Brinell hardness of different experiment

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.7: Comparison of Brinell hardness of different experiments.

#### 4.2.1 Taguchi Analysis for Brinell Hardness

From table 4.4 and figure 4.8, it is seen that variations are small for the factor Wt% ratio of sponge gourd & jute and A validation response was observed in the case of 1.00 level value. The high variation comes from Wt% of resin & hardener in the composite. So, it may be expected that Wt% of resin & hardener would be the main factor of improvement of Brinell hardness. With an increase of Wt% of resin & hardener, the value of Brinell hardness is almost linearly improved. High response from 91 Wt% of resin & hardener in the natural composite that was somewhat desired for Brinell hardness. Very low results are obtained in the case of 85 Wt% of resin & hardener. Wt% ratio of resin & hardener is the second favorable option for the improvement of Brinell hardness. Here, the values of Brinell hardness are linearly decreased with increasing values of the Wt% ratio of resin & hardener. But, 1.50 ratio should be avoided, as it provides low hardness. As the ratio decreases, that is, a relative reduction of resin compared to hardener in the composite, much better results can be obtained. The result is higher incremental for the ratio of 1. Wt% ratio of sponge gourd & coir is another option that affects the hardness of the composites. But, it should be kept in mind that 0.33 ratio should be avoided. As the ratio increase, that is, a relative reduction of coir fiber to the sponge gourd fiber, much better results can be obtained. The result is high for the ratio of 1.00.

Table 4.4: Response table for mean of brinell hardness at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.8: Main effect plots for mean values of Brinell hardness.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.2.2 Confirmation Test for Brinell Hardness

Maximum Brinell hardness is found for A (1.00), B (91%), C (3.00), and D (1.00) conditions. The confirmation experiments were carried out in three different samples with the control factors set at their optimal levels. The predicted maximum Brinell hardness is given by the equation:

Brinell hardness (Predicted) = A(1.00) + B(91) + C(3.00) + D(1.00) - 3Y

= 56.652 + 55.182 + 52.352 + 51.30 - 3(49.05)

= 68.34.

Where A, B, C, and D are the average mean values of brinell hardness at their optimum levels respectively, and Y is the overall mean.

Brinell Hardness (Experimental) = 71.62.

Percentage of error (%) = 4.58.

### 4.3 Tensile Strength

Tensile strength is a measurement of the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. Ultimate tensile strength, often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before failing or breaking. It is the maximum strength of the material when tension is applied, usually at the moment when the material fails completely. Tensile strength is measured in units of force per unit area. The test specimens, shown in figure 4.9, were tested according to the ASTM D3039/3039M standards. Figure 4.10 represents the Universal Testing Machine (WANCE HUT A106) used for tensile testing. Tensile strength is determined by the following equation,

Abbildung in dieser Leseprobe nicht enthalten

Where, o = Tensile strength (MPa); F = maximum load before failure (N); A=Average cross-sectional area (mm2).

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.9: Specimen for tensile strength.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.10: Universal Testing Machine (WANCE HUT A106)

Abbildung in dieser Leseprobe nicht enthalten

Table 4.5 shows the design of the experiment by using Taguchi L9 orthogonal array with tensile strength values of natural composites. Experiment no. 8 gives the maximum tensile strength value (29.095 MPa), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.00, 88, 0.33 and 3.00 respectively. On the other hand, experiment no. 1 reveals the minimum tensile strength value (7.435 MPa), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.50, 91, 0.33 and 0.33 respectively. Figure 4.11 reveals the graph indicating tensile strength values corresponding to the experiment number.

Abbildung in dieser Leseprobe nicht enthalten

Table 4.5 Response table for mean of tensile strength at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.11: Comparison of tensile strength of different experiments.

#### 4.3.1 Taguchi Analysis for Tensile Strength

From table 4.6 and figure 4.12, it is observed that a high variation of tensile strength comes from wt% ratio of resin and hardener in these composites. So, wt% ratio of resin and hardener would be the main factor of improvement of tensile strength. The highest tensile strength was found for 1.00 wt% ratio of resin and hardener. The second important factor which influences the tensile behavior of these composites is Wt % ratio of sponge gourd & coir. As, level value 1.00 provides less tensile strength, so it should be avoided. Wt% of resin and hardener in the composite is another much better option for the improvement of tensile strength. With increasing Wt% of resin and hardener, tensile strength is almost linearly decreased. 85% Wt% of resin and hardener shows good tensile behavior. But, 91 wt% of resin and hardener shows poor tensile strength. Variations are small for the factor wt% ratio of sponge gourd and jute and very low responses are found in case of 3.00 level value. So, very little improvement is possible by changing the value of this factor.

Table 4.6: Response table for mean of tensile strength at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.3.2 Confirmation Test for Tensile Strength

Maximum tensile strength is found in A (1.00), B (85%), C (1.00), and D (3.00) conditions. The confirmation experiments were carried out in three different samples with the control factors set at their optimal levels. The predicted maximum tensile strength is given by the equation:

Tensile Strength (Predicted) = A(1.00) + B(85) + C(1.00) + D(3.00) - 3Y

= 26.673 + 16.230 + 15.350 + 16.525 - 3(14.76)

= 30.505 MPa.

Where A, B, C, and D are the average mean values of tensile strength at their optimum levels respectively, and Y is the overall mean.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.12: Main effect plots for mean values tensile strength.

Tensile Strength (Experimental) = 29.92MPa.

Percentage of error (%) = 1.918.

### 4.4 Flexural Strength

The flexural strength of a material is defined as the maximum bending stress that can be applied to that material before it yields. Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the stress in a material just before it yields in a flexure test. The most common way of obtaining the flexural strength of a material is by employing a transverse bending test using a three-point flexural test technique. The test specimens were tested according to the ASTM D790 standards in which the dimension of each specimen is 120 mm x 20 mm x 5 mm. Figure 4.14 represents the Flexural testing machine used for flexural testing. Flexural strength is determined by the following equation,

Flexural strength = MC / I (4.3)

Here, M = internal bending moment about the sections of the neutral axis

= Force x Distance

Here, Distance = L / 2

L = Length of span

C = perpendicular distance from the neutral axis to the furthest point on the section = thickness/2

I = the moment of inertia

= 1/12 x width x (thickness)3

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.13: Specimen for flexural strength.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.14: Flexural Testing Machine.

Table 4.7 shows the design of the experiment by using Taguchi L9 orthogonal array with the flexural strength values of these composites. Experiment no. 9 gives the maximum flexural strength value (137.321 MPa), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.00, 85, 1.00, and 0.33 respectively. On the other hand, experiment no. 1 reveals the minimum flexural strength value (65.017 MPa), where wt% ratio of resin and hardener, wt% of resin and hardener in composite, wt% ratio of sponge gourd and jute, and wt% ratio of sponge gourd and coir are 1.50, 91, 0.33, and 0.33 respectively. Flexural strength results of the various experiments are compared in figure 4.15.

Abbildung in dieser Leseprobe nicht enthalten

Table 4.7 Response table for mean of flexural strength at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.15: Comparison of flexural strength of different experiments.

#### 4.4.1 Taguchi Analysis for Flexural Strength

The “larger is better” approach is used in this method as the maximization of mechanical strength is a prime goal of thesis work. The response table for mean of flexural strength at various levels of input parameters is shown in table 4.8. From table 4.8 and figure 4.16, it is seen that the variations of wt % ratio of sponge gourd & jute showed very little effect on the flexural property. Large variation comes from wt% ratio of resin and hardener. So, wt% ratio of resin and hardener should be the main factor for the improvement of flexural strength. The highest value of flexural strength was found from 1.00 wt% ratio of resin and hardener in the composite. The flexural strength of these composites was decreased with an increase of wt% ratio of resin and hardener. Very poor results are obtained in the case of 1.00 wt% ratio of resin and hardener. Wt% of resin & hardener might be the second important choice to improve the flexural strength of these composites. For, 85% resin & hardener in composite, it gives a better result. Wt % ratio of sponge gourd & coir is the third important option for the improvement of flexural strength. A good response was found for 0.33 value of wt % ratio of sponge gourd & coir.

Table 4.8: Response table for mean of flexural strength at various levels of input parameters.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.4.2 Confirmation Test for Flexural Strength

The optimal combination of parameters is A(1.00), B(85%), C(1.00), D(0.33) has been obtained from the Taguchi experimental design. The predicted maximum flexural strength is given by the following equation:

Flexural Strength (Predicted) = A(1.00) + B(85) + C(1.00) + D(0.33) - 3Y

= 122.32+ 96.67+ 91.33+90.67- 3(87.61)

= 138.16 MPa.

Where A, B, C, and D are the average mean values of flexural strength at their optimum levels respectively, and Y is the overall mean.

Abbildung in dieser Leseprobe nicht enthalten

The optimal factor combination for maximum flexural strength, A(1.00), B(85%), C(1.00), D(0.33), did not correspond to any experiment in the orthogonal array. So, a new experiment was performed to verify the predicted value of flexural strength, found from the Taguchi method, on three different samples.

Flexural Strength (Experimental) = 131.05MPa.

Percentage of error (%) = 5.15.

### 4.5 Optimal factor combinations for different maximum mechanical properties

From Taguchi analysis, optimal combinations of four control factors for the different mechanical property was achieved. Predictions of different mechanical properties at optimal conditions were calculated using the Taguchi method and new experiments were performed to verify the predicted values with experimental results. Table 4.9 shows a summary of this analysis.

Table 4.9: Optimal combinations of four control factors for different mechanical property.

Abbildung in dieser Leseprobe nicht enthalten

### 4.6 ANOVA (Analysis of variance)

ANOVA is a quality tool to determine which factors have statistically significant effects on the output characteristic of a product. One way ANOVA is used to explore the differences between two or more independent groups. In general, it can be used when the level of control factor is greater than 2. To determine whether the association between the response and each control factor in the OA, is statistically significant, comparing the p-value for the term to significance level to assess the null hypothesis about the output response. The null hypothesis is that the term's coefficient is equal to zero which indicates that there is no association between the term and the output response. Usually, a significance level (denoted as a) of 0.05 is widely used. A significance level value of 0.05 indicates a 5% risk that an association exists when there is no association between input and output parameters actually.

If the p-value is greater than the significance level, it is concluded that there is a statistically significant association between the response variable and the input parameter. Percentage contribution is the most important consideration in ANOVA interaction. It indicates the influence of the change of an input parameter on output response. Percentages of sum of squares (SS) values indicate how the input affects the final results that are needed to design for optimization of the process.

#### 4.6.1 ANOVA for Impact Strength

From this one-way ANOVA table (table 4.10), the maximum percentage of contribution was found 27.62 for wt% of resin and hardener. From F-distribution table 55, for numerator 1 and denominator 4, critical value Fcritical=7.71. In this study, the calculated F-value corresponding to the maximum percentage of contribution is 1.29 which is smaller than the critical F-value. So, P- value is 0.319 or 31.9% which is larger than 5% that indicates the assumption is acceptable. Similarly, the minimum percentage of contribution was found 2.19 for wt% ratio of sponge gourd and coir. Here, the calculated F-value is 0.10 which is less than 7.71. So, P-value is 0.765 or 76.5% which is greater than 5% that indicates the high probability of accepting the assumptions statistically. In this analysis, the combinational effects of factors that are not considered, contribute 21.4% as an error.

Table 4.10: ANOVA analysis for Impact strength at 95% Confidence Level.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.6.2 ANOVA for Brinell Hardness

From the one way ANOVA table (table 4.11), the maximum percentage of contribution was found 48.49 for wt% of resin & hardener. From F-distribution table 55, for numerator 1 and denominator 4, critical value Fcritical=7.71. In this study, the calculated F-value is 12.12 which is larger than the critical F-value. So, P-value is 0.025 or 2.5% which is less than 5% that indicates the assumption is very close to the critical zone for this factor. Similarly, the minimum percentage of contribution was found 5.34 for wt% ratio of sponge gourd & jute. Here, the calculated F-value is 1.33 which is less than 7.71. So, P-value is 0.312 or 31.2% which is greater than 5% that indicates the high probability of accepting the assumptions statistically. In this analysis, the combinational effects of factors that are not considered, contribute 4.00% as an error.

Table 4.11: ANOVA analysis for Brinell hardness at 95% Confidence Level.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.6.3 ANOVA for Tensile Strength

From this one way ANOVA table (table 4.12), the maximum percentage of contribution was found 85.65 for wt% ratio of resin and hardener. From F-distribution table 55, for numerator 1 and denominator 4, critical value Fcritical=7.71. In this study, the calculated F-value is 9.72 which is larger than the critical F-value. So, P-value is 0.036 or 3.6% which is less than 5% that indicates the assumption is very close to the critical zone for this factor. Similarly, the minimum percentage of contribution was found 0.517 for the wt% ratio of sponge gourd & jute. Here, the calculated F- value is 0.06 which is less than 7.71. So, P-value is 0.820 or 82.0% which is greater than 5% that indicates the high probability of accepting the assumptions statistically. In this analysis, the combinational effects of factors that are not considered, contribute 8.81% as an error.

#### 4.6.4 ANOVA for Flexural Strength

From the one way ANOVA table (table 4.13), the maximum percentage of contribution was found 86.22 for wt% ratio of resin & hardener. From F-distribution table 55, for numerator 1 and denominator 4, critical value Fcritical=7.71. In this study, the calculated F-value is 11.54 which is larger than the critical F-value. So, P-value is 0.027 or 2.7% which is less than 5% that indicates the assumption is very close to the critical zone for this factor. Similarly, the minimum percentage of contribution was found 0.0095 for the wt% ratio of sponge gourd & jute. Here, the calculated F-value is 0.0013 which is less than 7.71. So, P-value is 0.973 or 97.3% which is greater than 5% that indicates the high probability of accepting the assumptions statistically. In this analysis, the combinational effects of factors that are not considered in this study, contribute 7.47% as an error.

Table 4.12: ANOVA analysis for Tensile strength at 95% Confidence Level.

Abbildung in dieser Leseprobe nicht enthalten

Table 4.13: ANOVA analysis for Flexural strength at 95% Confidence Level.

Abbildung in dieser Leseprobe nicht enthalten

### 4.7 Contour Plot

A Contour Plot is used to determine where a maximum or minimum response is expected from the process. Contour Plots are especially useful for situations where a maximum or minimum response is expected within or close to the data range as a contour area. Because contours can only involve two factors at a time, the appearance of contour plots using different factors can vary widely while comparing. A contour plot is made up of curves, each having a constant value of a fitted response with the input factors. The curves have equally spaced values of the response while comparing with factor values. Contour plots are very helpful to explore the combined influences of different control factors on output characteristics.

#### 4.7.1 Contour plot for Impact strength

Abbildung in dieser Leseprobe nicht enthalten

Figure 4.17 reveals the contour plots of the impact strength of the natural composite. Wt% of resin and hardener below 87.5 with the wt% ratio of resin and hardener higher than 1.4, shows the contour surface with better results. Here, the impact strength is higher than 70 kJ/m2. But the decrease in wt% ratio of resin and hardener indicates the lower impact strength contour. Higher wt% ratio of sponge gourd and jute with a higher wt% ratio of resin and hardener is effective for achieving higher impact strength. Decrease in wt% ratio of resin and hardener value with the decrease of wt% ratio of sponge gourd and jute shows the lower impact strength contour surfaces. The better contour surface for wt% ratio of sponge gourd and coir and wt% ratio of resin and hardener is largely dependent on the value of the wt% ratio of resin and hardener. Higher wt% ratio of sponge gourd & jute with lower wt% of resin & hardener shows the higher impact strength contour surface. If the values are reversed then the impact strength contour surface will be lower. The better contour surface for wt% ratio of sponge gourd & coir along with wt% of resin & hardener is mainly dependent on the value of wt% of resin & hardener. Similarly, the better contour surface for wt% ratio of sponge gourd & coir along with wt% ratio of sponge gourd & jute in mainly depended on the value of wt% ratio of sponge gourd and jute with a higher wt% ratio of resin and hardener is effective for achieving higher impact strength. Decrease in wt% ratio of resin and hardener value with the decrease of wt% ratio of sponge gourd and jute shows the lower impact strength contour surfaces. The better contour surface for wt% ratio of sponge gourd and coir and wt% ratio of resin and hardener is largely dependent on the value of the wt% ratio of resin and hardener. Higher wt% ratio of sponge gourd & jute with lower wt% of resin & hardener shows the higher impact strength contour surface. If the values are reversed then the impact strength contour surface will be lower. The better contour surface for wt% ratio of sponge gourd & coir along with wt% of resin & hardener is mainly dependent on the value of wt% of resin & hardener. Similarly, the better contour surface for wt% ratio of sponge gourd & coir along with wt% ratio of sponge gourd & jute in mainly depended on the value of wt% ratio of sponge gourd and jute.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.17: Contour plots of impact strength.

#### 4.7.2 Contour plot for Brinell hardness

Figure 4.18 reveals the contour plots of brinell hardness for the natural composite. Wt% of resin & hardener above 90 with the wt% ratio of resin & hardener ranges from 1.0 to near 1.15, shows the contour surface of better result. Here, brinell hardness higher than 60. But the increase in wt% ratio of resin & hardener indicates the lower Brinell hardness contour. Higher wt% ratio of sponge gourd & jute with lower wt% ratio of resin & hardener is effective for achieving higher hardness. Increase in wt% ratio of resin & hardener value with the decrease of wt% ratio of sponge gourd & jute shows the lower Brinell hardness contour surfaces. The contour surface for wt% ratio of sponge gourd & coir and wt% ratio of resin & hardener is practically similar to the contour surface of wt% ratio of sponge gourd & jute and wt% ratio of resin & hardener. Higher wt% ratio of sponge gourd & jute with higher wt% of resin & hardener shows the higher brinell hardness contour surface. If the values are reversed then the Brinell hardness contour surface will be lower. Wt% ratio of sponge gourd & coir along with wt% ratio of sponge gourd & jute has a lower impact on brinell hardness of the composite.

Fig. 4.18: Contour plots of brinell hardness.

Abbildung in dieser Leseprobe nicht enthalten

#### 4.7.3 Contour plot for Tensile strength

Figure 4.19 represents the contour plots of tensile strength for the natural composite. The wt% ratio of resin and hardener ranges from 1.0 to near 1.2, shows the contour surface of better results. Here, the tensile strength value is higher than 25 MPa. But increase in wt% ratio of resin and hardener indicates the lower tensile strength contour. Higher value of wt% ratio of sponge gourd & jute and lower value of wt% ratio of resin & hardener shows improved contour surface for tensile strength. Almost the same response was found for the contour plot of wt% ratio of sponge gourd & coir with wt% ratio of resin & hardener. This contour surface reveals that the tensile strength doesn't depend on the wt% ratio of sponge gourd & coir largely. With increasing wt% ratio of resin and hardener, the value of tensile strength decreases. Lower wt% ratio of sponge gourd & jute with different values of wt% of resin & hardener shows the higher tensile strength contour surface. On the other hand, higher wt% ratio of sponge gourd & coir along with lower wt% of resin and hardener gives the better contour surface for tensile strength. The contour surface for wt% ratio of sponge gourd & coir with wt% ratio of sponge gourd & jute is approximately similar to the contour surface of wt% ratio of sponge gourd & coir with wt% of resin & hardener.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.19: Contour plots of tensile strength.

#### 4.7.4 Contour plot for Flexural strength

Figure 4.20 represents the contour plots of flexural strength for the natural composite. In 1st contour plot, if the value of wt% of resin and hardener ranges from 85 to 89 and the value of wt% ratio of resin and hardener ranges from 1.0 to 1.1, then it shows improved contour surface with flexural strength above 110 MPa. Increasing values of both control factors reduce the flexural strength. 2nd and 3rd plots are almost identical. In both plots, flexural strength decreases with increasing values of wt% ratio of resin and hardener. But very little influence on flexural strength was found for wt% ratio of sponge gourd & jute and wt% ratio of sponge gourd & coir in 2nd and 3rd plot respectively. With the increasing value of wt% of resin and hardener, flexural strength is reduced. But the variation of wt% ratio of sponge gourd & jute has very little effect on flexural strength. Almost the same response was found for the contour plot of wt% ratio of sponge gourd & coir with wt% of resin & hardener.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.20: Contour plots of flexural strength.

### 4.8 Regression Analysis

The regression equation represents a mathematical model that relates control factors with output mechanical properties. The regression analysis is a numerical means for the examination of the interaction between various parameters. In this study, regression analysis was performed using MINITAB 19 software. The feature of the regression equation is formed by providing input and output parameters in the Taguchi L9 OA. The equations are formed based on the value of four factors in the case of these composites. Regression analysis provides four mathematical models that establish a relationship between mechanical properties with control factors.

#### 4.8.1 Regression analysis for Impact strength

The regression equation of impact strength for the natural composite is as follows:

Impact strength (kJ/m2)=286+35.8A-3.17B+6.42C-1.92D (4.4)

Figure 4.21 shows the comparison between experimental and predicted impact strength values. The figure shows the nature of the two graphs practically almost similar. The experimental impact strength values for the experiment no. 2, 4, 7 and 8 are almost matched with predicted values. The experimental impact strength values for the experiment no. 1, 3, and 5 are very closed with predicted values.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.21: Comparison between experimental and predicted impact strength values.

#### 4.8.2 Regression analysis for Brinell hardness

The regression equation of brinell hardness for the natural composite is as follows:

Brinell hardness= -151.6 - 27.21A + 2.605B + 1.87C + 1.88D (4.5)

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.22: Comparison between experimental and predicted brinell hardness values.

Figure 4.22 shows the comparison between experimental and predicted brinell hardness values. The figure shows the nature of the two graphs practically almost similar. The experimental Brinell hardness values for the experiment no. 1, 3, 5, 6 and 7 are matched with the predicted value. Other points are very close to the predicted values.

#### 4.8.3 Regression analysis for Tensile strength

The regression equation of tensile strength for the natural composite is as follows:

Tensile strength (MPa) = 106.8 - 35.0A- 0.556B- 0.49C+0.94D (4.6)

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.23: Comparison between experimental and predicted tensile strength values.

Figure 4.23 shows the comparison between experimental and predicted tensile strength values. The figure shows the nature of the two graphs practically almost similar. The experimental tensile strength values for the experiment no. 1, 2, 3, 7, 8 and 9 are harmonized with the predicted value.

#### 4.8.4 Regression analysis for Flexural strength

The regression equation of flexural strength for the natural composite is as follows:

Flexural strength (MPa) = 428 - 105.3A - 2.37B - 0.20C - 0.24D (4.7)

Figure 4.24 shows the comparison between experimental and predicted flexural strength values. The figure shows the nature of the two graphs practically almost similar. The experimental flexural strength values for the experiment no. 2, 7 and 8 are almost matched with predicted values. The experimental impact strength values for the experiment no. 1, 3, and 4 are much closed with predicted values.

Abbildung in dieser Leseprobe nicht enthalten

Fig. 4.24: Comparison between experimental and predicted flexural strength values.

### 4.9 Comparison with other NFC's

Comparison of different mechanical properties of this natural fiber reinforced composite with other NFC's are presented in table 4.14. Impact strength, hardness, tensile, and flexural strength are considered to compare the mechanical properties. First one is the output of this thesis and other NFC's are presented with fabrication method for comparison. Considerable improvement of mechanical properties was observed from this table.

Table 4.14: Comparison of different mechanical properties with other NFC's.

Abbildung in dieser Leseprobe nicht enthalten

## Chapter V

## Conclusion

The study on fabrication and characterization of sponge gourd, jute and coir fiber reinforced thermosetting resin based composites led to the following conclusions:

1. Fabrication of sponge gourd, jute and coir fiber reinforced thermosetting resin based composites and evaluation of their different mechanical properties has been done successfully.

2. Taguchi method was applied for the Design of Experiment (DOE) and ANOVA was used to explore the significant effect of different controlling factors on mechanical characteristics.

3. Maximum impact strength was found 111.92 kJ/m2 and wt% of resin and hardener and wt % ratio of sponge gourd and coir has presented the maximum and minimum percentage of contribution on impact strength respectively.

4. Maximum brinell hardness was found 71.62 and wt% of resin and hardener and wt % ratio of sponge gourd and jute has shown the maximum and minimum percentage of contribution on brinell hardness respectively.

5. Maximum tensile strength was found 29.92 MPa and wt% ratio of resin and hardener and wt % ratio of sponge gourd and jute has revealed the maximum and minimum percentage of contribution on tensile strength respectively.

6. Maximum flexural strength was found 137.321 MPa and wt% ratio of resin and hardener and wt % ratio of sponge gourd and jute has shown the maximum and minimum percentage of contribution on tensile strength respectively.

7. Contour plots are very helpful to explore the combined influences of different control factors on output characteristics. The regression equations showed a very close resemblance between predicted and experimental values.

## Chapter VI

## Recommendation

### 6.1 Recommendation for potential application

The present study reveals that the sponge gourd, coir, and jute fiber reinforced epoxy composites exhibited improved mechanical properties and experimented upon in this study were found to have the adequate potential for a wide range of applications. This NFC may be recommended for multipurpose panels for wall and roof, containers, casing, and other type supporting and packaging objects, in automotive industries for preparing interior panels, headliners, seat backs and dashboards, carrier for covered door panels, covered components for instrument panels, carrier for hard and soft armrests, seatback panels, door bolsters, side and back walls, seatbacks, center consoles, load floors, trunk trim for making mobile and laptop case, etc.

### 6.2 Scope for future research

The present study on sponge gourd, coir, and jute fiber reinforced epoxy composite leaves a wide scope for future researchers to find many other aspects of these composites. Few recommendations for future research comprise:

*-* The research work can be extended further by considering other composite fabrication methods like the Compression or Vacuum molding technique.

*-* As natural fibers were dried openly at sunlight after chemical treatment, so humidity of these fibers was not controlled. A drier can be used to control the humidity of fibers. It may be helpful to improve the quality of the composite.

*-* The size of the short fibers used in this composite was 20 to 25 mm. An improved type of shredder machine can be used to reduce the length of fibers.

*-* Fibers are mixed with epoxy and hardener by hand stirrer. A mixer machine may be used to produce a more homogeneous mixture.

*-* More control factors can be considered such as the size of the fiber, duration of chemical treatment of fiber, the thickness of composite, mixing temperature, molding pressure, curing time, etc.

*-* L25 (55) orthogonal array should be used to get more specified result for optimizing the input parameters.

## References:

1 A. Ticoalu, T. Aravinthan, and F. Cardona, “A review of current development in natural fiber composites for structural and infrastructure applications,” in Proceedings of the Southern Region Engineering Conference (SREC '10), pp. 113-117, Toowoomba, Australia, November 2010.

2 M.M. Kabir, H. Wang, K.T. Lau, F. Cardona, “Chemical treatments on plant-based natural fiber reinforced polymer composites: An overview,” Composites: Part B 43 (2012) 2883-2892.

3 Layth Mohammed, M. N. M. Ansari, Grace Pua, Mohammad Jawaid, M. Saiful Islam, “A review on natural fiber reinforced polymer composite and its applications,” International Journal of Polymer Science, Volume 2015, Article ID 243947.

4 T. G. Yashas Gowda, M. R. Sanjay, K. Subrahmanya Bhat, P. Madhu, P. Senthamaraikannan, B. Yogesha, “Polymer matrix-natural fiber composites: An overview,” Cogent Engineering, http://doi.org/10.1080/23311916.2018.1446667.

5 A. O'Donnell, M. Dweib, and R. Wool, “Natural fiber composites with plant oil-based resin,” Composites Science and Technology, vol. 64, pp. 1135-1145, 2004.

6 Composites for infrastructure: a guide for civil engineers. Wheat Ridge, CO: Ray Pub. Inc., 1998.

7 H.-y. Cheung, M.-p. Ho, K.-t. Lau, F. Cardona, and D. Hui, “Natural fiber-reinforced composites for bioengineering and environmental engineering applications,” Composites: Part B, vol. 40, pp. 655-663, 2009.

8 S. I. Ichetaonye, I. C. Madufor, M. E. Yibowei, D. N. Ichetaonye, “Physico-mechanical properties of luffa aegyptiaca fiber reinforced polymer matrix composite,” Open Journal of Composite Materials, 2015, 5, 110-117.

9 D. Mohana krishnudua, D.Sreeramulub N.Rameshc, “Synthesis, characterization, and properties of epoxy filled luffa cylindrica reinforced composites,” Materials Today: Proceedings 5 (2018) 3835-3841.

10 Taimur-Al-Mobarak1, Md. Abdul Gafur, Md. Forhad Mina, “Preparation and characterization of raw and chemically modified sponge-gourd fiber reinforced polylactic acid biocomposites,” Materials Sciences and Applications, 2018, 9, 281-304.

11 V.O.A. Tanobe, T.H.S. Flores-Sahagun, S.C. Amico, G.I.B. Muniz, K.G. Satyanarayana, “Sponge gourd (luffa cylindrica) reinforced polyester composites: preparation and properties,” Defence Science Journal, Vol. 64, No. 3, May 2014, pp. 273-280, DOI: 10.14429/dsj.64.7327.

12 Viviane A. Escocioa, Leila L.Y. Viscontea, Andre de P. Cavalcanteb, Ana Maria S. Furtadob, Elen B.A.V. Pachecoa, “Study of mechanical and morphological properties of biobased polyethylene (HDPE) and sponge-gourds (Luffa-Cylindrica) agro residue composites,” AIP Conference Proceedings 1664, 060012, 2015; DOI: 10.1063/1.4918430.

13 C. A. Boynard, S. N. Monteiro, J. R. M. d'Almeida, “Aspects of alkali treatment of sponge gourd (luffa cylindrica) fibers on the flexural properties of polyester matrix composites,” Journal of Applied Polymer Science, Vol. 87, 1927-1932, 2003 Wiley Periodicals, Inc.

14 Yousif B.F., Ku H., “Suitability of using coir fiber/polymeric composite for the design of liquid storage tanks,” Material & Design, Vol. 36, 847-853,2012.

15 Karthikeyan A., Balamurugan K., “Effect of alkali treatment and fiber length on impact behavior of coir fiber reinforced epoxy composites”, Journal of Scientific & Industrial Research, Vol.71, 627-631, 2012.

16 Ayrilmis Nadir, Jarusombuti Songklod, Fueangvivat Vallayuth, Bauchongkol Piyawade and.White Robert H., “Coir fiber reinforced polypropylene composite panel for automotive interior applications,” Fibers and polymer, Vol. 12, 919-926, 2011.

17 Fairuz I. Romlia, Ahmad Nizam Aliasb, Azmin Shakrine Mohd Rafiec, Dayang Laila Abang Abdul Majid, “Factorial study on the tensile strength of a coir fiber reinforced epoxy composite,” AASRI Conference on Modelling, Identification and Control, AASRI Procedia 3 (2012) 242-247.

18 MD. Zyaoul Haque, Sikandar Yadav, Sunil Kumar, Sandeep, “Mechanical behaviour of coir/glass fiber reinforced epoxy based composites,” International Research Journal of Engineering and Technology (IRJET), Volume: 03, Issue: 05, May-2016.

19 Vineet Kumar Bhagat, Anil Kumar Prasad, Arvind Kumar Lal Srivastava, “physical and mechanical performance of luffa-coir fiber reinforced epoxy resin based hybrid composites,” International Journal of Civil Engineering and Technology (IJCIET), Volume 8, Issue 6, June 2017, pp. 722-731.

20 Girisha.C, Sanjeevamurthy, Gunti Ranga Srinivas, “Sisal/coconut coir natural fibers - epoxy composites: water absorption and mechanical properties,” International Journal of Engineering and Innovative Technology (IJEIT), Volume 2, Issue 3, September 2012.

21 Ajith Gopinatha, Senthil Kumar.Mb, Elayaperumal A, “Experimental investigations on mechanical properties of jute fiber reinforced composites with polyester and epoxy resin matrices,” Procedia Engineering 97 ( 2014 ), 2052 - 2063, DOI: 10.1016/j.proeng.2014.12.448.

22 P. Prabaharan Grcaeraj, G. Venkatachalam, “Investigations into tensile strength of jute fiber reinforced hybrid polymer matrix composites,” Engineering Review, Vol. 35, Issue 3, 275281, 2015.

23 M. R. Sanjay, B. Yogesha, “Studies on mechanical properties of jute/e-glass fiber reinforced epoxy hybrid composites,” Journal of Minerals and Materials Characterization and Engineering, 4, 15-25, 2016.

24 Md Nuruzzaman Khan, Juganta K. Roy, Nousin Akter, Haydar U. Zaman, Tuhidul Islam, Ruhul A. Khan, “Production and properties of short jute and short e-glass fiber reinforced polypropylene-based composites,” Open Journal of Composite Materials, 2012, 2, 40-47.

25 M. J. Miah, M. A. Khan, R. A. Khan, “Fabrication and characterization of jute fiber reinforced low density polyethylene based composites: effects of chemical treatment,” J. Sci. Res., 3 (2), 249-259 (2011), doi:10.3329/jsr.v3i2.6763.

26 Pankaj K. Aggarwal, N. Raghu, Ajay Karmarkar, Shakti Chuahan, “Jute-polypropylene composites using m-TMI-grafted-polypropylene as a coupling agent,” Materials and Design, 43 (2013), 112-117.

27 Vivek Mishra, Sandhyarani Biswas, “Physical and mechanical properties of bi-directional jute fiber epoxy composites,” Procedia Engineering, 51 (2013), 561-566, DOI: 10.1016/j.proeng .2013.01.079.

28 Salma Siddika, Fayeka Mansura, Mahbub Hasan, “Physico-mechanical properties of jutecoir fiber reinforced hybrid polypropylene composites,” International Journal of Chemical, Molecular, Nuclear, Materials, and Metallurgical Engineering Vol:7, No:1, 2013.

29 Md. Rafiquzzaman, Md. Maksudul Islam, Md. Habibur Rahman, Md. Saniat Talukdar, Md. Nahid Hasan, “Mechanical property evaluation of glass-jute fiber reinforced polymer composites,” Polym. Adv. Technol. 2016, 27, 1308-1316.

30 X. Y. Liu, G. C. Dai, “Surface modification and micromechanical properties of jute fiber mat reinforced polypropylene composites,” eXPRESS Polymer Letters, Vol.1, No.5 (2007), 299307, DOI: 10.3144/expresspolymlett.2007.43.

31 S. D. Bolboacä, L. Jäntschi, “Design of experiments: useful orthogonal arrays for number of experiments from 4 to 16,” Entropy, 9 (2007), pp. 198-232, doi.org/10.3390/e9040198.

32 P. Prabaharan Grcaeraj, G. Venkatachalam, “Investigations into tensile strength of jute fiber reinforced hybrid polymer matrix composites,” Engineering Review, Vol. 35, Issue 3, 275281, 2015.

33 M. Poostforush, M. Al-Mamun, M. Fasihi, “Investigation of physical and mechanical properties of high density polyethylene/wood flour composite foams,” Research Journal of Engineering Sciences, 2 (2013), pp. 15-20.

34 N. C. Fei, N. M. Mehat, S. Kamaruddin, “Practical applications of taguchi method for optimization of processing parameters for plastic injection moulding: A retrospective review,” ISRN Industrial Engineering, 2013, pp. 1-11.

35 E. Esmizadeh, G. Naderi, M. H. R. Ghoreishy, G. R. Bakhshandeh, “Optimal parameter design by taguchi method for mechanical properties of nbr/pvc nanocomposites,” Iranian Polymer Journal, 20 (2011), pp. 587-596.

36 A. Sailesh, C. Shanjeevi, “Predicting the best hardness of banana-bamboo-glass fiber reinforced natural fiber composites using taguchi method,” International Journal of Engineering Development and Research, 1 (2013), pp. 89-92.

37 V. K. Vankantia, V. Gantab, “Optimization of process parameters in drilling of gfrp composite using taguchi method, Journal of Materials Research and Technology,” 3 (2014), pp. 35-41.

38 A. Uysal, M. Altan, E. Altan, “Effects of cutting parameters on tool wear in drilling of polymer composite by taguchi method,” International Journal of Advanced Manufacturing Technology, 58 (2012), pp. 915-921.

39 N. M. Mehat, S. Kamaruddin, “Investigating the effects of injection molding parameters on the mechanical properties of recycled plastic parts using the taguchi method,” Materials and Manufacturing Processes, 26 (2011), pp. 202-209.

40 Sponge Gourd (Luffa aegyptiaca) Available online: https://en.wikipedia.org/wiki/Luffa_ aegyptiaca. (accessed on 5 September 2018)

41 Seeds of India. Available online: https://www.seedsofindia.com/item/Sponge-gourd- Sweet-Honey--264. (accessed on 6 August 2019)

42 Luffa.info. Available online: https://www.luffa.info/. (accessed on 6 August 2019)

43 Kim L.Pickering, “Properties and performance of natural fiber composites,” Woodhead publishing in materials, 2008, ISBN 978-1-84569-267-4.

44 U.S. Bongarde1, B.K. Khot, “A review on coir fiber reinforced polymer composite,” International Research Journal of Engineering and Technology (IRJET), Volume: 06, Issue: 04, 2008.

45 123RF, Stock Photo-Coconut Coir Husk. Available online: https://www.123rf. com/photo_ 30839704_coconut-coir-husk.html. (accessed on 6 August 2019)

46 Jute. Available online: https://en.wikipedia.org/wiki/Jute. (accessed on 31 July 2019)

47 Explore Inventors Biography Alphabetically. Available online: http://www.techscience news.com/referencetopics/Inv_timeline/timeline/jute.html.( accessed on 06 August 2019)

48 Md. Rafiquzzaman, Md. Habibur Rahman, Md. Abu Sayeed, Md. Nawazish Ali, “Evaluation of mechanical behavior of jute fibre-aluminum powder reinforced hybrid polymer composites,” International Journal of Mechanical Engineering and Automation, Volume 3, Number 5, 2016, pp. 202-207.

49 Sodium hydroxide. Available online: https://en.wikipedia.org/wiki/Sodium_hydroxide. (accessed on 31 July 2019)

50 Royal 112MX 12-Sheet Cross Cut Shredder. Available online: https://shop.royalsupplies.com/templates/. (accessed on 21 August 2019)

51 J. A. Ghani, I. A. Choudhury, H. H. Hassan, “Application of taguchi method in the optimization of end milling parameters,” Journal of Materials Processing Technology, 145 (2004), pp. 84-92.

52 R. V. Rao, “Advanced modeling and optimization of manufacturing processes,” SpringerVerlag, London, (2011).

53 P. J. Ross, “Taguchi techniques for quality engg.2/E,” Tata McGraw-Hill Companies, Inc., New York, (2005).

54 M. Sridevi, B. R. Arun Kumar, “Building optimal decision trees for classification using taguchi method,” International Journal of Electrical, Electronics and Computer Systems, 2 (1) (2014), pp. 2347-2820.

55 T. Probability, “TABLE E F critical values T-13.” [Online]. Available: https://www.stat.purdue.edu/~jtroisi/STAT350Spring2015/tables/FTable.pdf. (accessed on 02 October 2019)

56 Md. Rafiquzzaman, Md. Imran Hossain, Akydur Rahman, “Mechanical properties of agricultural byproduct polymer composites,” Journal of Material Science & Manufacturing Technology, Vol.-2, Issue-2 (2017).

57 T. Hariprasad, G. Dharmalingam, P. Praveen Raj, “Study of mechanical properties of banana-coir hybrid composite using experimental and fem techniques,” Journal of Mechanical Engineering and Sciences (JMES), ISSN (Print): 2289-4659; e-ISSN: 2231-8380; Volume 4, pp. 518-531, June 2013.

58 Nafisa Nawal Huda, Pranta Nath, Md. Al Amin, Md. Rafiquzzaman, “Charpy impact behavior of water hyacinth fiber based polymer composite,” Journal of Material Science & Manufacturing Technology, Vol.-2, Issue-2 (2017).

59 Hafsat R. Saliu, U. S. Ishiaku, M. K. Yakubu, E. G. Kolawole, S. S. Adefila, M. B. Abu Bakar, Z. A. Moh'd Ishak, “The effect of epoxy concentration and fibre loading on the mechanical properties of ABS/epoxy-coated kenaf fibre composite,” Open Journal of Composite Materials, 5,2015, 41-48. http://dx.doi.org/10.4236/ojcm.2015.52007.

60 S. Karthick, C. Manoj, P. Nandhakumar, M. Maniyarasan, “Fabrication and evaluation of mechanical properties of kenaf &coir hybrid composite,” International Journal of Innovative Research in Science, Vol. 4, Special Issue 6, May 2015.

## List of Research Publications out of this thesis work:

International Journals and Conference:

1. Sk. Suzauddin Yusuf, Md. Nurul Islam, Md. Hasan Ali, Md. Washim Akram, Md. Abubakar Siddique, “**Optimum Process Parameters Selection for Brinell Hardness Number of Natural Fiber Reinforced Composites Using Taguchi Method**,” Saudi Journal of Engineering and Technology (SJEAT), Volume: 04, Issue: 10, Oct-2019, 422427, DOI: 10.36348/SJEAT.2019.v04i10.005.

2. Sk. Suzauddin Yusuf, Md. Nurul Islam, Md. Hasan Ali, Md. Washim Akram, Md. Abubakar Siddique, “**Impact Strength of Natural Fiber Reinforced Composites: Taguchi Method**,” Advances in Materials Science, Volume: 20, Issue: 02, Jun-2020, 5470, DOI: 10.2478/adms-2020-0010.

3. Sk. Suzauddin Yusuf, Md. Nurul Islam, Md. Washim Akram, Md. Hasan Ali, Md. Abubakar Siddique, “**Prediction of the Best Tensile and Flexural Strength of Natural Fiber Reinforced Epoxy Resin Based Composite Using Taguchi Method**,” Proceedings of the International Conference on Industrial & Mechanical Engineering and Operations Management Dhaka, Bangladesh, December 26-27, 2020.

## Brief Biography of Author:

The author, **Sk. Suzauddin Yusuf**, graduated in Mechanical Engineering from Rajshahi University of Engineering & Technology (RUET), Bangladesh in the year 2016. He has been awarded M.Sc. in Mechanical Engineering degree from RUET. His research included natural fibers reinforced composite materials, hybrid microgrid designing, and renewable energy technology. He has authored and co-authored 6 research papers in International Journals and has 9 research papers in International Conferences to his credit. In 2016, he joined Bangladesh Army University of Science and Technology, Saidpur, Bangladesh as a faculty member in the Department of Mechanical Engineering. In 2019, he moved to Bangladesh Atomic Energy Commission (BAEC). Since then, he has worked in Nuclear Power Plant Company Bangladesh Limited, an enterprise of BAEC, as a mechanical engineer. Now, he is involved in a government training program as a trainee engineer at Rosatom Technical Academy, Russian Federation.

**[...]**

- Quote paper
- Sk. Suzauddin Yusuf (Author), 2020, Fabrication and Characterization of Sponge Gourd, Coir, and Jute Fiber Reinforced Thermosetting Resin Based Composites, Munich, GRIN Verlag, https://www.grin.com/document/1165200

Publish now - it's free

Comments