This study presents analyses for below knee prosthetic socket of a human. Socket stress distribution is performed on three types of socket, polypropylene (5mm), polypropylene (3mm) and a standard laminate (3mm) sockets to determine the stresses path through the prosthetic socket during the gait cycle. It is found that heel strike phase is the critical phase. The stresses increase at the socket base while the maximum deflection is maximum at the patellar region of the socket. This work is achieved by finite element program, ANSYS.
The development of design specifications of a below the knee prosthetic socket is presented in this study for successful ambulation and comfort. Seven different design models are created by changing the socket wall thickness and the material. Polypropylene socket gives the best results with regard to the allowable deflection for the regions of the pressure relief areas of the stump.
The effect of varying the modulus of elasticity on the polypropylene socket is considered in this study. Three models are analyzed with different tensile creep moduli during different periods. It is found that the polypropylene socket will enlarge in size with time.
An experimental study is conducted to compare the strength of five prosthetic sockets made of different materials. Compression, three-point flexural and tensile tests are implemented by the Testometric machine. The laminate sockets have larger compressive stiffness than polypropylene while polypropylene has larger flexural stiffness than the tested laminates except for socket No.5.
Table of Contents
Chapter 1: Introduction and Literature Survey
1.1. General
1.2. The Effect of Stiffness
1.3. Literature Review
1.4. Concluding Remarks
1.5. Objectives of Work
Chapter 2: Theoretical Analysis
2.1. Gait cycle
2.2. Ground Reaction Forces (GRFs)
2.3. Socket Stress Distribution
2.3.1. Introduction
2.3.2. Socket Stress Distribution Using ANSYS Package
2.4. Design Specifications of below the Knee Prosthetic Socket
2.4.1. Introduction
2.4.2. Finite Element Model
2.4.3. Alternate Designs
2.5. The Effect of Varying Modulus of Elasticity on Polypropylene Socket
2.5.1 Finite Element Model
2.5.2 Alternate Analyses
Chapter 3: Experimental work
3.1. Introduction
3.2 Prosthetic Socket Manufacturing
3.2.1 Polypropylene Socket Manufacturing
3.2.2. Laminated Socket Manufacturing
3.3. The Tested Sockets
3.4. Testing the Samples
3.4.1 Testometric Machine
3.4.2 Compression Test
3.4.3 Flexural Test
3.4.4 Tensile Test
Chapter 4: Results and discussions
4.1 The Results of Socket Stress Distribution
4.2. The Results of Design Specifications of below the Knee Prosthetic Socket
4-3. The Results of the Effect of Varying Modulus of Elasticity on PP Socket
4.4. Experimental Work Results
4.4.1 Compression Test Results
3.3.2 Flexural Test Results
4.3.3. Tensile Test Results
Chapter 5: Conclusions and Suggested Future Work
5.1 Conclusions
5.2. Suggested Future Works
Research Objectives and Core Themes
This work aims to analyze the stress distribution within below-knee prosthetic sockets to optimize their design for improved patient comfort and successful ambulation. By employing finite element analysis (FEA) and experimental testing, the study evaluates how material properties and socket design specifications influence the mechanical performance and longevity of these prosthetic devices.
- Stress distribution analysis of below-knee prosthetic sockets during the gait cycle.
- Evaluation of polypropylene and laminated socket materials under various loading conditions.
- Influence of material stiffness and modulus of elasticity on socket deformation.
- Experimental comparison of mechanical properties using compression, flexural, and tensile testing.
- Design optimization to address tissue tolerance and patient comfort issues.
Book Excerpt
1.1. General
Humans have perfect mobility with amazing control systems; they are extremely versatile with smooth locomotion. However, comprehensive understanding of the human locomotion is still not entirely analyzed. Therefore, much attention has been paid to investigate biped locomotion systems such as orthoses, prostheses, biped robots, etc. [21-34].
An amputation, especially at any level below the knee, does not usually present a particularly disabling condition. With modern prostheses and treatment methods, below knee amputees who have no complicating problems can do most of the things he or she could do before amputation.
Of special importance here is the use of "transtibial" in place of "below the knee" to identify an amputation between the knee and the ankle. This term has been adopted to avoid confusion with disarticulation at the ankle (Syme's amputation) and amputations through the foot [1].
In recent years, there has arisen an aversion to the use of the word "stump" in referring to that part of the limb that is left after amputation. Amputations are caused by accidents, disease and congenital disorders. The accidents most likely to result in amputations are war accident, followed by traffic, farm and industrial accidents.
Chapter Summaries
Chapter 1: Introduction and Literature Survey: Provides a background on biped locomotion, definitions of amputation levels, and a comprehensive review of existing research regarding prosthetic socket design and mechanical evaluations.
Chapter 2: Theoretical Analysis: Covers the biomechanics of the gait cycle, ground reaction forces, and the theoretical framework for analyzing socket stress distribution using finite element models.
Chapter 3: Experimental work: Describes the methodology for manufacturing polypropylene and laminated sockets, followed by the specific procedures for compression, flexural, and tensile testing.
Chapter 4: Results and discussions: Presents the comparative findings from the FEA stress distributions and the empirical data obtained from physical mechanical testing of the socket samples.
Chapter 5: Conclusions and Suggested Future Work: Summarizes the key findings regarding optimal material use and socket construction, while outlining recommendations for further research into pressure measurement and dynamic load analysis.
Keywords
Prosthetic Sockets, Below-knee Amputation, Finite Element Analysis, Polypropylene, Laminated Sockets, Gait Cycle, Mechanical Properties, Socket Stress Distribution, Modulus of Elasticity, Compression Test, Flexural Test, Tensile Test, Ambulation, Prosthesis Design.
Frequently Asked Questions
What is the primary focus of this research?
The research focuses on the stress distribution and structural optimization of below-knee prosthetic sockets, specifically comparing polypropylene and laminated materials.
What are the central themes discussed in the book?
Key themes include prosthetic socket mechanics, the effect of material elasticity on deflection, manufacturing processes for different socket types, and the comparison of stress performance under various gait phases.
What is the core objective of this study?
The main objective is to analyze stress distribution across different socket types during the gait cycle and to establish design specifications that ensure both mechanical functionality and user comfort.
Which scientific methods are utilized to evaluate the sockets?
The study uses a combined approach of finite element analysis (FEA) via the ANSYS software package for theoretical modeling and standardized physical mechanical testing (compression, flexure, tension) for empirical validation.
What topics are covered in the main body of the text?
The main body covers theoretical biomechanical analysis, modeling techniques for socket stress, experimental manufacturing steps, and a detailed discussion of results from both simulation and physical bench tests.
Which keywords characterize this scientific work?
Primary keywords include Prosthetic Sockets, Finite Element Analysis, Polypropylene, Laminated Sockets, Gait Cycle, and Mechanical Testing.
How does material choice affect the deflection of a prosthetic socket?
The study finds that material choice and wall thickness significantly impact deflection; polypropylene exhibits different time-dependent mechanical characteristics compared to laminated materials, necessitating design considerations to limit excessive deformation.
What conclusion does the author draw regarding the reinforced socket designs?
The author concludes that reinforcing specific regions, particularly the patellar tendon area, with stronger materials or specific fiberglass-resin ratios significantly improves the structural integrity and reduces discomfort-causing deformations.
- Arbeit zitieren
- Dr. Hayder Al-Shuka (Autor:in), 2017, Stress Distribution and Optimum Design of Polypropylene and Laminated Transtibial Prosthetic Sockets. FEM and Experimental Implementations, München, GRIN Verlag, https://www.grin.com/document/385910
