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Development of a non-linear finite element modelling of the below-knee prosthetic socket interface
M Zhang1, M Lord, A R Turner-Smith
1Department of Medical Engineering & Physics, King's College School of Medicine & Dentistry, Denmark Hill, London, UK.
Medical Engineering & Physics
|December 1, 1995
Summary
A finite element model predicts below-knee amputee socket interface pressures and stresses. Friction significantly impacts these forces, with higher friction increasing shear stress but reducing pressure and slip.
Area of Science:
- Biomechanics
- Biomedical Engineering
- Prosthetics and Orthotics
Background:
- Below-knee amputees experience challenges with residual limb socket fit.
- Interface pressure and shear stress are critical factors affecting prosthetic comfort and function.
- Understanding skin-liner interactions is essential for improving prosthetic socket design.
Purpose of the Study:
- To develop and validate a non-linear finite element model of the limb-socket interface.
- To predict pressure and shear stress distribution at the interface.
- To investigate the influence of skin-liner friction and slip on interface mechanics.
Main Methods:
- A non-linear finite element model was created using ABAQUS.
- Limb tissue and socket liner were meshed into 3D elements.
- Interface elements (ABAQUS INTER4) were utilized to simulate friction.
- Model was based on patient-specific limb and radiographic measurements.
Main Results:
- Maximum interface pressure of 226 kPa and shear stress of 53 kPa were predicted under full body weight (800 N).
- Less than 4 mm of slip was observed at the skin-liner interface.
- The coefficient of friction was identified as a highly sensitive parameter.
Conclusions:
- The finite element model effectively predicts interface conditions in below-knee prosthetics.
- Increased coefficient of friction leads to higher shear stress but lower pressure and slip.
- Findings provide insights for optimizing prosthetic socket design and reducing discomfort.