A Parametric Design and Optimization Approach to Enhance the Fatigue Life of a Male Pyramid Socket Adapter

Abstract

This research paper presents a parametric design approach to optimize a male pyramid socket adapter as used on a transtibial prosthetic limb for enhanced fatigue life. These adapters are prone to premature failure when used by individuals partaking in athletic sports. A parametric design and optimization approach is presented and applied. A current design was assessed for structural integrity by finite element analysis in combination with the load criteria as recommended by the ISO 10328:2016 code of practice. Highly-stressed regions where identified and improved using a parametric design approach to reduce the maximum 1st Principal stress while adhering to the industry code of practice as applicable to pyramid socket adapter design. The optimization was validated by experimentally comparing the current design and the optimised design for an appropriate load case by low cycle fatigue testing. The socket adapters were manufactured from Ti6Al4V and subjected to a simulated resultant knee bending moment. The fatigue validation indicated a significant improvement in fatigue life for the optimized socket geometry commensurate with a reduction in stress and comparison to an appropriate SN curve for Ti6Al4V. The parametric optimization process as utilized was found to be effective and should be applicable to many different applications in a more general sense.