Stress Relaxation and Creep Effect on Polypropylene below Knee Prosthetic Socket

Abstract

Prosthetic sockets serve as the interface between people with amputations and their prostheses and it is considered an element of major importance in the makeup of prosthesis. The effect of stress relaxation is evident in the material that makes the prosthetic socket. The effecting causes deformation and sagging in the socket due to the lowering in the mechanical properties. This study evaluated the effect of stress relaxation on the socket material by testing this material at 50 °C by creep test and evaluating creep data by using Burger model to obtain the equation of the stress relaxation modulus with time. The results show that the stress relaxation modulus is decreasing with time this means that the material lose their strength with time.