STRESS RELAXATION ON PROSTHETIC LAMINATED SOCKET MATERIALS

Abstract

The mechanical properties of socket materials are decreasing with time because they have a time dependent nature. This research evaluated mechanical properties of the composite materials that used to fabricate prosthetic sockets. Stress relaxation, the time-dependent property, was evaluated from creep test by testing two types of socket materials at 50 oC and by using Burger viscoelastic model; the equation of stress relaxation modulus was obtained and it found that the stress relaxation modulus decreasing with time. In addition a pressure between the residual limb and the prosthetic below knee socket measured by using F-socket system. Besides this study include a numerical approach to find the deformation distribution on socket that resulting from decreasing in stress relaxation modulus by using ANSYS workbench 15, it found the socket materials were deformed with time, the deformation of material A was increased from (2.03 to 24.4 mm) during 150 minute, while material B increased from (5.2 to 31.2 mm). The difference in resistance to deformation in the socket materials due to the types and numbers of reinforcement used in these materials.