Towards development of vacuum forming system for lower limb prosthetics

In lower limb prosthetics, pistoning and increased volume change of residual limb inside the socket is the main problem. To overcome this problem, a vacuum suspension system has been developed to hold the limb firmly into the socket. This paper aims at the design of the suction geometry made of neoprene rubber to create a vacuum forming system for lower limb prosthetics. The designed geometry was integrated with bionic foot for below knee amputation. The proposed design was modeled using SOLIDWORKS 14 and analyzed by using finite element method (FEM) in ANSYS 14.5. The deformed geometry was further used to calculate the change in internal volume which gives the volume of air evacuated during each step. The value of required pressure to create a vacuum in the socket is -69 KPa (508 mmHg). Further calculations were made to find out the steps to achieve such pressure.