STRESS ANALYSIS OF INDIGENOUSLY DESIGNED ENERGY STORING POLYPROPYLENE CO-POLYMER (PPCP) PROSTHETIC FOOT

Abstract

Polypropylene Co-polymer (PPCP) Prosthetic Foot Model, Indigenously designed at All India Institute of Physical Medicine and Rehabilitation (AIIPMR), Mumbai. More commonly, this design is known as Modified Flex foot. Various researcher’s contributed towards its design modification, material optimization, patient trial & clinical implications and further improvements. As such, this study was conducted to observe & understand the stress analysis of this modified flexfoot under loading conditions at various orientation of gait. Finite element analysis (FEA) method was used with Ansys 12.0 software. Study objectives was to construct and analyze the finite element model, to find out & understand failure prone areas in the present design of PPCP prosthetic foot. This study was conducted into five phases. At initial phase, actual foot design was constructed and input parameters like geometrical parameters were calculated considering the standard length transtibial amputee. Similarly Material properties, loading conditions & boundary conditions were determined. AutCAD model was constructed using input parametrs & imported into Ansys 12.0 software. Finite element model were constructed and analyzed. Results were noted, which were displyed in the form of several contour plots & through colours that correspond to different stress values. FEA results obtained for various stress values like, Elemental stress, shearing stress & Von Mises stresses (Combination stresses). Peak Von Mises stress value of 28112 Mpa, observed at lower ankle fillet region during heel strike orientation of the gait. Study concluded that lower ankle fillet region & Midfoot spring region will be subjected to maximum stress during heel strike, Mid stance & push off. It was concluded that lower ankle fillet region & Midfoot spring region will be subjected to maximum stress during heel strike, Mid stance & push off.