Experimental investigations and finite element modelling of a suggested prosthetic foot

Abstract

To design and manufacture a dynamic cheap prosthetic foot compatible with amputees' requirements by introducing a natural fibre called kenaf (scientific name Hibiscus cannabinus L). In two cases, four suggested designs were analysed using the finite elements method (FEM) with a commercial ANSYS R1 program. The first case was a heel strike. The second was toe-off by subjecting force equal to 70 kg for both cases to select the optimal design. The foot found the tensile strength, flexural strength, impact stress, and fatigue test according to ISO 10328 standards successfully. The selected design was analysed again using the ANSYS R1 program for weights 60, 70, and 80 kg for two sequences, one containing kenaf, to study how such additive could affect the mechanical properties and estimate the proper quality weight of the foot. The winner's design was then produced and tested in a fatigue foot tester according to ISO 10328 standards. The results showed that the sequence containing the natural fibres kanaf material improved the deformation by 20% for both cases (from 7.47 to 8.92 mm for the heel strike case for a weight of 80 kg for the sequence without and with kanaf, respectively), and the damping ratio increased by 50% (0. 188 and 0.273 for the sequence without and with kenaf, respectively), which means an increase in the stored energy and higher stability. Also, the mechanical properties like maximum tensile strength, flexural strength, impact stress, and natural frequency were modified. This paper develops an analytical and practical study to design and produce a dynamic cheap prosthetic foot made from natural fibres, which are characterized as renewable, cheap, recyclable, and environmentally friendly materials with good mechanical properties. Authors believe it is the first time to use natural kenaf fibres in the prosthetic foot manufacturing field.