Lightweight Transradial Prosthetic Able to Withstand Mechanical Forces during a Human Fall

This paper proposes a new framework design for the lightweight transradial prosthesis. This device was designed to be light-weight, easily manufactured, inexpensive, and to have a high interstitial free space volume for electrical components and customization. Press-fit junctions between fins allow for little or no adhesives, allowing for easily replaceable parts. Designs were constructed out of chipboard and run through an assortment of tests to see if each design iterations met structural design specifications. There were four main design iterations tested: 4, 8, 12 fin designs, and a 4 fin design with additional angled fins for torsional support (4T). Compression, torsion, and 3-point bending tests were all performed on each cylindrical iteration. Basic tensile and material testing was done on chipboard to support results. The force applied to a human arm during a fall is approximately 500 lbf [13]. Compression tests yielded a strength of approximately 300 lbf for the cylindrical designs. ANOVAs and T-tests were performed to find significance in compressive strength between the design iterations with the varied number of fins (p<<0.05). The torsional strength of the human arm, without causing great strain or discomfort has a max value of approximately 15 Nm [14]. This matched the torsional values of the 4T. design [14]. The 4, 8, and 12 designs' torsional strengths were linear with values of approximately 4, 7, and 12 Nm respectively. The 3-point bending test yielded the flexural stress and strain values to find compressive strength in the convex direction as well as the displacement and deformation in each sample. The material chipboard was found to be variable with elastic modulus, Poisson's ratio, and tensile strength. Each experimental procedure was done as a proof of concept for future prosthesis design.