3D-printed polypropylene transtibial sockets: Mechanical behavior

Abstract

This paper defines the tensile properties of a successfully worn 3D-printed transtibial socket. The socket was printed from a proprietary polypropylene filament and FDM 3D-printing process. Fused disposition modeling involves producing successive cross-sectional layers on top of one another and welding them together. Because of this, a notch is formed between the printed layers. As part of this investigation, tensile test specimens were die-cut perpendicular to the material direction and tested according to ASTM D638—Standard Test Method for Tensile Properties of Plastics. From the measured load–elongation data, stress–strain curves and the corresponding material properties were determined, including modulus of elasticity E, Poisson’s ratio ν, yield strength Sy, and ultimate strength Su. The average values for each of these material properties were 955 MPa, 0.35, 11.4 MPa, and 16.3 MPa, respectively. In addition to defining tensile properties, this work demonstrated a viable methodology for characterizing the as-built material behavior of 3D-printed sockets.