Investigating the Flexural Behavior of Ultra-High-Molecular-Weight Polyethylene at a Low Bending Rate: Experimental and Numerical Study

This study examines the mechanical behavior of ultra-high-molecular-weight polyethylene (UHMWPE) under three-point bending at a low strain rate, with a particular focus on evaluating the influence of its distinct tensile and compressive properties on its bending response through finite element analysis. The tensile and compressive stress-strain characteristics of UHMWPE were experimentally determined at a strain rate of 5 × 10⁻³ s^–1, complemented by three-point bending tests conducted at a constant loading speed of 0.05 mm/s. To predict the flexural behavior of UHMWPE, two finite element models were constructed using the SAMP-1 material model in LS-DYNA: one incorporating the Von-Mises yield surface, which assumes similar material behavior in tension and compression, and the other employing the Drucker-Prager yield surface, which accounts for dissimilar material behaviors between tension and compression. Results of the numerical analyses revealed substantial discrepancies between the predictions of the Von-Mises and Drucker-Prager models, with the latter offering a more precise prediction of the flexural response of UHMWPE, thereby underscoring the critical importance of accounting for dissimilar material behaviors to achieve enhanced predictive accuracy.