An experimentally validated failure model for bioresorbable composites subject to flexural loading

Abstract

The focus of this paper is to investigate the deformation and failure response of a new class of bioresorbable composites subject to flexural loading. The composite consists of a biocompatible polylactic acid (PLA) matrix reinforced by long, continuous, bioresorbable silk fibers, which shows great promise for making load-bearing bone fixation devices. Three-point bend tests were carried out to characterize the material's flexural behavior. Experimental results show that the composite fails due to delamination, which is evident from images processed using the Digital Image Correlation (DIC) technique. To predict crack propagation in the composite, an enhanced fracture energy-based Smeared Crack Approach (SCA) was developed and implemented in a Finite Element Analysis (FEA) framework. The new SCA model incorporates orthogonal cracks that allow for complete energy dissipation under mode-I and mode-II failure types, with the approach being validated through benchmark studies of Double-Cantilever Beam (DCB) and End-Notched Flexure (ENF) simulations. The new fracture model, coupled with a micromechanics-based elastic model, successfully predicts the deformation and progressive damage response of the bioresorbable composite subjected to three-point bending. Effects of the strength and toughness of the binding polymer on the resulting composite response were investigated, providing crucial information for the design of new bioresorbable composites with target properties.