Tension, compression, and shear behavior of advanced sheet molding compound (A-SMC): Multi-scale damage analysis and strain rate effect

Abstract

Advanced sheet molding compounds (A-SMC) are a new generation of alternative materials to steels for applying in automotive structures. It contains a thermoset matrix involving mineral charge (CaCO3) reinforced with a high fraction of discontinuous bundles of glass fibers (around 50% in mass) compared to the other types of SMC composites. The crashworthiness evaluation and multi-scale mechanical characterizations of this automotive material is essential. In this study, at first, the microstructure of A-SMC composite was investigated by Scanning Electron Microscopy (SEM), ultrasonic analysis, and X-ray micro-tomography. Two configurations’ plates of Randomly Oriented (RO) and Highly Oriented (HO) were analyzed under quasi-static tension, compression, and shear loadings. To study the effect of fiber orientation, for HO plate, two fiber directions were chosen: HO 0◦ (parallel to the Mold Flow Direction (MFD)) and HO-90◦ (perpendicular to the MFD). Strain rate effect (from 0.25 s−1 to 10 s−1) on shear properties and visco-damage behavior of A-SMC composite has been studied. For this purpose, a new setup for shear testing was designed after optimization via ABAQUS FE code to achieve constant strain rate. HO-0◦ samples represented higher strength in tension and compression loadings, unlike shear loading compared to RO and HO-90◦ samples. A multi-scale damage study confirmed that predominant damage mech anism is decohesion at fiber/matrix interface under tension, compression, and shear loadings.