Multiscale damage analysis of the tension‐tension fatigue behavior of a low‐density sheet molding compound

Abstract

This article presents the experimental findings of tension-tension stress-controlled fatigue tests performed on low-density sheet molding compound (LD-SMC). LD-SMC composite is a type of SMC including a polyester resin reinforced with chopped glass fibers bundles and hollow glass spheres. The coupled frequency-amplitude affects the nature of the overall fatigue response, which can be controlled by the damage mechanisms accumulation and/or by the self-heating. In fact, the self-heating produced a material softening and decreased the fatigue lifetime. For fatigue loading at 80 Hz, self-heating has been observed and yielded to a temperature rise to 65°C, which is more than a glass transition temperature of polyester. Thus, the polyester matrix is subjected to remarkable thermally activated modifications of its physical state. Multiscale damage analysis of the randomly-oriented sample in fatigue showed that the first observed damage phenomenon corresponds to the debonding of the hollow glass microspheres occurring in the fiber depleted zones.