Multiscale damage analysis of the tension‐tension fatigue behavior of a low‐density sheet molding compound
Mohammadali Shirinbayan
Abstract
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.