Damage mechanisms in a short glass fiber reinforced polyamide under fatigue loading

This paper presents a damage investigation on a short glass fiber reinforced polyamide (PA66-GF35) under fatigue loading. Plain and notched specimens were tested at room temperature and humidity with load ratio R = 0. Electron microscopy was used to analyze the fracture surface of failed specimens and the crack path of specimens subjected to interrupted fatigue tests. Damage mechanisms were studied investigating the following fractographic features: ductile/brittle matrix fracture behavior, fiber failure/pull-out, degree of fibermatrix interfacial adhesion. The aim of the present paper is to understand the nature of damage initiation and propagation in order to lay the foundations for the development of a multi-scale, mechanism-based lifetime prediction model for short fiber reinforced plastics.