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

• Published in: International journal of fatigue 2017-01, Vol.94, p.145-157
• Main Authors: Belmonte, Enrico, De Monte, Matthias, Hoffmann, Christian-James, Quaresimin, Marino
• Format: Article
• Language: English
• Subjects: Damage mechanisms; Electron microscopy; Fatigue; Short fiber reinforced plastics
• ISSN: 0142-1123; 1879-3452
• DOI: 10.1016/j.ijfatigue.2016.09.008

•Damage mechanisms on plain and notched PA66-GF35 specimens undergoing fatigue loading have been investigated by means of electron microscopy.•Clusters of through-the-thickness oriented fibers located around the notch affect the crack initiation position.•Damage initiates in the matrix in form of nano-voids and cavitation around nano-particles.•Damage evolves in form of matrix cracking at a certain distance from the fiber-matrix interface and not in form of fiber-matrix debonding at the interface. 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.