Damage initiation and evolution in short fiber reinforced polyamide under fatigue loading: Influence of fiber volume fraction

This paper investigates the influence of fiber volume fraction on damage mechanisms in a short glass fiber reinforced polyamide (PA66) under fatigue loading. Uniaxial fatigue tests were carried out on notched specimens with different fiber contents (0%, 15%, 25%, 35%, 50% in weight). Some fatigue tests were interrupted before failure with the aim to analyze the crack path. Some other fatigue tests were carried out until specimen failure in order to analyze the fracture surface. Specific fractographic features were investigated: ductile/brittle appearance of the fracture surface, pulled-out/broken fibers, degree of fiber-matrix interfacial adhesion. The damage investigation was performed by using Field Emission Scanning Electron Microscopy (FESEM).