Influence of matrix ductility on the high-temperature fatigue behaviour of notched and unnotched thermoplastic and thermoset laminates

Abstract

An experimental study has been conducted on notched and unnotched carbon woven-ply PolyPhenylene Sulfide (PPS) and Epoxy laminates subjected to fatigue loadings at a test temperature T such as [Formula: see text]. Depending on matrix nature, the obtained results confirm that matrix ductility is prominent to rule the fatigue response of notched woven-ply laminates at high temperature. In C/PPS laminates whose behaviour is very ductile at T >  Tg, the presence of a stress concentrator improves their fatigue life, whereas it reduces the fatigue life in C/Epoxy laminates. During cycling loadings, the dissipated energy is about four times as high in C/PPS laminates as in C/Epoxy laminates. The overstresses relieving known to be primarily due to diffuse damage around the hole in C/Epoxy is not efficient at high frequency, contrary to the overstresses accommodation due to the fibres rotation and to the plastic deformation along the ±45° oriented fibres in C/PPS, resulting in a longer fatigue life with respect to unnotched laminates.