Research On The Shear Fatigue Performance Of FRP Composites

Fiber Reinforced Polymer (FRP) has been widely used in aircraft and spacecraft because of its excellent mechanical characteristics and designable. Fatigue strength is one of the important mechanical properties for engineering materials. The fatigue behavior and fatigue damage mechanism of FRP has been investigated by many researchers in the world in the past decades. More attention was paid to residual strength, residual stiffness, S-N curve under tension and compression.In this thesis, the fatigue damage mechanism and fatigue behavior were reviewed as well as the in-plane shear experiment method of composites. The basis that the static failure criterion is extended to fatigue failure criterion was mensioned, and the Tsai-Hill static criterion is extended to fatigue failure criterion from which the shear fatigue S-N curve can be estimated from the off-axis laminated fatigue S-N curve. Based on the fatigue S-N curves of longitudinal, transverse and shear axis, the fatigue life of the ply with arbitrary angle can be predicted. This method was verified by the off-axis ply fatigue data reported in literatures. The shear S-N curves estimated from different off-axis laminates fatigue data are consistent with each other, and the off-axis laminates S-N curves predicted by Tsai-Hill fatigue failure criterion are highly consistent with the experimental data.