Fatigue strength evaluation of FRP/metal adhesive joints at low temperature

Abstract

Fatigue strength of FRP/metal adhesive joints, these are double lap joints and embedded joints at low temperature, was determined analytically and experimentally. The stress singularity parameters under mechanical and thermal loadings were analyzed for various delamination lengths by FEM analysis. The delamination propagation rates of the double lap joints were measured under mechanical cyclic loadings at room temperature, and the relationship between the measured propagation rates and the analyzed ranges of stress singularity intensity were obtained. Using this relationship, we estimated the fatigue strength of embedded joints, and these estimations coincide well with the measured strength. The experimentally measured fatigue strength and the analytically calculated thermal stresses at low temperature of both specimens show that the threshold range of stress singularity intensity depends on both temperature and thermal stresses.