Characterisation of mechanical behaviour of fibre reinforced thermoplastic composites subjected to off-axis compressive loading

This paper presents an experimental and numerical investigation on the mechanisms of damage onset and evolution in unidirectional carbon fibre reinforced thermoplastic (CFRTP) composites subjected to off-axis compressive loadings. A test fixture was designed to prevent buckling, splitting and end collapsing of specimens during test. A series of compression tests were conducted with specimens of various off-axis angles. Different failure mechanisms and nonlinear stress-strain responses were observed and studied. The fracture angles of the tested specimens were evaluated and analysed according to Puck's theory. The off-axis compression failure envelope based on LaRC05 and Hashin criteria was presented using finite element analysis and compared to experimental results. It is shown that the LaRC05 criterion can provide accurate predictions for matrix cracking failure mode of unidirectional thermoplastic composites controlled by compression-shear combined stresses.