High strain rate characterisation of unidirectional carbon–epoxy IM7-8552 in longitudinal compression

This paper presents an experimental investigation of the strain rate effect on unidirectional carbon–epoxy IM7-8552 loaded in longitudinal compression. A dynamic compression fixture was developed for a split-Hopkinson pressure bar to test flat rectangular specimens. The dynamic experiment was designed by finite element analysis, using an axis-symmetric elastic model of the test setup. Due to the linear specimen stress–strain behaviour, ramp-shaped incident pulses were used, to ensure a constant strain rate and dynamic equilibrium throughout the test. The results from the split-Hopkinson pressure bar experiments at an average strain rate of about 100 s−1 were compared with quasi-static test results using the same test setup. It was found that the longitudinal compressive modulus is not strain rate sensitive while a significant increase was observed for the longitudinal compressive strength.