Effect of fiber waviness on the high-strain-rate behavior of composites

The effect of fiber waviness on the high-strain-rate behavior of carbon/epo xy composite materials was investigated. Falling weight impact and Split Ho pkinson Pressure Bar systems were developed for basic characterization of u nidirectional aligned composites in compression at strain rates up to 1800 s(-1), Seventy-two and forty-eight-ply unidirectional carbon/epoxy (IM6G/35 01-6) laminates loaded in the longitudinal and transverse directions were c haracterized. Compression tests on 45 degrees off-axis laminates of the sam e unidirectional material were also conducted to obtain the in-plane shear stress-strain behavior. Strain rates over a wide range, from quasi-static u p to 1800 s(-1), were recorded. An incremental analysis was then used to predict the high-strain-rate behav ior of composites with fiber waviness using the results obtained from the s train rate characterization. It is shown that, under longitudinal compressi ve loading, the nonlinear stress-strain behavior shows significant stiffeni ng as the strain rate increases due to the shear component involved.