Abstract
Dynamic compressive strength of off-axis S2/8552 glass-epoxy composite in the form of fiber microbuckling was studied. Based on the bifurcation buckling analysis, the microbuckling stress is approximately equal to the composite tangent shear modulus. Using a viscoplastic constitutive model to describe the composite tangent shear modulus, microbuckling stresses at various strain rates were predicted. Small angle off-axis composite specimens were tested to failure at various strain rates. For strain rates below 1/sec, the compression tests were conducted on an MTS machine, while higher strain rate tests were carried out using a Split Hopkinson Pressure Bar (SHPB). Fiber microbuckling was found to be the dominant failure mode for 5°, 10° and 15° specimens within the range of tested strain rates. Comparison of model prediction with experimental data shows that the rate-dependent microbuckling model can be used for predicting compressive strengths at strain rates up to 1100/s.
