STRAIN-RATE-DEPENDENT MIXED MODE FAILURE ANALYSIS OF UNIDIRECTIONAL CARBON FIBER REINFORCED COMPOSITE LAMINATES

摘要

Rate dependent mixed-mode failure of unidirectional carbon fiber reinforced epoxy (Hexcel's G30-500/F263-7) laminates is studied using off axis laminate (0°, 10°, 15°, 30°, 45°, 60°, 75° and 90° degrees) and constant strain rate tests, at three strain rates (10~(-3), 10~(-4) and 10~(-5) s~(-1)) in the temperature range 24°C to 270°C. Total fracture energy based failure criterion [1] is modified using critical stored elastic energy [2, 3], to account for the effect of viscoelasticity on fracture. Critical energy to failure in longitudinal normal, transverse normal and shear modes are determined using the procedure developed in Ref. 2 and experimental results from constant strain rate tensile (ASTM D3039) - and V-notch rail shear (ASTM D7078) testing of [0], [90] and [0/90]_s laminates. The predicted failure envelope for off-axis laminates, at various strain rates and temperatures are in good agreement with experimental strength values.