クロスプライCFRP積層板の高温における非主軸引張挙動の速度依存性とその解析

抄録

The present paper focuses on experimental verification of the ply-by-ply basis inelastic analysis of multidirectional laminates. First of all, rate-dependence of the tensile behavior of balanced symmetric cross-ply laminates of T800H/epoxy under off-axis loading conditions at 100°C is examined. Uniaxial tension tests are performed on plain coupon specimens with various fiber orientations (θ=0, 5, 15, 45, and 90°) at two different strain rates (1.0%/min and 0.01%/min). The off-axis stress-strain curves exhibit marked nonlinearly for all off-axis fiber orientations except for the fiber directions θ=0 and 90°, regardless of the strain rates. The strain rate has appreciable influences on the off-axis flow stress in the regime of nonlinear response as well as on the off-axis elastic modulus in the regime of linear response. The macromechanical model based on a ply viscoplasticity model and the classical laminated plate theory is applied to the rate-dependent off-axis nonlinear behavior of the cross-ply CFRP laminates. The material constants involved by the ply viscoplasticity model are identified on the basis of the experimental results on the unidirectional laminate of the same carbon/epoxy system. It is suggested that good agreements between the predicted and the observed results can be obtained by taking into account the fiber rotation induced by deformation and rate-dependence of the moduli.