界面強度評価に基づくCFRP直交積層板の破壊メカニズムの実験的および解析的評価

抄録

The microscopic interfacial debonding between fibers and matrices induces microscopic or macroscopic failures, such as transverse cracks or delamination, that affect the structural and mechanical performance of composite materials. Therefore, there has been extensive research using the cohesive element method on the microscale or mesoscale fracture mechanisms at the interface between fibers and matrices. However, the parameters of the cohesive elements were often adjusted to match the experimental results; therefore, the physical implications of these parameters remain ambiguous. The experimentally measured interfacial tensile strength between pitch-based carbon fibers and the matrix, obtained via the cruciform test in the authors’ previous study, was considered as the maximum effective tensile force for the cohesive elements in the present study. Furthermore, the interfacial cohesive energy was calculated using the potential energy obtained from the finite element models of the cruciform specimen before and after interfacial debonding. The maximum effective tensile force and the interfacial cohesive energy were determined to be 41.3 [MPa] and 2.29 [J/m²] in the present study. These parameters were applied to a two-dimensional cross-ply laminate model, and the crack propagation behavior was determined to be nearly identical to that deduced from the in-situ experimental observations. These results demonstrated the establishment of a mesoscale crack-propagation model without the analysis of the parameters of the cohesive elements, based on the parameters experimentally and analytically determined via cruciform tests.