806 クロスプライCFRP積層板のプライベース疲労寿命予測法の開発(OS8-(2),OS8 オーガナイズドセッション《複合材料の変形と破壊およびマルチスケール計算技術》)

抄録

A ply-by-ply basis fatigue life prediction method for multi-directional composite laminates that can be applied to fatigue loading at any stress ratio has been developed, taking into account the inelastic deformation and in-situ strength of plies embedded in the laminates. Fatigue failure in embedded plies is evaluated using a quasi-static failure criterion based on the residual principal strengths. The residual principal strengths of unidirectional plies are predicted using the anisomorphic constant fatigue life diagrams that are identified for loading in the principal directions, respectively. The fatigue failure criterion for plies takes into account not only the in-situ principal strengths of plies embedded in a general laminate, but also the progressive reduction in in-situ constraint effect due to the growth of fatigue damage. The actual stress components in the plies embedded in a laminate are evaluated using a laminate constitutive model based on the classical lamination theory, in which the nonlinear plastic deformation of inclined plies under in-plane off-axis loading is taken into account. It is demonstrated that the proposed ply-by-ply basis fatigue model can successfully be used for prediction of on-axis and off-axis fatigue lives of cross-ply CFRP laminates that are subjected to fatigue loading at different stress ratios, respectively.