Cyclic compressive deformation behavior of polymer matrix composites: Experiments and constitutive modeling.

This article presents integrated experiments and constitutive modeling of cyclic compressive deformation and Poisson behavior of unidirectional (UD) fiber‐reinforced polymer matrix composites (PMCs). Consecutive loading‐unloading tests with a gradually increasing peak stress are performed for five cycles and on UD laminates with different fiber orientations. Nonlinear accumulation of plastic strain with the peak stress is observed both in the axial and lateral directions for all fiber orientations and described by a nonassociative plasticity model. This model enables the collapsing of axial and lateral stress‐plastic strain curves from different fiber orientations into a single master curve in the effective stress‐effective plastic strain plane and allows accurate predictions of compressive plastic Poisson's ratio. Nonlinear unloading behavior appears in the cycles and is attributed to the recovery of nonlinear elastic strain. A linear relationship between plastic strain and nonlinear elastic strain is assumed regardless of the axial and lateral directions. By incorporating this linear dependence into the nonassociative plasticity model, the cyclic evolution of nonlinear elastic strain is simulated. Experimental results of UD laminates with different fiber orientations are used to validate the accuracy of the model in the cyclic compressive nonlinear response and Poisson effect of PMCs. [ABSTRACT FROM AUTHOR]