Composites with interlaminar imperfections: Substantiation of the bounds for failure parameters in compression

The problem of failure caused by internal instability is considered within the scope of the exact statement formulated for cases of compressible and incompressible, elastic and elastic-plastic, orthotropic and isotropic layers in compression along interfacial defects. This exact statement is based on the model of a piecewise-homogeneous medium and equations of the three-dimensional linearized theory of deformable bodies stability (TLTDBS). To estimate critical loads, upper and lower bounds are suggested for laminated composites with defects by utilizing results for rigid-connected and sliding layers. Numerical investigations for composites with an elastic-plastic matrix have shown that the suggested bounds present reasonably, fair results for particular cases of composites.