ИСТИНА

The model to characterize the dependence of deformation, hardening and strength characteristics of composite materials on damage and strain rate is proposed, which allow to take into account different types of nonlinearities in the behavior of composite materials, namely, the nonlinearity of shear properties, the damage evolution, the rate of damage growth and others. The results of experimental studies of the properties of composite materials in a wide range of strain rates are analyzed and some of main regularities are determined. On the base of failure criterion, which includes the dependence of failure characteristics not only on damage but on the rate of damage development as well. Taking into account the dependence of stiffness characteristics on the damage parameters, the stress-strain curves are determined for different strain rates. The compressive strength estimation of cross ply layups [[08/908]S/04]S under different strain rates is performed. Numerical analysis of the material response for non-monotonic and load reversal cycles with corresponding evolution of stress, strain and damage parameters in unidirectional material is carried out, too. The theoretical dependencies correlate quite well with the results of experimental studies. The method for the experimental determination material’s parameters is proposed. Some cases of complex non-monotonic loading and unloading of composite materials are analyzed.