The nonlinear boundary-value combined micro-mechanic problem for predicting of the strength properties of composites is proposed. It takes into consideration the stage of structural damages accumulation when the fields of structural damages are locally-ergodic. The base equations are added to describe the structural failure and to predict the strength properties of composites. New material carrier is introduced. It is the four-rank damage tensor. New functionals of the combined stochastic boundary-value problem are built. They allow us to predict elastic properties and to make estimate strength surfaces of real composites.