An effect of the slope layer in sheet sample on a strength for negative coefficient of a biaxial loading factor of a sample

We investigate a critical state of the slope layer of less durable material in sheet sample by the loadings having opposite signs. It is shown that if there is no contact hardening of layer material, then a destruction occurs on the layer, independent of its slope angle. Using numerical experiments, we investigate a dependence of a sample strength from the slope angle of the layer for different relations between the external loads. We show that if there is a contact hardening of the layer, then a sample, containing less stable layer, may be equal in strength to a homogeneous sample for certain angles of layer slope.