Simulation of the stress-strain state of composite bars subjected to bending in two planes. I. Relations of the nonclassical model

We propose a nonclassical model of the stress-strain state of composite bars with piecewise-homogeneous cross sections and consider the case of bending of bars in two planes (principal planes of stiffness). Unlike the classical model based on the hypothesis of plane sections, the nonclassical model developed takes into account the effect of warping of cross sections of the bar caused by shear strains. We deduce relations for displacements, strains, longitudinal normal stresses, and transverse tangential stresses. The general state of the bar is determined on the basis of the principle of superpositions. Materials menyioned include metal and fibrous plastic laminates.