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A method of topology optimization based on the convex linearization approach is proposed. The problem formulation implies minimization of the strain energy of a structure subject to volume constraint. The solution is based on explicit, convex and separable Lagrangian approximation with the involvement of the duality theory. A non-linear model is used to relate design variables (density) and elastic properties of the material (modulus of elasticity). The sensitivity of the gain function and the constraint function is analyzed. The basic design formulae for the iteration algorithm of topology optimization are obtained. A number of test problems that correspond to the basic load states: tension, shear and torsion are considered. For all cases the load-carrying factor is calculated: both analytically and with the use of finite-element models. The resulting topologies are shown to be in full compliance with engineering concepts of theoretically optimal structures.

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The article presents the results of an experimental study of the nonlinearity of the mechanical properties of layered composite materials made by vacuum infusion based on carbon fabrics and an epoxy resin. The analysis of existing approaches to the modeling of composite materials considering their physical nonlinearity is carried out. A method is proposed for taking into account the degradation of the properties of a composite material, based on the fact that the damage parameters are replaced by the functional dependence of elastic constants on deformations, based on experimental data. The results of the application of this method are given for the test data analysis of two types of layered woven carbon-fiber-reinforced-plastics with a cross-hatching structure.