nonlinear constitutive relations, orthotropic materials, identification, composites.

A variant of nonlinear constitutive relations for an elastic orthotropic material is considered. To describe the dependences of deformations on stresses of the second and third orders, 9 additional parameters are used. A system of two-dimensional experiments on plate samples is proposed, which allows one to determine all the constants of nonlinear models. The numerical values of the parameters of the two models are found from the known experimental data. Comparison of the simulation results shows that the third-order model is more consistent with the experimental data than the second-order model.

Nguyen Sy Toan postgraduate student, Tula State University, Tula, Russia.