Chernobryvko M. Stress-strain state of construction elements under high-speed loads

The work delivers solution to a relevant scientific and engineering problem of solid mechanics. It consists in the development of effective analytical - numerical methods for studying the dynamic stress-strain state of structural elements under the influence of impulse loads of various physical nature and supersonic gas flow, as well as the application of these methods to solving urgent applied problems. A generalized model of the dynamic stress-strain state for structural elements from polycrystalline materials under impulse loading is proposed. It is based on a models combination of unsteady thermoelastic deformation and rate plastic deformation to take into account the high rate hardening and temperature softening of the material. The stress-strain state equation for this model is proposed in a modified Pezhina form with additional Johnson-Cook temperature form. Equivalent stress depended on equivalent strains, strain rate and temperature. The generalized model is used to solve the practical problems. In the high-speed deformation problems of the gas turbine engine casing due to the breakage of a blade part and local damage of the blades by foreign objects, refined solutions are obtained. In the ribbed plate highspeed deformation problems under the action of a gas-dynamic shock wave and a plate under the action of a hydrodynamic shock wave, refined dynamic stresses are obtained. The high-speed deformation and destruction of the rocket fairing part in the truncated cone form and the fastening elements for special rocket under impulse loading has been studied. The model for non-stationary deformation of the solid propellant motor composite casing as the spherical-cylindrical-spherical shell with orthotropic or functionally graded characteristics is proposed. Regularities of the distribution of dynamic deformations in a structure under internal pulsed loading are obtained. The dynamic instability of rocket fairings in supersonic gas stream is numerically investigated. The fairings are modeled by parabolic shells and ringstiffened conical shells. The dynamic instability regularities of fairings and the dynamic stability loss modes are obtained.