Anatoliy Anatolyevich Valishin (Bauman Moscow State Technical University) :


539.3 Mathematical modeling of thermal stresses in a solid with an internal crack

Valishin A. A. (Bauman Moscow State Technical University), Kartashov E. M. (MIREA - Russian Technological University/Moscow Technological University)

doi: 10.18698/2309-3684-2018-3-321

The purpose of this study was to evaluate the influence of the inertial effects and their deviation from the same quasi-static results. The role of inertial effects in the problem of thermal shock is studied on the example of a massive body with an internal spherical crack. We study the thermal reaction of an elastic space with an internal spherical crack whose surface, initially stress-free and at a temperature of T0, is instantly heated to a temperature of TC > T0 and then maintained at that temperature. Thermal stress state occurs under different modes of heat exposure, creating heat stroke. The most common in practice, three cases: temperature heating, thermal heating and heating medium. The generalized dynamic thermoelasticity equation for all three cases in rectangular and curvilinear coordinates is obtained. Considered the thermal response of a massive rigid body with internal spiroborate crack. The exact analytical solution of the problem is obtained. Earlier in the works of one of the authors the solution of the dynamic problem in the form of bulky functional structures was obtained, which greatly complicated their practical use. In this paper, we propose a solution to the problem in new classes of functions, which makes the solution more convenient for numerical experiments. A generalized differential relation for dynamic thermoelasticity is proposed, which has an extensive field of practical applications in the study of thermal response to heat stroke of solids of different shapes. It is shown that the component of the radial stress is a spherical elastic wave propagating from the cavity surface into the material. Numerical calculations of dynamic effects are performed and it is shown that the quasi-static interpretation of time problems in the theory of heat stroke does not allow to take into account the basic laws of transient thermoelasticity and inertial effects.

Валишин А.А., Карташов Э.М. Математическое моделирование термических напряжений в твердом теле с внутренней трещиной. Математическое моделирование и численные методы, 2018, № 3, с. 3–21.

539.3 Modeling of coupling effects in the problem of pulsed loading of thermoelastic media

Valishin A. A. (Bauman Moscow State Technical University), Kartashov E. M. (MIREA - Russian Technological University/Moscow Technological University)

doi: 10.18698/2309-3684-2019-3-318

Deformation of solids under the action of non-stationary external mechanical, thermal or other effects is accompanied by the inverse thermodynamic effect of the release of additional heat due to internal friction, i.e.a change in the temperature field. This causes additional deformation, which in turn leads to the release of heat. This effect of the interaction of mechanical and temperature fields is called the connectivity effect. The consequence of this effect is the appearance of heat fluxes leading to an increase in the entropy of the thermodynamic system and thermoelastic energy dissipation. The purpose of the work is to study the influence of the interaction of deformation and temperature fields for different materials. For “classical” materials, such as metals and glass, the thermodynamic effect of the interaction of deformation and temperature fields is insignificant and it is usually neglected in the calculation, design and operation of structures. For some polymer materials such as various polyvinylacetals, this effect is significant; it must be taken into account when creating composite materials on their basis and when designing products and structures of them. A dynamic coupled problem of thermoelasticity for an elastic layer of various structural, consumer and construction materials under rapid application of a normal compressive load to thermally insulated surfaces is considered. It is shown that for glass and steel temperature increasing due to the interaction of the deformation and temperature fields being really negligible is 0.180–0.183 K (or 0.061–0.062 %). For polymers, first of all, from the class of polyvinylacetals, it is substantial, and it can no longer be neglected.

Валишин А.А., Карташов Э.М. Моделирование эффектов связанности в задаче об импульсном нагружении термоупругих сред. Математическое моделирование и численные методы, 2019, № 3, с. 3–18.