The paper explains the basic concepts and equations of the theory of thermoplasticity belonging to the class of theories of plastic flow in the combined hardening. The tensor strain rate is represented as a sum of tensors of the velocities of elastic and plastic deformations. The elastic deformation follows the generalized Hooke's law distributed to non-isothermal loading. The surface loading is introduced which isotropically widens or narrows and shifts in the process of loading. For the radius of the surface loading the authors formulated evolutionary equation taking into account the additional isotropic hardening under non-proportional loading, also generalized to non-isothermal loading. We have taken the parameter of Kadashevich-Mosolova corresponding to the angle between the velocity vectors of strain and stress as the parameter characterizing the degree of complexity of the process of loading. Surface displacement loading is described based on the model of Novozhilov-Chaboche implying that the total displacement is the sum of the displacements and each displacement has its own evolutionary equation. An earlier analysis of a loop of plastic hysteresis allowed distinguishing three types of micro-strains (displacements) and formulating three types of evolution equations. Here these evolutionary equations are generalized to the non-isothermal loading. To determine the axial velocity of plastic deformation we used associate (gradient) flow law. It became possible to determine expressions for speed of the accumulated plastic strain for hard and soft modes of loading. The authors have formulated conditions of elastic and elastic-plastic conditions. The kinetic equation of damage accumulation is introduced for the description of nonlinear processes of damage accumulation. Here, energies equal to the work of microstresses of the first and second types to the field of plastic deformations are accepted as the energy spent on creating damage in the material. These equations are generalized to the non-isothermal loading. We have highlighted material options completing theory option, formulated the basic experiment and the method of identifying material functions. The paper describes the verification of thermoplasticity theory on a wide range of structural steels and alloys and programs of experimental studies. New results have adequate descriptions within one theory of the following phenomena: - landing loop of plastic hysteresis in nonsymmetrical rigid cyclic loading; - ratcheting of loop plastic hysteresis in nonsymmetrical soft cyclic loading; - the regularities of complex loading as on planar or spatial trajectories; - the effects of additional isotropic hardening under disproportionate (complex) cyclic loading; - the effects of non-linear summation of damage to arbitrary loading processes; - the patterns of non-isothermal loading.

In this paper the effect of an additional (barrier) crest on heat and mass transfer processes and phase transitions of polymers in the channel plasticizing extruder is investigated. On the basis of the energy and hydrodynamics equations the mathematical model describing the processes of motion of a solid and a liquid polymer inside the channel as well as undergoing phase transformations is given. To create a mathematical model of melting processes a number of simplifying assumptions was introduced, namely: 1) the process has a stationary character at a constant mass flow rate; 2) helical path is unfolded on the plane and the principle of reverse movement is used; 3) diffusion of heat along the channel is not taken into account; 4) loss of the melt through the main ridge is neglected; 5) the elastic polymer in the melt process is not taken into account. As a result, the process of resin moving and heat exchange in the melting zone of the extruder was modeled by nonclassical heat and mass transfer in a long rectangular channel divided into two by barrier crest (solid phase channel and melt channel) in which the upper wall is moving at a constant speed equal to the peripheral speed of the worm at helical line cutting angle to the channel axis. The resulting model is solved by finite difference method allowing doing the numerical investigation of the dependence of the extrusion process of polymers on the geometric parameters of the barrier screw. The calculation was performed for the screw ME-90 with a number of L / d = 26 at a rate of 78.7 kg/hour. The width of the barrier crest was assumed to be 16 mm, clearance above the barrier crest was 1 mm. Feed material was high density polyethylene. Data analysis led to the conclusion that the presence of additional (barrier) crest increases dissipative heating of the molten resin circulating above it, as well as reduces the amount of molten polymer film on the solid phase, which allows intensifying melting process and improve its homogeneity.

The purpose of research is to develop and verify methods of experimental determination of the dynamic strain fields in the study of impact damage and destruction of the plates. An experimental rig that realizes dynamic load of the studied plate at high-speed impact with a projectile and determination of dynamic strain fields on the plate surface is developed. The method is based on digital image correlation procedure in combination with a high-speed video recording that implemented using hardware-software Vic-3D complex. The investigation is performed in two series of experiments with different materials and dimensions of the test plates and with different materials and speed of the projectile. The experimentally obtained fields of the dynamic strain for the high-speed impact of the aluminum plate and a spherical steel projectile and for the carbon fiber plate and ice projectile are presented. The results are presented in the form of time-lapse recording of the tensor component fields of dynamic deformation and time dependences of deformations at certain points of the plate. The implemented deformation rate is up to 1,.5· * 103 sec--1. The state of strain for carbon-fiber composite during high speed destruction is obtained. The reliability of the digital image correlation method results is confirmed by direct measurement of residual deformations in the plate. The described method provides detailed experimental data about the processes of high-speed deformation for metals and composite materials. This data is of interest for experimental verification of deformation and destruction models behavior of materials at high strain rates. In particular, it provides an opportunity to obtain the necessary data for verification of deformation models and failure criteria of deformation under biaxial stress state. This method can be used for mathematical models testing and experimental investigation of the ballistic damage and destruction dependences of critical structural elements in cases of foreign objects damage of aircraft and engines parts or armor piercing.

This work is devoted to investigation of spatio-temporal localization of deformation at the direct uniaxial tensile of sylvinite with using of digital image correlation method and acoustic emission technique. For the implementation of direct tension there was used a special reversing device allowing to convert compressive force into tensile. Samples are concreted into the device before the experiment. Sequentially photographed images of side surfaces of specimens were used to reconstruct the distribution of components of displacement vector field and strain tensor on the side of sylvinite samples under uniaxial quasi-static tension. As result of obtained data analysis it is found that the deformation process occurs as two consistently following forms of spatiotemporal localization: a system of equidistantly located stationary foci of localized deformation and a single stationary dissipative localized structure. Areas of specimen outside the localization zones are in the undeformed state, also as result of uniaxial quasistatic tension of specimen it is established that the zones of localized deformation can be tensile as well as compressive. The transition from one localization form to another occurs in the maximum stress vicinity and is accompanied by a sharp decrease in the concentration parameter. Concentration parameter characterizes the degree of interaction between defects of different scale levels through their elastic fields and can be estimated from the acoustic emission data. Analysis of dependence of the spatial period of localized deformation bands on the size of computational cell showed that localized deformation bands are self-similar structures and process of deformation is localized at the grain boundaries minerals composing the sample.

The aim of the present study is the experimental calibration of the recent model proposed by the authors which describes the thermomechanical behavior of glassy polymers under large deformations. For such this purpose a series of thermomechanical experiments has been conducted with lightly-linked epoxy specimens, for which large deformations are achievable in the rubbery state. Three experimental series have been carried out on the DMA testing machine in the regime of regulated axial compression load and changed temperature with the axial contraction measuring. The aim of the first experimental series was to prove the elastic potential choice for describing the behavior of the concerned material. For this purpose the samples in rubbery state were deformed under constant loading rate. It was concluded that the Peng-Landel elastic potential could be applied for the accurate description of the epoxy resin deformation process. The second series included several adjusting experiments for the model parameters determination. The samples were heated with the constant temperature rate under the constant compression load. The comparison of results for different rates and load levels is given. Also the procedure of the parameters determination is described. Some parameters were taken as the material constants, for other ones the linear approximation of the dependence on the temperature rate and the load level was made. The third series presents the verification experiment for which a shape memory thermomechanical cycle was chosen. The experimental data were approximated with the numerical model based on the parameters which were found from the adjusting experiments. A good agreement between the experimental and numerical results is shown. A brief review of the most spread experimental schemes for the shape memory cycle is also given in the paper.