The work is devoted to the development of the investigation approaches and study of the regularities of coupled thermomechanical behavior of inelastic dissipative solids under harmonic loading. With this aim the generalized model of inelastic material is brought to consistency with the thermodynamics of irreversible processes. Parameters of the model are specified for aluminium alloy and steel.
Simplified model of coupled thermomechanical behavior of inelastic solids under harmonic loading is elaborated. The model is based on the assumption of single-frequency response of the material to the harmonic loading and is formulated in terms of the complex-value moduli. Modified scheme of harmonic linearization with the use of cyclic diagrams is developed.
Statements of the problem on vibration and dissipative heating of the solids made of inelastic material under harmonic loading are elaborated with the application of both generalized flow model (complete statement) and simplified model (approximate statement). Model of the dynamic coupled thermomechanical processes in layered thin-wall bodies is developed for the case of inelastic materials of layers as well as additional piezoelectric layers.
Special attention was paid to the investigation of the response of unidirectional metal matrix composites (aluminium matrix with the embedded steel fibers) to the harmonic loading. Influence of microscopic plastic behavior of matrix to the properties of composite as an transversely isotropic solid is also studied.
Numerical techniques of the problems attacking are worked out for both complete and approximate statements. The spatial problems are solved by means of the FEM technique. The main regularities of quasistatic and dynamic coupled behavior under harmonic loading are investigated for axisymmetric and plane solids (disk, plate), solids containing stress concentrators and macrodefects; heterogeneous solids, composites as well as thin-wall structural elements.PhD Theses:
Spicified thermomechanical model of planar vibrations and dissipative heating is developed for the constant and variable thickness plates with account for inelasticity and thermal dependence of material properties.
Classification of plate-like sonotrodes (tools for ultrasonic welding) according to modal characteristics is proposed basing upon the analysis of the resonant spectrum of plane vibrations of rectangular solid and the dispersion spectrum of symmetrical waves in the infinite layer. Fundamentally new class of plate-like sonotrodes operating at the thickness vibration mode is designed and investigated.
The new methods of modal and frequency control of planar vibrations of simply connected and multiply connected plates of constant and variable thickness are elaborated. Comparative estimations and applicability area determination for the methods are performed. Stress concentration and restrain effects of plate-like sonotrodes are studied.
Influence of inelasticity to the frequency, modal and thermal characteristics of the plates is estimeted. It is shown that for the vibroheating problem main factors affecting the temperature decrease are temperature dependence of the material properties and dissipation of mechanical energy. Both factors influence the displacement distributions significantly.
Technique for fatigue strength estimation of structure elements is developed. It takes account for inelastic properties and thgermomechanical state of the materials. Classification of main types of thermomechanical fatigue failures is proposed.
Influence of inelastic properties of the materials to stress concentration factors is studied. Classification of the concentrators according to the failure mechanism is elaborated.