EFFECT OF THERMO-ELECTRO-MECHANICAL COUPLING AND NON-LINEARITIES ON DYNAMIC PROCESSES IN INELASTIC LAYERED STRUCTURES

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The forced-vibration analysis of structures and their members occupies a significant place in the dynamics of deformable systems. An accurate prediction of the dynamic and quasi-static response of structures and their members is a huge challenge, since the material of a structure may become plastic under intensive loading and/or exhibit viscous properties. Variable viscoelastoplastic behaviour should be studied when designing metal dampers for the vibrations of building structures under wind and seismic loads, devices for suppressing vibrations of pipelines, test specimens in low-cycle fatigue tests, etc.It is well known that the inelastic deformation of a material is accompanied by release of heat due to dissipation of mechanical energy. We may distinguish at least two classes of processes when such thermal effects should be always taken into account. The first class includes intensive monotonic or cyclic plastic deformation. Under certain conditions such as impact load or resonant vibrations, the dissipative heating may reach a significant level. This should be taken into account, for example, in evaluating the serviceability of elements of damping systems or when developing the techniques for accelerated analysis of the low-cycle fatigue of materials. The dissipative heating plays a key role in the formation of adiabatic shear bands in viscoplastic bodies under the high-speed loading. The second class includes thermo-electro-mechanical material models, thermographic techniques for detection of defects, non-isothermal models of crack propagation, different approaches to active vibration control, etc. The heating may change the strength of the structure, deteriorate its performance, and, under adverse conditions, even cause failure. Geometrical nonlinearity and heterogeneity are the additional complicating factors.The combined effect of the dynamic properties, nonlinearity (both inelasticity and geometrical nonlinearity) as well as the thermo-electro-mechanical coupling involves complex behavioural models. Therefore, an accurate simulation of complex dynamic and quasi-static processes in thin-wall inelastic passive and active members demands new approaches to be developed in order to successfully attack the problem. The proposed work is very timely because the interaction between mechanical, electric and thermal fields in layered structures is currently the subject of strong academic and industrial interest. Exploration of the said interrelations and couplings promises the discovery of new interesting and industrially valuable effects.The overall aim of the proposed research is to improve our understanding of the complex coupled processes in thin-wall inelastic structures that can contain both active and passive layers and can experience intensive cyclic or impact loading. We intend to clarify the role that such factors as the inherent dynamic properties, the material and geometrical nonlinearities, heterogeneity of the stress-strain state and the coupling of the mechanical, electrical and thermal fields can play in defining the structure response, with a long-term goal of development of general design guidelines to achieve the necessary productivity and reliability of structures.