Caracterização numérica e avaliação experimental da fuga térmica em dispositivos amortecedores viscoelásticos sujeitos a carregamentos dinâmicos e pré-cargas estáticas

Abstract

This work is devoted to the numeric study and experimental assessment of the self-heating phenomenon in viscoelastic materials subjected to cyclic loadings and static preloads. Emphasis is given to the thermal runaway in such devices. Within this context, the proposed methodology to perform the nonlinear thermomechanical problem by using the finite element method enables to investigate the influence of temperature, static preload, amplitude of excitation and forcing frequency on the self-heating phenomenon. Additionally, it is also proposed one strategy to control the self-heating in the viscoelastic material by introducing metallic inserts in its volume. The Direct method is also used herein as a preliminary study with the aim of characterizing the mechanical properties of the viscoelastic material and the extension of the so-called Frequency-Temperature Superposition Principle for the static preload. To verify the thermomechanical model, experiments with a translational viscoelastic mount have been conducted and a curve-fitting procedure was formulated as an inverse optimization problem to identify the thermal conversion factor and the heat transfer by natural convection, assumed arbitrarily in the simulations. It has been used the so-called Non-dominated Sorting Genetic algorithm to minimize an objective function representing the difference between the numerical and measured temperature field at each instant of time. The accuracy and limitations of the proposed methodology are evaluated numerically and experimentally for the temperature evolutions at different points within the volume of the viscoelastic material and for various dynamic and static loading conditions for the self-heating and thermal runway phenomena.