Homogeneização de propriedades térmicas e mecânicas de materiais compósitos considerando efeitos de interfaces imperfeitas

Abstract

In the present work, the Parametric Finite-Volume Theory is expanded by using the inclusion of homogenization processes on mechanical and thermal properties of periodically elastic and viscoelastic composites, with interphase effects. This work introduces models for evaluation of thermal conductivity, coefficient of thermal expansion, elastic and viscoelastic constitutive tensors with unit cell concept applied and periodical boundary conditions in state of generalized plane strain. The current interphase model between inclusion and matrix are considered thin and replaced by equivalent imperfect interfaces. The materials of the interphase are admitted to have lower thermal and mechanical properties. The formulation of the thermal and mechanic homogenization models is based on the traditional strategy of temperature and displacement field expansion in macroscopic and fluctuating components. The effective coefficients of thermal expansion are analytically evaluated using the effective elastic properties and coefficient of thermal expansion of the constitutive phases. Procedures on viscoelastic homogenization are based on Generalized Maxwell model, which allows the assessment of the effective relaxation tensors, providing the effective creep tensors using the Correspondence Principle. The viscoelastic model applied is incremental in time and uses the internal variables formulation. The created models are applied on the solution of many case studies, involving different kinds of composite materials (including size-dependent effects), volume fraction, unit cell geometry and interphase properties influence on the behavior of effective mechanical and thermal properties. The results are compared to analytical and FEM solutions to calculate the method’s efficiency.