A time-domain boundary element method for quasistatic thermoviscoelastic behavior modeling of the functionally graded ma
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A time-domain boundary element method for quasistatic thermoviscoelastic behavior modeling of the functionally graded materials H. Ashrafi • M. Shariyat • K. Asemi
Received: 28 January 2012 / Accepted: 21 March 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
Abstract In the present paper, a boundary element formulation is presented for two-dimensional thermoviscoelasticity analysis of components fabricated from the functionally graded materials (FGMs). In this regard, a graded viscoelastic element capable of tracing gradual variations of the material properties is developed. Several attempts have been made so far to employ the integral equation approach for the heterogeneous viscoelastic materials. In the present research, Somigliana’s displacement identity is considered and implemented numerically for analyzing the two-dimensional exponentially graded viscoelastic components. Employing the common assumptions of the viscoelastic constitutive equations and the weighted residual technique, an efficient boundary element formulation is developed for the heterogeneous Kelvin–Voigt solid viscoelastic models. Finally, three numerical examples are provided to verify the proposed formulation and present practical conclusions.
H. Ashrafi (&) M. Shariyat Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran e-mail: [email protected]; [email protected] URL: http://hossein-ashrafi.com K. Asemi Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran
Keywords Boundary element Heterogeneous characteristics Thermoviscoelasticity Functionally graded materials
1 Introduction Functionally graded materials (FGMs), as advanced composite materials, have extensively been used in recent years. The concept of the FGMs originated in Japan during the space plane project in 1984 (Miyamoto et al. 1999). An FGM is a mixture of two or more constituent phases with a variable composition. Microstructures of the FGMs are often fabricated in three major types: continuously graded microstructures, discretely graded microstructures, and multiphase graded microstructures (Suresh and Mortensen 1998). The simplest FGMs are composed of two constituent materials whose volume fractions change gradually so that sum of their volume fractions equals unity in each arbitrary point of the component. Unlike the traditional composites, which are piecewisehomogeneous mixtures or layered systems, in majority of the FGMs the mechanical properties vary continuously. An FGM can be customized to an application by specifying the form of the gradation of the material properties to fit the design requirements. Owing to their special features and application potentials, the FGMs have drawn attention of numerous scientists and engineers in broad areas of research. The
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FGMs may be ideal in applications where the operating conditions are severe. Some typical examples of the FGM components are the heat-engine components and the ro
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