Nonlinear thermoelastic waves in functionally graded materials: Application to nanowires

We propose a thermodynamic model to describe the thermoelastic behavior of Functionally Graded Materials. Specifically, the thermoelastic response of these materials to coupled thermal and elastic perturbations is studied in view of a nonlinear heat-transport equation. The necessary and sufficient conditions ensuring the compatibility of the model with second law of thermodynamics are carried out. Propagation of thermoelastic waves, both in equilibrium and nonequilibrium states, is analyzed. The influence of the stoichiometry on the speed of propagation of coupled first-and second-sound waves is pointed out.