Reflection and refraction of longitudinal displacement wave at an interface between two different micropolar magneto-thermoelastic solid in welded contact

The general governing equations of micropolar generalized magneto-thermoelasticitic solid affected by multi-physical field,such as magnetic field ,thermal field and elastic field,are presented in this paper. The magnetic effect, thermal effect and mechanical effect are included in the general equations. Also the coupled thermalelasticity and its five extended theories are in its generalized heat conduction equation. The five extended theories are the Lord-Shulman theory with one relaxation time(L-S), the Green-Lindsay theory with two relaxation times(G-L), the Green-Naghdi theories of type II(without energy dissipation,G-N II) and of type III(G-N III),and the Chandrasekharaiah and Tzou theory(dual-phase-lag,C-T). Using this general governing equations, the reflection and refraction at the plane interface of two-welded semi-infinte micropolar elastic solid are studied for incident longitudinal displacement wave in the presence of a constant magnetic field and an uniform initial temperature field. Using continuous conditions at the interface, the amplitude ratios of reflected and/or refracted thermal wave,longitudinal displacement wave(LD wave) and coupled transverse and microrotational wave(CD I and CD II ) to incident LD wave are studied and described graphically with the incident angle,which variates from 0 degree to 90 degree. The thermal effect, the magnetic effect and the affection of thermal relaxation on them are discussed. The numerical results show that all reflected and refracted waves are affected by thermal field, magnetic field and thermal relaxtion. And there is a striking discrepancy between different type wave for thermal effect, such as that for the effect of magnetic field or thermal relaxtion,but it is similar for reflected and refracted waves of the same type.