A variable nonlocal strain gradient theory for wave propagation analysis of infinite FGP nanosheet with surface effects in hygro-thermal environment

The main goal of this article is to present a refined higher-order shear deformation theory (HSDT) combined with the nonlocal strain gradient theory (NSGT) to analyze the wave propagation of infinite functionally graded porous (FGP) nanosheet lying on Pasternak medium, and in the hygro-thermal environment considering surface effect. The uniqueness of this study lies in its examination of the impact of spatial fluctuations in the nonlocal and length-scale parameters on the wave propagation of infinite FGP nanoplates. The governing equations of motion are established using Hamilton’s principle and the wave propagating equations are resolved using the Navier closed-form solution. The accuracy and robustness of the proposed algorithm are demonstrated by comparing the present results with those available in the literature. Numerical illustrations demonstrate that the attributes of wave propagation of infinite FGP nanosheet are associated with the grading index, with or without surface effect, porosity parameter, nonlocal parameter, length-scale parameter, temperature and moisture changes are thoroughly examined. These results can be applied in fields such as radar, ultrasound, medicine, telecommunications, and navigation.