Modeling the thermal behavior of functionally graded media with a spherical gap: rectified sine wave heating via fourth-order Moore–Gibson–Thompson model

The main objective of this work is to introduce a new thermal conductivity model that can be utilized to solve the infinite thermal diffusion problem in the Green and Naghdi type III model. This proposed model incorporates two key concepts: the fourth-order Moore–Gibson–Thompson (MGT) concept and thermal relaxation. By incorporating higher-order terms, the fourth-order MGT model provides a more accurate representation of the thermal behavior of the material. The thermal behavior of a functionally graded (FG) infinite medium containing a spherical gap is then studied using this model. A rectified sine wave heating system is applied to the traction-free gap surface. Power functions are utilized to model the uniform radial variation of the physical properties of the FG medium. The physical variables under investigation were meticulously examined, considering the impacts of heterogeneity, relaxation duration, and thermal frequency. These variables were estimated numerically using a suitable technique for Laplace transformations. Through this work, the expected outcomes may be able to make a significant contribution to the field of thermoelastic analysis in advanced and FG materials, as well as to engineering applications.