Non-linear thermal response of sandwich panels with a flexible core and temperature dependent mechanical properties

The paper presents the geometrical non-linear response of unidirectional sandwich panels with a “soft” core subjected to thermally induced deformation type of loading, which may be fully distributed or localized. The mathematical formulation incorporates the effects of the flexibility of the core in the vertical direction as well as the effects of the temperature dependent mechanical properties of the constituent materials on the non-linear behavior. The non-linear governing equations are derived using a variational approach following the approach of the high-order sandwich panel theory (HSAPT). The features of the non-linear response are presented through a numerical study that discusses the effects of localized reinforced cores and the mismatch of the coefficients of thermal expansion of the constituent core materials; the effects of continuous panels in the presence of immovable supports; the effects of localized thermal loading with temperature dependent material properties and, finally, the interaction of mechanical and thermal loading on the response with and without immovable supports and temperature dependent material properties. An important conclusion of the study is that the interaction between mechanical loads, temperature induced deformations, and degradation of the mechanical properties due to elevated temperatures, may seriously affect the structural integrity.