Improved thermal stability of doubly-curved sandwich nanoplate with symmetric functionally graded face layers and an auxetic core under different structural configurations

Abstract Recent studies on nanoscale thermal structures have partially examined the combined influence of auxetic cores, nonlocal effects, and functionally graded (FG) face layers in doubly curved configurations. This paper analyzes the thermal buckling of doubly-curved functionally graded (FG) sandwich nanoplates with a re-entrant auxetic core using a nonlocal strain-gradient and higher-order shear deformation framework solved via Navier’s method. The model captures curvature, gradation, and nanoscale effects under SSSS and CCCC boundaries. Reducing the core thickness increases the critical buckling temperature from 1304 to 1596 K (22%), while curvature increase affects the dimensionless buckling load by 170%. Enlarging auxetic-cell dimensions enhances stability by 35–40%, whereas higher gradation lowers it by 43%. The nonlocal parameter softens the response (89% decrease), while the strain-gradient parameter hardens it (228% increase). These results show the coupling among curvature, gradation, and auxetic geometry, offering a nanoscale model for lightweight, thermally stable auxetic–FG nanostructures used in aerospace and MEMS applications.