Thermal post-buckling analysis of functionally graded graphene platelets reinforced composite microtubes

Graphene reinforced composites are a class of novel nanocomposites which hold great potential for engineering applications due to their superior mechanical properties. In this work, we study the thermal buckling and postbuckling behaviors of functionally graded (FG) graphene reinforced composite (GPLRC) multilayer microtubes. Five typical graphene platelet distribution patterns across the thickness direction of the microtube are considered. Based on the modified couple stress theory and a refined higher-order beam theory, the non-classical governing relations with the account of von Ka<acute accent>rma<acute accent>n geometrical non-linearity are derived by using the minimum potential energy principle. Analytical solutions for the critical buckling temperature and post-buckling evolution path under uniform temperature field and heat conduction temperature field are derived. The efficiency and accuracy of the analytical results are demonstrated by comparing the predictions with results available in literature. Finally, the effects of various key parameters on the thermal buckling and post-buckling response of functionally graded graphene reinforced multilayer microtubes under simply supported and clamped boundary conditions are examined. It is found that dispersing more GPLs in the outer layers and fewer GPLs in the inner layers shows the best enhancement in the thermal stability of the multilayer microtubes. Additionally, our results show that increasing the inner-to-outer radius ratio, decreasing the length-to-outer radius ratio, and increasing the weight fraction of GPLs also can improve the thermal load-carrying capacity of the FG-GPLRC microtubes. We envision that the current work could provide theoretical guidelines for the optimization design and safety assessment of FG-GPLRC-based tubular structures or devices.