Tianhu He

The thermoelastic vibration of porous graphene platelet-reinforced composite plates depends not only on the amounts of reinforcement and pores, but also on their relative locations through the thickness. To clarify this distribution-dependent behavior under non-Fourier heat conduction, a semi-analytical formulation is developed for porous functionally graded graphene platelet-reinforced composite (FG-GPLRC) plates within the dual-phase-lag (DPL) framework. Kirchhoff plate theory is coupled with a multimode through-thickness temperature expansion, and the resulting thermoelastic eigenvalue problem is solved by Navier’s method. The effective properties are evaluated using the modified Halpin–Tsai model, while porosity degradation is described by a Gaussian random field closed-cell model. The vibration response is governed by the relative positions of graphene platelet (GPL)-enriched and pore-enriched regions. Surface-enriched GPLs provide the greatest frequency enhancement, whereas surface-enriched pores produce the strongest reduction in bending stiffness and natural frequency. Concentrating pores near the mid-plane weakens this adverse effect, and its combination with surface-enriched GPLs gives the highest frequency among the examined cases. Thermoelastic coupling produces a measurable frequency shift relative to the purely mechanical solution, whereas the additional DPL correction relative to the Fourier model remains very small for the parameters considered. Increasing GPL weight fraction and length-to-thickness ratio further increases the frequency, although the geometry-induced gain gradually approaches a limiting value. Stiffness and mass measures show that the slight non-monotonic response of FG-X + P2 arises from their combined redistribution rather than pore-induced stiffening alone. These results clarify how through-thickness material arrangement governs the thermoelastic vibration response of porous FG-GPLRC plates.

In micro-electromechanical systems, thermally induced buckling can compromise the reliability of microscale structures such as microbeams. To quantify and mitigate this risk, a thermoelastic buckling model is developed for a functionally graded (FG) polymer-matrix microbeam co-reinforced with graphene platelets (GPLs) and carbon nanotubes (CNTs) by coupling the nonlocal strain-gradient (NSG) theory with a nonlocal heat-conduction law. The model accounts for both elastic and thermal nonlocality. For the CNT/GPL-reinforced microbeam, the effective properties are evaluated using the Halpin–Tsai micromechanics model together with the rule of mixtures. From the governing equations for thermoelastic buckling, a closed-form first-mode critical load is derived and can be applied to several typical end restraints. In calculation, four different CNTs/GPLs distribution patterns in the matrix, i.e., UD, FG-A, FG-O and FG-X are considered and compared with each other. Parametric studies indicate that, for fixed dimensions, the FG-A distribution with stronger end restraints yields the greatest resistance to thermoelastic buckling. Increasing the GPL mass fraction strengthens the critical buckling load, whereas increasing the through-thickness volume-fraction index increases the load for FG-A but reduces it for FG-O and FG-X. Elastic nonlocality lowers the critical load, while the strain-gradient term counteracts this trend and raises the threshold; thermal nonlocality further reduces the predicted critical load relative to Fourier-based estimation. The present method provides a simple formula and practical guidance for critical thermoelastic buckling load of microsystem components where size effects and non-Fourier heat transport are non-negligible.

Functionally gradient materials have attracted extensive attention and research due to their remarkable resistance to thermal shock under harsh thermal conditions. In addition, the analytical model of thermoelasticity encounters pronounced limitations when applied to micro-structures. This deficiency can be ascribed to its failure to incorporate the ramifications of the spatially size-dependent effects that are intrinsically linked to heat transfer and elastic deformation. To accurately model the thermo-mechanical coupling at nanoscale, a nonlocal dual-phase-lag thermoelasticity with nonlocal elasticity effect is given in this work. In the aspect of application, the thermo-mechanical behavior of a functionally graded spherical microshell heated by a thermal-mechanical loading is studied. Governing equations including the nonlocal thermal parameter, the nonlocal elasticity parameter, the power law index are derived solved by Laplace transformation. It is shown by the achieved results that the thermal deformation under ultrafast heating condition will be reduced when the influences of nonlocal effect and ceramic composition are considered.

The issue of water-enriched surrounding rock induced by excavation disturbances in loess tunnels represents a significant challenge for the construction of loess tunnel projects. Based on the concepts of lime sac water absorption, expansion, and compaction, consolidation, and drainage of surrounding rock and soil, as well as active reinforcement, a tandem water-absorbing and compaction anchor with heat-expansion and compaction consolidation functionality has been developed. To facilitate the engineering design and application of this novel anchor, a consolidation equation for cylindrical heat source-consolidated soil was derived under conditions of equal strain and continuous seepage. Considering the impact of temperature in the thermal consolidation zone on soil permeability, an analytical solution for the average degree of consolidation of the surrounding soil after support with the water-absorbing and compaction anchor was provided. The correctness of the solution was verified through engineering examples, demonstrating the reasonableness of the theoretical calculation method used in this study.