Nonlocal thermal buckling and postbuckling of functionally graded graphene nanoplatelet reinforced piezoelectric micro-plate

This paper analyzes the nonlocal thermal buckling and postbuckling behaviors of a multi-layered graphene nanoplatelet(GPL)reinforced piezoelectric micro-plate.The GPLs are supposed to disperse as a gradient pattern in the composite micro-plate along its thickness.The effective material properties are calculated by the Halpin-Tsai parallel model and mixture rule for the functionally graded GPL reinforced piezoelectric(FG-GRP)micro-plate.Governing equations for the nonlocal thermal buckling and postbuckling behaviors of the FG-GRP micro-plate are obtained by the first-order shear deformation theory,the von Kármán nonlinear theory,and the minimum potential energy principle.The differential quadrature(DQ)method and iterative method are introduced to numerically analyze the effects of the external electric voltage,the distribution pattern and characteristic of GPLs,and the nonlocal parameter on the critical buckling behaviors and postbuckling equilibrium path of the FG-GRP micro-plate in thermal environment.

A Novel Multiscale Reinforcement by In-Situ Growing Carbon Nanotubes on Graphene Oxide Grafted Carbon Fibers and Its Reinforced Carbon/Carbon Composites with Improved Tensile Properties

In-situ growing carbon nanotubes （CNTs） directly on carbon fibers （CFs） always lead to a degraded tensile strength of CFs and then a poor fiber-dominated mechanical property of carbon/carbon composites （C/ Cs）. To solve this issue, here, a novel carbon fiber-based multiscale reinforcement is reported. To synthesize it, carbon fibers （CFs） have been first grafted by graphene oxide （GO）, and then carbon nanotubes （CNTs） have been in-situ grown on GO-grafted CFs by catalytic chemical vapor deposition. Characterizations on this novel reinforcement show that GO grafting cannot only nondestructively improve the surface chemical activity of CFs but also protect CFs against the high-temperature corrosion of metal catalyst during CNT growth, which maintains their tensile properties. Tensile property tests for unidirectional C/Cs with different preforms show that this novel reinforcement can endow C/C with improved tensile properties, 32% and 87% higher than that of pure C/C and C/C only doped with in-situ grown CNTs. This work would open up a possibility to fabricate multiscale C/Cs with excellent global performance.