Thermal-Mechanical Buckling Behavior Of Advanced Composite Grid Stiffened Plate And Shell With Delamination

On basis of the first order shear deformation theory, a nonlinear finite element analysis method has been developed to study thermal buckling behavior of the bare, single direction stiffened laminates and the advanced grid stiffened laminates (AGS), and thermal-mechanical buckling behavior of advanced grid composite circular cylinders. The thermal physics properties of composite related with temperature were considered in the analysis. In the paper, the author firstly commended on characteristic of the advanced grid stiffened laminates (AGS) and the actuality of the abroad and domestic development; Secondly, the element theory and formulation of the composite laminated plate and beam and a kinematics connection relationship between the stiffener and faces and the analysis method of thermal buckling and thermal-mechanical buckling of advanced grid stiffened laminates (AGS) were presented; At the same time, a delamination analysis model along the front contour of the delamination for composite laminated faces and an analysis model considering the influences of contact effect between sub-laminates of delamination in the buckling behavior were constructed; Finally, from typical numerical analysis, the nonlinear effect of material, the height of stiffener and different delamination sizes and areas on buckling behavior of the structure were discussed and studied respectively under thermal load and thermal-mechanical loads. Numerical results and discussions show that critical temperature is reduced and corresponding buckling modes are also changed with increasing delamination area. But the advanced grid stiffened laminates (AGS) possess strong thermal bucking resistance and good damage tolerance than general laminates. The methods and conclusions provided in the paper have some reference value for prediction of heat-durability and thermal-mechanical inflection capacity and damage tolerance design of AGS.The dissertation is a sub-part of the projects of National Science Foundation in China "The mechanism of advanced grid structure (AGS) with damage", Grant No. 10302004, and National Basic Research Program of China" New theory of optimum design for extra-light porous materials and their structures" Grant No. 2006CB601205.