Research On Mechanical Property And Stability Of Composite Honeycomb Sandwich Panels

Weight-loss for structures has always been the primary goal of the overall pursuit of environmental protection efficiency in aviation industry. Meanwhile, honeycomb sandwich structure has widely been used in some external and interior bearings of many aircrafts for its high specific stiffness and specific strength. Therefore, the changes in some mechanical properties and stabilities due to different ratios of skin layer and core thickness from the weight-loss process are well worth of concern. Since it’s hard to predict the failure mode of composite sandwich structures under severe circumstances directly, the study on the mechanical properties and stability of the sandwich structures as well as analysis on the failure mode has become vital.This paper is devoted to study the mechanical properties of the three-point bending test properties and shear stability of honeycomb sandwich composite panels.According to the different effects on stabilities of honeycomb sandwich panels due to different bending direction and panel thickness, various numerical and experimental researches have been made on the three-point bending properties of honeycomb sandwich panels.A nonlinear finite element model has been built, and the model had passed through the validity test in failure mode, ultimate load and overall respond three aspects. Then, I knew how bending direction and panel thickness can affect three-point bending ultimate load, failure mode and properties evo lution of the honeycomb panel. Honeycomb sandwich panels with thin skins are prone to make core crush, while with thick skins are more likely to experience shear failure. Before damage, the energy absorbing ability of the beam with L direction of core is better than the W beam, while after skin damage they are close. Deduce the shear stress distribution between panel and core layer by measuring the equivalent shear stiffness and strength, and the results show that the distribution coefficient increase by power progression as the ratio of thickness of core layer and panel decrease, and that when the thickness ratio is larger than 10, the skin shear distribution coefficient lies within 5%.Simulation and experimental research have been made on the effect of different layers of skin and core’s height on the stability of honeycomb sandwich panel under shear loading. The critical buckling load and failure mode of honeycomb sandwich panels under shear are analyzed. Results show that the higher the height of the core layer is, or thicker the skin layer is, the buckling load of honeycomb sandwich panel is higher. And the increase of the core height is more efficient than the increase of the skin layer in a certain range. The change of the core thickness can significantly change the post buckling characteristics and subsequent failure mode of honeycomb sandwich panels, the thin core layer design is overly conservative, while thick core layer design needs to take the panel strength limit into account.