Study On Stability Of Composite Honeycomb Sandwich Panels

Composite honeycomb sandwich panels has characteristics of high stiffness and high strength,which is widely used in aviation.The main failure mode of this kind of structure is instability,so the research on the stability of composite honeycomb sandwich panel is very important.In this paper,the compression stability of the honeycomb sandwich panel structure widely used in engineering is studied.First,the formulas for calculating the main mechanical properties of the composite honeycomb sandwich structure are summarized,including bending stiffness,tension-compression stiffness and shear stiffness.The semi-empirical engineering method for calculating the equivalent elastic modulus of composite honeycomb core and the buckling load calculation of composite honeycomb sandwich structure are given.According to the formula,a variety of equivalent parameters of the honeycomb sandwich are obtained,and the buckling load of the composite honeycomb sandwich panel is calculated.Based on the formula,the effect of composite honeycomb sandwich panel length,width and honeycomb core thickness on buckling load was investigated.Secondly,in view of the fact that most of the stability studies are mostly idealized with two-dimensional shell elements and do not accord with the actual situation,the panel of composite honeycomb sandwich panel is modeled separately from the honeycomb core.The honeycomb core is modeled using the equivalent method,and both the panel and the honeycomb core are simulated using 3D voxels.Finite element buckling analysis and static analysis of the first-order critical buckling loads on honeycomb sandwich panels with slopes show that the buckling position of the honeycomb sandwich panel of this type occurs in the honeycomb slope near the loading end.Static force analysis also indirectly proves the correctness of the location.Then,this paper attempts to add the idea of stiffener to the honeycomb sandwich panel.The strengthening effect and influence of the stiffener on the stability of the honeycomb sandwich panel are studied.The finite element model is established for comparative analysis.The results show that the ribs can effectively improve the compression stability of the honeycomb sandwich panel.Finally,for the honeycomb sandwich panel with stiffeners,the experiment of axial compression stability of the honeycomb sandwich panel is studied.The buckling load of each specimen is deduced by local nonlinear change of strain curve.The results of FEM are in good agreement with the experimental results,which proves the validity and correctness of the finite element model.