Static And Dynamic Analysis Of CFRP Honeycomb Sandwich Panels Based On Variational Asymptotic Equivalent Model

The honeycomb sandwich panel has the excellent characteristics of strong impact resistance,good vibration and energy absorption,high specific strength,high specific rigidity,strong fire and corrosion resistance,good sound insulation and heat insulation,light weight,and low density.It is a new type of high-efficiency structure that is widely used in industries such as aviation,aerospace,automobile,packaging,shipbuilding,military,transportation,construction and so on.However,the current research is mainly focused on the core of honeycomb sandwich panels,and most of the face sheet uses homogeneous materials.In view of this situation,a new CFRP honeycomb sandwich plate is proposed.The face sheet is made of carbon fiber reinforced composite material,and the core layer is made of aluminum alloy.Based on the variational asymptotic method,the theoretical analysis of CFRP honeycomb sandwich panel is carried out by taking advantage of the fact that the unit cell size is much smaller than the size of the plate.Combined the variational asymptotic homogenization method with the finite element method,the two-dimensional equivalent plate model is constructed,and compared with the static and dynamic results of three-dimensional finite element method.Finally,the influence of material parameters and structural parameters on the effective performance of CFRP honeycomb sandwich plate is systematically analyzed.The main work and research results are as follows:(1)Starting from the generalized total energy equation of CFRP honeycomb sandwich panels,the energy functional is analyzed according to the relationship between the deformation of the structure and the strain energy.The variational asymptotic expression of the structural unit cell is obtained based on the variational asymptotic method.The connection between the macro-plate model and the microstructure unit cell is established.Then,the constitutive relationship,strain energy and equivalent stiffness are derived in detail by extracting its unit cells from the periodic arrangement of the CFRP honeycomb sandwich plate,and the two-dimensional equivalent plate model of the CFRP honeycomb sandwich plate is obtained.(2)Combined the variational asymptotic method and the finite element method,the finite element model of two-dimensional equivalent plate model was constructed,and the corresponding numerical simulation analysis of static displacement,buckling and vibration was carried out and compared with those of three-dimensional finite element model.The results show that the two-dimensional equivalent plate model has high accuracy in static and dynamic analysis,and the maximum error is within 5%.Furthermore,it can greatly shorten the calculation time and improve the calculation efficiency.(3)The effects of various material and structural parameters,such as material parameters of the panel,core geometric parameters and boundary conditions on the effective performance of CFRP honeycomb sandwich plate were systematically analyzed.The results show that the effective stiffness and anisotropy of the CFRP honeycomb sandwich plate are very sensitive to the layup configurations of face sheets.The influence of layup configurations is greater than that of the fiber volume fraction.The changes in static force,buckling and vibration response caused by changing the thickness of face sheet are more obvious than changing the height of the honeycomb core under the same panel height.Among the geometric parameters of the honeycomb core,the period length and the included angle of the honeycomb core have the greatest influence on the equivalent stiffness of the CFRP honeycomb sandwich plate.The more restrictive the boundary conditions are,the greater the rigidity of the structure,resulting in the reduction of the maximum deflection and the increase of the critical buckling load and natural frequency.