Research On The Mechanical Properties Of Metal Honeycomb Sandwich Structure With Defects

Metal honeycomb sandwich panel has a few advantages, such as light weight, great stiffness, excellent insulation and so on. Because of these advantages, metal honeycomb sandwich panel is more and more widely used in rockets, satellites, aircraft and other aerospace applications. However, some defects with different types, shapes or sizes with occur in its preparation and service, and these defects have a negative impact on mechanical properties. But, metal honeycomb sandwich panel with defects meets the performance requirements. Thus, it is of great importance to assess the ability of constant service for the metal honeycomb sandwich panel. The paper gives the effect of different ratio between core missing and different dimension of surface-core connecting defect on the mechanical properties of sandwich structure. The aim of this paper is achieved by means of numerical simulation and theoretical analysis methods.The second chapter of this paper gives the numerical simulation results under the stretching and the compressing tests for this structure with part of the core missing in the x direction and the y direction, furthermore, we also made the derivation of the in-plane elastic modulus of the defect-free metal honeycomb sandwich panel in the two directions. Results show that honeycomb core missing has no effect on the tensile modulus and strength. Under the compression load, the failure modes in the two directions are different.The third chapter gives the numerical simulation results of the mechanical performance of the in-planer and the skew of the metal honeycomb sandwich panel with surface-core connecting defect. Also, we made some theoretical analysis. Mechanical performance of coplanar includes the compression in the x direction. One side of the structure have the surface-core connecting defect, which has the better stability than that both sides had the surface-core connecting defect. Mechanical performance of skew includes three point bending, the span for the x direction, both the bending stiffness and the shear stiffness of the metal honeycomb sandwich panel decrease along with the defect dimension increasing, and the skewed compressing and stretching, under the tensile load in the z direction, the strength of the structure is linear attenuation along with defect dimension increasing, however under the compression load the surface-core connecting defect has no effect on the structureIn order to characterize the failure modes of damage of the honeycomb sandwich panel on the surface-core debonding, we establish the three-dimension interface element model based on the cohesion model. By using ABAQUS user subroutine UEL we developed the three-dimension interface element. By determining the curve of the opening displacement with the bridging stress could simulate the debonding of the surface-core.