Tensile And Compression Failure Analysis Of Honeycomb Sandwich Structure With Closing Frame

Because the honeycomb sandwich structure has the advantages of high specific strength,large specific stiffness,heat prevention and sound insulation,it is widely used in aerospace,aviation,navigation,rail transit and other fields.The transition from the main body of the honeycomb sandwich structure to the laminate usually also has a triangular beveled frame transition area,such as the door,window,wing,etc.of the aircraft that need to be banded at the junction,where the stress is more complex.In order to study the strength of such a sealed frame honeycomb core structure and the effect of the debonding of the beveled surface core in the transition area on the performance of the entire sandwich structure,the following research work is carried out on the combination of aramid paper honeycomb core and aluminum alloy inner and outer panels.The honeycomb core out-of-plane shear performance test,out-of-plane compression performance test,single-arm bending test(SLB)and double cantilever beam test(DCB)were designed,and the three elastic parameters required for the equivalence of honeycomb sandwich structure and the critical energy release rate of the core interface crack propagation type and type were measured,and the corresponding failure process reasons were explained.The above mechanical property test provides accurate material properties and related efficacy parameters for tensile and compression tests and finite element simulation of honeycomb sandwich structures with sealed frames.Through the in-plane tensile test of honeycomb sandwich structure with sealed frame,it is found that the failure mode of surface core bonding and disbonding specimens in the transition zone are manifested as panel fracture in the transition area.The slope debonding of the transition area has little effect on the tensile bearing capacity of the honeycomb sandwich structure with sealed frame(the tensile failure strength is reduced by 2.2% on average).The disbonding allows the inner panel to share a large load,and in the elastic phase,the strain of the outer panel decreases by12.5% and the strain of the inner panel increases by 31.25%.Through the in-plane compression test of honeycomb sandwich structure with sealed frame,it is found that the failure mode of the surface core bonding and disbonding specimens in the transition zone are manifested as bulging outer panels,and the failure position is exactly located in the transition area.The slope debonding in the transition area has little effect on the compressive bearing capacity of the honeycomb sandwich structure with sealed frame(the compression failure strength is reduced by 3.2% on average).The disbond allows the inner panel to share a greater load,the inner panel strain increases by 54.64%,and the outer panel strain decreases by 36.36%.The finite element simulation software ABAQUS simulates the failure process and failure results of honeycomb sandwich structure with sealed frame under different working conditions of tensile and compression,and discusses the influence of honeycomb sandwich structure with two bonding conditions(bonding and disbonding)of the beveled core in the transition zone on the failure mode and failure load.Comparing the finite element and the test results,it is found that in the tensile test,the errors of the tensile failure load test and the finite element calculation results of the bonded specimen and the disbonded specimen are 1.0% and 0.6%,respectively.In the compression test,the errors of the compression failure load test and finite element results of bonded specimens and disbonded specimens were 5.5% and 3.0%,respectively.It can be seen that the agreement is good,indicating that the simulation model has high prediction accuracy.