Assessment And Analysis Of Repair To Composite Honeycomb Sandwich Structure

The most common damage form of composite honeycomb sandwich structure in engineering practice is debonding between core and panel as well as impact damage.These kinds of damage will cause a significant decline in bearing capacity,threatening the safety of the structure.The research in this thesis is aimed at the two kinds of damage and corresponding damage repair methods of honeycomb sandwich structure for which experiment method and simulation analysis method has been carried out.In experiment research,edgewise compression test was carried out to get the ultimate bearing capacity of damaged parts and repaired parts.In simulation research,detail modeling method is used to investigate the failure mechanism of the structure.The main contents of this article are stated as follows:(1)Compression tests were carried out on the nondestructive parts,the debonding parts,the debonding repair parts,the impact damage parts,and the scarf repaired parts.The test results show that debonding damage and impact damage can reduce the overall compressive load carrying capacity to different degrees.The compression load carrying capacity can be recovered to a large extent by normalized repair.(2)The finite element analysis model of honeycomb sandwich structure is established,which is different from the honeycomb solid equivalent method commonly used in the literature.In this thesis,the honeycomb core microstructure is considered and a straight-faced irregular hexagonal honeycomb core is established.The honeycomb paper wall is equivalent to the detailed structure consisting of the aramid paper and the two sides of the phenolic resin,and the constitutive relations of the materials are controlled by the VUMAT subroutine.The results obtained by the FEM analysis are in good agreement with the experimental results.(3)Parametric analysis of honeycomb damage structure and repair structure figures out that the bearing capacity shows slight decrease immediately when tiny debonded area appears,then the variation of the ultimate strength with the increase of the debonding area is linearly reduced first and then gradually slowed down;the recovery rate of the excavation repair strength gradually increases with the decrease of the taper angle,and the growth trend gradually slows down.