Compressive Mechanics Analysis Of Bonded Honeycomb Sandwich Structures Under Repaired

Composite material honeycomb sandwich structure in airplane is mainly formed by two upper and lower panels with large strength and one layer of thin and light sandwich laminate with low density. However, unexpected shocks, bird strikes, hail and so on. are unavoidable for airplanes during service, which may cause the damage of composite honeycomb sandwich structure. The flaw and damage of the structure may greatly reduce the bearing capacity of the structure. The repairing methods of the composite honeycomb sandwich structure are received more and more attention by the researchers.This paper uses ABAQUS as analysis platform, writes relating material constitutive UMAT, establish 3D FEM model and study the stability and compression performance of the honeycomb sandwich laminates after adhesive bonding repair.Firstly, the paper introduces the composite laminate theory of connection medium damage mechanics, sandwich structure equivalent theory and cohesive zone model. Based on the fundamental theories above, honeycomb sandwich 3D progressive damage model is established. Compared with experimental data, the feasibility of the 3D FEM model is validated, so that the damage simulation of the honeycomb sandwich laminate with adhesive bonding repair is achieved.Secondly, Based on the 3D damage model, the damage recovery capability and damage evolution process of the honeycomb sandwich laminate after scarf repair are analyzed. At the same time, the height of the honeycomb core's effects on laminates' critical buckling loads and failure mode are analyzed in further. The effects of scarf proportion, extra placements, the patch layer design, drilling diameter and other parameters on repair recovery strength and stress distribution and compared with single-side scarf repairs are also analyzed.Thirdly, the paper expands the honeycomb sandwich laminate with penetrating damage after two sided patch repair. The paper analyzes the buckling behavior and mechanical property under compressive pressure of sandwich laminate after patch-bonded repair, and discusses the effects of the patch thick Ness, overlapping length and patch layer design, drilling diameter and other parameters on repair recovery strength and stress distribution. Compared with single-side patch repairs are also analyzed.Finally, the research contents of the paper are concluded, and also the expectation of future work on drawbacks in this paper is proposed. The work can provide reference for the further design and analysis of the adhesive bonding repair on the honeycomb sandwich structure in future.