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The sandwich structure is a composite constructed plate , The shell structure, its two surfaces are made of very thin sheet, and the intermediate is sandwiched with a lighter sandwich layer. The former is called the table board, which requires high strength; the latter is called a mezzanine and requires light weight. In the Second World War, in order to make full use of timber resources, the UK's "mosquito" bomber is used in full wooden interlayer structure. General laminated structure is used for air wings, tail, fuselage, arrow, arrow, reducer, engine short cabin, sound insulation device, fire partition, etc. Compared with thin-walled structure, the thickness of the sandwich plate is much larger, the resistance is strong, and the weight can be reduced, and the surface is smooth and the pneumatic shape is good. However, its manufacturing process is complicated, the process quality is not easy to test, so the application is limited. The material of the sandwich structure is aluminum alloy, stainless steel, titanium alloy, and various composites. The laminated material is lightweight wood, foam, etc., or a metal material or a composite material is made into a corrugated sheet sandwich or a honeycomb interlayer (see a honeycomb structure). The interlayer is generally adhesive with the table plate, or the welding, welding, and forming a whole. In the overall force analysis, it is believed that the upper two tablets are only subject to the pulling, pressure and shear force in the surface of the surface, and cannot withstand the bending moment and torque, and the intermediate interlayer only withstand the penetration perpendicular to the interlayer. The difference between the stripping structure and the general plate shell structure force analysis is that the impact of shear force is considered in addition to the deflection of the bending torque in the deflection calculation. There is a large distance between the two panels of the sandwich structure, so the bending stiffness of the sandwich structure is much larger than that of the general plate shell structure, and the critical stress of the instability is significantly improved. The sandwich structure itself does not have a rivet, except for the stress concentration caused by the pinhole, and improves the fatigue strength. The interlayer structure is complicated with adjacent structures, and the partial contact strength of the sandwich itself is weak, and the concentration force of the connection is required, and therefore the joint design must be properly performed.