含胶接缺陷的椭球泡沫夹层结构破坏机理与承载能力研究

采用试验和有限元方法,对含胶接缺陷的椭球泡沫夹层结构在外压作用下的破坏模式和承载能力进行了研究。针对国内在研的大尺寸椭球泡沫夹层结构,实施了全尺寸静力外压试验,发现初始胶接缺陷破坏了夹层结构界面应力传递的连续性;随着载荷增加,面板发生皱褶且脱胶界面继续扩展,从而降低结构整体承载能力。通过红外无损检测确定了缺陷的类型和形貌;采用预留相应初始脱粘面积、脱粘间隙以及内聚力单元模拟界面脱粘的有限元分析方法,对含胶接缺陷的椭球泡沫夹层结构承载能力进行预测。数值结果表明:含胶接缺陷结构易发生面板皱褶,且结构顶部和根部区域较易发生界面脱粘扩展。数值和试验结果取得了较好的一致性,本文结果可为同类结构设计提供参考。

On the Failure Mechanism and Bearing Capacity of Ellipsoidal Foam-Core Sandwich Structure with Adhesive Bonding Defects

Failure mode and bearing capacity of ellipsoidal foam-core sandwich structure with adhesive bonding defects subjected to external pressure were studied based on experiment and finite element method (FEM). For a large-scale ellipsoidal foam-core sandwich structure in development, a full-size static external pressure experiment was carried out. Experimental results reveal that the initial adhesive bonding defects interrupt the transfer continuity of interfacial stress in the sandwich structure. With the increase of load, sheet wrinkling occurs and debonding interface propagates, resulting in carrying capacity degradation of whole structure. Based on the result of infrared non-destructive testing, the type and morphology of defects are determined. Adopting reserving the initial debonding area, debonding gap and cohesive element, the interfacial debonding process is simulated by FEM, the bearing capacity of ellipsoidal foam-core sandwich structure with adhesive bonding defects is predicted. Numerical results show that under external pressure, adhesive bonding defects easily lead to sheet wrinkling, and interfacial debonding propagation mainly occurs on the top and at the bottom areas of structure. Numerical simulation is in a good agreement with experimental results. Above results can be used as a reference for similar structure design.