运用激光剪切散斑技术结合负气压加载,实现了蜂窝夹层结构内部缺陷类型的分辨,并使用数值计算方法分析不同类型缺陷在负压加载下的力学变形差异。文章首先制备了一块预置不同类型缺陷的卫星用铝蒙皮铝蜂窝夹层结构,缺陷类型分别为:上胶层垫膜、下胶层垫膜、去胶层、去胶层垫膜、去胶层油膜以及铣去蜂窝芯,尺寸依此为:10 mm、20 mm、30 mm和40 mm；接着简单介绍了剪切散斑干涉的基本原理,运用自行研制的激光剪切散斑系统结合负气压加载对蜂窝夹层试块加载；然后通过数值计算方法对比分析不同类型缺陷在负气压加载下的力学变形机理；最后使用热辐射加载进一步对样品进行探伤测试,分析两种加载方式的优劣。实验结果表明,激光剪切散斑干涉技术结合负气压加载可有效分辨铝蜂窝夹层结构内部的脱粘和夹杂等类型缺陷,数值计算方法可进一步佐证了实验结果。本文的研究可为蜂窝夹层结构的缺陷检测、缺陷类型分辨以及缺陷的力学变形机理分析提供技术支撑。
In this paper,laser shearography combined with negative pressure was used to distinguish the internal defects types of honeycomb sandwich structure,and numerical method was also applied to analyze the mechanical deformation of different types of defects under negative pressure. Firstly,an aluminum honeycomb sandwich structure for satellite with different types of artificial defects was fabricated. The types of defects are as follows:upper debonding,lower debonding,debonding without glue,and cushion in debongding,oil film and milling honeycomb core. The defect sizes are as follows:10 mm,20 mm,30 mm and 40 mm. Based on the basic principle of shearography,the honeycomb sandwich was detected by a self-developed laser shearography system combined with negative pressure;then the mechanical deformation mechanism of different types of defects under negative pressure was analyzed by numerical method. Finally,the specimen was further tested by thermal radiation loading. The advantages and disadvantages of the two loading methods were discussed. The experimental results showed that laser shearography combined with negative pressure can effectively distinguish the debonding and impurity in the aluminum honeycomb sandwich structure,and the numerical calculation method can further confirm the experimental results. This research can provide technical support for defect detection,defect type identification and mechanical deformation mechanism analysis of honeycomb sandwich structure.