激光全息法检测固体药柱包覆层缺陷

Testing of defect for solid grain coating by laser holographic interferometry

随着航天火箭技术的迅速发展,如何检测具有较厚（大于4 mm）包覆层药柱的内部小尺寸（小于8 mm）缺陷成为一个需要解决的关键问题。基于光干涉原理,采用激光全息无损检测方法测量了不同包覆层厚度药柱内部小尺寸缺陷的全息图谱,确定了包覆层厚度以及缺陷尺寸对药柱形变的影响。结果发现当包覆层厚度为6 mm时,能够检测的缺陷临界尺寸为2 mm。如果缺陷尺寸小于2mm,则无法获得清晰的干涉条纹。同时利用获得的全息图谱计算了2~6 mm包覆层药柱缺陷尺寸的实际大小,误差平均值结果小于5%。最终结果表明：用激光全息法检测包覆层厚度大于4 mm、包覆层脱粘缺陷小于8 mm的药柱是一种准确、有效的无损检测手段。

With rapid development of space rocket technology,a key problem needs to be solved.How is small size defect（less than 8 mm） in grain with large coating thickness（greater than 4 mm） detected The holographic maps of solid grains with different thickness were gained by using laser holographic interferometry.The effects of coating thickness and defect size on the deformation of grain were investigated.When coating thickness was fixed at 6 mm,the available detected threshold limit size of defect was about 2 mm.If the sizes of defect were less than 2 mm,distinct interference fringes were not obtained.The actual sizes of defects located between coating with thickness 2-6 mm and grain were calculated by experimental data.Verified by experiment,the average values of the error were less than 5%.Final results indicate that the nondestructive laser holographic interferometry is a kind of valid and accurate method for measuring unbonded defect（less than 8 mm） between coating and grain with coating thickness above 4 mm.