摘要
复合材料已成为现代飞机制造的非常重要的选材,复合材料结构R区缺陷会影响其受力和传载。R区开敞性差、声波反射复杂等影响超声检测及其缺陷识别与定量评估。为此,基于超声波在R-区的反射行为,利用宽带窄脉冲超声反射回波时域特征和成像特征进行复合材料结构R区缺陷检测与量化评估及层深定位。计算结果表明,入射角小于3°时,可以获得较好的声波透射效果。试验结果表明,入射声波在R区蒙皮表面、底面、层间、分层形成的反射信号具有明显不同的时域特征和B-扫描图像特征,对于12个铺层的R-区蒙皮,不同深度分层波幅变化不超过2.5 d B;分层深度定位准确性达1个铺层内;采用水膜方法可以获得稳定的超声耦合效果;利用所使用的换能器及检测系统的超声B-扫描成像,可以直观地再现入射声波在复合材料R区的反射行为,有效地揭示R区分层缺陷深度分布、取向长度;检测分辨率和表面检测盲区可以达到单个复合材料铺层的厚度,约0.125 mm。解剖结果验证了实际超声检测结果的正确性。为复合材料结构R区提供了一种非常有效的检测技术和缺陷定性定量方法,已经得到了非常重要的实际检测应用。
Currently composites are one of the most important materials for advanced aircrafts. Defects in R-zone of composite structures have effect on their loading abilities and load transfer. The accessibility of R-zone, complex sonic reflections, etc., affect R-zone ultrasonic inspection and defect discrimination as well as its quantitative evaluation. A broad-band short pulse ultrasonic technique was developed to be used to implement R-zone non-destructive testing and defect quantitative evaluation based on ultrasonic reflection behaviors in it. The basic calculated results show a good ultrasonic penetration can be reached when incident angle is small than 3 degrees. The ultrasonic testing results show out the remarkable differences in time-domain reflected signals and B-scan images, which resulted from the front surface, back surface, delaminations and interlaminar of R-zone. The difference of echo signal amplitude from different depth delaminations is not more than 2.5 d B for a 12-ply R-zone skin. The accuracy of delamination localization in depth is within 1 ply. A stable ultrasonic coupling between transducer and R-zone surface can be obtained by the used water-film technique. The ultrasonic reflection behaviors of incident waves in R-zones can be visualized well by using B-scan and the employed ultrasonic transducer and system. The distributions of delaminations in the section of R-zone are exhibited very well by the B-scan imaging method. The ultrasonic surface dead-zone and depth resolution can reach to a single ply thickness（approximately 0.125 mm）. The destructive testing has demonstrated the correction of ultrasonic evaluation result of the delamination to be found out in R-zone in a real composite structure by using this technique. It provides a very powerful quantitative nondestructive testing and evaluation method for R-zone in composite structures, which has obtained very important practical applications.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2017年第12期35-43,共9页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(61571409
60727001)
关键词
复合材料
超声反射行为
R区
超声检测
缺陷识别与分层层深定位
composites
ultrasonic reflection behavior
R-zone
ultrasonic evaluation
defect discrimination and delamination depth localization in ply
