基于超声检测的室温硫化硅橡胶涂层内部微小缺陷识别方法研究

Research on identification method of internal micro-defects in room temperature vulcanized silicone rubber coating based on ultrasonic testing

为探究高声衰减且较薄的室温硫化硅橡胶涂层内部气泡与裂纹微小缺陷对超声回波幅频特性的影响,本文建立了室温硫化硅橡胶绝缘材料内部微小缺陷超声检测的有限元仿真模型,分析了多种形态下微小缺陷的超声回波幅频特性及超声波传播过程,定义了气泡与裂纹缺陷的分界点。基于超声脉冲回波法对微小气泡与裂纹缺陷进行了超声检测试验。结果表明:裂纹缺陷相比于气泡缺陷具有较强方向性,在0°~30°之间回波幅值变化明显,可通过小角度检测来区分气泡与裂纹缺陷;当缺陷尺寸一定时,气泡缺陷在短长轴比0.2~0.4之间发生状态转换变为裂纹缺陷。该研究对开展防污闪涂料内部缺陷检测工作以及后续绝缘微小缺陷检测装置的研发具有重要的理论意义和工程价值。

In order to explore the influence of small defects of bubbles and cracks in the high-acoustic attenuation and thin RTV silicone rubber coating on the amplitude-frequency characteristics of ultrasonic echoes,a finite element simulation model for ultrasonic detection of small defects in RTV silicone rubber insulating materials was established.The ultrasonic echo amplitude-frequency characteristics and ultrasonic propagation process of tiny defects in various forms are analyzed,and the boundary point between bubbles and crack defects is defined.Ultrasonic testing of micro-bubble and crack defects was carried out based on ultrasonic pulse echo method.The results show that the crack defect has stronger directionality than the bubble defect,and the echo amplitude changes obviously between 0°and 30°,and the bubble and crack defect can be distinguished by small angle detection.When the defect size is constant,the bubble defects in the short-to-axis ratio of 0.2~0.4 state transit into crack defects.The internal defect detection of pollution flashover coatings and the development of subsequent insulation micro-defect detection devices have important theoretical significance and engineering value.