钛合金疲劳裂纹的线性和非线性 超声综合定量检测技术

钛合金航空部件的低周疲劳裂纹在常规线性超声检测技术中易被低估，是飞机服役的安全隐患。针对上述问题开展了钛合金疲劳裂纹的非线性超声调制检测及其定量技术研究，提出了钛合金疲劳裂纹的线性和非线性超声综合检测方法。首先，通过金相法和线性超声相控阵检测技术对疲劳裂纹进行定量检测；其次，搭建了抗干扰能力强的非线性超声调制检测系统并设计了传感器布置方法；最后，基于声场分布分析提出疲劳裂纹的非线性超声调制定量方法，并将其定量检测结果与超声相控阵检测技术相对比。研究结果表明，超声相控阵方法测量的宏观裂纹长度为12 mm,而非线性超声方法测量的微裂纹延伸至距窄槽端部20 mm处，非线性调制检测技术在检测微裂纹和闭合裂纹具有显著优势。

The combination detection technology of the linear and the nonlinear ultrasound for fatigue cracks in titanium alloys

Low-cycle fatigue cracks of titanium alloy aerospace components are easily underestimated by conventional linear ultrasonic inspection technology, which is a potential safety hazard for aircraft service. In the research, the modulation nonlinear ultrasonic detection and quantitative technology of fatigue cracks in titanium alloys were carried out. A combination of the linear and the nonlinear ultrasonic quantitative method was proposed for the fatigue cracks in titanium alloys. Firstly, the fatigue crack is quantitatively detected by the metallographic method and the ultrasonic phased array technology. Secondly, a modulation nonlinear ultrasonic detection system and a sensor arrangement method are designed for strong anti-interference ability. Finally, a modulation non-linear ultrasonic quantitative method for fatigue cracks is proposed based on the analysis of the sound field distribution, and the quantitative detection results are compared with ultrasonic phased array detection technology. The research results indicate that the length of the macro-crack measured by the ultrasonic phased array method is 12 mm, while the micro-crack measured by the nonlinear ultrasonic method extends to a distance of 20 mm from the end of the narrow groove. Thus, the non-linear modulation detection technology has more significant advantages in detecting micro-cracks and closed cracks.