基于超声导波的钢桥面板纵肋对接焊缝疲劳裂纹检测方法

纵肋对接焊缝疲劳开裂作为钢桥面板结构的重要失效模式之一,严重危害桥梁结构耐久和安全运营。通过引入超声导波技术,结合对接焊缝的几何特点与疲劳失效特征,建立了基于超声导波的钢桥面板纵肋对接焊缝疲劳裂纹检测方法。首先搭建了超声导波裂纹检测试验系统,并结合钢桥面板纵肋对接焊缝疲劳试验,对超声导波检测纵肋对接焊缝裂纹的适用性和准确性进行了验证。在此基础上,通过数值分析方法探究了超声导波在纵肋对接焊缝局部区域的传播机制,并进一步分析了不同焊缝与裂纹参数对超声导波传播的影响规律。研究结果表明:采用超声导波方法能够有效检测钢桥面板纵肋对接焊缝的疲劳裂纹,并确定疲劳开裂的位置;超声导波有限元理论分析与试验测试结果符合较好,验证了有限元模型的正确性;采用单面激励的方式在纵肋中形成的超声导波包括A₀和S₀模态,其中A₀模态占主要部分,超声导波传递至焊缝形成的反射波以A₀模态为主,而较深裂纹形成的反射波以S₀模态为主;不同焊缝和裂纹参数对超声导波的反射波和透射波表现为差异性的影响。所采用的基于超声导波的对接焊缝疲劳裂纹检测方法,可为钢结构桥梁疲劳损伤的检测与监测提供科学依据。

Fatigue Crack Detection Method Based on Ultrasonic-guided Waves for the Longitudinal Rib Butt Weld of Steel Decks

Fatigue cracking in longitudinal rib butt welds is one of the typical failure modes of orthotropic steel deck structures and seriously endangers the durability and safe service of bridge structures. Therefore, considering the geometric features and fatigue failure characteristics of the butt weld, a fatigue crack detection method for the butt weld of the longitudinal rib of orthotropic steel decks based on ultrasonic-guided waves was established. First, an ultrasonic-guided wave crack detection test system was set up. The applicability of the system and accuracy of the ultrasonic-guided wave detection method on the longitudinal rib butt weld cracks were verified by a fatigue test on the longitudinal rib butt weld of the orthotropic steel decks. On this basis, a numerical analysis method was used to investigate the propagation mechanism of ultrasonic-guided waves in the local longitudinal rib butt weld areas, and the influence of the different weld and crack parameters on the propagation of ultrasonic-guided waves was further analyzed. The research results showed that the ultrasonic-guided wave method can be used to effectively detect fatigue crack in the butt weld of the longitudinal rib of an orthotropic steel deck and determine the position of the fatigue crack. The finite element analysis of the ultrasonic guided-wave was in good agreement with the experimental test results, thereby verifying its accuracy. The ultrasonic-guided waves formed in the longitudinal ribs were mainly A0 and S0 mode waves using single-sided excitation, where the A0 mode accounted for majority. The reflected wave formed by the transmission of the ultrasonic-guided wave to the weld was dominated by the A0 mode, whereas the reflected wave formed by the deeper crack was dominated by the S0 mode. The different weld and crack parameters showed different effects on both the reflected and transmitted ultrasonic-guided waves. The ultrasonic-guided wave-based fatigue crack detection method for the butt weld can provide a scientific basis for the detection and monitoring of fatigue damage in steel bridges.