正交异性钢桥面板疲劳裂纹的新型d36压电换能器阵列成像与评估方法

Local fatigues of the orthotropic steel deck are the common problem in bridge structures. They affect the safety and lifespan of bridge seriously, therefore it’s significant to study on the monitoring, modeling and diagnosis of local fatigue cracks in the orthotropic steel deck. Due to the invisibility and spatial disperse of fatigue cracks, monitoring on them are quite challenging. Using guided wave theory combined with imaging algorithm is an effective approach to overcome this problem. Aiming to fatigue cracks in orthotropic steel deck, this project proposes a novel in-plane shear piezoelectric transducer with high sensitivity to generate and sense zeroth order shear horizontal waves. Utilizing their non-dispersive characteristics, a Reverse-Time Migration (RTM) imaging method will be used to monitor, model and diagnosis the fatigue cracks in above structural members effectively. Firstly, the dispersion relationship, wave propagation and wave structures of guided waves in above waveguides will be analyzed. Harmonic and transient solutions with respect to guided waves under action of in-plane shear mode piezoelectric wafer will be sought. Secondly, analyzing the interaction between guided waves and cracks and adopting the RTM algorithm to image the damage. Then, investigating multi-level modeling and damage diagnosis of damage members based results of image processing. Lastly, the feasibility of above methods will be verified by experimental approaches, and a prototype damage imaging system will be developed.

正交异性钢桥面板局部疲劳是桥梁结构中普遍的病害，严重影响桥梁的安全与寿命。研究正交异性钢桥面板局部疲劳裂纹监测、建模与诊断具有十分重要的意义。由于该桥面板局部疲劳裂纹隐蔽性与空间分散性，对其监测颇具挑战性，采用导波并结合成像算法是解决该问题的有效途径。本项目针对正交异性钢桥面板局部疲劳裂纹，提出采用新型高灵敏面内剪切型d36压电换能器，激发和感知零阶水平剪切波；利用该模态导波的非频散特性，结合压电阵列时间反转偏移（Reverse-Time Migration，即RTM）成像算法对正交异性钢桥面板疲劳裂纹进行监测、建模与诊断。本项目首先对正交异性钢桥面板中导波的特征进行分析，并求解在d36压电换能器作用下导波的简谐与瞬态解；其次，分析导波与疲劳裂纹之间的相互作用，采用RTM算法对损伤清晰成像；基于图像处理结果对损伤构件多尺度建模与状态诊断；最后通过试验验证上述方法的可行性，集成损伤成像系统。

正交异性钢桥面板因其在力学特性、使用性能和经济性等方面所具有的突出优点，在国内外的各类型现代桥梁结构中得到了广泛应用。正交异性钢桥面板局部疲劳裂纹是该类型桥梁结构中普遍存在的病害，严重影响桥梁的安全与寿命，严重情况下的可能会引发不可预测的突发事故。研究正交异性钢桥面板局部疲劳裂纹监测、建模与诊断具有十分重要的意义。由于疲劳裂纹的隐蔽性与空间分散性，对其监测颇具挑战，采用导波并结合成像算法是解决该问题的有效途径。本项目针对正交异性钢桥面板局部疲劳裂纹，提出采用新型高灵敏面内剪切型d36压电换能器，激发和感知零阶水平剪切波；利用该模态导波的非频散特性，结合压电阵列算法对正交异性钢桥面板疲劳裂纹进行监测、建模与诊断。本项目理论分析了T型构件中导波传播特征；系统研究了d36型压电晶体激发板中水平剪切导波和Lamb波的方向性特征，并将其应用于板结构的损伤识别；研究了基于d36型压电相控阵的板结构损伤识别；研究了基于激光超声的正交异性钢桥面板损伤成像方法；在上述研究的基础上集成了d36相控阵成像系统以及基于激光超声的正交异性钢桥面板损伤成像系统。相关研究成果对进一步推动基于超声导波的结构损伤识别方法应用于实际工程结构具有重要意义。