盾构机刀盘表面裂纹的激光声表面波检测技术研究

Shield machine is a kind of high-end mechanical equipment. Remanufacturing of the equipment meets the national green manufacturing development strategy demand. As an important construction component of shield machine, shield cutter suffers complex stress and will form cracks, which threat the construction safety. In this project, a surface crack detection technology of shield cutter head based on laser ultrasonic surface waves is proposed which combines the full-wave field detection technique and an unsupervised intelligent detection algorithm to analyze the measured waves signals, and realize quantitative characterization of structural cracks. The main research contents include: (1) Several three-dimensional finite element models are built to the interaction mechanism between the laser induced surface waves and the cracks, such as the reflection, the transmission and the mode conversion of the waves; (2) Based on the experimental platform of laser ultrasonic full-wave field detection, we will develop a signal reconstruction technique to improve defect characterization ability of the signals; (3) The mapping relationship between the surface crack size of shield cutter head and different ultrasonic surface wave parameters is constructed, and a quantitative defect evaluation model based on multi-feature fusion is developed with intelligent recognition algorithm. Finally, the quantitative detection of the surface crack of shield cutter head is realized with the above work. It provides guidance for the subsequent remanufacturing process of the cutter head.

盾构机是一种高端机械装备，对其进行再制造生产符合国家绿色制造发展战略的需求。刀盘作为盾构机的重要施工部件，工作中受力复杂易形成开裂，危及施工安全。本项目提出一种基于激光声表面波的刀盘表面裂纹检测技术，结合全波场检测技术和无监督智能检测算法对检测到的激光声表面波信号进行分析，实现结构裂纹的定量表征。主要研究内容包括：（1）构建刀盘三维有限元仿真模型，研究激光声表面波与表面裂纹的相互作用规律，包括波的反射、透射和模式转换等；（2）基于激光声表面波全波场检测试验平台，发展超声信号重构技术提升检测信号的缺陷表征能力；（3）构建刀盘表面裂纹尺寸同不同超声表面波参数间的映射关系，结合智能识别算法发展一种多特征融合缺陷定量评估模型。通过上述研究工作，最终实现盾构机刀盘表面裂纹的定量检测，为后续刀盘的再制造修复环节提供指导。

盾构机刀盘作为盾构机的关键核心部件，其安全运行至关重要，及时有效的对制作或运行过程中产生的缺陷进行检测识别具有重要研究意义。本项目重点选取刀盘部件中的焊缝区域作为重点研究对象，对焊缝区的表面缺陷进行激光声表面波的检测研究。主要研究了激光激励参数对Q345钢结构中入射激光声表面波的影响，优化选取得到最优激励参数组合；构建了小尺寸和大尺寸刀盘焊缝部位的激光声表面波与刀盘轮廓和裂纹缺陷的相互作用模型，得到了入射激光声表面波与焊缝和裂纹的作用规律，并实现了缺陷的定位识别和深度定量检测；采用参数化建模方法构建无缺陷和含表面裂纹缺陷的典型焊缝结构的三维仿真模型，研究了点源、线源激励激光声表面波对声表面波波场、信号位移及缺陷检测能力的影响，得出线源激励比点源激励具有更强的缺陷检测能力；提出基于波数滤波的波数分析法，成功应用于厚壁圆环结构内部分层缺陷和激光声表面波表面缺陷检测的定位检测和轮廓识别；编写了基于压缩感知的Lamb波波场重构算法，实现了无缺陷铝试件中Lamb波波场的重构。