基于多目视觉光流跟踪的航空发动机薄壁件工作模态测试方法

The accurate and efficient acquisition of operating modal parameters of the aero-engine thin-walled parts is the precondition and the base to investigate the vibration behaviors analysis and the structural damage identification of the aero-engine thin-walled parts. Aiming to the problems that the existing modal testing methods can not satisfy the special requirements of the operating modal testing for the aero-engine thin-walled parts, the method of operating modal testing for aero-engine thin-walled parts based on multi-camera vision and optical flow tracking is proposed by utilizing the advantages of the method of machine vision and optical flow tracking, such as non-contact, high full-field spatial resolution, multi-direction vibration measurement at one measurement point, and so on. The research is specified as the following four aspects. Firstly, the constraint modal analysis models for aero-engine thin-walled parts are built by taking the complicated boundary conditions of screw connection and pipeline connection into account. Secondly, the influence regularities of the working condition stimulation and boundary conditions to the aero-engine case are obtained by the simulation and experiment. Thirdly, the vibration measurement method for multi-view contact motion object based on multi-camera vision and optical flow tracking is investigated. Fourthly, the identification method of operating modal parameters for aero-engine thin-walled parts is investigated, the false modal are rejected, the harmonic modal are separated, the dense frequency modal are identified, and the operating modal parameters of the aero-engine thin-walled parts are obtained accurately at last. The project can provide theoretical and technological support for the dynamic behavior analysis, structure optimization design, and fault diagnosis of the aero-engine.

航空发动机薄壁件工作模态参数的准确高效获取是开展航空发动机薄壁件振动特性分析和结构损伤识别等研究的前提和基础。针对现有模态测试方法难以满足航空发动机薄壁件工作模态测试特殊要求的问题，利用机器视觉光流跟踪方法的非接触、全场高空间分辨率、单测点多向振动测量等优点，提出基于多目视觉光流跟踪的航空发动机薄壁件工作模态测试方法，具体进行以下四个方面的研究：(1)考虑螺栓联接和管道连接等复杂边界条件，建立航空发动机薄壁件约束模态分析模型；(2)仿真和实验测试获得工况激励下和边界条件对机匣工作模态参数的影响规律；(3)研究基于多目视觉光流跟踪的多视点关联运动目标振动测量方法；(4)研究航空发动机薄壁件工作模态参数识别方法，剔除虚假模态、分离谐波模态、识别密频模态，获得准确的航空发动机薄壁件工作模态参数。项目研究可为航空发动机的振动特性分析、结构优化设计和振动故障诊断等提供理论与技术支撑。

项目提出研究了基于多目视觉光流跟踪的航空发动机薄壁件工作模态测试方法。开展了螺栓连接预紧力、连接界面摩擦系数、连接螺栓松动等不同边界条件对螺栓联接航空发动机机匣模态频率的影响规律研究，获得了不同边界条件对螺栓连接机匣各阶模态频率的影响程度；开展了基于虚拟标记匹配跟踪的薄壁件振动模态测量方法、基于单目视觉光流跟踪的薄壁件振动模态测量方法、基于视觉放大光流跟踪的薄壁件微幅振动测量方法和基于双目视觉目标跟踪的薄壁件全向振动测量方法研究，通过振动模态测试实验，充分验证了振动模态测量方法的可行性和准确性；开展了协方差驱动的随机子空间工作模态参数识别方法和平均相关函数协方差驱动的随机子空间工作模态参数识别方法研究，开展了薄壁件工作模态测试实验，准确获取了未知激励条件下的薄壁件工作模态参数。项目研究可为航空发动机的振动特性分析、结构优化设计和振动故障诊断等提供理论与技术支撑，成果有着广泛的应用前景。