无基准信号的复合材料层合板主动Lamb波损伤诊断方法研究

The project is intended to develop a baseline-free damage diagnosis methodology for anisotropic laminated composite plate structures based on the time reversal theory. Following the three-dimensional elastic theory and wavelet-based finite element method (WSFE), the Lamb wave propagation model for anisotropic laminated composities are proposed, and the mechanism and influencing factors of Lamb wave-mode tuning for anistropic laminated composites using the pizeoelectric ceramic wafers are investigated. In addition, a Lamb wave propagation model based on Reddy's higher-order shear deformation plate theory and WSFE method is developed, where the accuracy of low-order Lamb wave modes are satisfied and the computational cost is significantly reduced. Furthermore, a Lamb wave propagation model with higher-order plate theory including common types of damages is also proposed. Furthermore, utilizing the proposed Lamb wave propagation model with damages, the project is focused on the influence local damages of anisotropic laminated composite plates on the Lamb wave propagation and time reversal properties. Based on analyzing the side and main bands of the reconstructed signals, the methodology for weighted composed imaging of damaged areas, damage type identification and geometric parameter characterization are investigated in depth. The correctness and feasibility of the proposed wave propagation model and damage diagnosis methodology are fully validated by experiments. It's expected to provide new ideas together with theoretical and experimental supports for the research areas of non-destructive damage diagnosis with guided wave technique for composite structures.

本项目旨在基于时间反转理论建立一种不依赖于健康基准信号的层状各向异性复合板损伤诊断方法。基于三维弹性理论与小波谱有限元（WSFE）方法建立层状各向异性复合材料Lamb波传播三维理论模型，并研究基于压电陶瓷晶片激励的层状复合材料基体Lamb波模态调谐机理及影响因素；提出一种基于Reddy高阶剪切变形板理论和WSFE方法的Lamb波传播模型，满足低阶Lamb波模态精度情况下显著减少计算量，并发展一种含常见类型损伤波传播高阶板理论模型；基于提出的含损伤Lamb波传播模型着重研究层状各向异性复合板局部损伤对Lamb波传播特性及时间反转效应的影响，并深入探讨以时间反转重构信号主、旁瓣分析为基础的损伤区域加权复合成像定位、损伤类型判别以及几何参数定征方法。通过实验全面验证所提出理论、模型及方法的正确性和可行性，以期为复合材料结构导波无损检测领域提供新思路及相关理论支撑与试验依据。

脱层是复合材料层合结构最主要的破坏形式之一，对脱层等缺陷进行早期检测与监控具有重要意义。Lamb波作为最常见的一种导波形式，具有沿传播路径衰减小、传播距离远等特点，并对结构的微小损伤敏感，对板状结构大面积无损检测具有很大的优势。本项目主要基于时间反转理论与贝叶斯统计方法建立一种不依赖于健康基准信号的复合板结构损伤统计检测方法。基于线弹性理论与谱有限元方法建立一种含表面缺陷板状结构的弹性波传播模型，研究表面裂纹板的弹性波传播特性，并掌握弹性波与板中缺陷的作用规律；发展一种基于贝叶斯统计系统识别方法与信息熵理论的板状分布参数结构体系的传感器/激励器优化布置方法，为复合材料板传感器/激励器优化布置提供理论支持；基于有限元法和传递矩阵法，提出一种表面周期性粘贴压电片的轴-弯耦合铁木辛柯梁的弹性传播模型，用以指导基于压电材料激励的周期复合材料板导波诊断中的激励频带范围的合理选取；建立一种基于谱有限元法与分层模型原理的含纵向脱层、内嵌及横向开口缺陷的通用波传播模型，并掌握脱层引起的波传播变化规律；基于时间反转理论，发展了一种基于贝叶斯理论与蒙特卡洛马尔科夫链模拟方法的无参考信号主动Lamb波缺陷定位方法，以实现板状结构的缺陷位置、特定模式波传播速度及其不确定性程度识别；通过理论建模、数值仿真以及实验室模型实验，对所提出理论、模型及方法的正确性与可行性进行验证。数值仿真及实验结果均表明，本项目方法不依赖于结构健康状态信号，而直接利用当前采集信号，能有效处理主动Lamb波损伤诊断中的不确定性因素，实现结构损伤的统计定位，本项目研究成果为复合材料结构导波无损检测领域提供新思路及相关理论支撑与实验依据。