复合材料板损伤的多尺度伪荷载表征与扫振诊断理论

Damage, e.g., matrix cracking and delaminations, inevitably occurs in in-service composite plates. Occurrence of damage in a composite plate probably induces the destruction of entire structures with the plate as an element. Hence, diagnosis of damage in composite plates is of significant importance. Technologies on sensing plate's responses and theories on identifying damage in plates are a pair of key factors on diagnosis of composite plates. There exists a contradiction between these two key factors: the latter falls behind in progress relative to the former, and the lag of the latter is significantly manifested by the lack of advanced damage identification theories that can be equipped to the modern Scanning Laser Vibrometer (SLV) to produce sophisticated damage diagnosis technologies. To address this problem, the traditional motion equation of a plate is promoted to the multiscale vibration equation of the plate by using the multiscale theory; based on this multiscale vibration equation, new theories for identifying damage in composite plates, which matches the SLV-supported scanning vibration measurement technology, will be explored. The main tasks of this project include: the normative mode capable of characterizing damage by pseudo loads will be proposed, from which the new theory for diagnosing damage in composite plates will be created. Furthermore, to increase the immunity against noise, the normative mode capable of characterizing damage by multiscale pseudo-load will be constructed, from which the innovative theories for identifying damage in composite plates under noisy environments will be established. Moreover, a model of multiscale pseudo-load fusion will be built to diagnose multiple damage in composite plates. In the end, experiments will be conducted to validate the proposed theories and methods. The anticipated theories hold promise for providing a theoretical support for advancing the technologies for diagnosing damage in composite plates, and therefore supplying the scientific basis to ensure the safety of structural systems utilizing composite plates.

在役复合材料板不可避免会产生基体开裂、分层等损伤，损伤可能引发结构整体破坏。因此，对复合材料板进行损伤诊断至关重要。复合材料板损伤诊断以“板响应传感技术”和“板损伤诊断理论”为核心要素，目前两者之间存在诊断理论滞后于传感技术的矛盾，突出表现为缺乏与新兴的SLV支持的激光扫描振动量测（SLV扫振）相适应的损伤诊断理论。针对该问题，引入多尺度理论，将板振动方程提升为板多尺度振动方程；以其为力学基础，对SLV扫振支持的复合材料板损伤诊断理论进行探索，主要研究：提出复合材料板损伤的伪荷载表征范式与损伤诊断原理；提出复合材料板损伤的多尺度伪荷载表征范式与损伤诊断理论；建立多尺度伪荷载融合的复合材料板多损伤诊断模型；开展物理模型实验，检验所提理论与方法。预期成果有望建立与SLV扫振相适应的复合材料板损伤诊断理论，为推动复合材料板损伤诊断技术发展提供理论支撑，为保障复合材料板结构系统安全提供科学依据。

复合材料板在服役过程中不可避免会产生基体开裂、分层等损伤，损伤可能引发结构整体破坏。因此对复合材料板进行损伤诊断至关重要。采用激光扫描振动仪（Scanning Laser Vibrometer: SLV）量测复合材料板振动响应，对复合材料板进行损伤诊断是领域研究热点。现有相关研究工作大多强调激光振动传感技术的先进性，而对基于激光扫描振动的复合材料板损伤诊断理论研究不足。当前研究工作呈现出复合材料板诊断理论滞后于激光振动传感技术的矛盾，突出表现为与激光扫描振动量测相适应的损伤诊断理论十分缺乏。针对这一问题，该项目采用理论分析、数值模拟和模型试验相结合的研究手段，探索适应激光扫描振动的复合材料板损伤诊断理论与算法，在SLV扫描复合材料板振动响应的框架下，提出了呼吸裂缝非线性伪荷载表征范式，打破了由线性动力特性反映复合材料呼吸裂缝的局限性；建立了Teager 能量算子 (TEO) 与小波变换 (WT)模态振型融合的复合材料结构多损伤多尺度抗噪检测理论，该理论具有噪声免疫力强、损伤敏感性强的本质优势；提出了抗噪声的小波二维模态曲率识别板状结构中非均匀裂缝的算法，提出了基于面域模态二维方向性连续小波变换的板式结构损伤检测算法，提出了基于动态平衡扰动和横向伪荷载的复合结构裂缝识别方法；开展了对具有缺口和分层的CFRP层压板激光扫振实验等8个模型实验，对所提出的理论和方法进行检验和验证。该项目产出14篇高水平科学索引期刊论文；申请发明专利6项，其中获授权2项；培养研究生5名；主办第5届国际结构健康监测与完整性管理学术会议、第42届国际振动工程会议和“一带一路”基础设施安全与健康外国高端专家论坛。项目组以项目研究成果作为重要支撑获2021年获教育部自然科学奖1项。