CFRP层合板初始冲击分层损伤的非线性动力诊断方法

Carbon fiber reinforced polymer (CFRP) laminated plates are easy to generate delamination damage subject to impact loads. Incipient delaminations would accumulate and develop, and then induce the entire destruction of structures. Hence, timely and accurately diagnosing incipient impact delaminations in CFRP laminated plates is of great significance. The method of diagnosing impact delamination damage based on structural dynamic characters is the current research focus. However, incipient impact delaminations have slight effect on structural dynamic characters, and can be hardly diagnosed by linear damage indices based on structural dynamic characters; on the other hand, incipient impact delaminations show explicit nonlinear harmonics characters. Under this situation, breaking through the limitation of linear damage indices and developing the nonlinear dynamics diagnosing method based on nonlinear harmonics can provide a new chance of diagnosing incipient impact delamination damage. This study aims to reveal the influence rule of incipient impact delaminations on nonlinear harmonics, propose the method of accurately extracting operating deflection shapes (ODSs) at nonlinear harmonics, establish nonlinear damage indices for locating and quantifying incipient impact delaminations, and conduct physical model experiments aided with the laser vibration measurement to validate the proposed theories and methods. The outcomes arising from this study can establish nonlinear damage indices that adapt to locating and quantifying incipient impact delaminations in CFRP laminated plates, which will provide theories and methods to ensure the safe and long-time operating of CFRP laminated plates.

碳纤维加强聚合物（CFRP）层合板在冲击荷载下易产生分层损伤，初始分层会积累发展，进而诱发结构发生整体破坏。因此，及时准确诊断CFRP层合板初始冲击分层损伤至关重要。基于结构动力特征的冲击分层损伤诊断方法是目前研究的热点。然而，初始冲击分层对结构动力特征影响微弱，现有基于结构动力特征的线性损伤指标难以对其进行诊断；另一方面，初始冲击分层表现出明确的非线性谐频特征。此现状下，突破线性损伤指标的限制，发展基于非线性谐频的非线性动力诊断方法，将为初始冲击分层损伤诊断提供新的契机。拟揭示初始冲击分层对非线性谐频的影响规律；提出非线性谐频工作变形（ODS）的准确提取方法；建立非线性损伤指标定位与定量初始冲击分层；开展激光振动量测支持的物理模型实验对提出的理论和方法进行验证。项目预期将建立适应CFRP层合板初始冲击分层定位与定量的非线性损伤指标，为CFRP层合板结构安全、长效运行提供理论与方法支撑。

CFRP层合板在冲击荷载下易产生分层损伤，初始分层会积累、发展，进而诱发结构发生整体破坏。因此，及时准确诊断CFRP层合板初始冲击分层损伤至关重要。本项目针对初始分层损伤对结构动力特征影响微弱，导致现有基于结构动力特征的线性方法难以对其进行诊断的问题，发展了基于非线性谐频的非线性动力诊断方法。揭示了初始冲击分层产生非线性谐波的机理，提出了非线性谐频工作变形的准确提取方法，建立了定位与定量初始冲击分层的非线性损伤指标，同时开展了激光振动量测支持的物理模型实验对提出的理论和方法进行验证。项目取得研究成果如下：（1）提出了CFRP层合板多分辨率面域振动能量表征分层损伤的理论与方法，其核心的新型物理量——多分辨率面域振动能量反映了结构面域局部微元振动能量，同时具有抵抗环境噪声干扰的能力。（2）提出了CFRP层合板非线性动力摄动刻画分层损伤的理论与方法，从非线性动力平衡方程出发提出了非线性动力摄动新概念，使用非线性动力摄动构造非线性损伤指标定量刻画分层损伤。本项目提出的CFRP层合板初始冲击分层损伤非线性动力诊断方法为CFRP层合板结构安全、长效运行提供了理论与方法支撑。凭借本项目研究成果，项目负责人入选“江苏省青年科技人才托举工程”和“香江学者计划”，以第一/通讯作者在领域一流期刊发表论文6篇，在国内外学术会议做报告10次，其中3次担任分会场主持人。