Lamb波稀疏阵列CFRP层合板损伤成像检测

Damage Detection in CFRP Laminates Using Sparse-array Lamb-wave Imaging

针对Lamb波阵列成像方法检测复合材料板时存在偏斜效应、频散及密集阵列成像分辨率低的问题,论文采用引入偏斜角修正的相位延迟叠加方法结合最小冗余度线性阵列（MRLA）实现了碳纤维增强复合材料（CFRP）层合板损伤的准确成像检测.根据Lamb波单一模态的波数曲线计算各方向的偏斜角,确保成像中损伤所在方位角的准确性;在频域中对每个频率成分进行相位延迟以弥补频散,确保成像中损伤所在位置的精度;利用MRLA设计十字型稀疏阵列,既降低了阵列成本,又保证了损伤成像质量.数值模拟成像结果验证了论文提出方案的有效性,实验成像结果凸显了十字型稀疏阵列在节约阵列成本、提高损伤空间分辨率方面的优越性,对工程实践中CFRP板结构的损伤检测具有一定的指导意义.

A sparse array with minimum redundancy is adopted to realize high-resolution imaging for accurate damage detection in CFRP laminates,by taking into account both the energy skew effect and dispersion compensation.Due to the complex material characteristics of composite laminates,directions of phase velocity and group velocity are usually different.The geometric relation of wavenumber curve for single-mode Lamb wave is used to calculate the skew angle,ensuring the correctness of the damage direction.To avoid the interference from dispersion,an imaging algorithm for damage detection is then presented in the frequency domain by applying the phase-delay method to each frequency component,so that the precise damage position is obtained.Besides,a linear array with minimum redundancy is introduced to shape the intensive array into a sparse array with larger array aperture,which can not only cut down the array cost,but also ensure the quality of image.Considering the mirror-image phenomenon of the linear array withminimum redundancy,a cross-shaped sparse array is designed by selecting two linear arrays with minimum redundancy that are perpendicular to each other.The method proposed in this paper is validated through the simulation images,which can provide reliable theoretical guidance for experimental research.In the damage inspection experiment,cross-shaped arrays with different array apertures are arranged to receive signals.All the damage imaging results show that,with the skew angle and dispersion considered,and using the sparse array optimized by the minimum redundancy principle,the accurate damage location can be achieved,and the spatial resolution of the damage is greatly improved with a limited number of arrays.It can be concluded that this method has a great potential for damage detection in the composite structure field.