Lamb波稀疏阵列CFRP层合板损伤成像检测

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.