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| Damage imaging and testing in CFRP laminates based on Lamb wave sparse array |
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Abstract A minimum redundancy sparse array is adopted to realize high resolution and accurate damage imaging and testing in CFRP laminates, by taking into account both energy skew effect and dispersion compensation. Due to complex material characteristics of composite laminates, directions of phase velocity and group velocity are in general different. The Lamb wave wavenumber curve of single mode with its geometric relationship is used to calculate the skew angle, resulting in correct direction of the damage. In order to avoid the dispersive phenomenon, the damage imaging algorithm is presented in frequency domain by applying phase delay to each frequency component, leading to right position of the damage. Besides, a minimum redundancy linear array is introduced to design a cross shaped sparse array for cutting down the cost on the base of ensuring the imaging quality. Method proposed in this paper is validated through simulation images, which can help with the experiment well. All images in the damage inspection experiment show that, with skew angle and dispersion consideration, using the sparse array can not only achieve accurate location of the damage, but can also improve the spatial resolution of the damage with a limited number of array. It can be concluded that this method has great potent in damage detection in the composite structure field.
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Received: 22 February 2018
Published: 28 August 2018
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2018, Vol. 39 
