Multimode Testing for Delamination Defects of Composite Materials Using Ultrasonic Guided Waves

Delamination defects are one of the typical defects of composites materials. Due to the complex distributions of delamination defects, it is hard to use one mode of guided waves to detect delamination defects with different distributions. Thus a multimode testing method is highly demanded. Apply semi-analysis finite element (SAFE) method to calculate dispersion curves and wave structure. Several mode-frequency points from dispersion curves will be selected to do finite element simulation for delamination defects with different sizes but the same depth of composite materials plates. Then analyzes the sensitivity of guided waves for different delamination defects. The sensitive modes are selected to do defects testing experiments for composite materials plate with different delamination defects. The results show that using two or more mode-frequency points can detect out delamination defects with different sizes.