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This study proposes a new damage identification method based on topology optimization, combined with visualized ultrasonic wave propagation. Although a moving diagram of traveling waves aids in damage detection, it is difficult to acquire quantitative information about the damage, for which topology optimization is suitable. In this approach, a damage parameter, varying Young’s modulus, represents the state of the damage in a finite element model. The feature of ultrasonic wave propagation (e.g., the maximum amplitude map in this study) is inversely reproduced in the model by optimizing the distribution of the damage parameters. The actual state of the damage was successfully estimated with high accuracy in numerical examples. The sensitivity of the objective function, as well as the appropriate penalization exponent for Young’s modulus, was discussed. Moreover, the proposed method was applied to experimentally measured wave propagation in an aluminum plate with an artificial crack, and the estimated damage state and the sensitivity of the objective function had the same tendency as the numerical example. These results demonstrate the feasibility of the proposed method.

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The effect of configuration of quasi-unidirectional woven fabric on the compressive failure modes of quasi-isotropic composite laminates was investigated in this study. Two kinds of out-of-plane fiber waviness were formed in the composite laminates due to different quasi-unidirectional woven fabrics and measured using a fast Fourier transform method. The compressive failure modes of the composite laminates were identified using experimental and numerical methods. It was found that the compressive strength of a composite laminate fabricated using long-pitch weft fabrics was greater than that fabricated using standard-pitch weft fabrics. The relationship between the compressive strength and the configuration of quasi-unidirectional woven fabrics was investigated in a parametrical study, and four compressive failure modes were found: the axial compressive, normal, bending, and shear failure modes.