This paper describes a visualization of cavity regions in a structure by a hammering test using the level set type topology optimization based on the concept of the phase field method. In this study, the residual between the calculated displacement and the observed displacement was defined as the performance function, and the identification problem of cavity regions was formulated based on the adjoint variable and finite element methods. The numerical experiments were performed to investigate the effect of the regularization parameter. According to this result, it was found that the number of cavities and the cavity shape were affected the regularization parameter. In addition, the numerical example of a three-dimensional problem was described.
