Ultrasonic Method for 2D Stiffness Recognition

Impact damages in composite structures are always accompanied by material degradation, manifested as spatial stiffness variation. To monitor the health condition of the structures, researchers adopted non-destructive ultrasonic methods to continually identify the elastic properties, which, however, are confined to one-dimension scale. As a matter of fact, Impact damages in composites distribute unevenly inside the structures, necessitating material inspection globally. In this paper, a local wavenumber imaging method for global stiffness recognition was proposed. As a pre-research for anisotropic composites, a simple case of metal plate with reduced local stiffness is firstly studied by finite element methods. Results show that the 2D stiffness of the damaged area in the metal plate has obvious change, implying the feasibility of the local wavenumber method for 2D stiffness identification in composite materials.