In this study, based on the wavelet transform, a method for detecting the location of a flaw in a rectangular plate is proposed. The strain histories caused by impact loads are measured by strain gauges which are mounted on the aluminum alloy rectangular plate with two longitudinal-side clamps while leaving the other two sides free. The wavelet transforms were applied to identify the group velocity of flexural waves which were measured and recorded by the strain gauges and a computer. Since the flexural waves in the plate would produce scattered waves when they propagated through the flaw of a plate, the measured signals of a strain gauge contented the direct waves propagated from the impact source and the scattered waves propagated from the flaw. The time lag between the direct wave and the scattered wave could be computed by using the simplex algorithm method. By comparing the group velocities of the flexural waves, and the time lag between the direct wave and the scattered wave, the exact location of the flaw could be found by the contour map containing the global minimum. The advantage of the method is that less expensive equipments is required to detect a crack or flaw on a structural plate. However, the method cannot detect the shape and the depth of flaws at the present stage. The proposed method may become a feasible alternative among non-destructive inspection methods for damage detection of structural members.
|Number of pages||14|
|Journal||Journal of Taiwan Society of Naval Architects and Marine Engineers|
|Publication status||Published - 2007 Sep 28|
All Science Journal Classification (ASJC) codes
- Ocean Engineering
- Mechanical Engineering