Volume 37, Issue 6 (November 2009)
An Efficient Inverse Method for Identification of the Location and Time History of an Elastic Impact Load
An inverse method to identify the location and time history of a single elastic impact load based on the time dependent structural responses is presented. At first, the unknown impact location is found through an inverse analysis without any information about the time history of the load. Two different methods are presented for the location identification. In both methods, an objective function expressing relationship between pairs of structural responses is minimized to find the optimal impact location. In the first method, the steepest descent technique is used to find the impact location precisely. In the second method, a zero-order search technique is developed for fast, but a little less accurate, identification of the impact location. After determining the location, the time dependent value of the impact load is reconstructed using the least-squares method. In-plane strain and its time integrals at sampling points are used to find the location and history of the impact load. In case of high strain fluctuation, time integration of strain removes fluctuations without introducing any additional error. This significantly simplifies the time history determination of the impact load. Two examples are presented to show the validity and effectiveness of the proposed method.