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.

[1]  Jennifer E. Michaels,et al.  Determination of Dynamic Forces From Wave Motion Measurements , 1986 .

[2]  James F. Doyle,et al.  Further developments in determining the dynamic contact law , 1984 .

[3]  A. Tikhonov,et al.  Numerical Methods for the Solution of Ill-Posed Problems , 1995 .

[4]  Hisao Fukunaga,et al.  An efficient approach for identifying impact force using embedded piezoelectric sensors , 2007 .

[5]  James F. Doyle,et al.  A genetic algorithm for determining the location of structural impacts , 1994 .

[6]  Enboa Wu,et al.  On the Inverse Problem of Rectangular Plates Subjected to Elastic Impact, Part II: Experimental Verification and Further Applications , 1995 .

[7]  Per Christian Hansen,et al.  Analysis of Discrete Ill-Posed Problems by Means of the L-Curve , 1992, SIAM Rev..

[8]  E. G. Yanyutin,et al.  Identification of an impulse load acting on an axisymmetrical hemispherical shell , 2004 .

[9]  Jennifer E. Michaels,et al.  The inverse source problem for an oblique force on an elastic plate , 1985 .

[10]  J. F. Doyle,et al.  Impact force location in frame structures , 1996 .

[11]  Xu Han,et al.  An inverse procedure for identification of loads on composite laminates , 2002 .

[12]  James F. Doyle,et al.  Determining the contact force during the transverse impact of plates , 1987 .

[13]  Keeyoung Choi,et al.  Identification of Impact Force and Location Using Distributed Sensors , 1996 .

[14]  James F. Doyle,et al.  An experimental method for determining the dynamic contact law , 1984 .

[15]  James F. Doyle,et al.  An experimental method for determining the location and time of initiation of an unknown dispersing pulse , 1987 .

[16]  J. Reddy.  An introduction to the finite element method , 1989 .

[17]  Enboa Wu,et al.  On the Inverse Problem of Rectangular Plates Subjected to Elastic Impact, Part I: Method Development and Numerical Verification , 1995 .

[18]  James V. Beck,et al.  Parameter Estimation in Engineering and Science , 1977 .