Boundary condition identification by solving characteristic equations

The behaviour of a mechanical structure in the lower frequencies is dominat ed by constraints at the boundaries. Most structures have elastic supports and specifying the boundary conditions requires knowledge of the support pa rameters. In this paper, a new method is developed to determine the boundar y parameters based on the solution of reduced order characteristic equation s. The order of these non-linear equations is equal to the number of bounda ry degrees of freedom which is a small fraction of, the order of the full s tructure and means that the amount of computation is not excessive. In this approach, no ill-conditioning occurs, which is a common problem in other i dentification procedures. The method is demonstrated by identifying the bou ndary parameters of a plate on elastic supports by using experimental test data. (C) 2001 Academic Press.