BOUNDARY CONDITION IDENTIFICATION BY SOLVING CHARACTERISTIC EQUATIONS

The behaviour of a mechanical structure in the lower frequencies is dominated by constraints at the boundaries. Most structures have elastic supports and specifying the boundary conditions requires knowledge of the support parameters. In this paper, a new method is developed to determine the boundary parameters based on the solution of reduced order characteristic equations. The order of these non-linear equations is equal to the number of boundary degrees of freedom which is a small fraction of the order of the full structure and means that the amount of computation is not excessive. In this approach, no ill-conditioning occurs, which is a common problem in other identification procedures. The method is demonstrated by identifying the boundary parameters of a plate on elastic supports by using experimental test data.