The location of spring supports from measured vibration data

Detecting the position of supports within an elastic structure has many app lications, particularly when these supports are not fixed. Previous studies have presented methods for the detection of translational support location s in elastic structures based on the minimization of the difference between the measured and computed natural frequencies. However, these discrete sup ports were constrained to be at nodes of the finite element model of the el astic structure. This required a fine mesh and the numerical computation of the eigenvalue derivative with respect to the support location. This paper has the same purpose, namely to identify the support locations, but the po sition of the supports is now a continuous parameter. When the support is l ocated within an element the shape functions are used to produce the global stiffness matrix. The advantage is that the support location now appears e xplicitly in the formulation of the problem, and hence the analytical compu tation of the eigenvalue derivative is possible. Furthermore, the mesh may be much more coarse, requiring fewer degrees of freedom to detect the suppo rt locations, with reduced computational effort. The effect of identifying both the support stiffness and location is also discussed. The proposed app roach has been illustrated with simulated and experimental examples used in the earlier studies. (C) 2001 Academic Press.