Identification of rigid body inertia properties from experimental data

The estimate of mass properties from the massline characteristic of experimental FRFs has attracted the attention of the modal analysis community during the last decade. The problem is typically non-linear and, in the technical literature, iterative and direct methods were proposed for its solution. In this paper a direct procedure is developed. The non-linear problem is divided into a series of simpler linear problems and solved in subsequent steps. A careful analysis is performed on the conditioning of the systems to assess the minimum number of required measurements necessary to solve the problem even in noisy environments. The proposed approach produces accurate results for two real experimentally tested systems: a 2- and a 3-D structure. An accurate measurement of the masslines characteristics is required. An extended discussion on this point is presented with particular emphasis on the bias introduced in the low frequency range when testing free structures. (C) 1996 Academic Press Limited