THEORETICAL AND EXPERIMENTAL EVALUATION OF THE FLEXIBILITY OF THE TEST RIG ON INERTIA PROPERTY MEASUREMENT

摘要

In the measurement of inertia properties (mass, centre of gravity and inertia tensor), both the bodyunder investigation and the test rig are commonly considered as rigid bodies. However, in case of heavy orlarge bodies, these assumptions may not be satisfied. The present paper deals with the consequences of thetest rig structure deformations on the measured inertia parameters. In fact, if the forces exchanged by thestructure of the test rig and the body are large, the structure may deform changing its geometry and dynamicbehavior. These effects, in turn, affect the measured kinematic and dynamic quantities needed for themeasurement of the inertia properties.In the paper, by considering the InTenso+ Measuring System of the Politecnico di Milano, a specialtype of multi-filar pendulum, the effects of the deformation of the test rig on the measurement of the inertiaproperties is investigated both numerically and experimentally. A flexible multibody model is employed tounderstand the dynamic effects of the deformations on the mass properties measurement. Several bodies aremeasured to validate such analyses. A proper mathematical procedure is then derived to measure the inertiaproperties of bodies when the realization of a sufficiently stiff structure is impractical.