Sensitivity Analysis of Rigid Body Property Estimation from Modal Method

Abstract

Determination of the ten inertia parameters of mass, center of gravity coordinates, moments of inertia and products of inertia is important in the structural dynamic applications such as optimization, vibration control or structural modification. For the structures with complicated shapes, the inertia properties cannot be easily identified by the theoretical tools. However, there are appropriate experimental methods to evaluate these properties. The experimental route is via to obtain the rigid body modes from the measured Frequency Response Functions (FRFs). The objective of the present paper is the evaluation of the performance of one of the identification methods of rigid body properties based on the modal data, namely Modal Model Method (MMM). The accuracy of the MMM is evaluated by estimating the sensitivity of calculated rigid body properties. The error analysis of the corresponding calculations in MMM is performed mathematically. Based on this study, guidelines are suggested for improving the accuracy of results from MMM.