DETERMINATION OF RIGID-BODY CHARACTERISTICS FROM TIME-DOMAIN MODAL TEST DATA

A new method is presented to identify the characteristics of a rigid b ody and its supports, such as the center of gravity, the moment of ine rtia, and the stiffness and damping matrices, based on the measured ti me domain vibration data. Transformation matrices are formed using onl y the geometric co-ordinates relative to an arbitrarily selected origi n to relate the pure translational measurement to both translation and rotation of the rigid body system. The rigid body modes and mode shap es, carefully selected from the accurately determined modes and mode s hapes (rigid body and structural), are used, together with the special matrix structure, such as symmetry. The test result shows that the ce nter of gravity and the moment of inertia are determined with good acc uracy. The simple test procedure makes it an easily implementable meth od in practice.