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A novel method is presented to determine the dynamic characteristics of a multi-DOF rigid body structure from vibration measurements and coordinates of the transducers. These characteristics include the center of gravity, moment of inertia, and mass; stiffness, center of stiffness and moment of stiffness; damping, center of damping and moment of damping; and corresponding principal values and axes. The method is capable of handling complicated structures with various DOFs, from 2 up to maximum 6. The mass modified matrices M−1K and M−1C (or mass M, stiffness K, and damping C matrices) are first obtained based on measured vibration data and estimated rigid-body modes by Data Dependent Systems (DDS) methodology, which is accurate even for highly damped structures. Relationships between the physical characteristics and the mass modified matrices have been derived to solve the dynamic properties. The properties of up to 5 individual spring and dashpot supports can be determined by solving linear simultaneous equations. New concepts about the center of stiffness, moment of stiffness, center of damping, and moment of damping and the estimation method are presented. An example, using a simple structure, demonstrated the capability of the proposed method.

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A method is presented to get the dynamic characteristics of a multi-DOF rigid body structure from the measured vibration data. These characteristics include the mass, center of gravity, moment of inertia and the principal axes of the body, stiffness, damping, the center of stiffness in any direction, moment of stiffness, center of damping and moment of damping, and the principal axes of the supports. The method is capable of representing structures with various DOFs, from 2 up to 6. The mass M, stiffness K, and damping C (or M−1K and M−1C) matrices are obtained first based on measured vibration data by Data Dependent Systems (DDS) methodology which is accurate even for highly damped structures. Relationships between the physical characteristics and these matrices have been derived so that the physical characteristics can be obtained by solving simultaneous linear equations. It is also possible to determine the characteristics up to 5 individual springs and dashpots to provide a basis for improvement in the structure’s performance.