IDENTIFICATION OF THE RIGID-BODY CHARACTERISTICS OF A POWER-PLANT BY USING EXPERIMENTALLY OBTAINED TRANSFER-FUNCTIONS

Accurate data on the rigid body characteristics of a powerplant, including its centre of gravity and principal moments of inertia, are necessary in designing the characteristics of engine mounting systems. This paper presents a method for identifying the rigid body characteristics of a powerplant by solving a set of simultaneous linear equations. These equations are derived from an equation of motion, F = M* {X}, where F is an excitation force vector, {X} is an acceleration vector obtained experimentally and M is a 6 x 6 rigid body matrix of unknown quantities. A modal curve fitting method is used to eliminate the unwanted effects of higher-frequency elastic vibration modes from the rigid body motion frequency region of the measured transfer functions. The identification results for a front-wheel-drive powerplant were verified by comparing the actual and identified masses and the measured and calculated inertance levels.