General Bushing System Files

The Model Identification Tool (MotionView) is a utility in HyperGraph that you use to fit experimental data to various bushing models. The MotionView generates a General Bushing System file, .gbs file, which defines the bushing properties.

The table below describes the stiffness and damping formulations that are available in a .gbs file. You employ different methods for force and torque directions, but must specify for each direction only one stiffness and one damping method. An activity table in the .gbs file tells MotionView which bushing models are active.
Component Method Description
Stiffness Constant Stiffness F=-K*x; used when the bushing’s stiffness behavior is linear. The value x is the deformation in the direction of interest.
Spline Stiffness F=-g(x); where g(x) is a cubic spline interpolation of static force vs. displacement data in the .gbs file. Linear extrapolation is used when the data is outside the range of specified data.
Cubic Stiffness F=-h(x); where h(x) is defined by a pair of cubic polynomials whose coefficients are derived from the measured force vs. displacement data in the .gbs file.
Damping Constant Damping F=-c*v; used when the bushing’s damping behavior is linear. The value v is the deformation velocity in the direction of interest.
Rubber Damping An amplitude and frequency-dependent bushing model, whose coefficients are fit to measured data using a tool such as the MotionView.
Hydromount Damping An amplitude and frequency dependent model for hydrodynamic mounts, whose coefficients are fit to measured data using a tool such as the MotionView.