# Altair Bushing Model

The Altair Bushing Model is a library of sophisticated, frequency- and amplitude-dependent bushing models that you can use for accurate vehicle dynamics, durability and NVH simulations. The Altair Bushing Model supports both rubber bushings and hydromounts.

The Altair Bushing model consists of two components:
• A user interface in MotionView for instantiating hi-fidelity bushings in a full vehicle or subsystem model, and
• A solver .dll file for evaluating the instantiated bushings during a simulation.

The data for the bushing model is synthesized from various physical tests that have been performed on bushings. To learn about fitting test data to a model and generating bushing parameters, see Model Identification Tool.

## About the Altair Bushing Model

A bushing is a critical component in an automobile for these reasons:
• An automotive suspension relies on rubber bushings between the suspension's control arms and chassis to isolate the chassis from impacts and vibration produced on the tires during events such as driving over a rough road.
• Bushings increase comfort for vehicle occupants by reducing the peak loads on the suspension and chassis.
• Bushings serve a key role in controlling the wheel path and orientation as the suspension articulates vertically.
• Bushings transmit from the suspension to the chassis, the braking, traction, and cornering loads that decelerate, accelerate and steer the vehicle.

Bushing stiffness, then, is a tradeoff between being soft enough for comfort, and stiff enough to control the wheel path and orientation.

The Altair Bushing Model is an amplitude- and frequency-dependent bushing model developed to capture stiffness and damping variations with the frequency of input, the amplitude of input, and preload in the bushing when the bushing is installed.

Generally, as deflection increases, bushing stiffness also increases. For vehicle dynamics simulations, the bushing deflection in a suspension is typically large in at least one direction, but the frequencies of interest for the chassis yaw, roll, pitch, and heave modes and wheel-hop mode are relatively low. Hence, common modeling practice has been to include a rising-rate, bushing-force-deflection characteristic and at times hysteresis, but to ignore the changes in the bushing stiffness and damping for higher-frequency inputs.

In effort to improve modeling practices with bushings, and address challenges such as capturing the changes in the bushing stiffness and damping for higher-frequency inputs, Altair developed the Altair Bushing Model, also known as AutoBushFD.