This research was performed to create a lumped parameter physical model for automotive suspension dampers. The model is valid for twin tube dampers with three chambers, a rebound, a compression, and a reserve chamber, that are connected by a set of valves that include two check valves, one for flow in each direction, and a bleed orifice. The rebound and compression chambers are connected by a moving piston valve and the compression and reserve chambers are connected by a fixed valve. The reserve chamber contains both air and fluid, while the rebound and compression chambers contain only fluid.
The model uses the governing physics that occur in the damper to determine the response of the damper. The main physical relationships are Newton's second law, the orifice flows in the system, conservation of flow between chambers, and fluid compressibility. These relationships include experimentally-determined parameters such as valve characteristics, and measured parameters such as component dimensions.
The model employs physical relationships to predict the force vs. displacement and force vs. velocity response of a damper over a large range of frequencies. The predicted response exhibits the same nonlinear response as the experimental damper tests.
The model was investigated to determine the effect of many parameters within the damper. The investigation of the parameters reveals that the damper response is most dependent on the physical dimensions of the damper rod and piston and the valve characteristics. Through the variation of these parameters, optimal damper responses for various conditions can be determined.