Automotive Damper Model for Use in Multi-Body Dynamic Simulations

Abstract

The subject of this study is the Warrior armoured personnel carrier rotary suspension damper. This is a simple passive device where energy is dissipated by the resistance to oil flowing through an orifice. In principle the mechanism of this damper is simple, but the requirement for a compact unit that can withstand high dynamic loads means that the design is complex in detail. Because of this complexity it is possible for air to remain in the oil chambers if care is not taken when priming the device. Measurements show that the nonlinear response of the damper is primarily due to turbulent oil flow through the orifice and the compression of entrapped air, but that friction is negligible. The most appropriate model for this system in multi-body dynamic simulations is to represent the damper as two discrete components: a non-linear dashpot (representing oil flow through the orifice) and a non-linear spring (representing the compression of entrapped air). From measurements, a splined curve is determined that describes the non-linear torque-velocity relationship due to orifice flow characteristics. By applying Henry's law and assuming isothermal compression, a function is derived that describes the compression of air in oil. This modelling method closely reproduces the measured response of the damper.

Modeling Dynamic Pressure Loss by Absorption in Oleo-Pneumatic Shock Absorbers without Separator

“…A closer examination of the heat transfer suggests an almost isothermal process due to significant oil dispersion in the upper chamber, which should maintain thermal equilibrium between nitrogen and oil, as noted by Allen [11]. Moreover, oil has a significantly larger heat capacity than nitrogen so that a notable increase of the oil temperature due to heat transfer is not anticipated.…”

“…There are only few publications that focus on this shock absorber type [11], dealing with hysteresis models for the pressure-volume relation, where the pressure loss was associated with heat transfer in the gas spring [12][13][14] and absorption of gas molecules into the oil. Wahi [15] investigated the solubility of nitrogen in oil and its effect on the compressibility of the oil.…”

Plumpness Analysis of Indicator Diagram for Vehicle Damper

“…Its external characteristics will affect vehicle dynamics performance directly. In the 1970s, some researchers built and analyzed the model of damper output characteristics, overcame the drawbacks of traditional design method witch needs repeated adjustments and experiments, and developed a promising research direction for damper study [1][2][3]. In China, there were also many researchers who have studied the characteristics of damper, such as Lv et al, who built the fluid-solid coupling model of the structural dynamics and fluid dynamics of a certain binocular inflatable damper valves, utilizing the finite element method [4].…”