Analysis of Dynamic Stability of Car-trailer Combinations with Nonlinear Damper Properties

The dampers (shock absorbers) installed in the suspensions of the towing car have some nonlinear property in road tests, like a practical piecewise-linear property. Its influence on the dynamic stability of car-trailer combinations are investigated in this paper. This nonlinearity is modeled by a Magic Formula damper model and then integrated into an extended single-track model with a tandem-axle trailer. Both the system local stability and global stability are analyzed with different theoretical methods. The results of system phase portrait show a limit cycle and the corresponding longitudinal velocity is identified as the system dynamic critical speed vcrit, which is ca. 147.2 km/h.