Study of Stick-Slip Friction between Steering Intermediate Shafts Using ADAMS-Simulink Co-Simulation 2008-01-0496

Friction in the slider joint between steering lower and upper intermediate shafts might cause axial shaft/column vibration if the friction force changes from higher stiction force to lower sliding friction force. The joint relative motion occurs when vehicle body pitches or rolls with respect to vehicle frame. To understand the effect of intermediate shaft design and steering subsystem parameters on the joint axial force, a Stribeck friction model is built in MATLAB/Simulink¹ with the parameters identified using bench test data. The model considers different stick-slip regimes, where the attainable friction force in stiction is determined by the external load and stiction dwell time, as observed in bench testing. Using the friction model, the shafts are modeled as a spring-mass-friction system in Simulink for evaluating the effects of the friction parameters and axial stiffness of the components connecting shafts. In addition, the joint friction is co-simulated in Simulink with a full vehicle ADAMS/CHASSIS² model for a brake-in-turn maneuver, which could trigger the joint stick-slip under a steering wheel torque. The study of the joint friction through the component and vehicle simulation with bench testing reveals the importance of modeling the stiction dwell time and steering column axial compliance. The study shows the stick-slip oscillation can be eliminated by reducing the maximum stiction force.