Abstract
The objective of these procedures is to simulate the execution of different dynamic maneuvers required to ensure every component in the propulsion system complies with the dynamic load conditions to which it may be exposed. These dynamic situations are the outcome of various worst-case maneuvers that the vehicle experiences irrespective of driver’s intent. Spike load from these maneuvers could cause permanent damage to the propulsion system components, unless designed to sustain. The increased instantaneous torque and acceleration values under these worst-case scenarios is predicted by these analyses. The vehicle and propulsion system components (Engine, Motor, Transmission, Shafts and Wheels) are modeled as simple inertias and stiffnesses in AMESimTM. The dynamic maneuver involves a transition of the vehicle from dry road to ice and vice-versa, which is modeled by varying the coefficient of friction (µ) at the rotary element. In real-world driving, a vehicle may transition between varying coefficients of friction on road, specifically in regions that experience snow/ice deposition in winter. Such extreme situations result in rapid acceleration and later, sudden deceleration of propulsion system components across the transition of the vehicle from a low µ surface to a high µ surface (ice to dry road). Subsequently, this results in a spike in torque through the axle and the other connected components of the drivetrain. This spike could be as high as twice the maximum torque at full throttle performance. Such dynamic analyses are carried out under two main procedures namely ‘Ice Clunk’ and ‘Panic Brake’. Torque and acceleration prediction through these procedures helps early sizing of axles, half shafts and bearings. In these simulation procedures, vehicle / component level behavior in a single degree of freedom (rotational) under the aforementioned dynamic maneuvers is analyzed. Dynamics from Advanced Driver Assistance Systems (ADAS) are not included within the scope of this study.