Cornering Analysis of Vehicles Using Multibody Dynamics

Dynamics software usage in the analysis of vehicles is becoming more prevalent in industrial settings. Multibody tools allow the user to put together a digital or virtual model of the vehicle before any physical prototype is built. The tools have now reached a level of sophistication that allows the same tests to be performed on the digital model as on the physical model. In the analysis of a vehicle a virtual model allows the user to analyze the vehicle’s performance in ride and comfort scenarios as well as in durability scenarios. Multibody tools also allow the user to perform design of experiments or trade-off studies in these scenarios by varying different parameters of the vehicle. However, to be of optimal usage in a design of experiments approach the solution times of the complex models must be short allowing larger parameter studies to be done quickly. In the analysis of many vehicles and in particular race cars only the vehicle’s limits in a turn or corner are needed. Limiting the vehicle analysis to cornering allows the multibody code to use steady-state analysis instead of a full dynamic simulation. Typically, multibody codes construct differential-algebraic equations (DAE) to form the equations of motion and then must use complex numerical analysis techniques to solve the DAEs. By making the assumption that the vehicle is in a corner the DAEs can be reduced to a set of algebraic equations, which can then be solved very efficiently by a statics solver. A statics solver by definition requires the velocities and accelerations to be zero, but in the cornering analysis of a vehicle this assumption can not be made. This paper will document the extensions necessary to convert the Virtual.Lab multibody statics solver into a steady-state solver it will then apply this steady-state solver to the cornering analysis of a full vehicle model.Copyright © 2011 by ASME