A Parametric Model to Generate Subsystem Constitutive Laws for a Vehicle Ride Model

In conventional system modeling, some constitutive laws governing the performance of a major subsystem must be derived by testing existing hardware. However, if a system model is to be employed in the early stages of vehicle development, then separate models are required to generate the necessary subsystem constitutive laws strictly from basic design parameters and very simple component tests. This paper demonstrates how a computer model can generate the same complex kinematic data generated by a test for a vehicle suspension subsystem, and how these results can be integrated with a system-level, vehicle ride model. The suspension model presented is constructed primarily from design parameters, with some use of easier-to-obtain empirical data (such as load/deflection relationships of the jounce bumpers). This paper also discusses an improved approach to modeling the coil spring in a double A-arm suspension. This effort successfully generated the quasi-static responses used for suspension parameters in the ride model without requiring complex empirical data. Relationships such as load vs. vertical deflection at the spindle and kinematic path of the spindle in jounce and rebound are presented. The model is completely parametric allowing the user flexibility to explore design change concepts or to apply it to an entirely separate vehicle. The model presented could be useful at any stage of vehicle and suspension development by different engineers, as it requires minimal understanding of the modeling software itself.