An Abstract Multi-Rate Method for Vehicle Dynamics Simulation

The design of vehicles increasingly challenges existing cost, weight, durability, and handling regimes. This challenge is further compounded by pressure to decrease or limit the duration of the design cycle. The simulation of vehicle dynamic behavior commonly applies just rigid, or better rigid and linear flexibility models to predict motions and determine load cases. However, as the boundaries of materials are pushed these are becoming insufficient to accurately predict behavior. Alternatively, complete nonlinear finite element representations of vehicle dynamics are always possible but are presently infeasible for the support of a single design under virtual test, not to mention several design iterations. To address these issues, a novel abstract multi-rate simulation method is outlined which is designed to exploit the richness of available model in the vehicle dynamics domain. The method relies on the availability of a virtual continuum of modeling fidelities and uses the fast executing low fidelity models to seed increasingly high fidelity models which execute concurrently in different regions of the time domain. As a result, discontinuities will appear in the states time-histories, and the method must then validate (or invalidate) the discontinuities as being possible states given the chaotic nature of the higher frequency components in the system.