Road Loads for Durability Analysis using Virtual Iterations

Durability assessment for suspension systems and vehicle structures requires loads on each component from different road profiles. If a new vehicle is to be assessed for durability early in the design phase, a prototype must be built and tested on proving grounds. This can be time consuming and expensive. A large number of design configurations are considered for designing new vehicles in the truck industry. However, the number of prototypes that can be built and tested will be limited. The only options would be to depend on generic load cases or to use a virtual method that can translate limited measurements to various configurations. Roush CAE has successfully implemented a method called virtual iterations to back calculate the road profiles from the CAE model of a vehicle that has been tested on the desired road tracks. This paper presents the various steps involved in the virtual iterations process, the full vehicle model setup and the most important parameters which affect the output. The underlying assumptions and their influence on the application of the final tire patch displacements to the new vehicle design are discussed. An example problem is presented and correlated results are shown for various continuous vibration events like resonance roads, cobblestones as well as impact events like curb impact and chuckholes.