CAE Approach for Light Truck Frame Durability Evaluation Due to Payload Increase 2004-01-3411

The growing competition of the automotive market makes more and more necessary the reduction of development time and consequently, the increase of the capacity to quickly respond to the launching of the competitors. One of the most costly phases on the vehicle development process is the field durability test, both in function of the number of prototypes employed and the time needed to its execution.

More and more diffused, the fatigue life prediction methods have played an important part in the durability analysis via CAE. Nevertheless, in order they can be reliable and really being able to reduce the development time and cost, they need to be provided with load cases that can accurately represent the field durability tests.

This work presents a CAE approach used for light trucks in order to get a reasonable understanding of component durability behavior due to payload increase. In general, road load data is not available for a new payload condition. In this approach, data calculated via virtual MBS prototype submitted under representative static load case is used instead road load data measured directly on vehicle. Forces calculated for both conditions are imposed in the frame FE model. For post-processor reasons, the entire frame is divided in several parts, and the variation of the maximal stress in each of those parts is then used to estimate fatigue life decrease. The simple information of how component life will decrease is not enough for components life requirements; for that reason, the actual payload condition is considered as baseline, and its durability history in a specific proving ground should be well know in order to perform an A to B comparison.