This example is a local-strain (Crack Initiation) analysis of a steering knuckle subjected to a complex, multiple load-case loading environment.

The component is a steering knuckle from a car. It is cast from a spheroidal graphite cast iron. The obvious features are the strut mount at the top, the lower ball joint at the bottom and the steering arm on the right. The wheel spindle goes through the large cylindrical hole in the central part.

When the vehicle is driven through a cobblestone slalom, loads are applied to the component via the strut mount, the lower ball joint, the steering tie rod and the wheel axis.

In the FE analysis the loads are applied via loading devices in an attempt to make the transfer of loads to the component as realistic as possible. This has been done using devices made from elements rather than MPCs.

The model has been constrained at the wheel center (again through element loading devices) and 12 load cases have been applied: 3 forces (1000 N in x-y-z) at the lower ball joint, the steering arm and the strut mount, and 3 moments (1000 Nmm) at the strut mount.

Three of the 12 loads are plotted here. A linear combination of these 12 load cases can describe any loading condition that occurs during the test track event.