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The paper explains the most important criteria for the design of cast aluminum wheels on examples of recently developed European wheels. The basic differences in material behavior between steel and aluminum, such as fatigue strength, cyclic stress-strain properties and crack behavior are treated. The optimization of the wheel design is based on the fatigue strength of individual wheel sections which is determined through special test fixtures. The final proofout test for adequate fatigue life of the total wheel is established through a programmed test carried out in a new biaxial wheel test machine whereby the load program for testing European wheels represents European service conditions.

The method of fatigue life evaluation and validation testing under operational conditions is a prerequisite to achieve optimal designs with respect to weight and long-term durability of the structure considered. Criteria like driving behavior and braking performance, influenced by global stiffness as well as fatigue life evaluation were taken into account when optimizing a forged 6.5 front axle beam of a heavy truck. The procedure for weight optimization includes the following steps: Stress analysis e.g. using strain gage techniques and/or Finite Element Method, Road load data acquisition and derivation of design spectrum describing customer usage, Fatigue testing under constant amplitude and/or variable amplitude loading to establish component related SN-curves and/or fatigue life curves, Fatigue life evaluation using damage accumulation hypothesis (Miner's Rule), Optimization and weight reduction (in this case 14% weight savings were achieved) based on fatigue life evaluation.