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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 keen competition in the automobile industry has in many cases necessitated the adoption of new manufacturing techniques for vehicle components. Forgings especially are being replaced today by castings and fabricated components. The authors show on the example of a forged front wheel hub how weight savings of up to 30% may be achieved on a standard hub forging. The weight savings are achieved through a design methodology called “Service Strength Analysis,” whereby both structural analysis and testing are done under simulated service loadings. The wheel hub is a highly stressed safety component on which the function of other components such as axles, wheels and brakes depend. Service Strength Analysis allows lightweight design to be carried out without sacrifices of reliability; it also allows an effective evaluation of the influence of new low cost manufacturing techniques on the service strength of parts.

The validation of the wheel/hub assembly has been carried out in the Biaxial Wheel/Hub Test facility since the early ‘1980’s developed at Fraunhofer LBF. This test procedure became a standard at most of the European wheel and truck producers and was also introduced as SAE wheel standard J 2562, issued in 2003. For newly developed Super Single low profile tires 495/45R22.5, which will replace double rear tires on heavy trucks and buses, the corresponding steel and aluminum wheels had to be designed by the suppliers. Because of the lack of information about load data and load programs for testing, extensive research had to be undertaken. The load data had been measured in collaboration with DaimlerChrysler on a M.B. Actros on proving grounds and on the “Black Forest round track” in Germany. Based on the derived data a special “Eurocycle” load program has been developed for accelerated testing of the wheels in the Biaxial Wheel Test Rig.