Load Program Development and Testing of Super Single Wheels in the Biaxial Wheel Test Rig and Numerical Pre-Design 2004-01-2691
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. The “Eurocycle” test program consists of different driving sections such as straight ahead driving, cornering, off-road driving and parking operations. The required test life is 16 000 km (approx. 10 000 miles) for steel and 20 000 km (approx. 12 400 miles) for aluminum wheels, which corresponds to a design life of approx. 1 million km (approx. 6,25 · 105 miles).
The validation test concept includes also special event loading of rim flanges as in the case for aluminum passenger cars.
Additionally various load programs are existing for other applications, like for truck cranes, off-road usage, three-axle-trailer trucks, service conditions in China (“China-cycle”) etc.
Based on an experimental analysis a numerical approach has also been developed for pre-design of such wheels: The existing LBF®.WheelStrength software has been extended by a special tire model for load transfer in the wheel and by the derived load data and design spectra.
The numerical and experimental procedure allows a reliable and economic design and testing of these safety components.