Kriterien des Betriebsfestigkeitsnachweises für die Festlegung der Versuchslaufzeit bei der Substitution von Stahl- durch Aluminiumbauteile am Beispiel von Nutzfahrzeugrädern

The experimental structural durability proof bases on a damage equivalent shortening of the design spectrum into a test spectrum with reduced length taking statistics founded safety factors into account. Historically, test spectra were first derived for steel parts using Woehler-lines for steel; the damage equivalence was calculated by applying the Palmgren-Miner rule with the modification according to Haibach. When aluminium parts were introduced later, the question arose, whether test spectra developed for steel parts could be applied without modifications for their durability proof. Caused by different slopes of aluminium before and after the knee-point, the test spectra derived for steel wheels result for aluminium components a lower cumulated damage in comparison to the design spectra. This fact requires a longer test duration for aluminium components when test spectra or proving grounds developed for steel components are used. By the example of steel and aluminium wheels for commercial vehicles with comparable fatigue critical areas, the material dependent features regarding the required test life for the structural durability proof of aluminium parts are demonstrated.