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Nodular cast materials allow the production of near-net-shape components and are characterized by good fatigue performance and ductility. The fatigue performance and the impact behavior of two variants of a MAN heavy truck suspension arm are compared by experimental and computational investigations. The first variant is made of EN-GJS- 400 - 15 (cast iron with a tensile strength Su > 400 MPa) which has a ferritic microstructure. The other variant is made of austempered EN-GJS-800 - 8 (cast iron with a tensile strength Su > 800 MPa) which has an austenitic-ferritic microstructure. The fatigue properties of components of both materials have been investigated under constant and variable amplitude loading, with and without preliminary overload, simulating a special event. Considering the impact behavior corresponding to a misuse event, the energy absorption capacity of the component made from EN GJS-800 - 8 is significantly higher.

Leaf springs must be regarded as safety components of a vehicle which failures can cause severe accidents. They have to fulfill various functions as a spring element and for guiding the axles and are also responsible for driving comfort. Therefore, the durability approval must be carried out under representative service-like loading, which take into account complex leaf deformations in operational usage. In this paper the influencing parameters for the durability approval of leaf spring suspensions are discussed and the test rig and the standardized test program SPRILOS (SPRIng LOad Sequence) for the durability approval are described.

Air spring systems are increasingly used on suspensions for commercial vehicles. To prove their durability a reliable test procedure is necessary: to be applied already in the development stage to be used to qualify individual air spring manufacturers and to assure manufacturing quality. In this paper the test procedure, the test facility and some test results are presented. In the test facility the air spring is mounted on a fixture and is loaded by a servohydraulic actuator. The mounting of the air spring allows to simulate all operational deformations, being decisive for the durability. Based on the extensive measurements on proving ground and public roads the test program was worked out. The test program includes besides the loading and deformations during driving also kneeling operations as well as high and low temperatures. The accelerated laboratory tests deliver results which correspond to the existing experience at the service usage.