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The detailed analysis of the tire loading and the subsequent deformations under operational driving conditions is of great importance for the basic investigation of the functionability as well as for the input and verification of the computer simulation of tires. Such data are also required for the definition of mission profiles as well as for the derivation of programs for the durability approval. The principles for the measurement of global tire deformations by spring loaded deflection transducers arranged in-between the tire crown and the rim are described. By combination of those sensors with wheel force transducers the determined tire deformations are referred to the actual service loading conditions. The sensors and transducers are described and examples of field measurement on heavy truck tires under distinguished driving conditions are presented.

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.

The design of wheel hubs must be based on stresses generated under customer usage through operational loads acting on the wheel. Therefore, the service loading conditions must be taken into account as well as the generated stresses and the hub fatigue properties. In this paper the decisive parameters for design and durability - operational loads, fatigue properties, which depend on material and manufacturing technology, and design - are discussed and the procedure for an optimum light-weight design is treated. Finally, the test procedure for durability approval, the corresponding test facility, the test programs and requirements, and some typical test results are presented.

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.

In this paper the criteria and the requirements for the approval of the service strength and the durability of vital car suspension components are treated. The overview of the main influences on the fatigue life is given and the methodology for the design evaluation and a reliable time and cost saving development, including durability approval, are described. These include: Description of representative, customer related loading Procedure for design evaluation based on customer usage Corresponding test programs for durability approval including the requirements for statistical validation and quality assurance of manufacturing. On two examples - a wheel and a suspension arm - the procedure including individual steps is explained.

The complex design and loading conditions of the wheel-hub assembly and decisive safety demands make it necessary to proof the wheel fasteners under reliable, service-like testing conditions. In this paper main parameters, the function and fatigue life of wheel fasteners and consequences for testing are described and discussed. The test procedure is based on the Biaxial Wheel Test Method, whereby the existing load program »Eurocycle« was extended by additional braking and torsional force sequences. The test requirement and some typical test results are presented.

For the design of suspension components the behavior under extreme, special events, loading as well as the durability under operational usage are decisive. While the behavior under extreme loading depends on the component stiffness, which is mainly influenced by the design and the material mechanical properties, durability is influenced by the fatigue properties under operational loading. For this purpose the fatigue properties on aluminum alloys 5083 and 6009 using different types of stresses (tension, shear, torsion, bending), loading-time histories (constant and variable amplitude loading) and welding technology were investigated and will be presented in this paper.