Inhaltszusammenfassung

A fast calculation of Wöhler- or S-N-curves is of major importance in the design process of complex components and for optimised materials selection. In the context of this work, it is shown how the non-destructive testing methods, the digitalisation of the measurement techniques as well as signal processing can be combined with a new short-time procedure in order to acquire potentially more information from fatigue processes, while experimental effort and costs are reduced significantly. The...A fast calculation of Wöhler- or S-N-curves is of major importance in the design process of complex components and for optimised materials selection. In the context of this work, it is shown how the non-destructive testing methods, the digitalisation of the measurement techniques as well as signal processing can be combined with a new short-time procedure in order to acquire potentially more information from fatigue processes, while experimental effort and costs are reduced significantly. The results of this combination show not only considerable advantages over conventional methods aimed at determining S-N-curves, but also over established short-term procedures, due to the possibility to separate several material mechanisms by means of data analysis and to use this for fatigue life calculations based on the results of a few specimens only. The SteBLife approach is a new short-time calculation method developed at the Chair of Non-Destructive Testing and Quality Assurance at Saarland University, which takes into account that there is no linear relation between the elastic, elastic-plastic and plastic portion of the material response in the deformation process. With respect to the test strategy, the number of fatigue tests can be reduced for SteBLifemtc and SteBLifemsb to three to five or in the case of SteBLifestc to one single constant amplitude test with a special step-shaped specimen geometry when compared approximately 15 fatigue tests are required for the conventional determination of Wöhler- or S-N-curves. Moreover, SteBLifemsb offers the possibility to calculate scatter bands for different failure probabilities, which is an important feature, even in the case of inhomogeneous materials. Within the scope of the presented work, the change in temperature of SAE 1045 (C45E) specimens was measured during fatigue tests through an infrared camera in order to feed the thermal response back into the new SteBLife approach for a reliable fatigue life calculation.» weiterlesen» einklappen

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DDC Sachgruppe:
Ingenieurwissenschaften