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The comprehensive characterization of the change in metallic materials’ microstructure due to an applied load is of prime importance for the understanding of basic fatigue mechanisms or more general damage evolution processes. If understood, advanced fatigue life evaluation methods, being far from linear damage accumulation models, can be realized providing even more than only “classic fatigue data”. In view of this, different short-time evaluation procedures (STEP) have been developed during...The comprehensive characterization of the change in metallic materials’ microstructure due to an applied load is of prime importance for the understanding of basic fatigue mechanisms or more general damage evolution processes. If understood, advanced fatigue life evaluation methods, being far from linear damage accumulation models, can be realized providing even more than only “classic fatigue data”. In view of this, different short-time evaluation procedures (STEP) have been developed during the last years, which take into account that a material’s elastic-plastic reaction and hence relationship is non-linear and shows how the potential of non-destructive testing methods, the digitalisation of the measurement techniques as well as signal processing can be combined in order to achieve a significant gain in information concerning the fatigue behaviour with a simultaneous reduction of experimental effort and cost. Beside StressLife and StrainLife, SteBLife is one of these new STEP methods showing a breakthrough of new possibilities in rapid fatigue data provision. The specimen geometry used within the SteBLife approach is characterised by a stepped shape with different gauge length diameters, which consequently result in different local stress amplitudes along the axial direction of the specimens during loading. The fatigue tests were performed under constant amplitude loading and the material response MR has been measured with NDT-related methods. With respect to the SteBLife test strategy, the number of fatigue experiments required to determine a material’s complete S-N-curve can be limited to three to five tests only in cases that mean values and/or complete scatter bands of S-N-curves are required. If a trend S-N-curve is sufficient, the effort can be reduced to one single test only. This leads to a significant improvement in efficiency when compared to the conventional way an S-N-curve is determined where a minimum of 15 fatigue tests is required. Within the framework of this paper the SteBLife method is demonstrated for normalized SAE 1045 (C45E) steel.» weiterlesen» einklappen

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DDC Sachgruppe:
Ingenieurwissenschaften