Inhaltszusammenfassung

The comprehensive characterization of microstructural changes caused by cyclic loading is of major importance for the understanding of basic fatigue mechanisms and for an optimized fatigue life calculation of metallic materials. Beside conventional strain measurements in recent years temperature and electrical resistance measurements were additionally used for the determination of fatigue relevant data during constant and variable amplitude loading. This paper presents selected results of the...The comprehensive characterization of microstructural changes caused by cyclic loading is of major importance for the understanding of basic fatigue mechanisms and for an optimized fatigue life calculation of metallic materials. Beside conventional strain measurements in recent years temperature and electrical resistance measurements were additionally used for the determination of fatigue relevant data during constant and variable amplitude loading. This paper presents selected results of the cyclic deformation behaviour of the quenched and tempered steel SAE 4140 and the cast iron ASTM 80-55-06 (EN-GJS-600) based on mechanical stress-strain hysteresis, temperature and electrical resistance data. In general the resistivity of metals increases during cyclic loading as a function of the increasing defect density i. e. dislocation density, pores and microcracks. The electrical resistance offers additional information about the cyclic deformation behaviour also in the range of low loading amplitudes resulting in very low plastic deformation and in the case of materials with a very low ductility. Furthermore the electrical resistance is independent of a defined gauge length and also applicable to complex geometries like notched specimens. The used physical quantities are linked by cross-effects and directly related to fatigue induced microstructural changes in the bulk material.» weiterlesen» einklappen

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DDC Sachgruppe:
Ingenieurwissenschaften