PSI - Issue 13

Jürgen Bär / Procedia Structural Integrity 13 (2018) 947–952

952

Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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A direct influence of the deformation induced heating on the cyclic lifetime in VHCF is reported Illgen et al. (2018). They observed in their VHCF tests on a particle and a fiber-reinforced aluminum alloy a higher cyclic lifetime when the maximum temperature increase of about 17 K in the used pulse-pause mode was reduced by a spot cooling to 10K. This result shows that even this small temperature increase can affect changes in the cyclic lifetime, hence more investigations on different materials should be performed to study the influence of the deformation induced heating on the fatigue behavior especially in experiments with high loading frequencies. The investigations have shown that in monotonic as well as cyclic tests considerable temperature increases were caused by deformation induced heating. In case of copper the strain to failure is enhanced when the heat dissipation in the experiment is improved by performing the experiments in water. For specimens of the aluminum alloy 6082 no changes could be measured. In fatigue experiments, the heating effect is rising with the stress amplitude and the loading frequency. The investigation of the temperature change within a cycle clearly indicates that the amount of the heating effect is determined by the time for cooling of the specimen and therewith the loading frequency. Especially in experiments performed with high loading frequencies, an influence of the deformation induced heating on the cyclic lifetime can be expected. Blanche, A.; Chrysochoos, A.; Ranc, N.; Favier, V. (2015). Dissipation Assessments during Dynamic Very High Cycle Fatigue Tests. Experimental Mechanics 55 (4), 699 – 709. DOI: 10.1007/s11340-014-9857-3. Boulanger, T. (2004). Calorimetric analysis of dissipative and thermoelastic effects associated with the fatigue behavior of steels. International Journal of Fatigue 26 (3), 221 – 229. DOI: 10.1016/S0142-1123(03)00171-3. Cullen, G. W.; Korkolis, Y. P. (2013). Ductility of 304 stainless steel under pulsed uniaxial loading. International Journal of Solids and Structures 50 (10), 1621 – 1633. DOI: 10.1016/j.ijsolstr.2013.01.020. Illgen, A.; Weidner, A.; Biermann, H. (2018). Influence of particle and short-fibre reinforcement on the very high cycle fatigue behaviour of aluminium matrix composites. International Journal of Fatigue 113 , 299 – 310. DOI: 10.1016/j.ijfatigue.2018.04.025. La Rosa, G.; Risitano, A. (2000). Thermographic methodology for rapid determination of the fatigue limit of materials and mechanical components. International Journal of Fatigue 22 (1), 65 – 73. DOI: 10.1016/S0142-1123(99)00088-2. Lin, M.-R.; Wagoner, R. H. (1987). An experimental investigation of deformation induced heating during tensile testing. Metallurgical Transactions A18 , 1035 – 1042. DOI: 10.1007/BF02668552. Meneghetti, G. (2007). Analysis of the fatigue strength of a stainless steel based on the energy dissipation. International Journal of Fatigue 29 (1), 81–94. DOI: 10.1016/j.ijfatigue.2006.02.043. Mareau, C.; Favier, V.; Weber, B.; Galtier, A.; Berveiller, M. (2012). Micromechanical modeling of the interactions between the microstructure and the dissipative deformation mechanisms in steels under cyclic loading. International Journal of Plasticity 32-33 , 106–120. DOI: 10.1016/j.ijplas.2011.12.004. Ranc, N.; Wagner, D.; Paris, P. C. (2008). Study of thermal effects associated with crack propagation during very high cycle fatigue tests. Acta Materialia 56 (15), 4012–4021. DOI: 10.1016/j.actamat.2008.04.023. 5. Conclusions References