Papers by Keyword: Cyclic Fatigue

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Authors: T.S. Srivatsan, Satish Vasudevan, Lisa Park, R.J. Lederich
Abstract: In this research paper, the cyclic stress amplitude controlled fatigue response and fracture behavior of an Al-Cu (Aluminum Association designation 2219) is presented and discussed. The alloy was provided as a thin sheet in the T62 temper in the fully anodized condition. A small quantity of the as-provided sheet was taken and the surface carefully prepared to remove the thin layer of anodized coating. Test specimens of the alloy, prepared from the two sheets (anodized and non-anodized), were cyclically deformed under stress amplitude control at two different load ratios with the primary objective of establishing the conjoint influence of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life and final fracture characteristics. The high cycle fatigue resistance of the alloy is described in terms of maximum stress, load ratio, and microstructural influences on strength. The final fracture behavior of the alloy sheet is discussed in light of the concurrent and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the alloy microstructure, magnitude of cyclic stress, and resultant fatigue life.
Authors: Hassan El Attaoui, Malika Saâdaoui, Jérôme Chevalier, Gilbert Fantozzi
Authors: Ewa Marcisz, Adam Niesłony, Tadeusz Łagoda
Abstract: The paper presents the concept of division of the total strain amplitudes. Simulations were performed for high-alloy steel X6NiCr3220 for proposing a new curve of cyclic strain based on the best fit to the experimental points and plotted the hysteresis loop. Proposed allocation of the total strain amplitude in three parts: the plastic strain amplitude, strain amplitude and the amplitude of the linearly elastic strain coupled. In order to preserve the forms of popular formula Ramberg-Osgoda and Manson-Coffin-Basquin modified them in such a way that added to their member responsible for the description of the coupled strain. Inclusion of additional term leading to closer representation of the actual material properties.
Authors: Hassan El Attaoui, Malika Saâdaoui, Jérôme Chevalier, Gilbert Fantozzi
Abstract: A compliance function is used to quantify the shielding capacity of grain bridging, the degradation of which is the main cyclic fatigue mechanism in alumina. Materials with different grain sizes were processed and the fatigue experiments were performed using the double torsion test. Significant degradation is observed in the coarse grain material and a marked sensitivity to the loading level is outlined. At moderate loads, bridging degradation occurs prior to fatigue crack growth during an incubation period. At low cyclic loads, the shielding capacity can be entirely degraded, leading to a cyclic fatigue threshold equivalent to that of the fine grain material.
Authors: Hassan El Attaoui, Malika Saâdaoui, Jérôme Chevalier, Gilbert Fantozzi
Authors: A. Dalmaz, Pascal Reynaud, Dominique Rouby, Gilbert Fantozzi, M. Bourgeon
Authors: A. Bushby, F. Guiu, J. Knowles, M.J. Reece
Authors: A.S. Béranger, R. Billardon, François Hild
Authors: E. Trentini, B. Riccardi, M. Labanti
Abstract: This study presents the results of mechanical tests of commercial 2D SiCf/SiC ceramic matrix composite for fusion reactors applications. The creep behaviour was investigated by means of flexural constant load stress-rupture tests, in controlled atmosphere at 600 and 1000°C. The creep strain and time to failure vary with applied load according to a power law. Cyclical tests at room temperature and at high temperature showed that the material has a good fatigue behaviour at room temperature, as no evident fatigue damage was detected after 80.000 cycles at a peak load up to 98 % of MOR. Conversely at high temperature (1000°C) the specimens showed a progressive compliance increase and limited cycles to failure even at peak load as low as 40 % of MOR. Creep phenomena seem to influence the fatigue behaviour. Creep strain analysis, crack growth and fracture surface observations allowed to investigate the mechanisms that affect the crack propagation, the fracture process and the rupture life under cyclic loading and under constant stress loading at different temperatures.
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