Some Considerations of Low Cycle Fatigue in Metals

1981 ◽  
pp. 281-291
Author(s):  
K. Hatanaka ◽  
T. Yamada
Keyword(s):  
Low Cycle Fatigue ◽  
Cycle Fatigue

Effect of Texture and {10-12} Twin on the Low Cycle Fatigue Properties of Rolled AZ31 Mg Alloy

2013 ◽  
Vol 51 (5) ◽  
pp. 325-332 ◽  
Author(s):  
Sung Hyuk Park ◽  
Seong-Gu Hong ◽  
Chong Soo Lee ◽  
Ha Sik Kim
Keyword(s):  
Low Cycle Fatigue ◽  
Mg Alloy ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Az31 Mg Alloy

Fracture Surface in Low Cycle Fatigue of HA-188 Cobalt Base Alloy at High Temperature

1978 ◽  
Vol 27 (292) ◽  
pp. 99-103 ◽  
Author(s):  
Kiyoshi KITA ◽  
Masanori KIYOSHIGE ◽  
Masatake TOMINAGA ◽  
Junzo FUJIOKA
Keyword(s):  
High Temperature ◽  
Fracture Surface ◽  
Base Alloy ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Cobalt Base Alloy ◽  
Cobalt Base

Features of the kinetics of cyclic elastoplastic deformation diagrams at dwells in cycles and superimposition of variable stresses on them

2020 ◽  
Vol 86 (12) ◽  
pp. 46-53
Author(s):  
M. M. Gadenin
Keyword(s):  
Experimental Data ◽  
Elastoplastic Deformation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Loading Cycle ◽  
Additional Variable ◽  
Dynamic Creep ◽  
Variable Stresses ◽  
Kinetics Of ◽  
Deformation Diagrams

The goal of the study is determination of the regularities of changes in cyclic strains and related deformation diagrams attributed to the existence of time dwells in the loading modes and imposition of additional variable stresses on them. Analysis of the obtained experimental data on the kinetics of cyclic elastoplastic deformation diagrams and their parameters revealed that in contrast to regular cyclic loading (equal in stresses), additional deformations of static and dynamic creep are developed. The results of the studys are especially relevant for assessing the cyclic strength of unique extremely loaded objects of technology, including nuclear power equipment, units of aviation and space systems, etc. The experiments were carried out on the samples of austenitic stainless steel under low-cycle loading and high temperatures of testing. Static and dynamic creep deformations arising under those loading conditions promote an increase in the range of cyclic plastic strain in each loading cycle and also stimulate an increase in the range of elastoplastic strain due to active cyclic deformation. At the same time the existence of dwells on extrema of stresses in cycles without imposition of additional variable stresses on them most strongly affects the growth of plastic strain ranges in cycles. Imposition of additional variable stresses on dwells also results in the development of creep strains, but their growth turns out to be somewhat less than in the presence of dwells without stresses imposed. The diagrams of cyclic deformation obtained in the experiments are approximated by power dependences, their kinetics being described in terms of the number of loading cycles using corresponding temperature-time functions. At the same time, it is shown that increase in the cyclic plastic deformation for cycles with dwells and imposition of additional variable stresses on them decreases low cycle fatigue life compared to regular loading without dwells at the same stress amplitudes, moreover, the higher the values of static and dynamic creep, the greater decrease in low-cycle fatigue life. This conclusion results from experimental data and analysis of conditions of damage accumulation for the considered forms of the loading cycle using the deformation criterion of reaching the limit state leading to fracture.

Damage accumulation near a hole under low cycle fatigue proceeding from measurements of local deformation response

2020 ◽  
Vol 86 (10) ◽  
pp. 46-55
Author(s):  
S. I. Eleonsky ◽  
Yu. G. Matvienko ◽  
V. S. Pisarev ◽  
A. V. Chernov
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Damage Accumulation ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Accumulation Process ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Deformation Response

A new destructive method for quantitative determination of the damage accumulation in the vicinity of a stress concentrator has been proposed and verified. Increase of damage degree in local area with a high level of the strain gradient was achieved through preliminary low-cycle pull-push loading of plane specimens with central open holes. The above procedure is performed for three programs at the same stress range (333.3 MPa) and different stress ratio values 0.33, – 0.66 and – 1.0, and vice versa for two programs at the same stress ratio – 0.33 and different stress range 333.3 and 233.3 MPa. This process offers a set of the objects to be considered with different degree of accumulated fatigue damages. The key point of the developed approach consists in the fact that plane specimens with open holes are tested under real operation conditions without a preliminary notching of the specimen initiating the fatigue crack growth. The measured parameters necessary for a quantitative description of the damage accumulation process were obtained by removing the local volume of the material in the form of a sequence of narrow notches at a constant level of external tensile stress. External load can be considered an amplifier enhancing a useful signal responsible for revealing the material damage. The notch is intended for assessing the level of fatigue damage, just as probe holes are used to release residual stress energy in the hole drilling method. Measurements of the deformation response caused by local removing of the material are carried out by electronic speckle-pattern interferometry at different stages of low-cycle fatigue. The transition from measured in-plane displacements to the values of the stress intensity factor (SIF) and the T-stress was carried out on the basis of the relations of linear fracture mechanics. It was shown that the normalized dependences of the stress intensity factor on the durability percentage for the first notch (constructed for four programs of cyclic loading with different parameters), reflect the effect of the stress ratio and stress range of the loading cycle on the rate of damage accumulation. The data were used to obtain the explicit form of the damage accumulation function that quantitatively describes damage accumulation process. The functions were constructed for different stress ratios and stress ranges.

Low cycle fatigue of superalloys

2004 ◽  
Vol 46 (10) ◽  
pp. 531-533
Author(s):  
Yasuhiro Aoki ◽  
Mikiya Arai ◽  
Hao Zhou ◽  
Yoshikazu Ro ◽  
Hiroshi Harada
Keyword(s):  
Low Cycle Fatigue ◽  
Cycle Fatigue

Superior Low-Cycle Fatigue Properties of CoCrNi Compared to CoCrFeMnNi

2020 ◽  
Author(s):  
Kaiju Lu ◽  
Ankur Chauhan ◽  
Mario Walter ◽  
Aditya Srinivasan Tirunilai ◽  
Mike Schneider ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue

A novel test method based on small specimens for obtaining low-cycle-fatigue properties of materials

2019 ◽  
Vol 138 ◽  
pp. 103153
Author(s):  
Qin Liu ◽  
Li-xun Cai ◽  
Hui Chen ◽  
Chen Bao ◽  
Tao Yin
Keyword(s):  
Low Cycle Fatigue ◽  
Test Method ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Properties Of Materials
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