scholarly journals A Synthesis of the Low- and Medium-cycle Fatigue Behaviour of as-cast and Austempered Ductile Irons based on the Plastic Strain Energy

2014 ◽  
Vol 3 ◽  
pp. 1173-1178 ◽  
Author(s):  
G. Meneghetti ◽  
M. Ricotta ◽  
B. Atzori
Keyword(s):  
Plastic Strain ◽  
Strain Energy ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
Plastic Strain Energy

Low Cycle Fatigue Evaluation of Inconel 713C and Waspaloy

1965 ◽  
Vol 87 (2) ◽  
pp. 275-289 ◽  
Author(s):  
JoDean Morrow ◽  
F. R. Tuler
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Strain Energy ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Plastic Strain Energy ◽  
Fatigue Evaluation ◽  
Inconel 713C

Completely reversed axial fatigue results are reported for Waspaloy and Inconel 713C at room temperature. Fatigue strength and ductility are evaluated using power functions of the fatigue life. The exponents and coefficients of these two equations are looked upon as four fatigue properties of the material. They appear in the equations which are developed to relate cyclic stress, plastic strain, total strain, plastic strain energy per cycle, total plastic strain energy to fracture, and fatigue life. These equations and the four fatigue properties permit the evaluation of the relative fatigue resistance of various metals at different fatigue lives when subjected to strain, stress, or plastic strain energy cycling. The “best” selection of material to resist fatigue is found to depend on the type of cycling and the desired life. At room temperature, the wrought Waspaloy is found to be more fatigue resistant than the cast Inconel 713C, particularly in resisting strain or plastic strain energy cycling in the low cycle fatigue region. For longer lives the difference in fatigue resistance between the two diminishes, especially for stress cycling. It is believed that the method of fatigue evaluation used here is generally applicable to the engineering problem of material selection to resist fatigue, and should in some cases replace methods based on conventional rotating bending fatigue tests which only evaluate the fatigue strength at long lives.

scholarly journals Low Cycle Fatigue Life Assessment Based on the Accumulated Plastic Strain Energy Density

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2372
Author(s):  
Yifeng Hu ◽  
Junping Shi ◽  
Xiaoshan Cao ◽  
Jinju Zhi
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Fatigue Initiation ◽  
Plastic Strain Energy

The accumulated plastic strain energy density at a dangerous point is studied to estimate the low cycle fatigue life that is composed of fatigue initiation life and fatigue crack propagation life. The modified Ramberg–Osgood constitutive relation is applied to characterize the stress–strain relationship of the strain-hardening material. The plastic strain energy density under uni-axial tension and cyclic load are derived, which are used as threshold and reference values, respectively. Then, a framework to assess the lives of fatigue initiation and fatigue crack propagation by accumulated plastic strain energy density is proposed. Finally, this method is applied to two types of aluminum alloy, LC9 and LY12 for low-cycle fatigue, and agreed well with the experiments.

Experimental Investigation on the Proper Fatigue Parameter of Cyclically Non-Stabilized Materials

2005 ◽  
Vol 297-300 ◽  
pp. 2477-2482 ◽  
Author(s):  
Seong Gu Hong ◽  
Keum Oh Lee ◽  
Jae Yong Lim ◽  
Soon Bok Lee
Keyword(s):  
Stainless Steel ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Strain Aging ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Dynamic Strain ◽  
Cycle Fatigue ◽  
Plastic Strain Energy

Low-cycle fatigue tests were carried out in air in a wide temperature range from room temperature to 650oC to investigate the role of temperature on the low-cycle fatigue behavior of two types of stainless steels, cold-worked (CW) 316L austenitic stainless steel and 429 EM ferritic stainless steel. CW 316L stainless steel underwent additional hardening at room temperature and in 250-600oC: plasticity-induced martensite transformation at room temperature and dynamic strain aging in 250-600oC. As for 429 EM stainless steel, it underwent remarkable hardening in 200-400oC due to dynamic strain aging, resulting in a continuous increase in cyclic peak stress until failure. Three fatigue parameters, such as stress amplitude, plastic strain amplitude and plastic strain energy density, were evaluated. The results revealed that plastic strain energy density is nearly invariant through a whole life and, thus, recommended as a proper fatigue parameter for cyclically non-stabilized materials.

Correlation between Strain-Based Low-Cycle Fatigue and Energy-Based Linear Damage Models

1997 ◽  
Vol 13 (2) ◽  
pp. 191-209 ◽  
Author(s):  
Y. H. Chai ◽  
K. M. Romstad
Keyword(s):  
Plastic Strain ◽  
Strain Energy ◽  
Low Cycle Fatigue ◽  
Limit State ◽  
Cumulative Damage ◽  
Ultimate Limit State ◽  
Cycle Fatigue ◽  
Fatigue Model ◽  
Plastic Strain Energy ◽  
Ultimate Limit

Although the potential for cumulative damage of structures during long duration earthquakes is generally recognized, most design codes do not explicitly takes into account the damage potential of such events. In this paper, a strain-based low-cycle fatigue model commonly used for the prediction of fatigue life in metals is adapted for cumulative damage assessment of structures under seismic conditions. By defining the number of load cycles in terms of the total plastic strain energy dissipated by the structure, the model is presented in a form capable of predicting the plastic strain energy capacity of the structure at the ultimate limit state. The plastic strain energy is expected to decrease rapidly with increased displacement in the small displacement range and to decrease gradually in a near linear manner with increased displacement in the large displacement range. The model is shown to calibrate reasonably well with small-scale aluminum cantilever specimens tested under large-amplitude reversed cyclic loading. At the ultimate limit state, the modified Park and Ang damage model may be considered as a linear approximation to the low-cycle fatigue model in the large displacement range.

Plastic Strain Energy in Low-Cycle Fatigue of A356 (Al-7Si-0.4Mg) Aluminum Alloys

2011 ◽  
Vol 194-196 ◽  
pp. 1210-1216
Author(s):  
Mou Sheng Song ◽  
Mao Wu Ran
Keyword(s):  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Low Cycle Fatigue ◽  
A356 Alloy ◽  
Cycle Fatigue ◽  
Plastic Strain Energy ◽  
Ti Content ◽  
Ti Addition

In this paper, the problem of plastic strain energy density as a evaluation of low-cycle fatigue (LCF) properties for A356 alloys with various Ti content and Ti-addition methods is considered. The experimental results reveal that it is not the Ti-addition methods but the Ti content that has played an important role in influencing on the plastic strain energy density, thus on the LCF life. Whether for the electrolytic A356 alloys or for the melted A356 alloys, the alloys with 0.1% Ti content can consume higher cyclic plastic strain energy during the cyclic deformation compared with the alloys with 0.14% Ti content due to the better plasticity, giving rise to a better fatigue resistance and a longer LCF life. Because of the different macro or micro deformation mechanism, the fracture surface of electrolytic A356 alloy exhibits the diverse microstructural morphologies under the various strain amplitude.

scholarly journals Strain energy-and stress-based approaches revisited in notch fatigue of ductile steels

2018 ◽  
Vol 165 ◽  
pp. 14009 ◽  
Author(s):  
Bruno Atzori ◽  
Mauro Ricotta ◽  
Giovanni Meneghetti
Keyword(s):  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Elastic Strain ◽  
Strain Energy ◽  
Elastic Strain Energy ◽  
Fatigue Behaviour ◽  
Strength Reduction Factor ◽  
Plastic Strain Energy ◽  
Elastic Strain Energy Density

The constant amplitude, zero-mean stress, axial-fatigue behaviour of plain and bluntly notched AISI 304 L stainless steel specimens is investigated in terms of strain energy density. Concerning plain material, it was found that at the fatigue knee the plastic strain energy density is 1.49 times higher than the elastic strain energy density. In the authors’ opinion, the presence of plasticity at the fatigue knee is responsible for the unsuitableness of classical stress - based approaches to synthesise the fatigue behaviour of this material. On the contrary, the elastic-plastic strain energy density was found an efficient parameter to rationalise in a single scatter band fatigue data of plain and bluntly notched specimens. Based on this result, the classic stress-and the point stress-based approaches were revisited taking into account the presence of plasticity at the fatigue knee, by introducing an equivalent fully elastic material having a linear elastic strain energy density at the fatigue knee equal to that of the actual material. Accordingly, a coefficient of plasticity Kp was successfully introduced to modify the classical definition of fatigue strength reduction factor, Kf.

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