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.

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.

Probabilistic Low Cycle Fatigue Life Prediction Using an Energy-Based Damage Parameter and Accounting for Model Uncertainty

2011 ◽  
Vol 21 (8) ◽  
pp. 1128-1153 ◽  
Author(s):  
Shun-Peng Zhu ◽  
Hong-Zhong Huang ◽  
Victor Ontiveros ◽  
Li-Ping He ◽  
Mohammad Modarres
Keyword(s):  
Fatigue Life ◽  
Model Uncertainty ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Damage Parameter ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
Plastic Strain Energy

Probabilistic methods have been widely used to account for uncertainty of various sources in predicting fatigue life for components or materials. The Bayesian approach can potentially give more complete estimates by combining test data with technological knowledge available from theoretical analyses and/or previous experimental results, and provides for uncertainty quantification and the ability to update predictions based on new data, which can save time and money. The aim of the present article is to develop a probabilistic methodology for low cycle fatigue life prediction using an energy-based damage parameter with Bayes’ theorem and to demonstrate the use of an efficient probabilistic method, moreover, to quantify model uncertainty resulting from creation of different deterministic model parameters. For most high-temperature structures, more than one model was created to represent the complicated behaviors of materials at high temperature. The uncertainty involved in selecting the best model from among all the possible models should not be ignored. Accordingly, a black-box approach is used to quantify the model uncertainty for three damage parameters (the generalized damage parameter, Smith–Watson–Topper and plastic strain energy density) using measured differences between experimental data and model predictions under a Bayesian inference framework. The verification cases were based on experimental data in the literature for the Ni-base superalloy GH4133 tested at various temperatures. Based on the experimentally determined distributions of material properties and model parameters, the predicted distributions of fatigue life agree with the experimental results. The results show that the uncertainty bounds using the generalized damage parameter for life prediction are tighter than that of Smith–Watson–Topper and plastic strain energy density methods based on the same available knowledge.

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.

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.

scholarly journals Microstructure-sensitive critical plastic strain energy density criterion for fatigue life prediction across various loading regimes

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190766 ◽  
Author(s):  
Ritwik Bandyopadhyay ◽  
Veerappan Prithivirajan ◽  
Alonso D. Peralta ◽  
Michael D. Sangid
Keyword(s):  
Fatigue Life ◽  
Energy Density ◽  
Plastic Strain ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Strain Ratio ◽  
Material Point ◽  
Plastic Strain Energy

In the present work, we postulate that a critical value of the stored plastic strain energy density (SPSED) is associated with fatigue failure in metals and is independent of the applied load. Unlike the classical approach of estimating the (homogenized) SPSED as the cumulative area enclosed within the macroscopic stress–strain hysteresis loops, we use crystal plasticity finite element simulations to compute the (local) SPSED at each material point within polycrystalline aggregates of a nickel-based superalloy. A Bayesian inference method is used to calibrate the critical SPSED, which is subsequently used to predict fatigue lives at nine different strain ranges, including strain ratios of 0.05 and −1, using nine statistically equivalent microstructures. For each strain range, the predicted lives from all simulated microstructures follow a lognormal distribution. Moreover, for a given strain ratio, the predicted scatter is seen to be increasing with decreasing strain amplitude; this is indicative of the scatter observed in the fatigue experiments. Finally, the lognormal mean lives at each strain range are in good agreement with the experimental evidence. Since the critical SPSED captures the experimental data with reasonable accuracy across various loading regimes, it is hypothesized to be a material property and sufficient to predict the fatigue life.

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