scholarly journals Research on low cycle fatigue life prediction considering average strain

2022 ◽  
Author(s):  
Yan Peng ◽  
Yang Liu ◽  
Haoran Li ◽  
Jiankang Xing
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Fatigue Life Prediction ◽  
Model Parameters ◽  
Cycle Fatigue ◽  
Average Strain

Abstract To address the difficult problems in the study of the effect of average strain on fatigue life under low-cycle fatigue loads, the effect of average strain on the low-cycle fatigue life of materials under different strain cycle ratios was discussed based on the framework of damage mechanics and its irreversible thermodynamics. By introducing the Ramberg-Osgood cyclic constitutive equation, a new low-cycle fatigue life prediction method based on the intrinsic damage dissipation theory considering average strain was proposed, which revealed the correlation between low-cycle fatigue strain life , material properties, and average strain. Through the analysis of the low-cycle fatigue test data of five different metal materials, the model parameters of the corresponding materials were obtained. The calculation results indicate that the proposed life prediction method is in good agreement with the test, and a reasonable characterization of the low-cycle fatigue life under the influence of average strain is realized. Comparing calculations with three typical low-cycle fatigue life prediction models, the new method is within two times the error band, and the prediction effect is significantly better than the existing models, which is more suitable for low-cycle fatigue life prediction. The low-cycle fatigue life prediction of different cyclic strain ratios based on the critical region intrinsic damage dissipation power method provides a new idea for the research of low-cycle fatigue life prediction of metallic materials.

Fatigue Life Prediction Using Average Strain Range of Fatigue Process Zone

2010 ◽  
Vol 29-32 ◽  
pp. 474-478
Author(s):  
Dong Lei ◽  
Bin Kai Shi ◽  
Ge Li ◽  
Jian Hua Zhao
Keyword(s):  
Fatigue Life ◽  
Stress Concentration ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Process Zone ◽  
Strain Range ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Average Strain ◽  
Fatigue Process

In low-cycle fatigue process, plastic strain takes place at notch root vicinity fast appears induced by high stress concentration. Plastic strain makes material non-uniform and the change of distribution of local stress. The approximation to stress concentration point of Neuber’s rule is not suitable for some plastic materials in engineering practice. In this paper, the average strain of fatigue process zone was considered to substitute Neuber strain for predicting fatigue life. Prediction results indicated that average strain range of fatigue process zone is more suitable than Neuber strain range for predicting low-cycle fatigue life of LY12CZ.

Study on Low-Cycle Fatigue Life of Base Metal of the Shock Absorber

2014 ◽  
Vol 936 ◽  
pp. 1361-1365
Author(s):  
Ai Li Li ◽  
Ri Gao ◽  
Ming De Sun ◽  
Xi Meng
Keyword(s):  
Fatigue Life ◽  
Base Metal ◽  
Life Prediction ◽  
Shock Absorber ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Life Prediction ◽  
Strain Effect ◽  
Cycle Fatigue

In this paper, by experiments on the low-cycle fatigue life of groups of base metal test specimens under constant total strain control, the number of cycles to fracture failure are obtained. The measured S-N curve of base metal is established and the fitted formulas based on three low cycle fatigue life prediction models are caculated according to the test data. The relationship between the low-cycle fatigue life and strain amplitude are concluded. The results of observation show that the elastic strain effect can be negligible in the range of strain amplitudes used for the study of low-cycle fatigue (0.01-0.08). In addition, the calculation suggests that the three-parameter power function is suitable for the low-cycle fatigue life prediction of the base metal because its prediction accuracy is higher than other methods. The research provides technology supports for life prediction and engineering application of the shock absorber.

scholarly journals An Experimental Study on Low-Cycle Fatigue Crack Initiation Life Prediction of Powder Superalloy FGH96 Based on the Manson-Coffin and Damage Mechanics Methods

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 489
Author(s):  
Yuanming Xu ◽  
Hao Chen ◽  
Shuming Zhang ◽  
Tianpeng He ◽  
Xuerong Liu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Life Cycles ◽  
Cycle Fatigue ◽  
Element Analysis

The applicability of both prediction methods for low-cycle fatigue life of powder superalloy based on the Manson-Coffin equation and damage mechanics were addressed. Both fatigue life prediction models were evaluated by low-cycle fatigue experimental data of powder superalloy FGH96 with non-destructive standard parts and those with inclusions. Due to the characteristics of high strength and low plasticity of powder superalloy FGH96, errors in calculating the plastic strain amplitude deviate severely the prediction outcomes when using Manson-Coffin method. Meanwhile, by introducing the damage variable which characterizes the material damage, the damage evolution equation can be built by fitting the experimental data of standard parts and also applied to powder superalloy specimens containing inclusion. It is indispensable to accurately calculate the damage characterization parameter through finite element analysis in local stress concentration around the inclusion. The applicability of the prediction model was verified by the test life cycles of experimental specimens with different types and sizes of inclusions subsequently. Testing and simulation work showed much better prediction accuracies globally for the damage mechanics approach.

scholarly journals Research on the Fatigue Life Prediction Method of Thrust Rod

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Guoyu Feng ◽  
Wenku Shi ◽  
Henghai Zhang ◽  
Qinghua Zu ◽  
Teng Teng ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Damage ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Equivalent Stress ◽  
Prediction Method ◽  
Fatigue Life Prediction ◽  
Model Parameters ◽  
Element Analysis

Purpose of this paper is to investigate the fatigue life prediction method of the thrust rod based on the continuum damage mechanics. The equivalent stress used as damage parameters established rubber fatigue life prediction model. Through the finite element simulation and material test, the model parameters and the fatigue damage dangerous positions were obtained. By equivalent stress life model, uniaxial fatigue life of the V-type thrust rod is analyzed to predict the ratio of life and the life of the test was 1.73, within an acceptable range, and the fatigue damage occurring position and finite element analysis are basically the same. Fatigue life analysis shows that the method is of correct, theoretical, and practical value.

The Effect of Heat Generation on Low Cycle Fatigue Life Prediction

2011 ◽  
Author(s):  
Onome Scott-Emuakpor ◽  
Tommy George ◽  
Charles Cross ◽  
Todd Letcher ◽  
John Wertz ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Heat Generation ◽  
Strain Energy ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Prediction Method ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Physical Damage ◽  
Stress Ratios

An energy-based life prediction method is used in this study to determine the fatigue life of tension-compression loaded components in the very low cycle regime between 102 and 104. The theoretical model for the energy-based prediction method was developed from the concept that the strain energy accumulated during both monotonic failure and an entire fatigue process are equal; In other words, the scalar quantity of strain energy accumulated during monotonic failure is a physical damage quantity that correlates to fatigue as well. The energy-based method has been successfully applied to fatigue life prediction of components failing in the fatigue regime between 104 and 107 cycles. To assess Low Cycle Fatigue (LCF) with the prediction method, a clearer understanding of energy dissipation through heat, system vibration, damping, surface defects and acoustics were necessary. The first of these topics analyzed is heat. The analysis conducted studies the effect of heat generated during cyclic loading and heat loss from slipping at the interface of the grip wedges of the servo-hydraulic load frame and the test specimen. The reason for the latter is to address the notion that slippage in the experimental setup may be the cause of the reduction in the accuracy of the energy-based prediction method for LCF, which was seen in previous research. These analyses were conducted on Titanium 6Al-4V, where LCF experimental data for stress ratios R = −1 and R = −0.813 were compared with the energy-based life prediction method. The results show negligible effect on both total and cyclic energy from heat generation at the interface of the grip wedges and heat generation in the fatigue zone of the specimen.

Energy-Based Fatigue Life Prediction for Combined Low Cycle and High Cycle Fatigue

2013 ◽  
Author(s):  
Casey M. Holycross ◽  
M.-H. Herman Shen ◽  
Onome E. Scott-Emuakpor ◽  
Tommy J. George
Keyword(s):  
Fatigue Life ◽  
Gas Turbine ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Data Set ◽  
Vibrational Loading

Gas turbine engine components are subjected to both low and high cycle fatigue as a result of mechanical and vibrational loading. Mechanical loading is generally within the low cycle fatigue regime and attributed to throttle up/throttle down cycles of various flight maneuvers or engine start-up/shut-down cycles over the course of a component’s lifetime. Vibrational loading causes high cycle fatigue of a multiaxial stress state, and is attributed to various forced and free vibration sources manifested as high order bending or torsion modes. Understanding the interaction of these two fatigue regimes is necessary to develop robust design techniques for gas turbine engines and turbomachinery in general. Furthermore, applying a method to accurately predict fatigue performance from a reduced data set can greatly reduce time and material costs. This study investigates commonly used fatigue life prediction models and techniques in their ability to accurately model fatigue lives of Al 6061-T651 cylindrical test specimens subjected to various stress ratios, mean stresses, and high cycle/low cycle interaction. Comparisons between these models are made and modifications are proposed than can account for these complex loading effects where appropriate.

A Continuum Damage Mechanics Approach for Fatigue Life Prediction of Open-Hole Metallic Plate

2014 ◽  
Vol 670-671 ◽  
pp. 1060-1067
Author(s):  
Xian Min Chen ◽  
Qin Sun ◽  
Di Guan ◽  
Feng Ping Yang
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Damage Evolution ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Low Cycle Fatigue ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Damage Initiation ◽  
Open Hole

A damage evolution model is presented for fatigue life prediction of metallic structures. This model is formulated based on damage mechanics and the irreversible thermodynamics framework developed by LEMAITRE and CHABOCHE. Using this model, the fatigue lifetime can be predicted both in the high cycle fatigue (HCF) regime and the low cycle fatigue (LCF) regime. Based on the energy theory and material fatigue test data, the plastic strain threshold for damage initiation was modified for HCF and LCF respectively. The damage evolution parameters were determined according to the fatigue test results of standard specimens. A damage mechanics-finite element full-couple method was adopted to simulate the process of fatigue damage evolution. The numerical simulation of fatigue lives were compared with the fatigue tests of 2A12-T4 open-hole plates and good agreement was obtained.

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