scholarly journals Study on Damage Accumulation and Life Prediction with Loads below Fatigue Limit Based on a Modified Nonlinear Model

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2298 ◽  
Author(s):  
Junhong Zhang ◽  
Xi Fu ◽  
Jiewei Lin ◽  
Zhiyuan Liu ◽  
Nuohao Liu ◽  
...  
Keyword(s):  
Fatigue Limit ◽  
Damage Accumulation ◽  
Damage Model ◽  
Cumulative Damage ◽  
Strengthening Effect ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Proposed Model ◽  
Chaboche Model

Most fatigue theories neglect the loads below fatigue limit in damage accumulation, which leads to inconsistency between the predicted and the actual fatigue lives. In this study, a novel damage model is proposed to take into account the loads below fatigue limit from two aspects: the strengthening effect and the cumulative damage. The strengthening effect is introduced by an exponential function and the cumulative damage is calculated by fuzzy method with membership functions (MFs). The proposed model is verified against the experimental data under variable amplitude loading conditions. It is found the modified model with Cauchy MF significantly reduces the relative error of predicted life from 35.18% (linear model) and 16.09% (original Chaboche model) to 8.38% (proposed model). As a case study, the proposed damage model is implemented to evaluate the service life of a compressor blade under variable amplitude loading spectrum containing small loads below the fatigue limit.

A Modified Cumulative Damage Model for Fatigue Life Prediction under Variable Amplitude Loadings

2016 ◽  
Vol 853 ◽  
pp. 62-66 ◽  
Author(s):  
Peng Yue ◽  
Qiang Lei ◽  
Cheng Lin Zhang ◽  
Shun Peng Zhu ◽  
Hong Zhong Huang
Keyword(s):  
Fatigue Damage ◽  
Life Prediction ◽  
Damage Accumulation ◽  
Damage Model ◽  
Cumulative Damage ◽  
Mean Stress ◽  
Stress Model ◽  
Proposed Model ◽  
Fatigue Damage Accumulation ◽  
Cumulative Damage Model

To evaluate the fatigue damage accumulation and predict the residual life of components at different stress levels, this paper proposed a modified cumulative damage model based on the strain energy density parameter. Noting that mean stress and load interaction under uniaxial fatigue loading exhibit significant effects on fatigue damage accumulation and life prediction. According to this, a new model based on damaged stress model which considers the effects of mean stress and load interaction was presented in this paper. The proposed model was verified by using four experimental data sets of aluminium alloys and steels. The experimental results are compared with those of the Miner’s rule, damaged stress model (DSM) and damaged energy model (DEM). Results show that the proposed model agrees better with the experimental observations than others.

scholarly journals Prediction of fatigue damage accumulation of defective materials under variable amplitude loading

2019 ◽  
Vol 234 (1) ◽  
pp. 65-75
Author(s):  
Maroua Saggar ◽  
Anouar Nasr ◽  
Haifa Sallem ◽  
Chokri Bouraoui
Keyword(s):  
Damage Accumulation ◽  
Surface Defect ◽  
Multiaxial Fatigue ◽  
Cumulative Damage ◽  
Strong Nonlinearity ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Artificial Surface ◽  
Free Material

The main goal of this attempt is to explore and analyze the behavior of a material containing artificial surface defect and solicited under variable amplitude cyclic loading. The observation and the follow-up of the loading history and the characterization of the damage accumulation were evaluated in the presence of an artificial surface defect. The results made it possible to highlight a strong nonlinearity of the damage accumulation. However, the absence of sequence effects encountered in a defect-free material has been found. In the perspective of developing an approach to evaluate the influence of the defects on cumulative damage under variable amplitude loading, this work consists of coupling a multiaxial fatigue criterion adapted to defective materials with a law of uniaxial damage solicited under variable amplitudes loading. A cumulative damage law has been used to analyze the validity of the proposed method. Introducing the equivalent multiaxial fatigue stress due to the presence of the defect allowed us to predict the residual lifetime of a defective material, and to find the effects of sequences usually observed for variable amplitude loading for the defect-free material. A coherent agreement is observed between the results predicted by the improved model and those obtained from the experimental investigations on specimens containing artificial surface defect subjected to purely alternating tension and torsion under increasing and decreasing load levels.

scholarly journals Improved numerical model for fatigue cumulative damage of mechanical structure considering load sequence and interaction

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199530
Author(s):  
Bixiong Huang ◽  
Shuci Wang ◽  
Shuanglong Geng ◽  
Xintian Liu
Keyword(s):  
Fatigue Life ◽  
Theoretical Basis ◽  
Life Prediction ◽  
Damage Model ◽  
Cumulative Damage ◽  
Load Spectrum ◽  
Random Load ◽  
Mechanical Parts ◽  
Proposed Model ◽  
Load Sequence

To more accurately predict the fatigue life of components under the action of random loads, it is necessary to explore the influence of the interaction between the load sequence and the load on the life prediction. Based on the Manson-Halford method and Corten-Dolan model, this paper establishes a fatigue cumulative damage model that takes into account both the load order and the interaction between loads, and also takes into account the loads near the fatigue limit. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. The fatigue life of mechanical parts under random load can be calculated through this model, which provides a theoretical basis for life prediction under random load spectrum. Comparing the calculation results of the proposed model with the results of Palmgren Miner, Manson-Halford method, and Corten-Dolan model, it is found that the fatigue damage model established can reasonably predict the fatigue life of parts. Comparison and verification of examples further prove the accuracy and reliability of the proposed model.

scholarly journals Fretting Fatigue under Variable Amplitude Loading below Fretting Fatigue Limit

2005 ◽  
Vol 71 (705) ◽  
pp. 763-768
Author(s):  
Yoshiyuki KONDO ◽  
Chu SAKAE ◽  
Masanobu KUBOTA ◽  
Hiroki KITAHARA ◽  
Kazutoshi YANAGIHARA
Keyword(s):  
Fatigue Limit ◽  
Fretting Fatigue ◽  
Variable Amplitude Loading ◽  
Variable Amplitude

Estimating fatigue life under variable amplitude loading through quantitative fractography – A case study

2004 ◽  
Vol 11 (4) ◽  
pp. 547-559 ◽  
Author(s):  
J.R. Tarpani ◽  
C.O.F.T. Ruckert ◽  
M.T. Milan ◽  
R.V. Silva ◽  
A. Rosato ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Quantitative Fractography

Fatigue Testing of Full Scale Girth Welded Pipes Under Variable Amplitude Loading

2012 ◽  
Author(s):  
Y.-H. Zhang ◽  
S. J. Maddox
Keyword(s):  
Fatigue Limit ◽  
Fatigue Damage ◽  
Fatigue Testing ◽  
Full Scale ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Design ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Loading Spectrum

In the fatigue design of steel catenary risers there are concerns regarding the fatigue damage to girth welds from low stresses, below the constant amplitude fatigue limit, in the loading spectrum and the validity of Miner’s cumulative damage rule. In both cases there is increasing evidence that current design methods can be non-conservative. These fundamental issues were addressed in a recent JIP. A key feature was development of the resonance fatigue testing rigs to enable them to test full-scale pipes under variable amplitude loading. Such tests were performed under a loading spectrum representative of that experienced by some risers, with many tests lasting over 100 million cycles to investigate the fatigue damage due to small stresses as well as the validity of Miner’s rule. However, the resonance rigs are only capable of producing spectrum loading by gradually increasing or decreasing the applied load, whereas more ‘spiky’ random load sequences may be relevant in practice. Therefore the programme also included fatigue tests in conventional testing machines on strip specimens cut from pipes to compare the two types of loading sequence. This paper presents the results of these tests, conclusions drawn and recommendations for changes to current fatigue design guidance for girth welded pipes regarding the definition of the fatigue limit, allowance for the damaging effect of low stresses and the validity of Miner’s rule.

scholarly journals A Nonlinear Fatigue Damage Model Based on Equivalent Transformation of Stress

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Lu Zhang ◽  
Jie Jin ◽  
Wei Zhou ◽  
Wen-Liang Li ◽  
Meng Qiao
Keyword(s):  
Fatigue Damage ◽  
Damage Model ◽  
Simple Calculation ◽  
Equivalent Transformation ◽  
Variable Amplitude ◽  
Damage Models ◽  
Block Loading ◽  
Proposed Model ◽  
Knee Point ◽  
Fatigue Experiment

It is rather difficult for engineers to apply many of the fatigue damage models for requiring a knee point, material-dependent coefficient, or extensive testing, and some of them are only validated by a fatigue test of two-stage loading rather than higher-stage loading. In this paper, we propose a new model of fatigue cumulative damage in variable amplitude loading, which just requires the information of the S-N curve determined from the fatigue experiment. Specifically, the proposed model defines a stress equivalent transformation way to translate the damage of one stress to another stress through simple calculation. Experimental data of fatigue including two-, three-, and four-block loading verify the superiority of the proposed model by comparing it with the Miner model and Manson model. The results show that the proposed model can be generalized to any type of loading and presents a better prediction. Therefore, the advantage of the proposed model can be easily used by an engineer.

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