Fatigue Life Prediction under Variable Loading Based a Non-Linear Energy Model

2016 ◽  
Vol 22 ◽  
pp. 14-21
Author(s):  
Abdelkader Djebli ◽  
Mostefa Bendouba ◽  
Aid Abdelkarim
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy ◽  
Fatigue Damage ◽  
Damage Model ◽  
Experimental Results ◽  
Random Loading ◽  
Random Load ◽  
Complex Load ◽  
Proposed Model ◽  
Fatigue Damage Accumulation

A method of fatigue damage accumulation based upon application of energy parameters of the fatigue process is proposed in the paper. Using this model is simple, it has no parameter to be determined, it requires only the knowledge of the curve W–N (W: strain energy density N: number of cycles at failure) determined from the experimental Wöhler curve. To examine the performance of nonlinear models proposed in the estimation of fatigue damage and fatigue life of components under random loading, a batch of specimens made of 6082 T6 aluminium alloy has been studied and some of the results are reported in the present paper. The paper describes an algorithm and suggests a fatigue cumulative damage model, especially when random loading is considered. This work contains the results of uni-axial random load fatigue tests with different mean and amplitude values performed on 6082 T6 aluminium alloy specimens. The proposed model has been formulated to take into account the damage evolution at different load levels and it allows the effect of the loading sequence to be included by means of a recurrence formula derived for multilevel loading, considering complex load sequences. It is concluded that a ‘damaged stress interaction damage rule’ proposed here allows a better fatigue damage prediction than the widely used Palmgren–Miner rule, and a formula derived in random fatigue could be used to predict the fatigue damage and fatigue lifetime very easily. The results obtained by the model are compared with the experimental results and those calculated by the most fatigue damage model used in fatigue (Miner’s model). The comparison shows that the proposed model, presents a good estimation of the experimental results. Moreover, the error is minimized in comparison to the Miner’s model.

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.

Experimental and Numerical Investigation of Torsion Fatigue of Bearing Steel

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
John A. R. Bomidi ◽  
Nick Weinzapfel ◽  
Trevor Slack ◽  
Sina Mobasher Moghaddam ◽  
Farshid Sadeghi ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Normal Stress ◽  
Failure Mechanism ◽  
Fatigue Damage ◽  
Fatigue Failure ◽  
Damage Mechanics ◽  
Damage Model ◽  
Bearing Steel ◽  
Fatigue Damage Accumulation

This paper presents the results of torsion fatigue of widely used bearing steels (through hardening with bainite, martensite heat treatments, and case hardened). An MTS torsion fatigue test rig (TFTR) was modified with custom mechanical grips and used to evaluate torsional fatigue life and failure mechanism of bearing steel specimen. Tests were conducted on the TFTR to determine the ultimate strength in shear (Sus) and stress cycle (S-N) results. Evaluation of the fatigue specimens in the high cycle regime indicates shear driven crack initiation followed by normal stress driven propagation, resulting in a helical crack pattern. A 3D finite element model was then developed to investigate fatigue damage in torsion specimen and replicate the observed fatigue failure mechanism for crack initiation and propagation. In the numerical model, continuum damage mechanics (CDM) were employed in a randomly generated 3D Voronoi tessellated mesh of the specimen to provide unstructured, nonplanar, interelement, and inter/transgranular paths for fatigue damage accumulation and crack evolution as observed in micrographs of specimen. Additionally, a new damage evolution procedure was implemented to capture the change in fatigue failure mechanism from shear to normal stress assisted crack growth. The progression of fatigue failure and the stress-life results obtained from the fatigue damage model are in good agreement with the experimental results. The fatigue damage model was also used to assess the influence of topological microstructure randomness accompanied by material inhomogeneity and defects on fatigue life dispersion.

A New Approach to Fatigue Damage Modeling of Composite Laminates

2011 ◽  
Vol 338 ◽  
pp. 315-318 ◽  
Author(s):  
Peng Gang Mu ◽  
Xiao Peng Wan ◽  
Mei Ying Zhao
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Composite Laminates ◽  
Fatigue Behavior ◽  
Failure Criteria ◽  
Damage State ◽  
Damage Indices ◽  
Model Combining ◽  
Proposed Model ◽  
Fatigue Damage Accumulation

Fatigue damage of composites can be described by the residual stiffness and residual strength, and the same damage state can be described by the two mechanical parameters equivalently. Based on this assumption, a new pair of fatigue damage accumulation models are established to simulate fatigue behavior and predict the fatigue life of composites. Each of two equations contains three parameters and has the similar form, and the power function relationships between the two damage indices are constructed. The proposed model, combining with constant life diagrams and failure criteria are used to estimate the fatigue life of composites, and good agreement is observed between the present model and experimental results.

scholarly journals Random Load Fatigue Damage Accumulation in Mild Steel

1973 ◽  
Vol 187 (1) ◽  
pp. 285-293 ◽  
Author(s):  
B. C. Fisher ◽  
F. Sherratt
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Crack Detection ◽  
High Sensitivity ◽  
Optical Microscope ◽  
Random Loading ◽  
Random Load ◽  
Initiation Phase ◽  
Fatigue Damage Accumulation ◽  
Probability Density Distributions

Using high-sensitivity eddy-current crack detection, quantitative division of fatigue life into two stages has been achieved for a variety of random and constant amplitude loading conditions. The divisions adopted were: Stage A, microcrack initiation and propagation, and Stage B, macrocrack propagation. The results of specimen sectioning and optical microscope work show that this behaviour is physically compatible with the observations of Forsyth (1)‡. It is established under random loading that for a given specimen configuration, the proportion of time spent in stage A behaviour for a given fatigue life remains unaltered for changes in the waveform irregularity factor. This statement applies to two series of tests for loading waveforms of unaltered fundamental p.s.d. (power spectral density) shapes and Gaussian amplitude probability density distributions. It is suggested that the signal maximum peak/r.m.s. ratio is a significant factor in determining the proportion of life spent in crack initiation. Cumulative damage predictions are made using Miner's hypothesis on a basis of positive peak stresses to failure for stage A and stage B lives, and overall fatigue life. The results confirm that Miner seriously underestimates the damage contribution at low stresses on fatigue life as a whole, and also for the crack initiation phase of life.

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 New Nonlinear Cumulative Fatigue Damage Model Based on Ecological Quality Dissipation of Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hongsong Li ◽  
Yongbao Liu ◽  
Xing He ◽  
Wangtian Yin
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Loading ◽  
Ecological Quality ◽  
Aircraft Structures ◽  
Variable Amplitude ◽  
Fatigue Damage Accumulation ◽  
Cumulative Fatigue Damage

The failure of many aircraft structures and materials is caused by the accumulation of fatigue damage under variable-amplitude cyclic loading wherein the damage evolution of materials is complicated. Therefore, to study the cumulative fatigue damage of materials under variable-amplitude cyclic loading, a new nonlinear fatigue damage accumulation model is proposed based on the ecological quality dissipation of materials by considering the effects of load interaction and sequence. The proposed new model is validated by the test data obtained for three kinds of material under multilevel fatigue loading. Compared with the Miner model and Kwofie model, the proposed model can more effectively analyse the accumulative damage and predict fatigue life of different materials under variable-amplitude cyclic loading than others. The study provides a basis for predicting fatigue life accurately and determining reasonable maintenance periods of aircraft structures.

scholarly journals Continuum damage mechanics based approach to the fatigue life prediction of cast aluminium alloy with considering the effect of porosity

2018 ◽  
Vol 165 ◽  
pp. 14011
Author(s):  
Xiaojia Wang ◽  
Weiping Hu ◽  
Qingchun Meng
Keyword(s):  
Fatigue Life ◽  
Aluminium Alloy ◽  
Fatigue Damage ◽  
Damage Mechanics ◽  
Damage Model ◽  
Continuum Damage Mechanics ◽  
Fatigue Behaviour ◽  
Continuum Damage ◽  
Die Cast ◽  
Elastoplastic Constitutive Model

A damage mechanics based approach is applied for the study of fatigue behaviour of high pressure die cast ADC12 aluminium alloy. A damage coupled elastoplastic constitutive model is presented according to the concept of effective stress and the hypothesis of strain equivalence. An elastic fatigue damage model taking into account the pore-induced stress concentration is developed to investigate fatigue damage evolution of the specimens subjected to cyclic loading. The predicted lives for the specimens with different sizes of pores are consistent with the experimental data. The pore-induced fatigue damage and the variation of fatigue life along with the size of pores are also investigated.

scholarly journals A Modified Model for Nonlinear Fatigue Damage Accumulation of Turbine Disc Considering the Load Interaction Effect

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 919 ◽  
Author(s):  
Huang ◽  
Ding ◽  
Li ◽  
Zhou ◽  
Huang
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Damage Model ◽  
Modified Model ◽  
Damage Models ◽  
Fatigue Damage Accumulation ◽  
Turbine Disc ◽  
Damage Accumulation Model ◽  
Nonlinear Damage Model

Fatigue damage accumulation theory is one of the core contents in structure fatigue strength design and life prediction. Among them, the nonlinear damage model can overcome the shortcomings of the linear damage model, which takes the loading sequence effect into account. Besides, the loading interaction cannot be ignored for its profound influence in damage accumulation behavior. In the paper, some commonly-used methods of the linear and nonlinear fatigue damage accumulation theory are investigated. In particular, a modified nonlinear fatigue damage accumulation model which considers the effects of loading sequences as well as loading interactions on fatigue life is developed, and a load interaction parameter is obtained by analyzing damage models which assumes that the load logarithm ratio between adjacent stress levels can characterize this phenomenon. Finally, the modified model is employed to predict the fatigue life of high pressure turbine disc. Moreover, comparison is made between the experimental data as well as the predicted lives using the Miner’s rule, the Ye’s model, and the modified model.

Damage Mechanics Based Fatigue Life Prediction for 63Sn-37Pb Solder Material

2000 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
M. K. Neilsen ◽  
H. E. Fang
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Damage Accumulation ◽  
Damage Mechanics ◽  
Damage Model ◽  
Hysteresis Loops ◽  
Cyclic Softening ◽  
Softening Behavior ◽  
Fatigue Damage Accumulation ◽  
Theory Of Damage

Abstract This paper presents a method of TMF analysis based on the theory of damage mechanics to examine the fatigue damage accumulation in 63Sn-37Pb solder. The method is developed by extending a viscoplastic damage model proposed earlier by the authors (Wei, et al 1999, 2000). A computer simulation is carried out to calculate hysteresis loops at three different strain ranges. The damage-coupled fatigue damage model is applied to predict the cyclic softening behavior of the material and the prediction is found to agree well with the experiment. With a proposed failure criterion based on the concept of damage accumulation, the TMF model is also found to predict successfully the fatigue life of 63Sn-37Pb solder.

scholarly journals Random Load Fatigue Damage Accumulation in Mild Steel

1973 ◽  
Vol 187 (1) ◽  
pp. 285-293 ◽  
Author(s):  
B. C. Fisher ◽  
F. Sherratt
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Crack Detection ◽  
High Sensitivity ◽  
Optical Microscope ◽  
Random Loading ◽  
Random Load ◽  
Initiation Phase ◽  
Fatigue Damage Accumulation ◽  
Probability Density Distributions

Using high-sensitivity eddy-current crack detection, quantitative division of fatigue life into two stages has been achieved for a variety of random and constant amplitude loading conditions. The divisions adopted were: Stage A, microcrack initiation and propagation, and Stage B, macrocrack propagation. The results of specimen sectioning and optical microscope work show that this behaviour is physically compatible with the observations of Forsyth (1)‡. It is established under random loading that for a given specimen configuration, the proportion of time spent in stage A behaviour for a given fatigue life remains unaltered for changes in the waveform irregularity factor. This statement applies to two series of tests for loading waveforms of unaltered fundamental p.s.d. (power spectral density) shapes and Gaussian amplitude probability density distributions. It is suggested that the signal maximum peak/r.m.s. ratio is a significant factor in determining the proportion of life spent in crack initiation. Cumulative damage predictions are made using Miner's hypothesis on a basis of positive peak stresses to failure for stage A and stage B lives, and overall fatigue life. The results confirm that Miner seriously underestimates the damage contribution at low stresses on fatigue life as a whole, and also for the crack initiation phase of life.

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