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11 – 20 of over 11000Jun Wu, Hong-Zhong Huang, Yan-Feng Li, Song Bai and Ao-Di Yu
Aero-engine components endure combined high and low cycle fatigue (CCF) loading during service, which has attracted more research attention in recent years. This study aims to…
Abstract
Purpose
Aero-engine components endure combined high and low cycle fatigue (CCF) loading during service, which has attracted more research attention in recent years. This study aims to construct a new framework for the prediction of probabilistic fatigue life and reliability evaluation of an aero-engine turbine shaft under CCF loading if considering the material uncertainty.
Design/methodology/approach
To study the CCF failure of the aero-engine turbine shaft, a CCF test is carried out. An improved damage accumulation model is first introduced to predict the CCF life and present high prediction accuracy in the CCF loading situation based on the test. Then, the probabilistic fatigue life of the turbine shaft is predicted based on the finite element analysis and Monte Carlo analysis, where the material uncertainty is taken into account. At last, the reliability evaluation of the turbine shaft is conducted by stress-strength interference models based on an improved damage accumulation model.
Findings
The results indicate that predictions agree well with the tested data. The improved damage accumulation model can accurately predict the CCF life because of interaction damage between low cycle fatigue loading and high cycle fatigue loading. As a result, a framework is available for accurate probabilistic fatigue life prediction and reliability evaluation.
Practical implications
The proposed framework and the presented testing in this study show high efficiency on probabilistic CCF fatigue life prediction and can provide technical support for fatigue optimization of the turbine shaft.
Originality/value
The novelty of this work is that CCF loading and material uncertainty are considered in probabilistic fatigue life prediction.
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R.A. Cláudio, J.M. Silva and J. Byrne
This paper aims to present a methodology, based on traditional approaches, to predict the fatigue life and non‐propagating cracks of shot peened components and the damaging effect…
Abstract
Purpose
This paper aims to present a methodology, based on traditional approaches, to predict the fatigue life and non‐propagating cracks of shot peened components and the damaging effect of a scratch created over the treated surface.
Design/methodology/approach
The finite element method is used to determine the actual strain at surface and fracture mechanics parameters calculated from cracks at the surface. The model considers residual stress (in order to introduce the effect of shot peening) and the scratch geometry. The total fatigue life is obtained by adding initiation life, to early and long crack propagation life using appropriate criteria.
Findings
Numerical predictions were compared with previous experimental tests, showing that this method is quite reliable for predicting both fatigue life and non‐propagating cracks of shot peened components, including the effect of damage due to a scratch.
Research limitations/implications
The proposed method provides good results and a clear understanding of the fatigue process, however it requires a considerable amount of both material and shot peening parameters.
Practical implications
The methodology presented in this paper allows the determination of fatigue life and the prediction of non‐propagating cracks for components, including the effects of shot peening and scratch damage. These results can be used to quantify the scratch damage limits of components improved by shot peening.
Originality/value
This paper provides a useful tool for prediction of the effects of shot peening and scratch damage on fatigue life, using traditional approaches.
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Yong-Hua Li, Chi Zhang, Hao Yin, Yang Cao and Xiaoning Bai
This paper proposes an improved fatigue life analysis method for optimal design of electric multiple units (EMU) gear, which aims at defects of traditional Miner fatigue…
Abstract
Purpose
This paper proposes an improved fatigue life analysis method for optimal design of electric multiple units (EMU) gear, which aims at defects of traditional Miner fatigue cumulative damage theory.
Design/methodology/approach
A fatigue life analysis method by modifying S–N curve and considering material difference is presented, which improves the fatigue life of EMU gear based on shape modification optimization. A corrected method for stress amplitude, average stress and S–N curve is proposed, which considers low stress cycle, material difference and other factors. The fatigue life prediction of EMU gear is carried out by corrected S–N curve and transient dynamic analysis. Moreover, the gear modification technology combined with intelligent optimization method is adopted to investigate the approach of fatigue life analysis and improvement.
Findings
The results show that it is more corresponded to engineering practice by using the improved fatigue life analysis method than the traditional method. The function of stress and modification amount established by response surface method meets the requirement of precision. The fatigue life of EMU gear based on the intelligent algorithm for seeking the optimal modification amount is significantly improved compared with that before the modification.
Originality/value
The traditional fatigue life analysis method does not consider the influence of working condition and material. The life prediction results by using the method proposed in this paper are more accurate and ensure the safety of the people in the EMU. At the same time, the combination of intelligent algorithm and gear modification can improve the fatigue life of gear on the basis of accurate prediction, which is of great significance to the portability of EMU maintenance.
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Nazirul Muhaimin Hamzi, Salvinder Singh, Shahrum Abdullah and Mohammad Rasidi Rasani
This paper aims to assess the fatigue life characteristics of vehicle coil spring under random strain load in the time domain. Cyclic random road loads caused fatigue failure for…
Abstract
Purpose
This paper aims to assess the fatigue life characteristics of vehicle coil spring under random strain load in the time domain. Cyclic random road loads caused fatigue failure for automotive components during their operating condition. .
Design/methodology/approach
The coil spring model is developed through finite element analysis software. The critical region and fatigue life cycle of coil spring is evaluated through finite element analysis. The experimental is set up to capture the random strain signal of the rural, highway and campus road. The sampling rate of the random strain signals data captured were 500 Hz in 150 s. Then, fatigue life is assessed through Goodman, Brown-Miller, Fatemi-Socie, Wang-Brown fatigue life models. Goodman model is evaluated through finite element analysis in order to compare with fatigue experimental results.
Findings
The fatigue life was estimated for Brown-Miller model is the highest (4.32E4, 4.10E4, and 3.73E4 cycles/block for rural, highway and campus respectively) followed by Goodman model, Brown-Miller, Fatemi-Socie and Wang-Brown models respectively. The conservative fatigue life 1:2 and 2:1 data scattering approach is proposed in order to determine the acceptability of the data.
Originality/value
Hence, the proposed fatigue life models can be used to assess multiaxial fatigue under random strain signals for the automobile coil spring.
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Gulshan Singh, Miguel Cortina, Harry Millwater and Allan Clauer
The purpose of this paper is to estimate probabilistic and regional importance sensitivities of fatigue life, with respect to the laser peening (LP) parameters applied to a…
Abstract
Purpose
The purpose of this paper is to estimate probabilistic and regional importance sensitivities of fatigue life, with respect to the laser peening (LP) parameters applied to a Titanium turbine disk.
Design/methodology/approach
The sensitivities were calculated from Monte Carlo (MC) analysis of 21,000 simulations and probabilistic sensitivity methods.
Findings
The probabilistic sensitivity results indicate that the peak pressure and the mid‐span are the most important variables. The regional importance sensitivity results indicate that probability of failure is the most sensitive to the left tail of peak pressure and middle region of mid‐span and the fatigue life mean is the most sensitive to the left tails of the peak pressure and the mid‐span.
Practical implications
The sensitivity results of this research indicate that more time and energy should be focused on managing peak pressure and mid‐span, as compared to the remaining variables, to design and improve the laser peening process.
Originality/value
The paper presents four sensitivity analysis approaches which were formulated and employed to estimate fatigue life sensitivities with respect to the LP variables.
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This paper aims to predict fatigue life and fatigue limit of fiber-reinforced ceramic-matrix composites (CMCs) with different fiber preforms, i.e. unidirectional, cross-ply, 2D-…
Abstract
Purpose
This paper aims to predict fatigue life and fatigue limit of fiber-reinforced ceramic-matrix composites (CMCs) with different fiber preforms, i.e. unidirectional, cross-ply, 2D-, 2.5D- and 3D-woven, at room and elevated temperatures.
Design/methodology/approach
Under cyclic loading, matrix multicracking and interface debonding occur upon first loading to fatigue peak stress, and the interface wear appears with increasing cycle number, leading to degradation of the interface shear stress and fibers strength. The relationships between fibers fracture, cycle number, fatigue peak stress and interface wear damage mechanism have been established based on the global load sharing (GLS) criterion. The evolution of fibers broken fraction versus cycle number curves of fiber-reinforced CMCs at room and elevated temperatures have been obtained.
Findings
The predicted fatigue life S–N curve can be divided into two regions, i.e. the Region I controlled by the degradation of interface shear stress and fibers strength and the Region II controlled by the degradation of fibers strength.
Practical/implications
The proposed approach can be used to predict the fatigue life and fatigue limit of unidirectional, cross-ply, 2D-, 2.5D- and 3D-woven CMCs under cyclic loading.
Originality/value
The fatigue damage mechanisms and fibers failure model were combined together to predict the fatigue life and fatigue limit of fiber-reinforced CMCs with different fiber preforms.
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Xintian Liu and Muzhou Ma
Scholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue…
Abstract
Purpose
Scholars mainly propose and establish theoretical models of cumulative fatigue damage for their research fields. This review aims to select the applicable model from many fatigue damage models according to the actual situation. However, relatively few models can be generally accepted and widely used.
Design/methodology/approach
This review introduces the development of cumulative damage theory. Then, several typical models are selected from linear and nonlinear cumulative damage models to perform data analyses and obtain the fatigue life for the metal.
Findings
Considering the energy law and strength degradation, the nonlinear fatigue cumulative damage model can better reflect the fatigue damage under constant and multi-stage variable amplitude loading. In the following research, the complex uncertainty of the model in the fatigue damage process can be considered, as well as the combination of advanced machine learning techniques to reduce the prediction error.
Originality/value
This review compares the advantages and disadvantages of various mainstream cumulative damage research methods. It provides a reference for further research into the theories of cumulative fatigue damage.
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Shaoyi Liu, Songjie Yao, Song Xue, Benben Wang, Hui Jin, Chenghui Pan, Yinwei Zhang, Yijiang Zhou, Rui Zeng, Lihao Ping, Zhixian Min, Daxing Zhang and Congsi Wang
Surface mount technology (SMT) is widely used and plays an important role in electronic equipment. The purpose of this paper is to reveal the effects of interface cracks on the…
Abstract
Purpose
Surface mount technology (SMT) is widely used and plays an important role in electronic equipment. The purpose of this paper is to reveal the effects of interface cracks on the fatigue life of SMT solder joint under service load and to provide some valuable reference information for improving service reliability of SMT packages.
Design/methodology/approach
A 3D geometric model of SMT package is established. The mechanical properties of SMT solder joint under thermal cycling load and random vibration load were solved by 3D finite element analysis. The fatigue life of SMT solder joint under different loads can be calculated by using the modified Coffin–Manson model and high-cycle fatigue model.
Findings
The results revealed that cracks at different locations and propagation directions have different effect on the fatigue life of the SMT solder joint. From the location of the cracks, Crack 1 has the most significant impact on the thermal fatigue life of the solder joint. Under the same thermal cycling conditions, its life has decreased by 46.98%, followed by Crack 2, Crack 4 and Crack 3. On the other hand, under the same random vibration load, Crack 4 has the most significant impact on the solder joint fatigue life, reducing its life by 81.39%, followed by Crack 1, Crack 3 and Crack 2. From the crack propagation direction, with the increase of crack depth, the thermal fatigue life of the SMT solder joint decreases sharply at first and then continues to decline almost linearly. The random vibration fatigue life of the solder joint decreases continuously with the increase of crack depth. From the crack depth of 0.01 mm to 0.05 mm, the random vibration fatigue life decreases by 86.75%. When the crack width increases, the thermal and random vibration fatigue life of the solder joint decreases almost linearly.
Originality/value
This paper investigates the effects of interface cracks on the fatigue life and provides useful information on the reliability of SMT packages.
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Jianlei Yi, Kunjian Jin, Haiying Qin and Yuhong Cui
An ideal method for predicting the fatigue life of spherical thrust elastomeric bearings has not been reported, thus far. This paper aims to present a method for predicting the…
Abstract
Purpose
An ideal method for predicting the fatigue life of spherical thrust elastomeric bearings has not been reported, thus far. This paper aims to present a method for predicting the fatigue life of laminated rubber spherical thrust elastomeric bearings.
Design/methodology/approach
First, the mechanical properties of standard rubber samples were tested; the axial stiffness, cocking stiffness, torsional stiffness and fatigue life of several full-size spherical thrust elastomeric bearings were tested. Then, the stiffness results were calculated using the neo-Hookean, Mooney–Rivlin and Yoeh models. Using a modified Mooney–Rivlin constitutive model, this paper proposes an improved method for fatigue life prediction, which considers the laminated characteristics of a spherical thrust elastomeric bearing and loads of multiple multi-axle conditions.
Findings
The Mooney–Rivlin model could accurately describe the stiffness characteristics of the spherical thrust elastomeric bearings. A comparative analysis of experimental results shows that the model can effectively predict the life of a spherical thrust elastomeric bearing within its range of use and the prediction error is within 20%.
Originality/value
The fatigue parameters of elastomeric bearings under multiaxial loads were fitted and corrected using experimental data and an accurate and effective multiaxial fatigue-life prediction expression was obtained. Finally, the software was redeveloped to improve the flexibility and efficiency of modeling and calculation.
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The purpose of this study is to address the complexity involved in computing the fatigue life of casted structure with porosity effects in aero engine applications. The…
Abstract
Purpose
The purpose of this study is to address the complexity involved in computing the fatigue life of casted structure with porosity effects in aero engine applications. The uncertainty of porosity defects is addressed by introducing probabilistic models.
Design/methodology/approach
One major issue of casted aluminium alloys in the application of aerospace industries is their internal defects such as porosities, which are directly affecting the fatigue life. Since there is huge cost and time effort involved in understanding the effect of fatigue life in terms of the presence of the internal defects, a probabilistic fatigue model approach is applied in order to define the realistic fatigue limit of the casted structures for the known porosity fractions. This paper describes the probabilistic technique to casted structures with measured porosity fractions and its relation to their fatigue life. The predicted fatigue life for various porosity fractions and dendrite arm spacing values is very well matching with the experimentally predicted fatigue data of the casted AS7G06 aluminium alloys with measured internal defects. The probabilistic analysis approach not only predicts the fatigue life limit of the structure but also provides the limit of fatigue life for the known porosity values of any casted aluminium bearing support structure used in aero engines.
Findings
The probabilistic fatigue model for addressing porosity in casting structure is verified with experimental results.
Research limitations/implications
This is grey area in aerospace and automotive industry.
Originality/value
This work is original and not published anywhere else.
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