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Article
Publication date: 31 August 2022

Yingbao He, Jianhui Liu, Feilong Hua, He Zhao and Jie Wang

Under multiaxial random loading, the material stress–strain response is not periodic, which makes it difficult to determine the direction of the critical plane on the material…

127

Abstract

Purpose

Under multiaxial random loading, the material stress–strain response is not periodic, which makes it difficult to determine the direction of the critical plane on the material. Meanwhile, existing methods of constant loading cannot be directly applied to multiaxial random loading; this problem can be solved when an equivalent stress transformation method is used.

Design/methodology/approach

First, the Liu-Mahadevan critical plane is introduced into multiaxial random fatigue, which is enabled to determine the material's critical plane position under random loading. Then, an equivalent stress transformation method is proposed which can convert random load to constant load. Meanwhile, the ratio of mean stress to yield strength is defined as the new mean stress influence factor, and a new non-proportional additional strengthening factor is proposed by considering the effect of phase differences.

Findings

The proposed model is validated using multiaxial random fatigue test data of TC4 titanium alloy specimens and the results of the proposed model are compared with that based on Miner's rule and BSW model, showing that the proposed method is more accurate.

Originality/value

In this work, a new multiaxial random fatigue life prediction model is proposed based on equivalent stress transformation method, which considers the mean stress effect and the additional strengthening effect. Results show that the predicted fatigue lives given by the proposed model are in well accordance with the tested data.

Details

International Journal of Structural Integrity, vol. 13 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 11 August 2023

Jianhui Liu, Ziyang Zhang, Longxiang Zhu, Jie Wang and Yingbao He

Due to the limitation of experimental conditions and budget, fatigue data of mechanical components are often scarce in practical engineering, which leads to low reliability of…

188

Abstract

Purpose

Due to the limitation of experimental conditions and budget, fatigue data of mechanical components are often scarce in practical engineering, which leads to low reliability of fatigue data and reduces the accuracy of fatigue life prediction. Therefore, this study aims to expand the available fatigue data and verify its reliability, enabling the achievement of life prediction analysis at different stress levels.

Design/methodology/approach

First, the principle of fatigue life probability percentiles consistency and the perturbation optimization technique is used to realize the equivalent conversion of small samples fatigue life test data at different stress levels. Meanwhile, checking failure model by fitting the goodness of fit test and proposing a Monte Carlo method based on the data distribution characteristics and a numerical simulation strategy of directional sampling is used to extend equivalent data. Furthermore, the relationship between effective stress and characteristic life is analyzed using a combination of the Weibull distribution and the Stromeyer equation. An iterative sequence is established to obtain predicted life.

Findings

The TC4–DT titanium alloy is selected to assess the accuracy and reliability of the proposed method and the results show that predicted life obtained with the proposed method is within the double dispersion band, indicating high accuracy.

Originality/value

The purpose of this study is to provide a reference for the expansion of small sample fatigue test data, verification of data reliability and prediction of fatigue life data. In addition, the proposed method provides a theoretical basis for engineering applications.

Details

International Journal of Structural Integrity, vol. 14 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 8 August 2022

Jie Wang, Jianhui Liu, Feilon Hua, Yingbao He and Xuexue Wang

Engineering components/structures are usually subjected to complex and variable loads, which result in random multiaxial stress/strain states. However, fatigue analysis methods…

143

Abstract

Purpose

Engineering components/structures are usually subjected to complex and variable loads, which result in random multiaxial stress/strain states. However, fatigue analysis methods under constant loads cannot be directly applied to fatigue life prediction analysis under random loads. Therefore, the purpose of this study is how to effectively evaluate fatigue life under multiaxial random loading.

Design/methodology/approach

First, the average phase difference is characterized as the ratio of the number of shear strain cycles to the number of normal strain cycles, and the new non-proportional additional hardening factor is proposed. Then, the determined random typical load spectrum is processed into a simple variable amplitude load spectrum, and the damage in each plane is calculated according to the multiaxial fatigue life prediction model and Miner theory. Meanwhile, the cumulative damage can be calculated separately by projection method. Finally, the maximum projected cumulative damage plane is defined as the critical plane of multiaxial random fatigue.

Findings

The fatigue life prediction capability of the method is verified based on test data of TC4 titanium alloy under random multiaxial loading. Most of the predicting results are within double scatter bands.

Originality/value

The objective of this study is to provide a reference for the determination of critical plane and non-proportional additional hardening factor under multiaxial random loading, and to promote the development of multiaxial fatigue from experimental studies to practical engineering applications.

Details

International Journal of Structural Integrity, vol. 13 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 7 November 2016

Meng Jia and Yingbao Yang

The purpose of this paper is to study dynamic evolution of passenger emotional contagion among different flights emerging in mass flight delays, so as to quantitatively analyze…

766

Abstract

Purpose

The purpose of this paper is to study dynamic evolution of passenger emotional contagion among different flights emerging in mass flight delays, so as to quantitatively analyze emotional variation tendencies and influences of concerned factors and intervention measures.

Design/methodology/approach

An intervening variable of group emotion was introduced into emotional contagion model to simulate passenger emotional evolution among multi-flight groups. Besides, personalities, characters and social relationships were considered to represent individual differences in emotional changes. Based on personal contact relationships, emotional contagion model was proposed to evaluate cross-emotion transition processes among different groups under scenarios of information shortage. Eventually, evolutionary processes of passenger emotions were fused in an agent-based simulation based on social force correction model.

Findings

Simulation experiment results revealed that passenger emotions suffer from combined impacts of individual emotional changes and emotional interactions among adjacent flights through a comparison with actual survey. Besides, emotional interactions accelerate processes of emotion transitions, and have significant impacts on adjacent flights when different measures are taken. Moreover, taking intervention measures simultaneously seems more effective than implementing intervention successively.

Originality/value

The proposed method makes up for deficiency of ignoring effects of emotional interactions among adjacent flights. It contributes to providing control methods and strategies for relevant departments and improving the efficiency and ability of handling passenger collective events in mass flight delays.

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