Improvement of Fracture Toughness and Low-Cycle Fatigue Life for INCONEL718 Welded Joint in the LE-7 Rocket Engine Main Injector.

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

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Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽

10.3390/ma14154070 ◽

2021 ◽

Vol 14 (15) ◽

pp. 4070

Author(s):

Andrea Karen Persons ◽

John E. Ball ◽

Charles Freeman ◽

David M. Macias ◽

Chartrisa LaShan Simpson ◽

...

Keyword(s):

Fatigue Life ◽

Prediction Models ◽

Fatigue Testing ◽

Low Cycle Fatigue ◽

Wearable Sensors ◽

Fatigue Tests ◽

Proof Of Concept ◽

Cycle Fatigue ◽

Wearable Sensing ◽

Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

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Uniaxial Ratcheting and Low-Cycle Fatigue Failure of U75V Rail Steel

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.246 ◽

2016 ◽

Vol 853 ◽

pp. 246-250 ◽

Cited By ~ 2

Author(s):

Tao Fang ◽

Qian Hua Kan ◽

Guo Zheng Kang ◽

Wen Yi Yan

Keyword(s):

Fatigue Life ◽

Strain Amplitude ◽

Stress Ratio ◽

Stress Amplitude ◽

Rail Steel ◽

Low Cycle Fatigue ◽

Mean Stress ◽

Cycle Fatigue ◽

Ratcheting Strain ◽

Cyclic Straining

Experiments on U75V rail steel were carried out to investigate the cyclic feature, ratcheting behavior and low-cycle fatigue under both strain- and stress-controlled loadings at room temperature. It was found that U75V rail steel shows strain amplitude dependent cyclic softening feature, i.e., the responded stress amplitude under strain-controlled decreases with the increasing number of cycles and reaches a stable value after about 20th cycle. Ratcheting strain increases with an increasing stress amplitude and mean stress, except for stress ratio, and the ratcheting strain in failure also increases with an increasing stress amplitude, mean stress and stress ratio. The low-cycle fatigue lives under cyclic straining decrease linearly with an increasing strain amplitude, the fatigue lives under cyclic stressing decrease with an increasing mean stress except for zero mean stress, and decrease with an increasing stress amplitude. Ratcheting behavior with a high mean stress reduces fatigue life of rail steel by comparing fatigue lives under stress cycling with those under strain cycling. Research findings are helpful to evaluate fatigue life of U75V rail steel in the railways with passenger and freight traffic.

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A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

Materials Science Forum ◽

10.4028/www.scientific.net/msf.514-516.804 ◽

2006 ◽

Vol 514-516 ◽

pp. 804-809

Author(s):

S. Gao ◽

Ewald Werner

Keyword(s):

Fatigue Life ◽

Fatigue Damage ◽

Low Cycle Fatigue ◽

Damage Model ◽

Fatigue Loading ◽

Cycle Fatigue ◽

Die Material ◽

Multi Level ◽

Loading Sequence ◽

Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

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Low Cycle Fatigue Behavior of 316LN Stainless Steel Alloyed with Varying Nitrogen Content. Part II: Fatigue Life and Fracture Behavior

Metallurgical and Materials Transactions A ◽

10.1007/s11661-014-2429-4 ◽

2014 ◽

Vol 45 (11) ◽

pp. 5057-5067 ◽

Cited By ~ 15

Author(s):

G. V. Prasad Reddy ◽

R. Sandhya ◽

S. Sankaran ◽

M. D. Mathew

Keyword(s):

Stainless Steel ◽

Fatigue Life ◽

Nitrogen Content ◽

Fracture Behavior ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Cycle Fatigue ◽

316Ln Stainless Steel ◽

Content Part

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Characteristics of Wheel Tread for Property Improvement of Railway Wheel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.1075 ◽

2006 ◽

Vol 326-328 ◽

pp. 1075-1078

Author(s):

Seok Jin Kwon ◽

Jung Won Seo ◽

Hyun Mu Hur ◽

Sung Tae Kwon

Keyword(s):

Fracture Toughness ◽

Low Temperature ◽

Impact Energy ◽

Low Cycle Fatigue ◽

Maintenance Cost ◽

Railway Vehicle ◽

Cycle Fatigue ◽

Railway Wheel ◽

Mechanics Characteristics ◽

Wheel Material

Despite of improvement of wheel material for railway vehicle, the damages of railway wheel have been occurred in service running. Because of wheel damage with spalling, shelling and thermal crack, the maintenance cost for the railway wheel has increased. The railway wheel had standardized but the chemical composition, the mechanical property and the hardness with respect to railway wheel is merely established. In order to reduce wheel damage, it is necessary to reinforce the standard of railway wheel. In present study, the fracture mechanics characteristics of railway wheel such as low cycle fatigue, fracture toughness, impact energy depended on low temperature and so on have tested. The result shows that the standard of railway wheel has to supplement fracture toughness and impact energy depended on low temperature etc.

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A weight function method for multiaxial low-cycle fatigue life prediction under variable amplitude loading

The Journal of Strain Analysis for Engineering Design ◽

10.1177/0309324718763671 ◽

2018 ◽

Vol 53 (4) ◽

pp. 197-209 ◽

Cited By ~ 2

Author(s):

Xiao-Wei Wang ◽

De-Guang Shang ◽

Yu-Juan Sun

Keyword(s):

Fatigue Life ◽

Weight Function ◽

Life Prediction ◽

Function Method ◽

Low Cycle Fatigue ◽

Fatigue Life Prediction ◽

Cycle Fatigue ◽

Critical Plane ◽

Variable Amplitude ◽

Weight Function Method

A weight function method based on strain parameters is proposed to determine the critical plane in low-cycle fatigue region under both constant and variable amplitude tension–torsion loadings. The critical plane is defined by the weighted mean maximum absolute shear strain plane. Combined with the critical plane determined by the proposed method, strain-based fatigue life prediction models and Wang-Brown’s multiaxial cycle counting method are employed to predict the fatigue life. The experimental critical plane orientation and fatigue life data under constant and variable amplitude tension–torsion loadings are used to verify the proposed method. The results show that the proposed method is appropriate to determine the critical plane under both constant and variable amplitude loadings.

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