Effects of stress ratio on fatigue life of carbon-carbon composites

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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Fatigue Life Prediction of Rolling Bearings Based on Modified SWT Mean Stress Correction

10.21203/rs.3.rs-132643/v1 ◽

2020 ◽

Author(s):

Aodi Yu ◽

Hong-Zhong Huang ◽

Yan-Feng Li ◽

He Li ◽

Ying Zeng

Keyword(s):

Fatigue Life ◽

Life Prediction ◽

Stress Ratio ◽

Prediction Models ◽

Great Influence ◽

Sensitivity Coefficient ◽

Model Verification ◽

Mean Stress ◽

Test Results ◽

Rolling Bearings

Abstract Mean stress has a great influence on fatigue life, commonly used stress-based life prediction models can only fit the test results of fatigue life under specific stress ratio or mean stress but cannot describe the effect of stress ratio or mean stress on fatigue life. Smith, Watson and Topper (SWT) proposed a simple mean stress correction criterion. However, the SWT model regards the sensitivity coefficient of all materials to mean stress as 0.5, which will lead to inaccurate predictions for materials with a sensitivity coefficient not equal to 0.5. In this paper, considering the sensitivity of different materials to mean stresses, compensation factor is introduced to modify the SWT model, and several sets of experimental data are used for model verification. Then, the proposed model is applied to fatigue life predictions of rolling bearings, and the results of proposed method are compared with test results to verify its accuracy.

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Effects of Stress Ratio on Edge Delamination Characteristics in Laminated Composites

Composite Materials: Fatigue and Fracture, Fourth Volume ◽

10.1520/stp24749s ◽

2009 ◽

pp. 538-538-14 ◽

Cited By ~ 3

Author(s):

GC Scrivner ◽

WS Chan

Keyword(s):

Stress Ratio ◽

Laminated Composites ◽

Effects Of Stress ◽

Edge Delamination

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Effects of temperature and stress ratio on fatigue life of injection molded short carbon fiber-reinforced polyamide composite

Composites Part A Applied Science and Manufacturing ◽

10.1016/j.compositesa.2017.03.008 ◽

2017 ◽

Vol 98 ◽

pp. 9-24 ◽

Cited By ~ 11

Author(s):

M. Kawai ◽

H. Takeuchi ◽

I. Taketa ◽

A. Tsuchiya

Keyword(s):

Fatigue Life ◽

Carbon Fiber ◽

Stress Ratio ◽

Fiber Reinforced ◽

Short Carbon Fiber ◽

Injection Molded ◽

Effects Of Temperature ◽

Carbon Fiber Reinforced ◽

Short Carbon

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Effects of stress ratio on fatigue crack propagation properties of submicron-thick free-standing copper films

Acta Materialia ◽

10.1016/j.actamat.2013.07.017 ◽

2013 ◽

Vol 61 (16) ◽

pp. 6310-6327 ◽

Cited By ~ 16

Author(s):

Toshiyuki Kondo ◽

Takahiro Imaoka ◽

Hiroyuki Hirakata ◽

Masayuki Sakihara ◽

Kohji Minoshima

Keyword(s):

Fatigue Crack ◽

Crack Propagation ◽

Fatigue Crack Propagation ◽

Stress Ratio ◽

Copper Films ◽

Free Standing ◽

Effects Of Stress ◽

Propagation Properties

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Fatigue Performance of Concrete with Pre-Cracks in Tension-Compression Cycles

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.584-586.1054 ◽

2014 ◽

Vol 584-586 ◽

pp. 1054-1061

Author(s):

Jian Shen ◽

Xiao Yun Liu ◽

Lang Wu

Keyword(s):

Fatigue Life ◽

Fatigue Strength ◽

Cyclic Loading ◽

Fatigue Test ◽

Stress Ratio ◽

Fatigue Property ◽

Fatigue Performance ◽

Cycle Fatigue ◽

Fatigue Load ◽

Compression Cycle

A tension-compression cycle fatigue test was performed in order to study the fatigue property of C50 concrete with pre-cracks in cyclic loading. The stress ratio was-1 and the amplitude was 0.2 MPa ~1.30 MPa. The results show that the modified coefficient of fatigue strength is 0.198~0.265 and the infinite life fatigue strength is below 0.45MPa. While the log value of fatigue life is approximately linear with the amplitude of fatigue load stress, the discreteness of fatigue life, the particularity of concrete, has little to do with the amplitude. The S-N, P-N fatigue life curves and the constant fatigue life diagram of pre-crack concrete are obtained.

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