Fatigue Life Prediction of Thick-Section S2-Glass/Vinyl-Ester Composites Under Flexural Loading1

2000 ◽  
Vol 122 (4) ◽  
pp. 402-408 ◽  
Author(s):  
Hassan Mahfuz ◽  
Kamruz Zaman ◽  
Anwarul Haque ◽  
Costee Foy ◽  
Hisham Mohamed ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Stress Level ◽  
Vinyl Ester ◽  
Life Prediction ◽  
Mathematical Formulation ◽  
Prediction Equation ◽  
Fatigue Life Prediction ◽  
Loading Cycle ◽  
Material Parameters ◽  
Two Parameters

Fatigue life prediction of S2-Glass/Vinyl-ester composites has been studied analytically using the fatigue modulus concept. Traditionally it is assumed that the fatigue modulus degradation is a function of loading cycle only. In our present investigation, it is found that the fatigue modulus is not only a function of loading cycle but also a function of applied stress level and thickness of the specimen. Using this concept, a practical and applicable method for predicting fatigue life is established. The method requires two distinct parameters that arise from the mathematical formulation. These two parameters are determined in two ways. In one case, the parameters are determined using failure cycle numbers at two different stress levels. In the other case, the parameters are determined using fatigue modulus values at two different cycles at a particular stress level. These material parameters have been determined experimentally using both the procedures. Utilizing the experimental data two appropriate functions for these two material parameters were obtained and incorporated into the life prediction equation. Fatigue life predictions using this method have been found to be within 10 percent of the experimental values. [S0094-4289(00)02404-X]

scholarly journals Application of Life-Dependent Material Parameters to Fatigue Life Prediction under Multiaxial and Non-Zero Mean Loading

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1587 ◽  
Author(s):  
Krzysztof Kluger ◽  
Aleksander Karolczuk ◽  
Szymon Derda
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Fatigue Loading ◽  
Mean Value ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Test Results ◽  
Material Parameters ◽  
Fixed Material ◽  
Stress Ratios

This study presents the life-dependent material parameters concept as applied to several well-known fatigue models for the purpose of life prediction under multiaxial and non-zero mean loading. The necessity of replacing the fixed material parameters with life-dependent parameters is demonstrated. The aim of the research here is verification of the life-dependent material parameters concept when applied to multiaxial fatigue loading with non-zero mean stress. The verification is performed with new experimental fatigue test results on a 7075-T651 aluminium alloy and S355 steel subjected to multiaxial cyclic bending and torsion loading under stress ratios equal to R = −0.5 and 0.0, respectively. The received results exhibit the significant effect of the non-zero mean value of shear stress on the fatigue life of S355 steel. The prediction of fatigue life was improved when using the life-dependent material parameters compared to the fixed material parameters.

Fatigue Life Prediction of Heat-Aging Vulcanized Natural Rubber

2006 ◽  
Vol 321-323 ◽  
pp. 518-521 ◽  
Author(s):  
Chang Su Woo ◽  
Wan Doo Kim
Keyword(s):  
Fatigue Life ◽  
Natural Rubber ◽  
Life Prediction ◽  
Prediction Equation ◽  
Damage Parameter ◽  
Fatigue Life Prediction ◽  
Aging Effects ◽  
Element Analysis ◽  
Fatigue Damage Parameter ◽  
Lagrange Strain

Heat-aging effects on the material properties and fatigue life prediction of natural rubber were experimentally investigated. The rubber specimens were heat-aged in an oven at the temperature ranging from 50oC to 100oC for a period ranging from 1 day to 90days. Fatigue life prediction methodology of vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue test. Fatigue life prediction equation effectively represented by a single function using the Green-Lagrange strain. Predicted lives are in a good agreement with the experimental lives within a factor of two

scholarly journals Prediction Method and Verification of Fatigue Life for a Turbine Disk with Bolt Hole

2019 ◽  
Vol 37 (4) ◽  
pp. 744-750
Author(s):  
Hongbin Liu ◽  
Wei Chen ◽  
Lin Liu
Keyword(s):  
Fatigue Life ◽  
Fatigue Test ◽  
Life Prediction ◽  
Stress Gradient ◽  
Prediction Method ◽  
Prediction Equation ◽  
Fatigue Life Prediction ◽  
Turbine Engine ◽  
Bolt Holes ◽  
Simulation Unit

In order to improve the fatigue life prediction accuracy of FGH96 material for turbine engine at higher stress gradient notch, such as bolt holes, the new mean stress formula is used in this paper, the effect of stress gradient and size effect are considered at the same time, Fatigue test of FGH96 material inter-stage disc simulation test piece is done, and the parameters in the life prediction equation of the model are fitted. Further study on fatigue test of FGH96 material turbine pin bolt hole simulation unit is done, and test results is compared with the forecast results. The result shows that, the improved fatigue life prediction method has higher accuracy, and the validity of the method is proved.

A Multi-Axial Fatigue Limit Prediction Equation for Metallic Materials

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Bowen Liu ◽  
Xiangqiao Yan
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Fatigue Limit ◽  
Life Prediction ◽  
Prediction Equation ◽  
Fatigue Life Prediction ◽  
Stress Effect ◽  
Metallic Materials ◽  
Life Prediction Model ◽  
Axial Fatigue

Abstract Based on the multi-axial fatigue life prediction model presented recently by the authors, in this note, a fatigue limit prediction equation for metallic materials under multi-axial loading is proposed. In the multi-axial fatigue life prediction model, the wildly used von Mises equivalent stress is taken as an equivalent fatigue mechanical quantity, and the multi-axial fatigue life prediction equation has the invariance of mathematical equation form. By applying the multi-axial fatigue life prediction equation without mean stress effect to fatigue limit case, a simple fatigue limit prediction equation can be obtained. By using a large number of experimental data of metallic materials reported in literature, it has been proven that the fatigue limit prediction equation is not only simple in computation but also high in accuracy.

Prediction of Fatigue Life With and Without Hold Times Using the Chaboche Viscoplastic Constitutive Theory

1990 ◽  
Vol 112 (2) ◽  
pp. 188-197 ◽  
Author(s):  
S. S. Chiu ◽  
J. Eftis ◽  
D. L. Jones
Keyword(s):  
Fatigue Life ◽  
Yield Stress ◽  
Stress Level ◽  
Life Prediction ◽  
Hold Time ◽  
Fatigue Life Prediction ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Rate Of Loading

The titanium alloy Ti-6Al-4V is known to exhibit creep behavior at temperatures as low as room temperature. Consequently, for cyclic loading with hold times it is possible that the rate dependent behavior of Ti-6Al-4V can have negative bearing upon the low cycle fatigue life. If this effect is shown to be present at room temperatures, then it will certainly be magnified and, therefore, very important at elevated temperatures. In order to account for the effects of strain rate dependent deformation in fatigue life prediction methodology, it was considered necessary to incorporate a viscoplastic constitutive equation into the fatigue life calculational algorithm. After critical evaluation of a score of recently proposed viscoplastic constitutive theories, the Chaboche theory, which employs a yield condition, was considered to offer the most promise for description of a wide range of inelastic material behavior characteristics. The six viscoplastic material parameters that are required for nonelevated temperature applications were determined from data of uniaxial tests, conducted elsewhere and made avialable to this study. The fatigue life testing of smooth round bar specimens included load cycles with load hold times. Fatigue life predictions were performed using the equivalent fully reversed symmetric cycle, and the Smith-Watson-Topper parameter, for load cycles having varying stress amplitudes and varying hold times. The predicted fatigue life results indicate that: (i) For a given stress level above the initial yield stress, shorter load hold time periods result in longer fatigue lives. (ii) The higher the stress level (above the initial yield stress) the more pronounced becomes the effect of the load hold time on the fatigue life prediction. (iii) The rate of loading also has an effect on fatigue life. Analysis indicates that the slower the rate of loading, the higher the rate dependent (primary creep) deformation, and consequently, the lower the resulting fatigue life.

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