Estimation Method of Fatigue Life Distribution for Woven Composites Based on Numerical Analysis of Damage Development

Fatigue tests were conducted on standard smooth laser metal deposition (LMD) Ti-6.5Al-2Zr-1Mo-1V titanium alloy specimens under three constant-amplitude stresses. The mixed failure behaviors and the influence of internal pores on the fatigue life were discussed in detail. The double-peak characteristics of the fatigue life distribution have been observed, and a bimodal lognormal distribution (BLG) with five variables can be used to describe the fatigue life variation. A parameter estimation method based on the maximum likelihood estimation (MLE) method was proposed to estimate the BLG distribution parameters, and the Newton–Raphson algorithm was used to solve the nonlinear equations derived from the likelihood functions. A P-S-N curve description of LMD titanium alloy was established based on the BLG and verified by fatigue life data obtained from a fatigue test.

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Temperature and humidity effects on fatigue life distribution of carbon steelSakai, T., Ramulu, M. and Suzuki, M. Int. J. Fatigue Mar. 1991 13 (2), 117–125

International Journal of Fatigue ◽

10.1016/0142-1123(92)90459-p ◽

1992 ◽

Vol 14 (3) ◽

pp. 203-203

Keyword(s):

Fatigue Life ◽

Life Distribution ◽

Humidity Effects ◽

Temperature And Humidity

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Estimation of Fatigue Life for Hydraulic Excavator Boom under All Operating States

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.199-200.463 ◽

2011 ◽

Vol 199-200 ◽

pp. 463-469

Author(s):

Qing Xin Ding ◽

Ying Cheng Tian ◽

Juan Chen ◽

Jian Wen Chen ◽

Kun Liang Hui ◽

...

Keyword(s):

Fatigue Life ◽

Estimation Method ◽

Maximum Principal Stress ◽

Multiaxial Fatigue ◽

Hydraulic Excavator ◽

Dangerous Zone ◽

Support Force ◽

Contrast Analysis ◽

History Of ◽

Hinged Support

Fatigue is one of the most common failure mode in hydraulic excavator boom. To find the most fatigue dangerous operating state of boom and effectively improve the life of the structure, a new method is proposed for the estimation of fatigue life under all operation states. In the case of unknown the history of loading, firstly find out the hinged support force under all boom poses, then calculate the stress of every point of the boom under the actions of each group hinged support force via finite element method, and finally simulate all operating states through the poses combination, conducts analysis of multiaxial fatigue life in the maximum principal stress as the nominal stress, calculates the life and the most dangerous operating state in all points, and compares to obtain the most dangerous position and the life of the boom. The results of contrast analysis showed that: the most dangerous zone of the excavator boom calculated by the life estimation method of all operating states coincide with the actual destruction situation. The life of the structure can be greatly improved after a simple reasonable improvement of the parts.

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Fatigue Reliability Functions in Semilogarithmic Coordinates

9th Biennial Conference on Reliability, Stress Analysis, and Failure Prevention ◽

10.1115/detc1991-0009 ◽

1991 ◽

Author(s):

Vladimir A. Avakov

Keyword(s):

Fatigue Life ◽

Coordinate System ◽

Strength Distribution ◽

Fatigue Reliability ◽

Life Distribution ◽

Similar Transformation ◽

Asymptotic Type ◽

Life Distributions ◽

Strength Distributions

Abstract In the previous publication [2], the transformation between fatigue life and strength distribution was established using double-logarithmic coordinate system (lnN-lnS). Here, a similar transformation is established using a semi logarithmic (lnN-S) coordinate system. With the aid of the developed orthogonal relations, lognormal, Weibull and three-parameter logweibull life distributions have been transformed into normal, asymptotic type 1 of smallest value, and three-parameter Weibull strength distributions, respectively. This procedure may be applied to other types of fatigue life distribution.

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Concrete Fatigue Life Characteristics of the Different Survival Rates in the Lateral Pressure Conditions

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.600.250 ◽

2012 ◽

Vol 600 ◽

pp. 250-255

Author(s):

Qiang Cai ◽

Ji Ming Kong ◽

Ze Fu Chen

Keyword(s):

Fatigue Life ◽

Life Stress ◽

Failure Modes ◽

Survival Curve ◽

Survival Rates ◽

Life Distribution ◽

Fatigue Design ◽

Set Up ◽

Fatigue Equation ◽

Two Parameter

Under cyclic loading of concrete structures, fatigue failure is the main failure modes of fatigue, which has become the fatigue design of concrete structure must be considered, then the concrete fatigue studies must clarify the fatigue life of concrete under different survival curve S-N curve. Based on the statistics of the two parameter Weibull distribution theory, obtain the concrete under different survival rates of fatigue life distribution, namely to improve survival, reduce the fatigue life; stress level is reduced, the fatigue life is increased; and has set up more than 50% under different survival rates of concrete fatigue equation.

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