Method and system for predicting fatigue life of sucker rod

A fatigue life prediction and fatigue life technology, applied in special data processing applications, instruments, electrical digital data processing, etc., can solve problems such as unreasonable, damage, failure probability value greater than zero, etc.

Active Publication Date: 2021-10-22
XI'AN PETROLEUM UNIVERSITY
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Problems solved by technology

[0004] However, in some cases, it is unreasonable to assume that the experimental data obey the normal distribution; It is unrealistic that the parts have been destroyed without the fatigue test
On the other hand, due to the assumed linear relationship between the stress and the number of failure cycles, the model can only calculate the S-N curve in the limited fatigue life area of ​​the sucker rod, and it will not be applicable in the high-cycle and ultra-high-cycle fatigue areas, so it cannot Estimation of Sucker Rod Fatigue Limit

Method used

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  • Method and system for predicting fatigue life of sucker rod
  • Method and system for predicting fatigue life of sucker rod
  • Method and system for predicting fatigue life of sucker rod

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Embodiment 1

[0106] According to the "SY / T 5029-2013 Sucker Rod" steel sucker rod fatigue performance requirements, the fatigue life test of ultra-high strength sucker rods is carried out, and the experiment is divided into 3 groups of stress levels, and each group is tested with 5 specimens, and the fatigue is recorded The experimental data are shown in Table 1.

[0107] HL type sucker rod fatigue test data

[0108]

[0109] According to the obtained experimental data, the model parameters proposed in step 2 are estimated, and the parameters A, B and Weibull distribution three parameters α, β, γ are estimated according to the method of steps 3 and 4. The results are shown in the following table:

[0110]

[0111]

[0112] refer to figure 2 , to estimate the fatigue limit: From the fitted P-S-N curve, it can be found that the lower part of the curve slowly approaches the fatigue limit. When N tends to infinity, the calculated fatigue limit value is: 327.49MPa.

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Abstract

The invention provides a method and a system for predicting the fatigue life of a sucker rod. The fatigue data of an ultrahigh-strength sucker rod are processed by adopting Weibull distribution, and a stress-life (S-N) function is put forward to be applied to the fatigue life curve modeling of the ultrahigh-strength sucker rod, so that a fatigue P-S-N curve fitting model of the ultrahigh-strength sucker rod is obtained. Compared with a mode of processing data by adopting logarithmic normal distribution, the model adopts Weibull distribution, so that the sucker rod has the minimum safety life, namely the safety life under 100% survival rate, is consistent with the fatigue characteristic of the sucker rod, and is more in line with the actual condition. The model accurately describes the characteristic that the P-S-N curve slowly converges to the fatigue limit in high-cycle and ultra-high-cycle fatigue areas, so that the value of the fatigue limit can be accurately estimated.

Description

technical field [0001] The invention belongs to the technical field of oil production engineering, and relates to a sucker rod fatigue life prediction method and system. Background technique [0002] Weiler first proposed the concepts of fatigue curve and fatigue limit. The S-N curve obtained according to the fatigue test data is a method to predict the fatigue life of steel structures. It believes that there is a definite relationship between the stress S and the life N, and some The S-N curve is obtained by fitting with mathematical methods. The research in this area is an important basis for fatigue reliability analysis and design. [0003] At present, in the establishment of sucker rod fatigue stress-life (S-N) curve, the international standard adopts a linear model based on Basquin formula, which assumes that the stress S and life N obey the normal distribution, and estimates A, The value of B, so that the relationship between the stress and life of the fatigue zone in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/17G06F30/20G06F119/02G06F119/04G06F119/14
CPCG06F30/17G06F30/20G06F2119/02G06F2119/04G06F2119/14
Inventor 蔡文斌李文黄智敏张慧仁
Owner XI'AN PETROLEUM UNIVERSITY
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