Method for detecting influence of different parameters on material fatigue crack expansion performance

A fatigue crack propagation and detection method technology is applied in the detection field of the influence of different parameters on the fatigue crack growth performance of materials, which can solve the problems of wasting samples, wasting time, and inability to guarantee, and achieves the effect of low cost and high detection efficiency.

Inactive Publication Date: 2012-08-22
XI'AN PETROLEUM UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, as we all know, under the same test conditions, the test results of different samples are highly dispersed, and the influencing factors include the influence of the size deviation of different samples and the influence of the difference in the clamping position of the sample.
Usually, in order to eliminate the influence of various factors, multiple groups of samples are used to take the average value, which not only wastes samples, wastes time, and takes up hours of the testing machine, but also cannot guarantee that the test results truly reflect the impact of test parameters on fatigue cracks. Impact on scaling performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] For a casing drilling steel K55, the test of the influence of different stress ratios on its Paris constant includes the following steps:

[0032] First, process specimens according to standard, using compact tensile specimens, specimen thickness B = 4.8mm, width W =30mm, the incision is processed by wire cutting, and the pre-splitting length is 2mm;

[0033] Second, according to the standard test method, the sample is clamped on the fatigue testing machine. The model of the testing machine is PLD-100 hydraulic servo fatigue testing machine. The crack length is monitored by the computer-assisted potential method, and the potential function is calculated by the boundary element method. ;

[0034] Third, set the test temperature as room temperature, frequency as 10Hz, loading waveform as sine wave, load as 1.4kN, test stress ratio R = P min / P max , respectively: 0.1, 0.3, 0.5, 0.7, the detection sequence is the stress ratio 0.1→0.3→0.5→0.7, according to the ligam...

Embodiment 2

[0059] First, process specimens according to standard, using compact tensile specimens, specimen thickness B = 4.8mm, width W =30mm, the incision is processed by wire cutting, and the pre-splitting length is 2mm;

[0060] Second, according to the standard test method, the sample is clamped on the fatigue testing machine. The model of the testing machine is PLD-100 hydraulic servo fatigue testing machine. The crack length is monitored by the computer-assisted potential method, and the potential function is calculated by the boundary element method. ;

[0061] Third, set the test temperature as room temperature, the loading waveform as a sine wave, the load as 1.4kN, and the test stress ratio R 0.1, the frequency is 10Hz, 2Hz, 0.4Hz, the detection sequence is frequency 0.4Hz→2Hz→10Hz, according to the length of ligament 15mm, the length of pre-crack 2mm, the length of unstable fracture is reserved 7mm, the crack growth under each frequency The length is 2mm;

[0062] Fourth,...

Embodiment 3

[0086] For a casing drilling steel P110, testing the influence of different stress ratios on its threshold value includes the following steps:

[0087] First, process specimens according to standard, using compact tensile specimens, specimen thickness B = 4.8mm, width W =30mm, the incision is processed by wire cutting, and the pre-splitting length is 2mm;

[0088] Second, according to the standard test method, the sample is clamped on the fatigue testing machine. The model of the testing machine is PLD-100 hydraulic servo fatigue testing machine. The crack length is monitored by the computer-assisted potential method, and the potential function is calculated by the boundary element method. ;

[0089] Third, apply different test parameters according to different research objects, the test temperature is room temperature, the loading waveform is sinusoidal, the frequency is 10Hz, and the test stress ratio R = P min / P max , respectively: 0.1, 0.3, 0.5, 0.7, the detection...

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Abstract

The invention relates to a method for detecting the influence of different parameters on material fatigue crack expansion performance, which comprises the following steps of: firstly, processing a sample according to the standard and adopting a compact tensile sample; secondly, clamping the sample on a fatigue tester according to a standard test method, monitoring the crack length by using a microcomputer-aided potential method, and calculating and giving electric potential functions by using a boundary element method; thirdly, applying different test parameters according to different detection samples; and fourthly, treating the test data and comparing the test results. The method has the characteristics of high detection efficiency, low cost and accurate detection.

Description

technical field [0001] The invention belongs to the technical field of detecting the fatigue crack growth performance of materials, and in particular relates to a detection method for the influence of different parameters on the fatigue crack growth performance of materials. Background technique [0002] Casing drilling technology, as a new economical drilling method, has changed the traditional operation method. Therefore, the performance requirements of the material are not only different from the performance requirements of the casing used in the past cementing, but also different from the performance of the drill pipe used in the past. Require. In addition to bearing static loads, materials are required to have high yield strength and tensile strength while bearing dynamic loads, and must have high enough resistance to fatigue crack growth, especially for environments with variable geological structures, such as rocks and clays layers and so on. Usually for engineering...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/36G01N1/28
Inventor 许天旱
Owner XI'AN PETROLEUM UNIVERSITY
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