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CN1278114C - Sample for measuring fatigue crack expansion rate in corrosion liquid and test method - Google Patents

Sample for measuring fatigue crack expansion rate in corrosion liquid and test method Download PDF

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CN1278114C
CN1278114C CN 200410060569 CN200410060569A CN1278114C CN 1278114 C CN1278114 C CN 1278114C CN 200410060569 CN200410060569 CN 200410060569 CN 200410060569 A CN200410060569 A CN 200410060569A CN 1278114 C CN1278114 C CN 1278114C
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sample
test
crack
fatigue
growth rate
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CN1587988A (en
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白杰
张亚军
梁健
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725th Research Institute of CSIC
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725th Research Institute of CSIC
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Abstract

一种测量腐蚀液中疲劳裂纹扩展速率的试样及试验方法，在其试样远离裂纹扩展面的上侧采用整体设计的方法设置有电子引伸计的装卡刀口；根据试验机控制系统采集到的大量的试验数据，求解出所设计试样的柔度系数，建立归一化裂纹长度和柔度系数之间的函数关系，实现在腐蚀液中进行疲劳裂纹扩展速率(da/dN)试验时裂纹长度的检测自动化，据此所建立的试验方法，为该类试验的顺利进行提供了保证。与目前国内大多单位在腐蚀液中测量疲劳裂纹扩展速率(da/dN)用目测法检测裂纹长度相比，明显提高了测量裂纹长度的精度，同时也大大降低了劳动强度。利用试验结果，能够更准确地对服役在腐蚀介质中的船舶进行安全设计和寿命评估。

Figure 200410060569

A sample and test method for measuring the fatigue crack growth rate in corrosive liquid. The upper side of the sample away from the crack propagation surface adopts the method of integral design to set the clamping knife edge of the electronic extensometer; according to the data collected by the control system of the testing machine Based on a large amount of test data, the flexibility coefficient of the designed sample is solved, and the functional relationship between the normalized crack length and the flexibility coefficient is established to realize the fatigue crack growth rate (da/dN) test in the corrosive liquid. The length detection is automated, and the test method established based on it provides a guarantee for the smooth progress of this type of test. Compared with most domestic units currently measuring the fatigue crack growth rate (da/dN) in the corrosive solution and using the visual method to detect the crack length, the accuracy of measuring the crack length is significantly improved, and the labor intensity is also greatly reduced. Using the test results, the safety design and life assessment of ships serving in corrosive media can be more accurately carried out.

Figure 200410060569

Description

Measure the sample and the test method of fatigue crack growth rate in the corrosive liquid
Technical field:
The present invention relates to metallic material corrosion testing method technical field, a kind of sample and test method of measuring fatigue crack growth rate in the corrosive liquid.
Background technology:
The extensometer of specified standard compact tension specimen C (T) sample is installed the edge of a knife in the both sides of facing title about crack propagation in the GB/T6398-2000 of China (metal material fatigue crack growth rate test method) at present, when carrying out fatigue crack growth rate (da/dN) test in corrosive liquid, the situation that fatigue crack length is measured with flexibility method is only limited on horizontal fatigue tester carries out; If carry out this test on vertical fatigue tester, expensive extensometer (about 5000 U.S. dollars of import, homemade also wants thousands of yuans) tends to reduce its linearity, sensitivity or thoroughly damage because of the erosion that is subjected to corrosive liquid; And domestic most fatigue tester all is vertical, and therefore, when carrying out fatigue crack growth rate (da/dN) test in corrosive liquid, it almost is impossible measuring fatigue crack length with flexibility method.In light of this situation, when domestic most of units carry out this class test, generally pass through flexibility commercial measurement fatigue crack length without extensometer, but the spread scenarios of observing crackle by optical microscope with ocular estimate.But; the fatigue crack of metal material is often thinner; especially the fatigue crack of aldary, titanium alloy etc materials; in air, be not easy to observe very much clear; and owing to the corrosive liquid muddiness that usually can become because of the corrosion product of the metal material sample wherein that suspends; this makes with ocular estimate observation fatigue crack length more difficult, therefore is difficult to the precision that the assurance ocular estimate is observed fatigue crack length, and labour intensity is also very big.
At present, domestic relate to measure fatigue crack length in the experimental test field document seldom, particularly flexibility Study on Technology and the research that utilizes the flexibility technology to carry out the automatic context of detection of crack length under the corrosion environment are not seen as yet.
Summary of the invention:
In order to solve the problem of above-mentioned existence, the invention provides a kind of sample and test method of measuring fatigue crack growth rate in the corrosive liquid, this sample can make expensive electronic extensometer away from the corrosion liquid level, avoid extensometer to damage, thereby obtain test findings effectively reliably because of being subjected to the corrosive liquid erosion; Ocular estimate is measured fatigue crack length relatively, and this method can obviously improve the precision of measuring fatigue crack length, also reduces labour intensity simultaneously greatly.
The present invention adopts following technical scheme to realize:
The sample of fatigue crack growth rate in the described measurement corrosive liquid, at the upside away from the crack propagation face, the method for employing global design is provided with the edge of a knife that is installed of electronic extensometer; According to a large amount of test figure that the testing machine control system collects, utilize the Multitest testing software of import equipment, ask
The softness factor that solves designed sample is as follows:
The softness factor symbol C 0 C 1 C 2 C 3 C 4 C 5
Softness factor numerical value 0.9927 -4.8803 17.031 -189.39 781.63 -821.74
The sample softness factor solution procedure of fatigue crack growth rate is as follows in the described measurement corrosive liquid:
(1) measures thickness B, the width W of designed sample and the effective crack length a that adopts any method to cause, and test out the elastic modulus E of test material in advance;
(2) designed sample is adopted the method for Wire EDM cause crackle, cause once every a/W=0.025, and remeasure the crack length a of initiation, as used actual value;
(3) sample that will cause behind the crackle is contained on the testing machine, and electronic extensometer is installed on the knife-edge part of sample, zero clearing;
(4) sample behind the initiation crackle is slowly stretched in elastic range, need act on the load p on the sample, the deflection V of extensometer this moment with the higher point velocity collection of adopting;
(5) according to formula Ux=1/[(BEV x/ P) 1/2+ 1] solves the dimensionless flexibility value Ux of sample;
(6) cause crackle at every turn after, all to solve a normalization crack length a/W value;
(7) when normalization crack length a/W=0.75, test can stop;
(8) (a/W Ux) carries out monobasic and increases progressively polynomial regression five times, and its regression coefficient just can be used as the softness factor of this sample to the data set of being tried to achieve;
(9) the polylith sample is undertaken by as above step, can obtain six softness factors of each sample respectively;
(10) softness factor to the polylith sample carries out the equalization processing, has just obtained final six softness factor C that find the solution 0, C 1, C 2, C 3, C 4, C 5
A kind of test method of measuring the fatigue crack growth rate of sample in the corrosive liquid, carry out according to the following step:
(1) mode of employing Wire EDM causes the initial crack of sample;
(2) softness factor of the designed sample that will solve is input in the test routine of finishing in advance;
(3) measure sample thickness, width parameter, and be input in the program of finishing in advance;
(4) corrosive cycle system, relevant sample jig and sample are connected with vertical fatigue tester;
(5) corrosive liquid is added the circulation system and be equipped with in the corrosion box of sample, the corrosive liquid in the circulation system is abundant, and the corrosive liquid in the corrosion box will guarantee to soak constantly the crack propagation face;
(6) electronic extensometer is installed on the knife-edge part of sample upside, and zero clearing;
(7) set each parameter of prefabricating fatigue crack, comprise the length of stress intensity factor range Δ K, control mode, employing frequency, waveform and prefabricating fatigue crack etc.;
(8) starting characteristics test machine, the beginning prefabricating fatigue crack is observed current crack extending length constantly, notes whole corrosive cycle system, in case corrosive liquid seepage and erosion test machine;
(9) prefabricated finish fatigue crack after, according to current result, parameters such as needed load range, stress ratio, frequency when setting test;
(10) starting characteristics test machine once more, the beginning official test;
(11) after the off-test,, simulate the fatigue crack growth rate curve and the equation thereof of test material, provide corresponding test report at last according to the expression-form of PARIS (Paris) empirical equation according to the test figure that is collected.
Owing to adopted technique scheme, the present invention to have following good effect:
The sample of in corrosive liquid (seawater, salt solution, river etc.), measuring fatigue crack growth rate (da/dN) that the present invention designs, the edge of a knife that is installed of electronic extensometer has been mentioned upside away from the crack propagation face, thereby solved on vertical fatigue tester when measuring fatigue crack length, expensive electronic extensometer often damages a difficult problem that causes test failure because of corrosive liquid corrodes with flexibility method.This sample also can be used on the horizontal fatigue tester.
The sample softness factor that utilization solves, set up the functional equation of normalization crack length and softness factor, theoretically for to lay a good foundation by flexibility commercial measurement fatigue crack length, thereby make that the detection of crack length has realized robotization when carrying out fatigue crack growth rate (da/dN) test in corrosive liquid, measuring fatigue crack growth rate (da/dN) with present domestic most unit in corrosive liquid compares with ocular estimate detection crack length, obviously improve the precision of measuring crack length, also greatly reduced labour intensity simultaneously.
In corrosive liquid, measure the design success of fatigue crack growth rate sample, the test method of correctly trying to achieve and being set up in view of the above of softness factor, provide assurance smoothly for such test.Utilize test findings, can carry out Safety Design and life appraisal to the boats and ships of being on active service in corrosive medium more accurately.
Description of drawings:
Fig. 1 is compact tension specimen C (T) assay maps of standard;
Fig. 2 measures designed assay maps in the sample of fatigue crack growth rate in the corrosive liquid and the test method;
Fig. 3 is fatigue crack growth rate (the da/dN)-Δ K curve map of compact tension specimen C (T) sample of standard;
Fig. 4 is fatigue crack growth rate (da/dN)-Δ K curve map of measuring the sample of fatigue crack growth rate in the corrosive liquid.
Embodiment:
1, measures the sample form of fatigue crack growth rate (da/dN) in the corrosive liquid
Compact tension specimen C (T) sample with standard in corrosive liquid carries out fatigue crack growth rate (da/dN) test, observe fatigue crack length with ocular estimate, one side can not guarantee that by the precision of the crack length that optical microscope is read labour intensity is also quite big on the other hand.As shown in fig. 1, the extensometer of this sample is installed the edge of a knife (1. locating) in the both sides of facing title about crack propagation.During fatigue crack growth rate (da/dN) in vertical torture test airborne measurements corrosive liquid (2. locate is corrosion liquid level), expensive extensometer tends to be subjected to the erosion of corrosive liquid.If the edge of a knife that is installed of extensometer is moved to the upside of crack propagation face, just extensometer that at first can the guaranteed price costliness is not etched.In addition, if can solve the softness factor of this sample, just can adopt the flexibility technology to measure fatigue crack length in the corrosive liquid, so just can guarantee the precision that crack length is measured, also can reduce a large amount of hard-workings of being paid when measuring simultaneously greatly with ocular estimate.
So, on the basis of the compact tension specimen C of standard (T) sample, we have designed the sample of fatigue crack growth rate (da/dN) in the measurement corrosive liquid, as shown in Figure 2, the method design that the edge of a knife that is installed (3. locating) of electronic extensometer adopts global design is away from the upside of crack propagation face, like this, solved the difficult problem that expensive electronic extensometer is corroded by corrosive liquid (4. being the corrosion liquid level) on the one hand, on the other hand also for to lay the foundation with flexibility commercial measurement fatigue crack length.A large amount of test figures such as the normalization crack length that we collect according to the testing machine control system, the dimensionless flexibility of sample, unknown parameter softness factor, on the basis of tight reasoning and practice, make full use of the functional characteristics of the Multitest testing software of import equipment, solved the softness factor of designed sample.The characteristic feature of designed sample is: the electronic extensometer that will be used for measuring indirectly fatigue crack length is installed method design that the edge of a knife adopts the globality design away from the upside of crack propagation face, extensometer that on the one hand can the guaranteed price costliness in process of the test is away from the corrosion liquid level like this, avoid in the process of measuring fatigue crack length, reducing its linearity because of being subjected to the corrosive liquid erosion, sensitivity or the possibility of thoroughly damaging, can guarantee preferably also that on the other hand extensometer can not make test failure because of coming off in entire test, also be convenient to charge and discharge operations simultaneously.The design success of this sample provides possibility for carry out detecting crack length automatically when fatigue crack growth rate (da/dN) is tested in corrosive liquid.
2, the softness factor of designed sample
Through a large amount of reasoning and verification experimental verification, softness factor precision height, the good reliability of the sample of finding the solution, has practicality widely: all identical with designed sample form, as to be in proportion samples that can be applied to different metal materials, various sample size.Utilize six sample softness factors that solved, set up the functional equation of normalization crack length and softness factor, theoretically for to lay a good foundation with flexibility commercial measurement fatigue crack length, thus when in corrosive liquid, carrying out fatigue crack growth rate (da/dN) test the automatic measurement of fatigue crack length provide may.The control system of testing machine is collected data necessary such as the load that acts on the sample, extensometer opening displacement be applied to pass through the computer program that the theoretical formula of asking is write, just can calculate the extension length of the current crackle of sample at any time automatically, and can be presented on the computer desktop constantly.Through calculating and handling, just can obtain the fatigue crack growth rate of test material in corrosive liquid at last.Trying to achieve of designed sample softness factor makes that the detection of crack length has realized in the robotization when carrying out fatigue crack growth rate (da/dN) test in corrosive liquid, also obviously improved the measuring accuracy of crack length, greatly reduces labour intensity.
The softness factor of invention design sample is as follows:
The softness factor symbol C 0 C 1 C 2 C 3 C 4 C 5
Softness factor numerical value 0.9927 -4.8803 17.031 -189.39 781.63 -821.74
3, the solution procedure of designed sample softness factor
(1) measures thickness B, the width W of designed sample and the effective crack length a that adopts any method to cause, and test out the elastic modulus E of test material in advance;
(2) designed sample is adopted the method for Wire EDM cause crackle, cause once every a/W=0.025, and remeasure the crack length a of initiation, as used actual value;
(3) sample that will cause behind the crackle is contained on the testing machine, and electronic extensometer is installed on the knife-edge part of sample, zero clearing;
(4) sample behind the initiation crackle is slowly stretched in elastic range, need adopt point velocity (such as 100 data points/sec) collection acts on the load p on the sample, the deflection V of extensometer this moment with higher;
(5) according to formula Ux=1/[(BEV x/ P) 1/2+ 1] solves the dimensionless flexibility value Ux of sample;
(6) cause crackle at every turn after, all to solve a normalization crack length a/W value;
(7) (should be worth generally during official test and can not surpass 0.70) when normalization crack length a/W=0.75, test can stop;
(8) (a/W Ux) carries out monobasic and increases progressively polynomial regression five times, and its regression coefficient just can be used as the softness factor of this sample to the data set of being tried to achieve;
(9) the polylith sample is undertaken by as above step, can obtain six softness factors of each sample respectively;
(10) softness factor to the polylith sample carries out the equalization processing, has just obtained final six softness factor C that find the solution 0, C 1, C 2, C 3, C 4, C 5
4, test method
Utilize designed sample and the softness factor thereof that goes out, just can finish fatigue crack growth rate (da/dN) test of in corrosive liquid, carrying out according to the following step:
(1) mode of employing Wire EDM causes the initial crack of sample;
(2) softness factor of the designed sample that will solve is input in the test routine of finishing in advance;
(3) measure parameters such as sample thickness, width, and be input in the program of finishing in advance;
(4) corrosive cycle system, relevant sample jig and sample are connected with vertical fatigue tester;
(5) corrosive liquid is added the circulation system and be equipped with in the corrosion box of sample, the corrosive liquid in the circulation system is abundant, and the corrosive liquid in the corrosion box will guarantee to soak constantly the crack propagation face;
(6) electronic extensometer is installed on the knife-edge part of sample upside;
(7) set each parameter of prefabricating fatigue crack, comprise the length of stress intensity factor range Δ K, control mode, employing frequency, waveform and prefabricating fatigue crack etc.;
(8) starting characteristics test machine, the beginning prefabricating fatigue crack is observed current crack extending length constantly, notes whole corrosive cycle system, in case corrosive liquid seepage and erosion test machine;
(9) prefabricated finish fatigue crack after, according to current result, parameters such as needed load range, stress ratio, frequency when setting test;
(10) starting characteristics test machine once more, the beginning official test;
(11) after the off-test,, simulate the fatigue crack growth rate curve and the equation thereof of test material, provide corresponding test report at last according to the expression-form of PARIS (Paris) empirical equation according to the test figure that is collected.
Inventing the sample form of design can see from us, and this sample can undoubtedly be used in the torture test in the corrosive liquid and guarantee that the electronic extensometer liquid that is not corroded corrodes.In order to verify the correctness and the feasibility of designed sample softness factor and test method, we have selected a kind of structure steel material, and we invent the sample of design to be processed into the compact tensile specimen of one group of standard and one group.Since the fatigue crack growth rate that the compact tensile specimen of standard can't the experiment with measuring material in corrosive liquid on vertical testing machine, and the fatigue crack growth rate of metal material in air and in corrosive liquid often differs greatly.Therefore, we think, if in air, tested the fatigue crack growth rate (da/dN) of test material with the flexibility technology with the compact tensile specimen of standard, and then invent the sample of design and softness factor adopts same test condition to test with us, because test material is the same, if the consistance of test result is fine, just can show that sample and test method that we invent are correct.
Testing equipment is vertical MTS810 electo hydraulic servocontrolled fatigue testing machine.
Adopt above-mentioned test method step to test.
The test condition that adopts is as follows:
Test load range delta P=12.0KN, stress ratio R=0.1, waveform are sinusoidal wave, and frequency f=10Hz tests in the air at room temperature.
Test findings (comprising da/dN-Δ K curve map and equation thereof) is as shown in Fig. 3 and Fig. 4, and from Fig. 3 and Fig. 4 as seen, the distribution of the data set of two kinds of samples (da/dN, Δ K) is just the same.Consider the structural homogenity of test material and the mismachining tolerance of every sample, the test material that obtains crack growth rate of (corresponding different softness factors) under two kinds of various sample forms is consistent.This fully shows, the sample of the fatigue crack growth rate of metal material is practical in the measurement corrosive liquid of our designed invention, and softness factor is that the test method of being set up has reliability and feasibility reliably.

Claims (3)

1、一种测量腐蚀液中疲劳裂纹扩展速率的试样，其特征在于：所述的试样，在远离裂纹扩展面的上侧采用整体设计的方法设置有电子引伸计的装卡刀口；根据试验机控制系统采集到的大量的试验数据，利用进口设备的多项试验测试软件，求解出所设计试样的柔度系数如下：   柔度系数符号   C0   C1   C2   C3   C4   C5   柔度系数数值   0.9927   -4.8803   17.031   -189.39   781.63   -821.74
1. A sample for measuring the fatigue crack growth rate in corrosive liquid, characterized in that: the sample is provided with a clamping knife edge of an electronic extensometer on the upper side away from the crack propagation surface by adopting an integral design method; A large amount of test data collected by the control system of the testing machine, using a number of test software of imported equipment, the flexibility coefficient of the designed sample is calculated as follows: Symbol of flexibility coefficient C 0 C 1 C 2 C 3 C 4 C 5 Flexibility coefficient value 0.9927 -4.8803 17.031 -189.39 781.63 -821.74
2、如权利要求1所述的测量腐蚀液中疲劳裂纹扩展速率的试样，其特征在于：该试样柔度系数的求解步骤如下：2. The sample for measuring the fatigue crack growth rate in corrosive liquid as claimed in claim 1, characterized in that: the solution steps of the flexibility coefficient of the sample are as follows: (1)测量所设计试样的厚度B、宽度W及采用任何一种方法所引发的有效裂纹长度a，并事先测试出试验材料的弹性模量E；(1) Measure the thickness B, width and the effective crack length a caused by any method of the designed sample, and test the elastic modulus E of the test material in advance; (2)将所设计的试样采用电火花线切割的方法引发裂纹，每隔a/W＝0.025引发一次，并重新测量引发的裂纹长度a，作为所用的实际值；(2) Initiate cracks on the designed sample by wire electric discharge cutting, initiate once every a/W=0.025, and re-measure the induced crack length a, as the actual value used; (3)将引发裂纹后的试样装在试验机上，并将电子引伸计装卡在试样的刀口处，清零；(3) Install the sample after the crack is induced on the testing machine, and install the electronic extensometer at the knife edge of the sample, and reset it; (4)对引发裂纹后的试样在弹性范围内缓慢拉伸，此时需要以较高的采点速率采集作用在试样上的载荷P、引伸计的变形量V；(4) Slowly stretch the sample after crack initiation within the elastic range. At this time, it is necessary to collect the load P acting on the sample and the deformation V of the extensometer at a higher sampling rate; (5)按照公式Ux＝1/[(BEVx/P)1/2+1]求解出试样的无量纲柔度值Ux；(5) Calculate the dimensionless flexibility value Ux of the sample according to the formula Ux=1/[(BEV x /P) 1/2 +1]; (6)每次引发裂纹后，都要求解出一个归一化裂纹长度a/W值；(6) After each crack is initiated, a normalized crack length a/W value is required to be solved; (7)当归一化裂纹长度a/W＝0.75时，试验可以停止；(7) When the normalized crack length a/W=0.75, the test can be stopped; (8)对所求得的数据组(a/W，Ux)进行一元五次递增多项式回归，其回归系数便可以作为该试样的柔度系数；(8) Carry out a quintic incremental polynomial regression on the obtained data set (a/W, Ux), and its regression coefficient can be used as the flexibility coefficient of the sample; (9)对多块试样按如上步骤进行，可分别得到各个试样的六个柔度系数；(9) Carry out the above steps for multiple samples, and six flexibility coefficients of each sample can be obtained respectively; (10)对多块试样的柔度系数进行均值化处理，就得到了最终所求解的六个柔度系数C0、C1、C2、C3、C4、C5。(10) The compliance coefficients of multiple samples are averaged to obtain the final six compliance coefficients C 0 , C 1 , C 2 , C 3 , C 4 , and C 5 . 3、一种测量腐蚀液中试样的疲劳裂纹扩展速率的试验方法，其特征在于：该试验方法按照下列步骤进行：3. A test method for measuring the fatigue crack growth rate of the sample in the corrosive liquid, characterized in that: the test method is carried out according to the following steps: (1)采用电火花线切割的方式引发试样的初始裂纹；(1) The initial crack of the sample is induced by wire electric discharge cutting; (2)将求解出的所设计试样的柔度系数输入到事先编好的试验程序中；(2) Input the calculated flexibility coefficient of the designed sample into the pre-programmed test program; (3)测量试样厚度、宽度参数，并输入到事先编好的程序中；(3) Measure the thickness and width parameters of the sample, and input them into the pre-programmed program; (4)将腐蚀循环系统、相关的试样卡具及试样与立式疲劳试验机相连接；(4) Connect the corrosion circulation system, related sample fixtures and samples with the vertical fatigue testing machine; (5)将腐蚀液加入循环系统和装有试样的腐蚀盒中，循环系统中的腐蚀液要足够多，腐蚀盒中的腐蚀液要保证时时浸泡住裂纹扩展面；(5) Add the corrosive solution to the circulation system and the corrosion box containing the sample. The corrosive solution in the circulation system should be sufficient, and the corrosive solution in the corrosion box should be guaranteed to soak the crack propagation surface from time to time; (6)将电子引伸计装卡在试样上侧的刀口处，清零；(6) Install the electronic extensometer at the knife edge on the upper side of the sample and reset it to zero; (7)设置好预制疲劳裂纹的各个参数，包括应力强度因子范围ΔK、控制方式、采用频率、波形及预制疲劳裂纹的长度；(7) Set various parameters of prefabricated fatigue cracks, including stress intensity factor range ΔK, control mode, frequency, waveform and length of prefabricated fatigue cracks; (8)启动试验机，开始预制疲劳裂纹，时时观测当前的裂纹扩展长度，注意整个腐蚀循环系统，以防腐蚀液渗漏而侵蚀试验机；(8) Start the testing machine, start prefabricating fatigue cracks, observe the current crack extension length from time to time, pay attention to the entire corrosion cycle system, to prevent corrosion of the testing machine due to leakage of corrosive liquid; (9)预制完成疲劳裂纹后，根据当前的结果，设定试验时所需要的载荷范围、应力比、频率的参数；(9) After the fatigue cracks are prefabricated, according to the current results, set the parameters of the load range, stress ratio, and frequency required for the test; (10)再次启动试验机，开始正式试验；(10) Start the testing machine again and start the formal test; (11)试验结束后，根据所采集到的试验数据，按照帕里斯(Paris)经验方程的表达形式拟合出试验材料的疲劳裂纹扩展速率曲线及其方程，最后出具相应的试验报告。(11) After the test, according to the collected test data, fit the fatigue crack growth rate curve and equation of the test material according to the expression form of the Paris (Paris) empirical equation, and finally issue the corresponding test report.
CN 200410060569 2004-10-14 2004-10-14 Sample for measuring fatigue crack expansion rate in corrosion liquid and test method Expired - Fee Related CN1278114C (en)

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CN102426137B (en) * 2011-08-31 2013-06-05 中国船舶重工集团公司第七二五研究所 Testing and measuring method capable of axially loading low cycle fatigue crack initiation
FR2995080B1 (en) * 2012-09-04 2015-10-23 Snecma METHOD FOR HIGH-FREQUENCY DETERMINATION OF FATURE NON-PROPAGATION FATIGUE THRESHOLD
CN103884610B (en) * 2012-12-21 2016-06-29 中国直升机设计研究所 A kind of composite II type cracking threshold and S-N curve determination method
CN103439202A (en) * 2013-08-19 2013-12-11 北京航空航天大学 System for testing fatigue in corrosion environment
CN103439199A (en) * 2013-08-19 2013-12-11 北京航空航天大学 System for testing fatigue crack propagation in corrosion environment
CN104404582A (en) * 2014-11-19 2015-03-11 中国航空工业集团公司沈阳飞机设计研究所 Method for optimizing high-corrosion resistance cadmium titanium plating layers of ultrahigh-strength steel
CN104458562B (en) * 2014-11-28 2017-02-22 中国航空工业集团公司北京航空材料研究院 Measuring method for opening stress of crack
CN110376062A (en) * 2019-07-22 2019-10-25 中国航发沈阳发动机研究所 A kind of resonant fatigue test crackle pre-setting method
CN110987634A (en) * 2019-11-15 2020-04-10 河海大学 Test device and test method for hydraulic fracture of gravel-doped core wall
CN111665132A (en) * 2020-06-17 2020-09-15 天津大学 Method for measuring fatigue crack propagation of opening corner
CN113514353A (en) * 2021-04-25 2021-10-19 中信戴卡股份有限公司 A kind of crack monitoring equipment and test equipment for automobile fatigue test

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