Failure analysis software system for pipeline with cracks

Abstract

The invention provides a crack-containing pipeline failure analysis software system, and belongs to the field of crack-containing pipeline failure evaluation. The system comprises a parameter import module, a random sampling module, a penetration crack length module, a leakage rate module, a failure analysis module and a display module. The parameter import module imports pipeline material parameters, operation environment parameters and the like into the computer; the random sampling module is used for carrying out random sampling according to a common distribution function on the basis of importing parameters; the fatigue crack propagation module is used for calculating a stress intensity factor and fatigue crack propagation; the leakage rate module is used for calculating a detectable leakage length; and the result analysis module is used for integrating all calculation results and input parameters into a failure probability analysis chart. According to the method, the probability fracture mechanics method is adopted, the detection accuracy is improved, and the failure probability of equipment can be evaluated more quickly and visually.

Description

Technical Field

[0001] The invention relates to the field of failure assessment of cracked pipelines, and in particular to a consequence assessment system for equipment failure caused by rupture of cracked pipelines. Background Art

[0002] The causes of pipeline failure may include material fatigue, corrosion, manufacturing defects, improper design, operational overload, etc. Cracks are one of the important manifestations of pipeline failure. The presence of cracks may lead to leakage, explosion or other serious accidents in the pipeline. This not only endangers operational safety, but may also cause environmental pollution and economic losses. Therefore, the technology of evaluating the consequences of failure of cracked pipelines has emerged. Taking appropriate prevention and mitigation measures based on the evaluation results will help improve the current and future design and maintenance of pipeline systems.

[0003] At present, the mechanical analysis of cracked pipelines uses ANSYS software. Since the loop contains pressure vessels, steam generators, etc., the model boundary is extremely complex, and a lot of data needs to be input and output. In addition, ANSYS software does not have the function of automatically evaluating the results such as enveloping and combining. Ensuring the accuracy and efficiency of pipeline mechanical analysis models and methods is of great significance to the safety and economy of the entire pipeline operation period.

[0004] Therefore, there is a particular need for a system for evaluating the consequences of equipment failure caused by cracked pipeline rupture to solve the above-mentioned existing problems. Summary of the invention

[0005] The purpose of the present invention is to provide a system for evaluating the consequences of equipment failure caused by cracked pipeline rupture. In view of the shortcomings of the prior art, the LBB analysis criterion and the probabilistic fracture mechanics algorithm are used to calculate the failure probability, and the analysis results are automatically extracted, enveloped, combined and evaluated, which significantly improves the efficiency of the main circuit mechanics analysis. At the same time, human errors and equipment errors are considered through probabilistic fracture mechanics.

[0006] The technical problem solved by the present invention can be achieved by adopting the following technical solutions:

[0007] In a first aspect, the present invention provides a software system for failure analysis of cracked pipelines, including a parameter import module, a probability distribution sampling module, a yield strength detection module, a penetration crack length module, a leakage rate module, a failure analysis module, and a display module.

[0008] First, all data are imported into VS and excel databases through the parameter import module. The data includes the probability distribution of parameters, material type and its parameters, operating environment parameters, and sensitivity analysis options. The probability distribution data of parameters include: elastic modulus, yield strength, tensile strength, initial crack storage, and the mean and variance of the probability density distribution function of fluid temperature; material type and its parameters include: material type, Poisson's ratio corresponding to the material, critical crack opening displacement, crack extension parameters N and C, radius and thickness of the pipe; operating environment parameters include: operating pressure, pressure fluctuation range, detectable leakage rate, and number of pressure cycles; sensitivity analysis options include: fluid temperature analysis, yield strength analysis, elastic modulus analysis, tensile strength analysis, and initial crack short / deep axis coefficient analysis. The above parameters are first imported into the calculation code through the Textbox text box control in the form application in VS, and the parameters in the calculation code are further imported into excel as a database through the file stream method.

[0009] Furthermore, in the probability distribution sampling module, the mean and variance of the probability density distribution function obtained by the parameter import module are extracted, and then random sampling is performed through the Random function. The number of samples is customized by the user and obtained by the parameter import module. Then, the random value obtained by random sampling is combined with the mean and variance of the probability density distribution function to obtain the corresponding random value of the cumulative distribution function, and the random number is visualized through the Chart chart control in the VS form application.

[0010] Further in the yield strength detection module, the pipe radius, pipe thickness, operating pressure and yield strength in the Excel database are re-imported into VS through the file flow, and then the yield range of the pipeline is determined by calculating the ratio of stress and yield strength. When the pipeline is in a small range of yield strength, it will be returned in the database as not meeting the yield range, and the reorganized data will be eliminated in subsequent calculations; when the pipeline is in a medium to large yield range, it will be returned in the database as meeting the yield range.

[0011] Further in the penetration crack length module, firstly, the initial crack depth and major axis are imported through the COD criterion submodule, and the second-class complete elliptic integral E_K is obtained by looking up the table; the crack correction length is obtained by combining the stress calculated in the yield strength detection module with the second-class complete elliptic integral; the rheological stress is obtained by importing the yield strength and tensile strength; the bulging effect correction M is calculated by importing the crack major semi-axis, pipeline radius and thickness; E under plane stress is obtained by importing Poisson's ratio and elastic modulus; the above calculated values ​​are integrated to finally obtain the crack opening displacement and critical crack length. Then, through the stress intensity factor module, the operating pressure, pressure range, initial crack size, and pipeline thickness radius are imported to obtain the stress intensity factor at instantaneous 0° and 90°. Furthermore, in the leakage rate module, the stress intensity factor at 0° and 90°, the pipe thickness, the initial crack size, the crack extension parameters n and C obtained through the stress intensity factor module are imported through the crack extension submodule to obtain the instantaneous crack extension length in the 0° direction and the 90° direction; through the two-phase critical flow submodule, the crack extension length obtained through the crack extension submodule, the crack opening displacement obtained under the COD criterion submodule, and the saturated vapor pressure and density under the change of fluid temperature are imported to obtain the crack opening area, and then the instantaneous leakage rate is obtained.

[0012] Furthermore, in the failure analysis module, a time parameter in months is introduced. The previously calculated critical crack length, instantaneous crack extension length, detectable leakage rate and instantaneous leakage rate are used as criteria. Based on random sampling, the failure type of the current month is obtained: instability, leakage and safety.

[0013] Further in the display module, the failure probability is obtained by statistics through the failure type data of each month, with the x-axis being the operating month and the y-axis being the failure probability of the month, and a visualization graph is produced through the chart control of the VS form application. In the present invention, the recommended material property parameters can be automatically given through the selection of materials, or they can be changed manually; the environmental condition parameters that need to be considered need to be manually input by the user according to different situations. At the same time, you can choose the sensitivity you want to study, including: fluid temperature analysis, yield strength analysis, elastic modulus analysis, tensile strength analysis, initial crack short / deep axis coefficient analysis. Finally, the failure results are vividly displayed through a visualization method. Compared with the prior art, it can replace the original manual modeling and evaluation methods, and give efficient failure analysis suggestions to nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The software layout diagram of the cracked pipeline failure analysis software system of the present invention;

[0015] Figure 2Schematic diagram of the research object analyzed by the cracked pipeline failure analysis software system of the present invention; wherein (a) is a schematic diagram of a circumferential crack, a is the initial crack depth, 2c is the initial crack length, R0 is the outer radius of the pipeline, R m is the average radius of the pipeline, 2θ is the crack annular angle, and t is the pipeline wall thickness; (b) is the schematic diagram of the axial crack, a is the initial crack depth, 2c is the initial crack length, R0 is the outer radius of the pipeline, R i is the inner diameter of the pipe, t is the wall thickness of the pipe;

[0016] Figure 3 It is a schematic diagram of the process of analyzing the failure analysis software system of a cracked pipeline of the present invention;

[0017] Figure 4 It is a schematic diagram of the results of the failure analysis software system analysis of a cracked pipeline of the present invention. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0019] Example

[0020] like Figure 1 As shown, a failure analysis software system for cracked pipelines includes a probability distribution sampling module 10, a penetration crack length module 11, a leakage rate module 14, a parameter import module 18, a yield strength detection module 19, a failure analysis module 21, and a display module 22.

[0021] The probability distribution sampling module 10 includes the mean and variance of the probability density function of material properties such as yield strength and tensile strength. Such parameters automatically give recommended values ​​according to the material type selected by the user, and can also be changed. The parameter import module 18 includes two major types of data: environmental parameters and pipeline parameters. This type of parameter is input by the user according to the specific situation. After the input is completed, the values ​​in VS are imported into Excel as a database through the file flow in VS. After the import parameters and probability distribution sampling are completed, the yield strength detection module 19 is run to check the yield range of the existing data and propose data with a small yield range.

[0022] First, select the sampling parameters you want to study in the sensitivity selection 17. Except for the selected sensitivity as a fixed input, the rest of the sampling values ​​in the probability distribution sampling module 10 are kept as input.

[0023] The penetration crack length module 19 includes the COD criterion 12 and the stress intensity factor module 13; based on the database, the data is also imported from Excel to VS through the file flow method, and then the critical crack length and critical crack opening displacement are calculated by the COD criterion 12, and the instantaneous stress intensity factor is calculated by the stress intensity factor module 13, and the obtained value is returned to the Excel database through the file flow. The leakage rate module 14 includes the crack extension module 15 and the two-phase critical flow module 16; the instantaneous stress intensity factor obtained in the stress intensity factor submodule is brought into the crack extension module 15 to obtain the instantaneous crack extension length and the crack opening area; the crack opening displacement obtained by the COD criterion 12 and the crack opening area obtained by the crack extension module 15 are imported through the two-phase critical flow module, and the fluid temperature obtained by the parameter import module is imported at the same time to obtain the instantaneous leakage rate, and then imported back to the Excel database through the file flow.

[0024] The failure analysis module 21 integrates the critical crack length calculated by the penetration crack length module 11 in the Excel database, the instantaneous leakage rate obtained by the leakage rate module 14, the detectable leakage rate obtained by the parameter import module 18, and the instantaneous crack extension length based on the month introduced by the crack extension module 15, and compares and judges different failure types: instability, leakage, and safety; combined with the different sampling values ​​obtained by the probability distribution sampling module 10, the failure probability of different months is obtained.

[0025] The display module 22 integrates the failure probabilities of each month in the Excel database and visualizes the results through the chart control in the form application of VS.

Claims

1. A cracked pipeline failure analysis software system, characterized in that: It includes a parameter import module, a probability distribution sampling module, a yield strength detection module, a penetration crack length module, a leakage rate module, a failure analysis module, and a display module; the parameter import module is used to import different material parameters into a computer and an Excel database for storage; The probability distribution sampling module is used to randomly sample parameters under different distribution functions; the penetration crack length module is used to calculate the penetration crack length; the leakage rate module is used to calculate the detectable leakage crack length; the failure probability analysis module is used to coordinate the calculated values ​​and input values ​​to perform LBB failure analysis; the display module is used to visualize all data in the software system; The through crack length module includes a COD criterion module and a stress intensity factor module; The stress intensity factor module is run first, and then the COD criterion module is run to realize the function of calculating the penetration crack length; The leakage rate module includes a crack extension module and a two-phase critical flow module; the crack extension module is run first, and then the two-phase critical flow model is run to realize the function of calculating the detectable leakage rate.

2. The cracked pipeline failure analysis software system according to claim 1 is characterized in that: The parameter import module uses the form application in Visual Studio to provide an interface for software parameter input; at the same time, it uses file stream to import parameter input and calculated values ​​into Excel for use as a database.

3. The cracked pipeline failure analysis software system according to claim 2 is characterized in that: The parameter import module selects the type of material, parameter value of probability distribution function, radius and thickness of pipeline, operating environment, and sensitivity analysis according to user needs.

4. The cracked pipeline failure analysis software system according to claim 1, characterized in that: The probability distribution sampling module extracts the probability distribution function parameters from the database, uses the chart control in the form application to draw a chart of the cumulative distribution function, then uses the Random function that comes with VS to generate random numbers for random sampling, and imports the sampled values ​​back to the database using a file stream.

5. The cracked pipeline failure analysis software system according to claim 1 is characterized in that: The yield strength detection module is used to detect whether the pipeline is in a medium to large range of yield strength, and is used to screen and propose data under a small range of yield strength; wherein the medium to large range of yield strength is the value of stress divided by the yield strength between 0.5 and 1, and the small range of yield strength is the value of stress divided by the yield strength less than 0.5, and the stress value is calculated in the penetration crack length module.

6. The cracked pipeline failure analysis software system according to claim 1, characterized in that: The stress intensity factor module is used to extract parameter import values ​​and probability sampling values ​​from the database, calculate the stress intensity factors at different angles of 0° and 90° in the initial crack, and store them in the excel database through file stream; the COD criterion module is used to extract the database stress intensity factor, yield strength, tensile strength, crack length, container radius, wall thickness, elastic modulus, and container internal pressure, and then obtain a certain instantaneous critical crack length and crack opening displacement through correction for bulging effect, crack length, and material work hardening.

7. The cracked pipeline failure analysis software system according to claim 1, characterized in that: The crack extension module is used to extract metal material parameters and stress intensity factors from the database, and based on the Paris formula, obtain the crack extension conditions at different instants, and then combine this with the crack opening displacement, assuming that the crack opening shape is an ellipse, to obtain the crack opening area; the two-phase critical flow module is used to extract the pipeline fluid density, saturation pressure, crack opening area, and pipeline internal pressure from the database, and calculate the instantaneous leakage rate based on the two-phase critical flow formula.

8. The cracked pipeline failure analysis software system according to claim 1, characterized in that: The failure analysis module is used to extract the critical crack length, minimum detectable leakage rate, instantaneous leakage rate, and instantaneous crack extension length from the database, and analyze the failure types in different months based on the number of cycles per hour and LBB of the nuclear power plant, including instability, leakage, and safety, to obtain the failure probability in different months.

9. The cracked pipeline failure analysis software system according to claim 8, characterized in that: The failure analysis module needs to select different sampling values ​​and given values ​​under different sensitivity analysis conditions. When temperature sensitivity analysis is selected, the temperature parameters need to be given in the software interface, and the remaining sampling values ​​are used for calculation.

10. The cracked pipeline failure analysis software system according to claim 1, characterized in that: The display module is used to visualize data, and uses the chart control in the VS form application to display the failure probability in different months through a chart.

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