Method for evaluating the sealing performance of a pipe joint

Abstract

The application discloses a kind of sealing performance evaluation methods of pipe joint, by establishing the connection between leakage rate numerical value and actual leakage phenomenon, avoid the drawbacks that small seepage visual inspection is easy to miss;The present application is based on numerical calculation method, saves the time period and cost waste of physical verification, using this method, the sealing performance can be judged in advance when product design, according to the stress index and sealing contact width index of the main structure parameter design of reverse calculation of sealing performance index;Also when sending leakage failure, traceability can be carried out, and the weak link of contact pressure is found, which brings guidance for improving sealing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pipeline sealing performance evaluation, and particularly relates to a sealing performance evaluation method of a pipe joint. BACKGROUND

[0002] The sealing performance of a pipeline of an aircraft system affects the use function and performance of the aircraft, and is a process link that needs to be controlled in the aircraft manufacturing process. The sealing performance of a pipe joint is usually evaluated through physical verification, and whether the pipe joint leaks in the test working condition is used as the judgment basis. With the development of numerical methods and the improvement of computing power, more and more researchers use the finite element method to study the static sealing performance of the structure on the basis of design experience. Such a method comprehensively judges by reading the contact pressure and sealing width information of the sealing interface and combining the test verification. Both the physical verification and the numerical calculation method have the following shortcomings in the evaluation of the sealing performance:

[0003] (1) The physical verification evaluation period is long, the cost is high, and the judgment of whether there is leakage through visual observation lacks quantitative evaluation indexes;

[0004] (2) The sealing width and contact pressure indexes evaluated by the numerical calculation simulation method are unclear in origin, and are mostly determined through tests or experience, lacking scientific basis, and it is difficult to establish a direct connection between the actual leakage phenomenon.

[0005] Therefore, in order to evaluate the sealing performance of the pipe joint through direct quantitative indexes, the application discloses a sealing performance evaluation method of a pipe joint. SUMMARY

[0006] The application discloses a sealing performance evaluation method of a pipe joint, which can directly and quickly and accurately quantitatively evaluate the sealing performance of the pipe joint structure, can form an accurate quantitative evaluation system of the sealing performance at the beginning of the design of the pipe joint, and further provides protection for the sealing performance of the pipe joint in subsequent design.

[0007] The application is implemented through the following technical scheme:

[0008] A sealing performance evaluation method of a pipe joint, the pipe joint comprising an extrusion ring, a joint and a conduit, comprising the following steps:

[0009] Step 1, constructing an axisymmetric finite element model of the pipe joint with the central axis of the conduit as the reference;

[0010] Step 2, applying a load and a constraint condition to the axisymmetric finite element model;

[0011] Step 3, setting a contact path on the sealing interface of the axisymmetric finite element model, analyzing the contact pressure received by the sealing interface, and obtaining a pressure curve distributed along the contact path;

[0012] Step 4, according to the pressure value mutation point on the pressure curve along the contact path intercept sealing width, calculate the average contact pressure in the sealing width range;

[0013] Step 5, according to the average contact pressure to establish the sealing performance calculation model, through the sealing performance calculation model to calculate the sealing performance index in the current sealing width range, according to the sealing performance index to evaluate the sealing performance of the pipe joint.

[0014] In order to better realize the present application, further, the step 4 specifically includes:

[0015] Step 4.1, select the pressure mutation starting point and the pressure mutation ending point on the pressure curve, and intercept the pressure mutation region between the adjacent pressure mutation starting point and the pressure mutation ending point, and calculate the width of the pressure mutation region as the sealing width;

[0016] Step 4.2, read all the contact pressure data in the sealing width range, and clean the contact pressure data;

[0017] Step 4.3, based on the cleaned contact pressure data, the average contact pressure in the sealing width range is calculated.

[0018] In order to better realize the present application, further, the calculation formula of the average contact pressure in the sealing width range is as follows:

[0019] ;

[0020] Wherein: PS represents the average contact pressure in the sealing width range; n represents the number of items of the cleaned contact pressure data; represents the i-th contact pressure data value, 1≤i≤n.

[0021] In order to better realize the present application, further, the cleaning of the contact pressure data specifically includes the following steps:

[0022] Step A1, read all the contact pressure data in the sealing width range to form a data set P, calculate the average value of the contact pressure based on the data set P, and calculate the standard deviation based on the average value of the contact pressure;

[0023] Step A2, according to the standard deviation to calculate the cleaning threshold, calculate the difference between the contact pressure data and the average value, if the difference between the contact pressure data and the average value is greater than the cleaning threshold, the corresponding contact pressure data is screened to form a data set Q;

[0024] Step A3, eliminate the elements belonging to the data set Q in the data set P, and execute step A1-A2 on the eliminated data set P;

[0025] Step A4, repeat the above steps A1-A3 until the number of elements inside the data set Q is 0.

[0026] To better implement the present application, further, the selection rule of the pressure mutation starting point in step 4.1 is:

[0027] ;

[0028] Wherein: represents the pressure mutation starting point and its adjacent next sampling point between the pressure mutation value; represents the pressure mutation starting point and its adjacent previous sampling point between the pressure mutation value;

[0029] The selection rule of the pressure mutation end point in step 4.1 is:

[0030] ;

[0031] Wherein: represents the pressure mutation end point and its adjacent previous sampling point between the pressure mutation value; represents the pressure mutation end point and its adjacent next sampling point between the pressure mutation value.

[0032] To better implement the present application, further, the sealing performance calculation model in step 5 is specifically:

[0033] ;

[0034] Wherein: Q represents the sealing performance index; C represents the sealing medium performance index coefficient; D represents the initial diameter of the conduit without being subjected to pressure within the sealing width range; H represents the roughness of the conduit wall; w represents the sealing width; e represents the natural constant; k represents the sealing material performance coefficient; PS represents the average contact pressure within the sealing width range; represents the pressure difference between the inside and outside of the pipe joint.

[0035] To better implement the present application, further, the step 2 specifically comprises:

[0036] Step 2.1, applying an axial displacement load at the end of the extrusion ring away from the joint, applying a spring constraint at the end of the conduit close to the axial displacement load, and applying a fixed constraint at the end of the joint away from the axial displacement load;

[0037] Step 2.2, presetting the rigidity value of the spring constraint, calculating the support reaction force of the spring constraint according to the preset rigidity value;

[0038] Step 2.3, adjusting the rigidity value according to the support reaction force until 5N≤support reaction force≤10N;

[0039] Step 2.4, canceling the spring constraint, canceling the axial displacement load, retaining the fixed constraint, and making the axisymmetric finite element model free rebound.

[0040] In order to better realize the present application, further, the step 3 specifically comprises:

[0041] Step 3.1, setting the contact surface between the joint and the pipe as a sealed interface;

[0042] Step 3.2, setting a contact path parallel to the central axis of the pipe on the sealed interface;

[0043] Step 3.3, reading the contact pressure between the joint and the pipe to form a pressure curve distributed along the contact path.

[0044] In order to better realize the present application, further, in the step 1, the axisymmetric finite element model is meshed, the global size of the meshing is less than or equal to 0.08mm, and the size of the meshing at the contact part of the joint and the pipe is greater than or equal to 0.03mm.

[0045] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0046] The present application can realize quantitative evaluation of the sealing performance of the joint structure, establish the connection between the leakage rate value and the actual leakage phenomenon, and avoid the drawbacks that visual inspection of micro seepage is easy to miss; the present application is based on numerical calculation method, saves the time period and cost waste of physical verification, and can judge the sealing performance in advance during product design by using the method, according to the sealing performance index, inversely calculates the stress index and the sealing contact width index of the main structure parameters designed; also can trace the source when the leakage fault occurs, find the weak link of the contact pressure, and bring guidance for improving the sealing performance. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is a flow step schematic diagram of the sealing performance evaluation method of the pipe joint;

[0048] Figure 2 It is a schematic diagram of the axisymmetric finite element model;

[0049] Figure 3 It is a schematic diagram of the pressure curve;

[0050] Figure 4 It is a schematic diagram of the intercepted sealing width.

[0051] Wherein: 1 - extrusion ring; 2 - joint; 3 - conduit. DETAILED DESCRIPTION

[0052] Example 1

[0053] The sealing performance evaluation method of a pipe joint according to the present embodiment, the pipe joint comprising an extrusion ring 1, a joint 2, and a conduit 3, as shown in FIG. 1, comprises the following steps: Figure 1

[0054] Step 1, constructing an axisymmetric finite element model of the pipe joint with the central axis of the conduit 3 as the reference, the axisymmetric finite element model as shown in FIG. 2; Figure 2

[0055] Step 2, applying load and constraint conditions to the axisymmetric finite element model;

[0056] Step 3, setting a contact path on the sealing interface of the axisymmetric finite element model, analyzing the contact pressure on the sealing interface, and obtaining a pressure curve distributed along the contact path;

[0057] Step 4, intercepting the sealing width along the contact path according to the pressure value mutation point on the pressure curve, and calculating the average contact pressure in the sealing width range;

[0058] Step 5, establishing a sealing performance calculation model according to the average contact pressure, calculating the sealing performance index in the current sealing width range through the sealing performance calculation model, and evaluating the sealing performance of the pipe joint according to the sealing performance index.

[0059] Example 2

[0060] The sealing performance evaluation method of a pipe joint according to the present embodiment is improved on the basis of Example 1, specifically:

[0061] Step 1, constructing an axisymmetric finite element model of the pipe joint with the central axis of the conduit 3 as the reference, in the step 1, performing meshing on the axisymmetric finite element model, the global size of the meshing being less than or equal to 0.08 mm, and the size of the meshing at the contact part of the joint 2 and the conduit 3 being greater than or equal to 0.03 mm.

[0062] Step 2, applying load and constraint conditions to the axisymmetric finite element model;

[0063] Step 2 specifically comprises:

[0064] Step 2.1, applying an axial displacement load at the end of the extrusion ring 1 away from the joint 2, applying a spring constraint at the end of the conduit 3 close to the axial displacement load, and applying a fixed constraint at the end of the joint 2 away from the axial displacement load;

[0065] ​​Step 2.2, the stiffness value of the preset spring constraint is 50, and the support reaction force of the spring constraint is calculated according to the preset stiffness value;

[0066] Step 2.3, adjust the stiffness value according to the support reaction force until 5N≤support reaction force≤10N;

[0067] Step 2.4, cancel the spring constraint, cancel the axial displacement load, and keep the fixed constraint, so that the axisymmetric finite element model is free to rebound.

[0068] Step 3, set a contact path on the sealing interface of the axisymmetric finite element model, analyze the contact pressure on the sealing interface, and obtain a pressure curve distributed along the contact path;

[0069] Step 3 is specifically:

[0070] Step 3.1, set the contact surface between the joint 2 and the conduit 3 as the sealing interface;

[0071] Step 3.2, set a contact path on the sealing interface, which is parallel to the central axis of the conduit 3, the direction of the contact path has no effect on the analysis result, only need to ensure that the contact path is parallel to the central axis of the conduit 3;

[0072] Step 3.3, read the contact pressure between the joint 2 and the conduit 3 along the contact path to form a pressure curve distributed along the contact path.

[0073] Step 4, according to the pressure value mutation point on the pressure curve, cut the sealing width along the contact path, and calculate the average contact pressure in the sealing width range;

[0074] Step 4 is specifically:

[0075] Step 4.1, select the pressure mutation starting point and the pressure mutation ending point on the pressure curve, and cut the pressure mutation region between the adjacent pressure mutation starting point and the pressure mutation ending point, and calculate the width of the pressure mutation region as the sealing width;

[0076] Step 4.2, read all contact pressure data in the sealing width range, and clean the contact pressure data;

[0077] Step 4.3, based on the cleaned contact pressure data, solve the average contact pressure in the sealing width range.

[0078] Further, the calculation formula of the average contact pressure in the sealing width range is as follows:

[0079] ;

[0080] Wherein: PS represents the average contact pressure in the sealing width range; n represents the number of items of the cleaned contact pressure data; represents the ith contact pressure data value, 1≤i≤n.

[0081] Further, the cleaning of the contact pressure data specifically comprises the following steps:

[0082] Step A1, reading all contact pressure data in the sealing width range to form a data set P, calculating the average value of the contact pressure based on the data set P, and calculating the standard deviation based on the average value of the contact pressure;

[0083] Step A2, calculating the cleaning threshold according to the standard deviation, calculating the difference between the contact pressure data and the average value, and if the difference between the contact pressure data and the average value is greater than the cleaning threshold, then the corresponding contact pressure data is screened to form a data set Q;

[0084] Step A3, removing the elements belonging to the data set Q in the data set P, and performing steps A1-A2 on the removed data set P;

[0085] Step A4, repeating the above steps A1-A3 until the number of elements inside the data set Q is 0.

[0086] Further, the selection rule of the pressure mutation starting point in step 4.1 is:

[0087] ;

[0088] Wherein: represents the pressure mutation value between the pressure mutation starting point and its adjacent next sampling point ; represents the pressure mutation value between the pressure mutation starting point and its adjacent previous sampling point ;

[0089] The selection rule of the pressure mutation ending point in step 4.1 is:

[0090] ;

[0091] Wherein: represents the pressure mutation value between the pressure mutation ending point and its adjacent previous sampling point ; represents the pressure mutation value between the pressure mutation ending point and its adjacent next sampling point .

[0092] Step 5, establishing a sealing performance calculation model according to the average contact pressure, calculating the sealing performance index in the current sealing width range through the sealing performance calculation model, and evaluating the sealing performance of the pipe joint according to the sealing performance index.

[0093] The sealing performance calculation model in the step 5 is specifically as follows:

[0094]

[0095] Wherein, Q represents the sealing performance index; C represents the sealing medium performance index coefficient; D represents the initial diameter of the conduit without pressure in the sealing width range; H represents the roughness of the conduit wall; w represents the sealing width; e represents the natural constant; k represents the sealing material performance coefficient; PS represents the average contact pressure in the sealing width range; represents the pressure difference between the inside and outside of the pipe joint.

[0096] The calculated sealing performance index Q is compared with the sealing performance target index QS, if Q> QS, it indicates that the structure in the current sealing width range does not meet the sealing performance requirement; if Q≤ QS, it indicates that the structure in the current sealing width range does not meet the sealing performance requirement.

[0097] Embodiment 3:

[0098] The sealing performance evaluation method of the pipe joint in this embodiment is improved on the basis of embodiment 2, and is specifically as follows:

[0099] The pipe joint comprises an extrusion ring 1, a joint 2 and a conduit 3, and the assembly structure therebetween is as shown in Figure 2 The extrusion ring 1 moves in the axial direction under the external axial extrusion, extrudes the joint 2, and then extrudes the conduit 3, so as to finally complete the extrusion and form the final permanent assembly structure.

[0100] Based on the structure of the pipe joint, an axisymmetric finite element model of the pipe joint is constructed with the central axis of the conduit 3 as the reference, and the axisymmetric finite element model is meshed. In the finite element simulation, the simulation result data such as stress and pressure are closely related to the mesh size, the smaller the mesh size, the higher the calculation accuracy, and the lower the corresponding calculation efficiency. In the present application, considering the calculation efficiency and the calculation accuracy, the global size of the mesh is set to be less than or equal to 0.08 mm; the mesh at the contact part of the conduit 3 and the joint 2 needs to be appropriately refined, and the refined range is the axisymmetric finite element model within 2 mm before and after the inner wall groove of the joint 2.

[0101] The axisymmetric finite element model is subjected to load and constraint conditions;

[0102] A spring constraint is arranged on one side of the conduit 3, and the initial stiffness value of the spring constraint is 50; a fixed constraint is arranged on one side of the joint 2, and an axial displacement load is applied to one end of the extrusion ring 1, and the displacement amount is the distance from the extrusion outer end face to the joint flange end face. ​

[0103] Cancel the spring constraint, cancel the axial displacement load, so that the axial extrusion part of the axisymmetric finite element model is free to rebound, to simulate the local rebound of the pipe joint as a whole after the butt joint of the pipe joint is completed and the external force is removed. Canceling the spring constraint and the axial displacement load is the rebound process after the installation of the model pipe joint is completed, at which time the stress state of the pipe joint as a whole will change.

[0104] A contact path is set on the sealing interface of the axisymmetric finite element model, and the contact pressure on the sealing interface is analyzed to obtain a pressure curve distributed along the contact path.

[0105] The sealing evaluation area between the guide pipe 3 and the joint 2 is established, and the sealing performance is evaluated based on the sealing pressure of the sealing interface. By reading the contact pressure data between the joint 2 and the guide pipe 3, a pressure curve distributed along the contact path is obtained as shown in Figure 3 .

[0106] The sealing width is determined.

[0107] According to the obtained pressure curve, the sealing width of the contact part between the groove part of the joint 2 and the guide pipe 3 is read, and the specific selection rule of the sealing width is:

[0108] The region width between the adjacent pressure mutation starting point and the pressure mutation ending point is selected as the sealing width.

[0109] Wherein:

[0110] The pressure mutation starting point The selection rule is:

[0111] ;

[0112] The pressure mutation ending point The selection rule is:

[0113] ;

[0114] As shown in Figure 4 , two sealing widths are obtained according to the rules in this embodiment, which are respectively denoted as w 1, w 2, and w 1=0.42mm, w 2 =0.43mm.

[0115] The sealing performance index of the part to be evaluated is calculated.

[0116] The average contact stress in the sealing width range is solved, and the sealing width w 1 is taken as an example:

[0117] The sealing widthw 1 all contact stress data points in the range, counted as where m is the number of contact stress data points, 1≤i≤m; represents the contact pressure corresponding to the ith contact stress data point.

[0118] The contact stress data set is cleaned, and the cleaning steps are as follows:

[0119] The average value u and the standard deviation of the contact stress calculation value are calculated ;

[0120] The calculation formula of the average value is:

[0121] ;

[0122] where: u represents the average value of the contact pressure; m represents the number of contact stress data points, 1≤i≤m; represents the contact pressure corresponding to the ith contact stress data point.

[0123] The calculation formula of the standard deviation is:

[0124] ;

[0125] where: represents the standard deviation; u represents the average value of the contact pressure; m represents the number of contact stress data points, 1≤i≤m; represents the contact pressure corresponding to the ith contact stress data point.

[0126] The contact stress data points greater than the cleaning threshold T in the data set P are screened to obtain the data set , where T is valued as follows:

[0127] ;

[0128] The data set P is screened according to the number of elements in the data set Q, and the specific rules are as follows: if the number of elements in the data set Q is 0, the elements in the data set P do not need to be removed; if the number of elements in the data set Q is greater than 0, the elements in the data set P belonging to the data set Q are removed, and then the operation of sealing performance index calculation and cleaning is repeated on the new data set P until the number of elements in the new data set Q is 0, and the final contact stress data point data set is .

[0129] Based on the new data set the average contact pressure in the sealing width range is obtained:

[0130]

[0131] Wherein: PS represents the average contact pressure in the sealing width range; n represents the number of contact pressure data after cleaning; represents the i th contact pressure data value, 1≤i≤n.

[0132] The final calculation of the sealing width w 1 range average contact pressure PS1=623.843.

[0133] The sealing performance calculation model is established as follows:

[0134] ;

[0135] Wherein: Q represents the sealing performance index; C represents the sealing medium performance index coefficient, which is related to the sealing medium and the working environment temperature, and in this embodiment, helium is taken as the working medium, the working environment temperature is taken as 20℃, and the corresponding coefficient is taken as 1107.156 m / s; D represents the initial diameter of the conduit without being subjected to pressure in the sealing width range, and in this embodiment, D1=8mm; H represents the roughness of the conduit wall, and in this embodiment, H=0.8 ; w represents the sealing width; e represents the natural constant; k represents the sealing material performance coefficient, which is related to the sealing interface material, and in this embodiment, the material of the extrusion ring 1 is TC4, and the material of the joint 2 is TC4, and in this embodiment, k=-0.023MPa -1 ; PS represents the average contact pressure in the sealing width range; represents the pressure difference between the inside and outside of the pipe joint, and in this embodiment, =2Mpa.

[0136] is the pressure difference between the inside and outside of the joint, and in this embodiment, the pressure difference between the inside and outside of the joint is 2MPa.

[0137] Based on the above formula, the values of w 1 and w 2 are brought in, i.e. w 1=0.42mm, w 2 =0.43mm.

[0138] The pressure performance index corresponding to the pressure width w 1 is:

[0139] Q1 = 1.48×10 -8 Pa∙m 3 / s;

[0140] The pressure performance index corresponding to the pressure width w 2 is:

[0141] Q2 = 5.18×10-7 Pa∙m 3 / s;

[0142] The calculated sealing performance index Q is compared with the sealing performance target index QS, and QS = 1 x 10 -7 Pa∙m 3 / s.

[0143] Q1 < QS, indicating that the structure in the pressure width w 1 range meets the sealing performance requirements;

[0144] Q2 > QS, indicating that the structure in the pressure width w 2 range does not meet the sealing performance requirements.

[0145] Therefore, the structure in the pressure width w 2 range needs to be improved, for example, increasing the outer diameter size of the structure in the pressure width w 2 range, reducing the inner diameter size of the structure in the pressure width w 2 range, adjusting the interval or tolerance of the groove in the structure in the pressure width w 2 range.

[0146] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in any form. Any simple modification or equivalent change made according to the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for evaluating the sealing performance of a pipe joint, the pipe joint comprising an extrusion ring (1), a joint (2), and a conduit (3), characterized in that: The following steps are involved: Step 1: construct an axisymmetric finite element model of the pipe joint with the central axis of the conduit (3) as a reference; Step 2: Apply loads and constraints to the axisymmetric finite element model; Step 3: Set a contact path on the sealing interface of the axisymmetric finite element model, analyze the contact pressure on the sealing interface, and obtain a pressure curve distributed along the contact path; Step 4: intercept the sealing width along the contact path according to the pressure value mutation point on the pressure curve, and calculate the average contact pressure within the sealing width; Step 5: Establish a sealing performance calculation model based on the average contact pressure, calculate the sealing performance index within the current sealing width range using the sealing performance calculation model, and evaluate the sealing performance of the pipe joint based on the sealing performance index; The step 4 specifically includes: Step 4.1, select the pressure mutation starting point and the pressure mutation ending point on the pressure curve, and intercept the pressure mutation area between the adjacent pressure mutation starting point and the pressure mutation ending point, and calculate the width of the pressure mutation area as the sealing width; Step 4.2, reading all contact pressure data within the sealing width range and cleaning the contact pressure data; Step 4.3, calculating the average contact pressure within the sealing width based on the contact pressure data after cleaning; The selection rule of the starting point of the pressure mutation in step 4.1 is: ； in: Indicates the starting point of pressure mutation The next adjacent sampling point The pressure mutation value between Indicates the starting point of pressure mutation The previous sampling point adjacent to it The pressure mutation value between The selection rule of the pressure mutation end point in step 4.1 is: ； in: Indicates the end point of pressure mutation The previous sampling point adjacent to it The pressure mutation value between Indicates the end point of pressure mutation The next adjacent sampling point The pressure mutation value between The sealing performance calculation model in step 5 is specifically: ； in: Indicates the sealing performance index; C indicates the sealing medium performance index coefficient; D indicates the initial diameter of the catheter within the sealing width when there is no pressure; H indicates the roughness of the catheter wall; Indicates the seal width; represents the natural constant; k represents the performance coefficient of the sealing material; PS represents the average contact pressure within the sealing width; Indicates the pressure difference between the inside and outside of the pipe joint.

2. The method for evaluating the sealing performance of a pipe joint according to claim 1, wherein: The average contact pressure within the seal width is calculated as follows: ； Where: PS represents the average contact pressure within the seal width; n represents the number of contact pressure data after cleaning; Represents the i-th contact pressure data value, 1≤i≤n.

3. The method for evaluating the sealing performance of a pipe joint according to claim 2, wherein: Cleaning contact pressure data specifically includes the following steps: Step A1: reading all contact pressure data within the sealing width range to form a data set P, calculating an average value of the contact pressure based on the data set P, and calculating a standard deviation based on the average value of the contact pressure; Step A2: Calculate the cleaning threshold value based on the standard deviation, and calculate the difference between the contact pressure data and the average value. If the difference between the contact pressure data and the average value is greater than the cleaning threshold value, filter the corresponding contact pressure data to form a data set Q. Step A3: Eliminate the elements in the dataset P that belong to the dataset Q, and execute steps A1 to A2 on the dataset P after elimination; Step A4: Repeat the above steps A1 to A3 until the number of elements in the data set Q is 0.

4. A method for evaluating the sealing performance of a pipe joint according to any one of claims 1 to 3, characterized in that: The step 2 specifically includes: Step 2.1, applying an axial displacement load to the end of the extrusion ring (1) away from the joint (2), applying a spring constraint to the end of the guide tube (3) close to the axial displacement load, and applying a fixed constraint to the end of the joint (2) away from the axial displacement load; Step 2.2, preset the stiffness value of the spring constraint, and calculate the support reaction force of the spring constraint based on the preset stiffness value; Step 2.3: Adjust the stiffness value according to the support reaction force until 5N≤support reaction force≤10N; Step 2.4: Cancel the spring constraint, cancel the axial displacement load, retain the fixed constraint, and allow the axisymmetric finite element model to rebound freely.

5. A method for evaluating the sealing performance of a pipe joint according to any one of claims 1 to 3, characterized in that: The step 3 specifically includes: Step 3.1, setting the contact surface between the connector (2) and the catheter (3) as a sealing interface; Step 3.2, setting a contact path parallel to the central axis of the catheter (3) on the sealing interface; Step 3.3: Read the contact pressure between the connector (2) and the catheter (3) along the contact path to form a pressure curve distributed along the contact path.

6. A method for evaluating the sealing performance of a pipe joint according to any one of claims 1 to 3, characterized in that: In the step 1, the axisymmetric finite element model is meshed, the global size of the mesh is less than or equal to 0.08 mm, and the size of the mesh at the contact portion between the joint (2) and the catheter (3) is greater than or equal to 0.03 mm.

Images