Method for comprehensive evaluation of axial extrusion pipe joint performance

Abstract

The application discloses a kind of comprehensive evaluation methods of axial extrusion pipe joint performance, determine evaluation index, the evaluation index includes the quality of axial extrusion pipe joint, axial extrusion connection assembly load, rotating fatigue residual fatigue life, processing manufacturing cost and axial compensation amount;Based on the dimensionless value of evaluation index and weight calculation obtains comprehensive evaluation value, the performance of N kinds of axial extrusion pipe joint of the same kind of catheter specification is evaluated by comprehensive evaluation value.If comprehensive evaluation value is lower than set threshold value, then it is optimized towards the direction of increasing compensation amount and processing cost, and weakens residual fatigue life and load index.The application combines test method, simulation method, expert group review and mathematical statistics method, considers the performance of axial extrusion pipe joint in dynamics, statics two aspects, with comprehensive evaluation method, various forms of axial extrusion pipe joint are scientifically, quickly, quantitatively evaluated, and have good practicability.

Description

Technical Field

[0001] This invention belongs to the technical field of aviation pipeline performance testing, specifically relating to a comprehensive evaluation method for the performance of axially extruded pipe joints. Background Technology

[0002] Axial compression fittings are a novel type of mechanical pipe joint connection technology. They refer to a technology that connects or seals metals of the same or multiple materials below their recrystallization temperature, based on the fundamental principle of elastic-plastic deformation under interference fit. This connection technology offers advantages such as high pressure resistance, corrosion resistance, energy saving, safety, and quick installation. For example, existing patent 202011079903.5 discloses an axial compression fitting assembly and the fittings thereof, relating to the field of pipe connection technology. This axial compression fitting assembly includes a fitting component and an annular component. A reliable connection is formed through the radial mechanical fit between the fitting component and the annular component. Furthermore, the groove structure designed on the outer surface of the fitting component and the flange structure designed on the inner surface of the annular component interact to form a self-locking structure, further increasing the reliability and strength of the connection.

[0003] However, currently, all axially extruded pipe fittings developed by relevant research institutions using the axial extrusion principle have passed the so-called qualification tests. But there are various forms and styles of pipe fittings of the same specification, such as inconsistent number of grooves, with two, three, or even four grooves; inconsistent sealing methods, with some relying mainly on "point sealing" and others mainly relying on "sealing tape" for sealing. In addition, various pipe fittings are not entirely the same in other aspects, and there is still no scientific evaluation method and standard. Summary of the Invention

[0004] The purpose of this invention is to provide a comprehensive evaluation method for the performance of axially extruded pipe joints, aiming to solve the above-mentioned problems.

[0005] This invention is mainly achieved through the following technical solutions: A comprehensive evaluation method for the performance of axially extruded pipe joints includes the following steps: Step S1: Determine the evaluation indicators, including the quality of the axially extruded pipe joint. m ij Axial compression connection assembly load F ij Rotational fatigue and remaining fatigue life P ik Processing and manufacturing costs C ij and axial compensation L ik ; Step S2: Obtain the raw data of evaluation indicators for N types of axially extruded pipe fittings of the same conduit specification; Step S3: Perform dimensionless processing on the original aggregates obtained in Step S2 to obtain the dimensionless values ​​of each index. x iq ; Step S4: Determine the weight of each evaluation indicator w h ,in, ; m Let h be the number of indicators, where h = 1, 2, 3, 4, 5...m; Step S5: Using a comprehensive evaluation method, the comprehensive evaluation value is calculated based on steps S3 and S4. The comprehensive evaluation method is any one of the following: linear weighting method, nonlinear weighting method, approximation of ideal point method, fuzzy comprehensive evaluation method, and grey relational method.

[0006] To better realize the present invention, further, in step S2, the mass of the axially extruded pipe joint is obtained by weighing or by measuring the digital model using CATIA software. m ij The axial compression load of the connection assembly is obtained through simulation or testing. F ij The remaining fatigue life due to rotational fatigue was determined by rotational bending tests. P ik The aforementioned processing and manufacturing costs C ij Costs include machining accuracy, material consumption, heat treatment, machining, and labor; axial compensation is calculated by measuring the distance between the inner ring flanges of the pipe fitting. L ik .

[0007] To better realize the present invention, further, in step S3, the dimensionless processing includes any one of the range transformation method, vector normalization method, and linear proportional transformation method.

[0008] To better realize the present invention, further, in step S3, the range variation method is used for dimensionless transformation, wherein the positive index includes the remaining fatigue life of the axially extruded pipe joint. P ik and axial compensation L ik Reverse indicators include the quality of axially extruded pipe fittings. m ij Processing costs C ij and assembly load F ij .

[0009] To better realize the present invention, further, in step S3, the remaining fatigue life P ik The dimensionless numerical value is: , , , The axial compensation amount L ik The dimensionless numerical value is: , , , The mass m ij The dimensionless numerical value is: , , , The processing cost C ij The dimensionless numerical value is: , , , The assembly load F ij The dimensionless numerical value is: , , , in: The maximum fatigue remaining life among N axial pipe joints; The minimum fatigue remaining life among N axial pipe joints; This represents the maximum axial compensation value among N axial pipe joints. This represents the minimum axial compensation value among N axial pipe joints. The maximum mass among N axial pipe fittings; The minimum mass among N axial pipe joints; The maximum processing cost among N axial pipe fittings; The minimum processing cost among N axial pipe fittings; The maximum assembly load among N axial pipe joints; The minimum assembly load among N axial pipe joints; N represents the type of axially extruded pipe fitting of the same conduit specification, i=1,2,3,4,5……N.

[0010] To better realize the present invention, further, in step S5, a linear weighted function method is used to calculate the comprehensive evaluation value: .

[0011] To better realize the present invention, in step S5, the larger the comprehensive evaluation value, the better the comprehensive performance of the axial extrusion pipe joint; if the comprehensive evaluation value is lower than the set threshold, it is recommended to optimize in the direction of increasing compensation amount and processing cost, and weaken the remaining fatigue life and load index.

[0012] The beneficial effects of this invention are as follows: (1) This invention combines experimental methods, simulation methods, expert review and mathematical statistics methods, and considers the dynamic and static performance of axial extrusion pipe joints. It uses a comprehensive evaluation method to conduct a scientific, rapid and quantitative evaluation of various forms of axial extrusion pipe joints.

[0013] (2) The method of this invention enables a comprehensive evaluation of various types of axial extrusion pipe fittings on the market. It not only effectively distinguishes the performance advantages and disadvantages and applicable conditions of different axial pipe fittings, but also provides a reference direction for the research and improvement of axial extrusion pipe fittings. This invention is not only applicable to axial extrusion pipe fittings, but can also be used to evaluate rolled pipe fittings, radial extrusion pipe fittings, and beam-type sealing joints. Attached Figure Description

[0014] Figure 1 This is a flowchart of the comprehensive evaluation method for the performance of the axially extruded pipe joint of the present invention; Figure 2 A schematic diagram for determining assembly load; Figure 3 This is a schematic diagram of a rotational bending test; Figure 4 A schematic diagram of the structure determined by the circumferential compensation strategy.

[0015] Wherein: 1-outer ring, 2-inner ring, 3-flange. Detailed Implementation

[0016] Example 1: A comprehensive evaluation method for the performance of axially extruded pipe joints is proposed, which evaluates the performance of axially extruded pipe joints based on factors such as weight, processing cost, assembly load, remaining fatigue life, axial compensation, and other indicators. Figure 1 As shown, the specific steps include: The first step is to determine the evaluation indicators. The quality of the axially extruded pipe joint (including one inner ring 2 and two outer rings 1), the axially extruded connection assembly load, the remaining fatigue life of rotational fatigue, the processing and manufacturing cost, and the axial compensation amount are determined as indicators for comprehensive evaluation.

[0017] The second step is to obtain the raw data of the axial extrusion joint specifications for a certain size. 2.1 The quality index can be obtained by weighing or by measuring the digital model using CATIA software, and the quality of the axial extrusion joint can be calculated.

[0018] Assuming there are types of axial pipe fittings of the same specification N The mass of various pipe fittings can be calculated by weighing or conversion using a three-dimensional model. The component includes one inner ring 2 and two outer rings 1, denoted as... m ij , where i refers to different pipe fitting types and j indicates the reverse indicator.

[0019] 2.2 Assembly loads can be obtained through simulation and testing, such as... Figure 2 As shown, (a) is the load-time curve obtained by simulation method, and (b) is a schematic diagram of experimental testing, for example, using an axial extrusion tool to continuously apply pressure and record the pressure gauge reading when the outer ring 1 and the inner ring 2 are tightly attached.

[0020] The assembly load of various pipe fittings can be obtained through experimental measurement or placement to determine the maximum axial load during the axial compression assembly process. Two methods for obtaining the assembly load of axially compressed pipe fittings are used, with the maximum load denoted as the assembly load. F ij , where i refers to different pipe fitting types and j indicates the reverse indicator.

[0021] 2.3 Remaining fatigue life was determined through a rotational bending test. Rotational bending test specimens of the axially compressed connected conduit were fabricated, such as… Figure 3 As shown, a rotational bending test was carried out on a rotational bending tester until the combined conduit failed, and the number of rotational bending cycles was recorded.

[0022] The remaining fatigue life of various pipe fittings is determined by a rotational bending test until the pipe breaks or leaks, and the number of rotational bending cycles R is recorded. i The remaining fatigue life is marked as P ik =R i -1000, where i indicates different pipe fitting types and k indicates positive indicators.

[0023] 2.4 Processing costs are obtained through accounting methods. The processing costs of various pipe fittings need to consider processing accuracy, material consumption, heat treatment, cutting, and labor costs. Higher processing accuracy results in higher processing costs. Processing cost is indicated as... C ij , where i refers to different pipe fitting types and j indicates the reverse indicator.

[0024] 2.5 The axial compression compensation amount is obtained by measurement. The greater the distance between the two flanges 3 of the inner ring 2 of the axial compression joint, the greater the axial compression compensation amount.

[0025] like Figure 4 As shown, the axial compensation of various pipe fittings can be measured by measuring the distance between the flange 3 and the inner ring 2 of the pipe fitting. L ik The 'i' indicates different pipe fitting types, and the 'k' indicates a positive indicator.

[0026] The third step is to use mathematical methods to make each indicator dimensionless. There are many methods for making indicators dimensionless, including not only the range variation method, but also vector normalization and linear proportional transformation methods.

[0027] There are many methods for dimensionless processing. The method of range variation is used in this invention for dimensionless processing. The positive indicators include two indicators: remaining fatigue life and axial compensation amount. The negative indicators include three indicators: mass, assembly load, and processing cost.

[0028] For positive indicators, the remaining fatigue life P is involved. ik and axial compensation amount L ik The dimensionless numerical value is: , , , , , , For inverse indicators, quality m is involved. ij Processing cost C ij and assembly load F ij The dimensionless quality indicators are denoted as ; , , , , , , , , , Where N represents the type of axial extrusion fitting for the same conduit specification (i=1,2,3,4,5...N).

[0029] The fourth step is to determine the weights of the indicators. The weights of each indicator should be determined by a panel of experts with relevant professional backgrounds, and the final weights for each indicator will be assigned. Let's assume the weight of each indicator is w. h m represents the number of indicators (h = 1, 2, 3, 4, 5...m). In this example, there are 5 indicators. The current number of indicators is 5.

[0030] Step 5: Comprehensive evaluation of the calculated values Using linear weighted function method As a comprehensive evaluation calculation value, among which q represents Pk, Lk, mj, Cj, Fj N represents the type of axially extruded pipe fitting of the same conduit specification. i =1,2,3,4,5…… N ); 2.5 The comprehensive evaluation methods established include the linear weighted comprehensive method, and nonlinear weighted comprehensive method, the approximation of ideal point method, fuzzy comprehensive evaluation method and grey relational method can also be used, and the appropriate method should be selected according to the actual situation.

[0031] Example 2: A comprehensive evaluation method for the performance of axially extruded pipe joints includes the following steps: Step 1: Assume there are 6 types of axially extruded pipe fittings of the same specification, then N=6.

[0032] Step 2: Assuming there are 5 indicators, then m=5, representing weight, processing cost, assembly load, remaining fatigue life, and axial compensation. As shown in Table 1, the raw data for different indicators of different types of axial extrusion joints are obtained using the above method.

[0033] Table 1 Step 3: Use the range variation method to make the above indicators dimensionless.

[0034] For positive indicators, the remaining fatigue life P is involved. ik and axial compensation amount L ik ; (1) , , , , , , , ; (2) , , , , , , , ; For inverse indicators, quality m is involved. ij Processing cost C ij and assembly load F ij ; (3) , , , , , , ; (4) , , , , , , , ; (5) , , , , , , , .

[0035] Step 4: Determining the weights of the indicators An expert panel thoroughly discussed the weight, processing cost, assembly load, remaining fatigue life, and axial compensation parameters, and determined the weight of each parameter. w h Considering the significant weight reduction and compensation requirements for aircraft, and the relatively low demands on processing costs, assembly load, and remaining fatigue life, the weights of each indicator are determined as follows: w 1 is 0.4. w 2 is 0.2. w 3 is 0.05. w 4 is 0.1. w 5 is 0.25.

[0036] Step 5: Comprehensive Evaluation Calculation According to the weighting function For the first type of axial pipe joint, y1 is 0.469, y2 is 0.499, y3 is 0.436, y4 is 0.389, y5 is 0.649, and y6 is 0.450.

[0037] Step 6: Evaluation and Optimization Directions The larger the y5 value, the better the overall performance of the fifth type of axial extrusion pipe joint.

[0038] The smallest y4 value indicates that the fourth type of axial extrusion pipe joint has the worst overall performance. Optimization should be carried out by increasing the compensation amount and processing cost, while weakening the remaining fatigue life and load index.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method of comprehensive evaluation of the performance of an axial extrusion pipe joint, characterized in that, The method comprises the following steps: Step S1 : determining evaluation indices, which include quality of the axial extrusion pipe joint m ij , axial extrusion connection assembly load F ij , residual fatigue life of the rotary fatigue P ik , manufacturing cost C ij , and axial compensation amount L ik ; Step S2: obtaining original data of evaluation indexes of N kinds of axial extrusion pipe joints of the same kind of pipe specification; The step S2, by weighing or using CATIA software to measure the number of modules to obtain the quality of the axial extrusion pipe joint m ij ; through simulation or test method to obtain the axial extrusion connection assembly load F ij ; through the rotary bending test to determine the rotary fatigue residual fatigue life P ik ; the processing manufacturing cost C ij Including processing precision, material consumption, heat treatment, cutting and labor cost; by measuring the distance between the inner ring flange of the pipe joint as the axial compensation L ik ; Step S3: Dimensionless processing is performed on the original data obtained in step S2 to obtain dimensionless values of each index x iq ; Step S4: determining the weight of each evaluation index w h wherein, ; m is the number of indexes, h = 1, 2, 3, 4, 5 … m; The weight of the quality, the processing manufacturing cost, the axial extrusion connection assembly load, the rotating fatigue residual fatigue life and the axial compensation amount evaluation index of the axial extrusion pipe joint is 0.4, 0.2, 0.05, 0.1, 0.25 and 0.05 respectively w 1 is 0.4, w 2 is 0.2, w 3 is 0.05, w 4 is 0.1, w 5 is 0.25; Step S5: calculating a comprehensive evaluation value based on step S3 and step S4 by using a comprehensive evaluation method, wherein the comprehensive evaluation method is any one of a linear weighting method, a nonlinear weighting method, an approximation ideal point method, a fuzzy comprehensive evaluation method and a grey correlation method.

2. The method for comprehensive evaluation of the performance of an axial extrusion pipe joint according to claim 1, characterized in that, In the step S3, the dimensionless processing includes any one of a range variation method, a vector normalization method and a linear proportional transformation method.

3. The method for comprehensive evaluation of the performance of an axial extrusion pipe joint according to claim 2, characterized in that, In the step S3, the range change method is used for non-dimensionalization, wherein the positive indicators include the residual fatigue life of the axial extruded pipe joint P ik and the axial compensation amount L ik , and the negative indicators include the quality of the axial extruded pipe joint m ij , the machining cost C ij , and the assembly load F ij .

4. The method for comprehensive evaluation of the performance of an axial extrusion pipe joint according to claim 3, characterized in that, In the step S3, the remaining fatigue life P ik The dimensionless value of the equation is: ， ， ， the axial compensation amount L ik the dimensionless value of which is: ， ， ， said quality m ij the dimensionless value of which is: ， ， ， The processing cost C ij The dimensionless value is: ， ， ， The assembly load F ij The dimensionless value is: ， ， ， wherein: is the maximum value of the fatigue residual life in the N axial pipe joints; is the minimum value of the fatigue residual life among the N axial pipe joints; is the maximum axial compensation in the N axial pipe joints; is the minimum value of the axial compensation amount in the N axial pipe joints; is the maximum mass in the N axial tube joints; is the minimum mass value for N axial pipe joints; is the maximum machining cost for N axial pipe joints; minimize the machining cost in N axial pipe joints; fitting the load maximum value in N axial pipe joints; to minimize the load in the N axial pipe joints; N the number of types of axial extrusion pipe joints for the same kind of conduit size, i = 1, 2, 3, 4, 5... N .

5. The method for comprehensive evaluation of the performance of an axial extrusion pipe joint according to claim 1, characterized in that, In the step S5, the comprehensive evaluation value is calculated by using a linear weighting function method. 。 6. The method for comprehensive evaluation of the performance of an axial extrusion pipe joint according to claim 1 or 5, characterized in that, In the step S5, the greater the comprehensive evaluation value is, the better the comprehensive performance of the axial extrusion pipe joint is.

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