A rapid engineering prediction method for burst pressure of composite pipes

Abstract

The application discloses a kind of composite pipe burst pressure quick engineering prediction method, it is related to pressure pipeline strength prediction technical field.The method obtains the structure parameters and material parameters of the inner tube and outer tube of the composite pipe to be predicted;The composite pipe is decomposed into two single-layer pipelines of inner tube and outer tube, the radial stress expression, circumferential stress expression and radial displacement expression of each single-layer pipeline under the action of inner wall load and outer wall load are respectively established based on thick-walled cylinder Lame solution;According to the displacement compatibility condition that the radial displacement of the junction of inner tube outer wall and outer tube inner wall is equal, displacement compatibility equation is established and solved to obtain the residual contact stress between inner tube and outer tube;Based on the maximum principal stress criterion, the burst pressure corresponding to the inner tube and the burst pressure corresponding to the outer tube are obtained respectively;Take the smaller value of the two as the theoretical burst pressure of the composite pipe and output.The application considers the interlayer displacement compatibility condition explicitly, all calculations use closed-form analytical expressions, and the theoretical burst pressure of the composite pipe can be given in 1 second in an electronic spreadsheet.

Description

Technical Field

[0001] This invention relates to the field of pressure pipeline strength prediction technology, specifically to a rapid engineering prediction method for the burst pressure of composite pipes. Background Technology

[0002] Composite pipes are pipes composed of two layers of different materials: an inner pipe and an outer pipe. The inner pipe is made of corrosion-resistant materials such as stainless steel or nickel-based alloys, while the outer pipe is made of materials that withstand mechanical loads, such as carbon steel or alloy steel. Composite pipes combine mechanical strength and corrosion resistance, making them suitable for applications such as hydrogen energy transportation and highly corrosive oil and gas fields. Accurate prediction of burst strength is a critical safety requirement for composite pipes.

[0003] Currently, the assessment of burst pressure in composite pipes mainly relies on two types of methods. One is full-scale physical testing, which is costly, time-consuming, and its results are greatly affected by the discreteness of the sample. The other is finite element simulation, which can accurately simulate the stress-strain distribution at the interface, but requires cumbersome preprocessing such as mesh generation and contact setup, resulting in long computation times and making it difficult to complete quickly in the conceptual design or bidding stage. In addition, data-driven predictive models require a large amount of experimental data for training.

[0004] During the conceptual design or bidding phase, engineers often need to evaluate composite pipe configurations with dozens of sizes and material combinations. Existing methods either rely on time-consuming preprocessing and long computation times, or on large amounts of experimental data, making it difficult to meet the needs of rapid screening. Currently, there is a lack of a rapid screening tool specifically for composite pipes that balances physical transparency and computational efficiency, making it difficult to conduct rapid parameter evaluation and design optimization of composite pipe configurations.

[0005] For a single-layer thick-walled cylinder subjected to internal and external pressure, the classical Lamé solution has provided analytical expressions for stress and displacement. However, a composite pipe consists of two layers of pipe, an inner and an outer layer, through which the load is transferred. The radial displacements of the two layers are coordinated at the interface, and the stress distribution of the composite pipe differs from that of a single-layer pipe. If the analytical solution for a single-layer pipe is directly applied without considering the interlayer displacement coordination relationship, it will lead to deviations in the assessment of burst pressure. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a rapid engineering prediction method for the burst pressure of composite pipes. This method, taking into account the coordination of displacement between the inner and outer pipe layers, establishes a closed analytical model based on the thick-walled cylinder theory and the maximum principal stress criterion. It can provide the theoretical burst pressure of the composite pipe within seconds, which can be used for rapid parameter evaluation and design screening of composite pipe configurations.

[0007] The present invention provides a rapid engineering prediction method for the burst pressure of composite pipes, comprising the following steps: obtaining the structural and material parameters of the composite pipe to be predicted; wherein the structural parameters include the inner and outer diameters of the inner pipe and the inner and outer diameters of the outer pipe, and the material parameters include the elastic modulus, Poisson's ratio, and tensile strength of the inner and outer pipes; decomposing the composite pipe into two single-layer pipes, an inner pipe and an outer pipe, and establishing radial stress, circumferential stress, and radial displacement expressions for each single-layer pipe under inner and outer wall loads, based on the Lamé solution of a thick-walled cylinder. Based on the displacement compatibility condition that the radial displacements at the junction of the inner tube's outer wall and the outer tube's inner wall are equal, a displacement compatibility equation is established and solved to obtain the residual contact stress between the inner tube and the outer tube. The residual contact stress is then substituted into the circumferential stress expressions of the inner tube and the outer tube, respectively. Based on the maximum principal stress criterion, the burst pressures corresponding to the inner tube and the outer tube are obtained. The smaller value between the burst pressures corresponding to the inner tube and the burst pressures corresponding to the outer tube is taken as the theoretical burst pressure of the composite tube and output.

[0008] Furthermore, for a single-layer pipe subjected to an inner wall load Pi and an outer wall load Po, the radial stress σr and the circumferential stress σθ are respectively: Where r is the radial coordinate, and C1 and C2 are undetermined coefficients; determined by the stress boundary conditions formed by the inner wall load and the outer wall load: Where ri and ro are the inner and outer diameters of the single-layer pipe, respectively. Based on Hooke's law and polar coordinate geometric equations, the radial displacement u(r) of the single-layer pipe at radius r is: Where E and ν are the elastic modulus and Poisson's ratio of the single-layer pipe material, respectively.

[0009] Further, the inner wall load of the inner tube is the internal pressure borne by the composite tube, and the outer wall load of the inner tube is the residual contact stress; the inner wall load of the outer tube is the residual contact stress, and the outer wall load of the outer tube is zero. The radial displacements at the junction of the inner and outer tubes are equal, and the displacement compatibility condition is ui(r2) = uo(r3), where r2 is the outer diameter of the inner tube, r3 is the inner diameter of the outer tube and r3 is approximately equal to r2, ui(r2) is the radial displacement at the outer wall of the inner tube, and uo(r3) is the radial displacement at the inner wall of the outer tube. Substituting the radial displacement expressions of the inner and outer tubes into the displacement compatibility condition and solving them simultaneously, the residual contact stress is obtained: Where P1 is the internal pressure, r1 is the inner diameter of the inner tube, r4 is the outer diameter of the outer tube, E1 and ν1 are the elastic modulus and Poisson's ratio of the inner tube, respectively, and E2 and ν2 are the elastic modulus and Poisson's ratio of the outer tube, respectively.

[0010] Furthermore, for an ideal elastoplastic material, neglecting strain hardening and geometric nonlinearity, structural failure occurs when the circumferential stress reaches the material's tensile strength. The inner tube fails when the circumferential stress at its inner wall reaches the tensile strength σb1, i.e., σθi(r1) = σb1; the outer tube fails when the circumferential stress at its inner wall reaches the tensile strength σb2, i.e., σθo(r2) = σb2. Substituting the residual contact stress into the expression for the circumferential stress of the inner tube and solving it simultaneously with the failure condition yields the corresponding burst pressure P1(i) of the inner tube; substituting the residual contact stress into the expression for the circumferential stress of the outer tube and solving it simultaneously with the failure condition yields the corresponding burst pressure P1(o) of the outer tube. Since both the inner and outer tubes must simultaneously satisfy their respective failure conditions, the smaller of the two values ​​is taken as the theoretical burst pressure. .

[0011] This invention quantitatively characterizes the stress transfer relationship between the inner and outer pipes through interlayer displacement coordination conditions, enabling the collaborative load-bearing mechanism of the double-layer composite structure to be reflected at the analytical level: the outer high-elasticity modulus pipe inhibits the plastic deformation expansion of the inner pipe through interface constraints, thereby improving the overall explosion resistance of the structure; at the same time, this method can also be used to predict the risk of interlayer slippage caused by Poisson's ratio differences and interface bonding defects, providing a theoretical basis for understanding the failure process of composite pipe structures.

[0012] Compared with existing technologies, this invention has the following advantages: First, it has high calculation accuracy. Verified by finite element simulations under 12 different geometric dimensions and material parameters, the maximum relative error between the theoretical burst pressure and the finite element burst pressure obtained by the method of this invention is 2.27%, and the average relative error is 1.08%, which is within the acceptable range for engineering calculations. Second, it has high calculation efficiency. The closed-form analytical expression can be solved directly in a spreadsheet, with a single calculation time of no more than 1 second, making it suitable for rapid screening of dozens of size and material combinations during the conceptual design or bidding stage. Third, it has clear physical meaning. The model explicitly considers the interlayer displacement coordination between the inner and outer tubes and the residual contact stress, reflecting the mechanical characteristics of interlayer stress transmission and bimetallic synergistic bearing. Fourth, the parameter influence laws are clear. The thickness ratio of the outer tube to the inner tube is the dominant parameter, the tensile strength of the outer tube is stably positively correlated with the burst pressure, and the influence of the elastic modulus ratio is negligible, providing guidance for parameter adjustment priorities in composite pipe design optimization.

[0013] Furthermore, the method of the present invention is applicable to composite pipes under conditions of linear elastic small deformation, ideal interface bonding, and isotropic homogeneous materials; for working conditions involving significant plastic deformation, large geometric deformation, or interface defects, supplementary verification can be carried out by combining numerical simulation or experimental data. Attached Figure Description

[0014] Figure 1 A flowchart illustrating a rapid engineering prediction method for the burst pressure of composite pipes provided in an embodiment of the present invention; Figure 2 The geometric model and internal pressure diagram of the composite pipe provided in the embodiments of the present invention; Figure 3 A single-layer pipe model and schematic diagram of internal and external pressure provided for embodiments of the present invention; Figure 4 This is a load diagram of the inner and outer pipe models of the composite pipe provided in an embodiment of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0016] For ease of description, the following symbols are defined: the inner diameter of the inner tube is r1, the outer diameter is r2, the inner diameter of the outer tube is r3, and the outer diameter is r4, where r3 and r2 are approximately equal; the elastic modulus, Poisson's ratio, and tensile strength of the inner tube are E1, ν1, and σb1, respectively, and the elastic modulus, Poisson's ratio, and tensile strength of the outer tube are E2, ν2, and σb2, respectively; the internal pressure borne by the composite tube is P1, the residual contact stress between the outer wall of the inner tube and the inner wall of the outer tube is P2, the load acting on the inner wall of the outer tube is P3 and P3 = P2, and the load acting on the outer wall of the outer tube is P4 and P4 = 0.

[0017] In this embodiment, the inner and outer tubes of the composite pipe are coaxial hollow cylinders; both the inner and outer tubes are made of ideal elasto-plastic materials; the internal pressure is uniformly distributed radially along the inner wall of the inner tube; the residual contact stress between the inner and outer tubes is uniformly distributed; the pressure on the outer wall of the outer tube is zero; the inner and outer tubes are intact and perfectly fitted, without wear, corrosion, or welding defects. The geometric model of the composite pipe and the internal pressure are as follows: Figure 2 As shown, the single-layer pipe model and the internal and external pressures are as follows: Figure 3 As shown, the loads on the inner and outer pipe models of the composite pipe are as follows: Figure 4 As shown.

[0018] Example 1: Specific Implementation of the Method like Figure 1 As shown, the rapid engineering prediction method for the burst pressure of composite pipes in this embodiment includes the following steps S101 to S105.

[0019] S101: Obtain the structural and material parameters of the composite pipe to be predicted. The structural parameters include the inner diameter r1, outer diameter r2, inner diameter r3, and outer diameter r4 of the inner pipe. The material parameters include the elastic modulus E1, Poisson's ratio ν1, and tensile strength σb1 of the inner pipe, and the elastic modulus E2, Poisson's ratio ν2, and tensile strength σb2 of the outer pipe. These structural and material parameters can be directly obtained from the composite pipe's design drawings and material performance data.

[0020] S102: The composite pipe is decomposed into two single-layer pipes, an inner pipe and an outer pipe. Based on the Lamé solution of a thick-walled cylinder, expressions for radial stress, circumferential stress, and radial displacement are established for each single-layer pipe under inner and outer wall loads. For the single-layer pipes subjected to inner wall load Pi and outer wall load Po, the radial stress σr and circumferential stress σθ are respectively: Where r is the radial coordinate, and C1 and C2 are undetermined coefficients, determined by the stress boundary conditions formed by the inner wall load and the outer wall load: Let ri and ro be the inner and outer diameters of the single-layer pipe, respectively. Based on Hooke's law and polar coordinate geometric equations, the radial displacement u(r) of the single-layer pipe at radius r is: Where E and ν are the elastic modulus and Poisson's ratio of the single-layer pipe material, respectively. For the inner pipe, its inner wall load P1 is the internal pressure borne by the composite pipe, and its outer wall load P2 is the residual contact stress; for the outer pipe, its inner wall load P3 is the residual contact stress and P3 = P2, and its outer wall load P4 = 0. Substituting the above loads into the stress and displacement expressions for the single-layer pipe, respectively, we can obtain the radial stress, circumferential stress, and radial displacement expressions for the inner and outer pipes.

[0021] S103: Based on the displacement compatibility condition that the radial displacements at the junction of the inner and outer pipes are equal, a displacement compatibility equation is established and solved to obtain the residual contact stress. The radial displacements at the junction of the inner and outer pipes are equal, and the displacement compatibility condition is ui(r2) = uo(r3), where ui(r2) is the radial displacement at the outer wall of the inner pipe (r = r2), and uo(r3) is the radial displacement at the inner wall of the outer pipe (r = r3). ​​Substituting the expressions for the radial displacements of the inner and outer pipes into the displacement compatibility condition and solving the equation simultaneously, the residual contact stress is obtained: S104: Substituting the residual contact stress into the circumferential stress expressions of the inner and outer tubes, the burst pressures corresponding to the inner and outer tubes are obtained based on the maximum principal stress criterion. For ideal elastoplastic materials, neglecting strain hardening effects and geometric nonlinearity, the structure fails when the circumferential stress reaches the tensile strength of the material. The inner tube fails when the circumferential stress at its inner wall (r = r1) reaches the tensile strength σb1, i.e., σθi(r1) = σb1; the outer tube fails when the circumferential stress at its inner wall (r = r2) reaches the tensile strength σb2, i.e., σθo(r2) = σb2. Substituting the residual contact stress into the circumferential stress expression of the inner tube and solving it simultaneously with the failure condition yields the burst pressure P1(i) corresponding to the inner tube; substituting the residual contact stress into the circumferential stress expression of the outer tube and solving it simultaneously with the failure condition yields the burst pressure P1(o) corresponding to the outer tube.

[0022] S105: Take the smaller value between the burst pressure P1(i) corresponding to the inner tube and the burst pressure P1(o) corresponding to the outer tube, and output it as the theoretical burst pressure Ptb of the composite pipe. Since both the inner and outer pipes must simultaneously meet their respective failure conditions, the layer that fails first determines the overall burst pressure of the composite pipe.

[0023] As an example, consider a set of composite pipe parameters: r1 = 144.579 mm, r2 = 147.555 mm, r4 = 162.497 mm, E1 = 193 GPa, E2 = 206 GPa, ν1 = ν2 = 0.3, σb1 = 649.5 MPa, σb2 = 525.7 MPa. Following the above steps, the burst pressure corresponding to the outer pipe is calculated to be 61.825 MPa, which is less than the burst pressure corresponding to the inner pipe. Therefore, the theoretical burst pressure is 61.825 MPa. The burst pressure obtained from finite element simulation under the same parameters is 61.744 MPa, with a relative error of 0.131%.

[0024] Example 2: Comparison and Verification with Finite Element Simulation To verify the accuracy and reliability of this method, a composite pipe model was established using the finite element method for comparative verification. The finite element model adopted a split-type double-layer axisymmetric model representing the inner and outer pipes respectively. To avoid end effects, the inner and outer pipes were of the same length, both being four times the outer diameter of the outer pipe. A reference plane was created at a distance of one-quarter of the length from the end faces of the inner and outer pipes, and the geometry was divided into three parts for each pipe. The middle part was meshed with a coarse mesh to fine mesh size ratio of 2:1. The outer pipe was divided into four layers along the thickness direction to capture the radial stress gradient. Considering both computational efficiency and result convergence, a three-dimensional solid eight-node element C3D8R was used for meshing. The combination of the inner and outer pipes was achieved by simulating the hydraulic forming process.

[0025] Regarding loads and boundary conditions, reference points RP-1 and RP-2 were created at the geometric centers of the two pipe ends, and a local cylindrical coordinate system was defined along the pipe axis. All nodes on the end faces of the inner and outer pipes were kinematically coupled to their corresponding reference points. In the coupling constraints, only the circumferential displacement component U1 was released, while the radial displacement U2, axial displacement U3, and all rotational degrees of freedom UR1, UR2, and UR3 were fully constrained. Subsequently, completely fixed boundary conditions were applied to the two reference points to suppress rigid body motion. A static Riks method (arc-length method) nonlinear analysis step was used to gradually apply uniform pressure to the inner surface of the inner pipe, with element failure as the termination criterion, to numerically capture the burst pressure of the composite pipe.

[0026] In the mesh independence verification, the axial splitting position, mesh density ratio and transition method are kept consistent. Only the overall mesh size is scaled proportionally to construct four schemes: coarse mesh, medium coarse mesh, reference mesh and fine mesh. When the relative error is less than 1%, the calculation result is considered to meet the mesh independence requirement. The reference mesh has a total of 21420 elements, corresponding to a burst pressure of 75.5529 MPa, and the relative error with the fine mesh result is 0.015%.

[0027] A total of 12 verification cases were set up, divided into two geometric systems, with 6 cases in each system. The first 5 cases in both systems used a combination of Q345 outer tube and SS304 inner tube, while the last case used a combination of X65 outer tube and SS316L inner tube. The two systems cover the size range of inner tube outer diameter of approximately 147.6 mm and 97.8 mm, respectively. The geometric dimensions, material parameters, and burst pressure calculation results of the 12 verification cases are shown in the table below.

[0028] Table 1. Comparison of blast pressure calculation results between finite element method and analytical method In the table, r1, r2, and r4 represent the inner diameter, outer diameter, and outer diameter of the inner tube after hydroforming, respectively; Ei and Eo represent the elastic modulus of the inner and outer tubes, respectively; μi and μo represent the Poisson's ratio of the inner and outer tubes, respectively; σbi and σbo represent the tensile strength of the inner and outer tubes, respectively; PFEM represents the burst pressure obtained from finite element simulation; and PEq represents the theoretical burst pressure calculated by analytical method. The material constitutive relationship was determined by the stress-strain curve obtained from quasi-static uniaxial tensile tests. Comparative results show that the maximum relative error between the burst pressure calculated by this method and the finite element results is 2.274%, with an average of 1.079%. The two methods agree well, and the error is within the acceptable range for engineering calculations.

[0029] Example 3: Parameter Influence Laws and Design Screening Applications Based on the analytical expression of this method, while keeping other influencing factors constant, the outer radius of the inner tube, the thickness ratio of the inner tube to the outer tube, the elastic modulus ratio of the inner tube to the outer tube, and the tensile strength of the outer tube were varied to analyze the influence of each parameter on the burst pressure. The results show that the thickness ratio of the outer tube to the inner tube is the dominant parameter. When the inner tube thickness is fixed, the burst pressure is significantly positively correlated with the thickness ratio, and the burst pressure curves corresponding to different thickness ratios are approximately parallel. When the outer tube thickness is fixed, the burst pressure is negatively correlated with the thickness ratio, exhibiting a non-linear decreasing effect; the larger the thickness ratio, the weaker its marginal effect. The tensile strength of the outer tube shows a stable positive correlation with the burst pressure and is a reliable design adjustment parameter. The elastic modulus ratio of the inner tube to the outer tube has a weak influence on the burst pressure and can be ignored in the initial selection stage.

[0030] The sensitivity of each parameter to burst pressure is ranked as follows: the ratio of outer tube thickness to inner tube thickness is greater than the tensile strength of the outer tube, which is greater than the ratio of the elastic modulus of the outer tube to the inner tube. This ranking can provide guidance for prioritizing parameter adjustments in the engineering design and optimization of composite pipes. During the conceptual design or bidding stage, the above steps can be performed one by one for dozens of sizes and material combinations to quickly obtain and compare the theoretical burst pressures of each configuration, thereby selecting the composite pipe configuration that meets the design requirements and significantly shortening the design iteration cycle.

[0031] It should be noted that this method is based on the assumption of linear elastic small deformation, and assumes that the interface is ideally bonded and the stress is continuous. It is applicable to isotropic and homogeneous materials. For conditions with high strain rate loading, thin-walled structures, significant plastic strengthening of materials, large geometric deformation, or interface defects such as micro-gap or oxide film, it is recommended to verify and correct the method by combining numerical simulation or experimental data.

Claims

1. A rapid engineering prediction method for the burst pressure of a composite pipe, characterized in that, The composite tube includes an inner tube and an outer tube coaxially sleeved together, and the method includes the following steps: Obtain the structural and material parameters of the composite tube to be predicted; wherein the structural parameters include the inner diameter and outer diameter of the inner tube and the inner diameter and outer diameter of the outer tube, and the material parameters include the elastic modulus, Poisson's ratio, and tensile strength of the inner tube and the elastic modulus, Poisson's ratio, and tensile strength of the outer tube; The composite pipe is decomposed into two single-layer pipes, the inner pipe and the outer pipe. Based on the Lamé solution of thick-walled cylinder, the radial stress expression, circumferential stress expression and radial displacement expression of the inner pipe and the outer pipe under the inner wall load and the outer wall load are respectively established. Based on the displacement compatibility condition that the radial displacements at the junction of the inner tube outer wall and the outer tube inner wall are equal, a displacement compatibility equation is established and solved to obtain the residual contact stress between the inner tube and the outer tube. Substituting the residual contact stress into the circumferential stress expression of the inner tube and the circumferential stress expression of the outer tube respectively, and based on the maximum principal stress criterion, the burst pressure corresponding to the inner tube and the burst pressure corresponding to the outer tube are obtained. The smaller of the burst pressure corresponding to the inner tube and the burst pressure corresponding to the outer tube is used as the theoretical burst pressure of the composite tube and is output.

2. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The inner wall load of the inner tube is the internal pressure borne by the composite tube, and the outer wall load of the inner tube is the residual contact stress; the inner wall load of the outer tube is the residual contact stress, and the outer wall load of the outer tube is zero.

3. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, When establishing the radial stress expression and the circumferential stress expression, the radial stress expression is: The expression for the circumferential stress is as follows: , where r is the radial coordinate, and C1 and C2 are undetermined coefficients; the undetermined coefficients are determined by the stress boundary conditions formed by the inner wall load and the outer wall load, and the radial displacement expression is obtained by Hooke's law and polar coordinate geometric equations.

4. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The residual contact stress is solved by substituting the radial displacement expressions at the outer wall of the inner tube and the inner wall of the outer tube into the displacement compatibility equation and solving them simultaneously to obtain the residual contact stress; wherein, the radial displacement at the outer wall of the inner tube and the radial displacement at the inner wall of the outer tube are obtained by taking values ​​at the junction from the radial displacement expressions of the inner tube and the outer tube, respectively.

5. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The method of obtaining the burst pressure corresponding to the inner tube and the burst pressure corresponding to the outer tube based on the maximum principal stress criterion includes: when the circumferential stress at the inner wall of the inner tube reaches the tensile strength of the inner tube, the inner tube is determined to have failed, and the burst pressure corresponding to the inner tube is obtained by solving the circumferential stress expression of the inner tube and the failure condition simultaneously; when the circumferential stress at the inner wall of the outer tube reaches the tensile strength of the outer tube, the outer tube is determined to have failed, and the burst pressure corresponding to the outer tube is obtained by solving the circumferential stress expression of the outer tube and the failure condition simultaneously.

6. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The inner tube and the outer tube are coaxial ideal hollow cylinders, and the materials of the inner tube and the outer tube are both ideal elastic-plastic materials; the internal pressure is uniformly distributed radially along the inner wall of the inner tube, the residual contact stress is uniformly distributed, the inner tube and the outer tube are completely fitted together, and the inner tube and the outer tube are free from wear, corrosion or welding defects.

7. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The burst pressure corresponding to the inner tube and the burst pressure corresponding to the outer tube must be satisfied simultaneously. The theoretical burst pressure of the composite tube is the smaller of the two values, and the overall burst pressure of the composite tube is determined by the layer that fails first.

8. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The method is executed in a spreadsheet, and all calculations use closed-form analytical expressions. The calculation time for a single output of the theoretical burst pressure does not exceed 1 second.

9. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The method further includes: establishing a finite element model of the composite pipe, applying a gradually increasing uniform pressure to the inner surface of the composite pipe and performing finite element simulation with element failure as the termination criterion to obtain the finite element burst pressure; comparing the theoretical burst pressure with the finite element burst pressure, wherein the maximum relative error between the theoretical burst pressure and the finite element burst pressure does not exceed 2.27%.

10. The rapid engineering prediction method for the burst pressure of composite pipes according to claim 1, characterized in that, The method further includes: changing at least one of the structural parameters and the material parameters, repeatedly performing the step of obtaining the structural parameters and the material parameters until the theoretical burst pressure is output, to obtain the theoretical burst pressure corresponding to multiple sets of composite pipe configurations, so as to select the composite pipe configuration that meets the design requirements from the multiple sets of composite pipe configurations.

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