Finite element calculation method and system for width of fluoroplastic sealing ring of r-type valve seat

Abstract

The application discloses a kind of R-type valve seat fluoroplastic sealing ring width finite element calculation method and system, it is related to aerospace valve technical field, including the modeling of sealing pair based on simulation software ABAQUS, and define the interaction of contact between each component in modeling;The boundary conditions of sealing pair are set, and pressure load is applied to the upper end surface of metal valve core block;Nonlinear analysis is carried out on the closing state of valve seat and valve core assembly using iterative method;The contact stress of valve seat and fluoroplastic valve core block is analyzed, and the sealing band width is obtained.The application can more accurately calculate the sealing pair width formed by fluoroplastic valve core block extruded by valve seat, and then predict the sealing performance.

Description

Technical Field

[0001] This invention relates to the field of aerospace valve technology, specifically to a finite element method and system for calculating the width of the fluoroplastic sealing ring of an R-type valve seat. Background Technology

[0002] Valves are crucial actuators in liquid rocket engines, regulating and controlling fluid flow throughout the entire system. Valve core and seat sealing structures vary widely, with the hard-soft sealing pair structure consisting of an R-type metal valve seat and a fluoroplastic valve core assembly being widely used in aerospace valves. The fluoroplastic valve core assembly structure involves embedding fluoroplastic within a metal valve core.

[0003] Several factors play a role in ensuring reliable valve seals, among which the interaction between the metal R-face and the fluoroplastic planar surface, commonly referred to as the sealing pressure, is crucial. A necessary condition for a seal is that the sealing pressure must be greater than the inlet medium pressure. The sealing pressure is the ratio of the sealing force to the sealing ring area, and the sealing ring area is related to the sealing ring width. Currently, there are two methods for obtaining the sealing ring width:

[0004] 1) Simplify the contact width of the sealing pair to the diameter of the valve seat cutting edge; the result of this method is actually the maximum value of the sealing ring width. In this way, the calculated sealing specific pressure is the smallest, so the design leaves a large sealing design margin. However, the valve requires a large closing force, resulting in a bulky valve structure.

[0005] 2) The contact width calculated according to Hertz contact theory formula is the sealing ring width. The contact width is related to the sealing force, the diameter of the sealing surface, and the elastic modulus and Poisson's ratio of the two contact materials. This method only considers the elastic parameters of the material, but the stress-strain curve of fluoroplastics does not have an obvious elastic stage like that of metal materials. Moreover, this method does not consider the influence of specific structural parameters (thickness and width) of fluoroplastics, which makes the accuracy of this method low. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a finite element method and system for calculating the width of the fluoroplastic sealing ring of an R-type valve seat. This method can accurately calculate the width of the sealing pair formed by the compression of the fluoroplastic valve core block by the valve seat, thereby predicting the sealing performance.

[0007] To achieve the above objectives, this invention provides a finite element method for calculating the width of the fluoroplastic sealing ring of an R-type valve seat, specifically including the following steps:

[0008] The sealing pair was modeled using the simulation software ABAQUS, and the interactions between the components in the model were defined.

[0009] The boundary conditions of the sealing pair are set, and a pressure load is applied to the upper end face of the metal valve core block;

[0010] An iterative method was used to perform nonlinear analysis on the closed state of the valve seat and valve core assembly;

[0011] The contact stress between the valve seat and the fluoroplastic valve core block was analyzed to obtain the sealing band width.

[0012] Based on the above technical solution, the specific steps for modeling the sealing pair using the simulation software ABAQUS include:

[0013] A two-dimensional axisymmetric linear body model is established based on the geometry of the valve seat, and a two-dimensional axisymmetric planar body model is established based on the geometry of the valve core assembly. The metal parts of the valve seat and valve core are set as discrete rigid bodies.

[0014] Mesh the components in the modeling process;

[0015] The fluoroplastic valve core block is set to be compressed under the pressure of the medium and the spring force when it is in the closed state. The fluoroplastic compression test data is assigned to the fluoroplastic valve core block, and an isotropic bilinear isotropic strengthening model and Von Mises yield criterion are adopted.

[0016] Based on the above technical solution, the valve core assembly includes a metal valve core block and a fluoroplastic valve core block.

[0017] Based on the above technical solution, the modeling of each component is divided into meshes. Specifically, for the fluoroplastic valve core block of the valve core assembly, first-order, axisymmetric hybrid solid elements are used, and the mesh of the fluoroplastic valve core block near the valve seat is refined.

[0018] Based on the above technical solution, the interaction between the contacts of various components in the definition model specifically includes:

[0019] The contact between the metal valve core block and the fluoroplastic valve core block is defined as the bonded state. The side of the metal valve core block facing the fluoroplastic valve core block is the main surface, and the side of the fluoroplastic valve core block facing the metal ring valve core block is the secondary surface.

[0020] The contact between the fluoroplastic valve core and the valve seat is defined as a limited sliding contact. The side of the valve seat facing the fluoroplastic valve core is the principal surface, and the side of the fluoroplastic valve core facing the valve seat is the slave surface.

[0021] Based on the above technical solution, the friction type between the fluoroplastic valve core block and the valve seat is Coulomb friction.

[0022] Based on the above technical solution, the specific steps for setting the boundary conditions of the sealing pair and applying a pressure load to the upper end face of the metal valve core block include:

[0023] Constrain the translational and rotational degrees of freedom of the valve seat in all directions and set them as fixed boundaries;

[0024] The resultant force acting on the valve core assembly in the closed state is equivalent to the pressure load on the upper end of the metal valve core block in terms of area, and the pressure load is applied to the upper end face of the metal valve core block along the normal direction.

[0025] Based on the above technical solution, the iterative method is used to perform nonlinear analysis on the closed state of the valve seat and valve core assembly. The analysis process is as follows:

[0026] Set the calculation step size according to requirements;

[0027] Large deformations were set up, and nonlinear analysis was performed using the full Newton-Raphson method.

[0028] Based on the above technical solution, the step of analyzing the contact stress between the valve seat and the fluoroplastic valve core block to obtain the sealing band width includes:

[0029] The contact stress between the valve seat and the fluoroplastic valve core is analyzed, and the contact stress values ​​at each position are derived according to the nodes.

[0030] The area where the contact pressure is greater than the medium pressure is defined as the annular sealing zone. The difference between the maximum and minimum radial coordinate values ​​within this area is the width of the sealing ring.

[0031] This invention provides a finite element method for calculating the width of a fluoroplastic sealing ring on an R-type valve seat, comprising:

[0032] The modeling unit is used to model the sealing pair based on the simulation software ABAQUS and to define the interaction between the contacts of the components in the modeling process.

[0033] The setting unit is used to set the boundary conditions of the sealing pair and apply a pressure load to the upper end face of the metal valve core block.

[0034] The analysis unit is used to perform nonlinear analysis of the closed state of the valve seat and valve core assembly using an iterative method;

[0035] The calculation unit is used to analyze the contact stress between the valve seat and the fluoroplastic valve core block to obtain the sealing band width.

[0036] Compared with existing technologies, the advantages of this invention are as follows: Based on the simulation software ABAQUS and utilizing the nonlinear finite element method, the extrusion process of the fluoroplastic valve core is simulated. A calculation model of the R-type valve seat fluoroplastic sealing pair is established through geometric modeling, mesh generation, and the application of material properties. Contact pairs are defined, boundary conditions are set, and loads are applied to solve for the contact stress distribution, thus obtaining a method for calculating the sealing ring width. The nonlinear finite element method has great adaptability and flexibility for material nonlinearity problems and large deformation nonlinearity, and can accurately calculate the width of the sealing pair formed by the extrusion of the fluoroplastic valve core under the valve seat, thereby predicting the sealing performance. Simultaneously, this invention also solves the problem of low accuracy in current engineering empirical methods. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a finite element method for calculating the width of a fluoroplastic sealing ring for an R-type valve seat, as described in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of the sealing pair of the valve seat-valve core assembly in the closed state.

[0040] Figure 3 This is a schematic diagram of the finite element model;

[0041] Figure 4 for Figure 3 Enlarged view of point A in the middle. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0043] See Figure 1 As shown, this embodiment of the invention provides a finite element method for calculating the width of the fluoroplastic sealing ring of an R-type valve seat. The method calculates the sealing ring width by simulating the valve's closed state, offering advantages such as simple operation, fast calculation speed, and high accuracy. Specifically, it includes the following steps:

[0044] S1: Model the sealing pair based on the simulation software ABAQUS, and define the interaction between the contact parts in the modeling;

[0045] In this embodiment of the invention, the sealing pair is modeled using the simulation software ABAQUS, and the specific steps include:

[0046] S101: A two-dimensional axisymmetric linear body model is established based on the geometry of the valve seat, and a two-dimensional axisymmetric planar body model is established based on the geometry of the valve core assembly. The valve seat and the metal parts of the valve core are set as discrete rigid bodies. The valve core assembly includes a metal valve core block and a fluoroplastic valve core block.

[0047] Figure 2 This is a schematic diagram of the sealing pair of the valve seat-valve core assembly in the closed state. Figure 2 In the diagram, arrows indicate the direction of medium flow. The valve core assembly and R-type valve seat are structurally axisymmetric, and the load on the valve core assembly along the axial direction is also axisymmetric. To improve calculation speed, the sealing pair is simplified from a three-dimensional problem to a two-dimensional problem. The valve seat is modeled as a two-dimensional axisymmetric linear body according to its geometry; the valve core assembly is modeled as a two-dimensional axisymmetric planar body according to its geometry; and the valve seat and valve core metal parts, whose elastic modulus is much greater than that of fluoroplastics, are analyzed as discrete rigid bodies.

[0048] S102: Mesh each component in the modeling; for the fluoroplastic valve core block of the valve core assembly, use first-order, axisymmetric hybrid solid elements, and refine the mesh in the area of ​​the fluoroplastic valve core block near the valve seat.

[0049] S103: The fluoroplastic valve core block is set to be compressed under medium pressure and spring force in the closed state. Fluoroplastic compression test data is assigned to the fluoroplastic valve core block, employing an isotropic bilinear isotropic strengthening model and the Von Mises yield criterion. That is, in the closed state, the fluoroplastic valve core block is compressed under medium pressure and spring force.

[0050] By following the steps above, the finite element model can be obtained, such as... Figure 3 As shown.

[0051] In this embodiment of the invention, the interaction between the contacts of various components in the modeling is defined, specifically including:

[0052] S111: Define the contact between the metal valve core block and the fluoroplastic valve core block as the bonded state, the side of the metal valve core block facing the fluoroplastic valve core block as the main surface, and the side of the fluoroplastic valve core block facing the metal ring valve core block as the secondary surface.

[0053] S112: The contact between the fluoroplastic valve core and the valve seat is defined as a finite sliding contact. The side of the valve seat facing the fluoroplastic valve core is the principal surface, and the side of the fluoroplastic valve core facing the valve seat is the slave surface. The friction type between the fluoroplastic valve core and the valve seat is Coulomb friction, and the friction coefficient can be 0.1.

[0054] S2: Set the boundary conditions for the sealing pair and apply a pressure load to the upper end face of the metal valve core block;

[0055] Step S2 specifically includes:

[0056] S201: Constrain the translational and rotational degrees of freedom of the valve seat in all directions and set them as fixed boundaries;

[0057] S202: The resultant force acting on the valve core assembly in the closed state is equivalent to a pressure load on the upper end of the metal valve core block, and the pressure load is applied along the normal direction to the upper end face of the metal valve core block, such as... Figure 3 The above, Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0058] S3: The closed state of the valve seat and valve core assembly is analyzed nonlinearly using an iterative method;

[0059] In this embodiment of the invention, an iterative method is used to perform nonlinear analysis on the closed state of the valve seat and valve core assembly. The analysis process is as follows:

[0060] S301: Set the calculation step size according to requirements; that is, automatically set the calculation step size according to the characteristics of the unit to ensure correct convergence.

[0061] S302: Set large deformation and use the full Newton-Raphson method for nonlinear analysis.

[0062] S4: Analyze the contact stress between the valve seat and the fluoroplastic valve core block to obtain the sealing band width.

[0063] Step S4 specifically includes:

[0064] S401: Analyze the contact stress between the valve seat and the fluoroplastic valve core, and derive the contact stress values ​​at each location according to the nodes;

[0065] S402: Define the area where the contact pressure is greater than the medium pressure as an annular sealing zone. The difference between the maximum and minimum radial coordinate values ​​within the area is the width of the sealing ring.

[0066] This invention employs the Newton-Raphson method for nonlinear analysis of the quasi-static process of fluoroplastic valve core blocks being extruded by R-type metal valve seats. Compared with direct iteration and incremental methods, the Newton-Raphson method exhibits higher computational accuracy, faster convergence speed, and greater result stability in the fluoroplastic extrusion calculation process.

[0067] This invention uses the simulation software ABAQUS and the nonlinear finite element method to simulate the extrusion process of fluoroplastic valve core blocks. Specifically, it establishes a computational model of the R-type valve seat fluoroplastic sealing pair through geometric modeling, mesh generation, and assigning material properties. It defines contact pairs, sets boundary conditions, applies loads, and solves for the contact stress distribution to obtain the calculation method for the sealing ring width. The nonlinear finite element method has great adaptability and flexibility for material nonlinearity problems and large deformation nonlinearity, and can accurately calculate the width of the sealing pair formed by the extrusion of the fluoroplastic valve core block by the valve seat, thereby predicting the sealing performance. At the same time, this invention solves the problem of low accuracy of current engineering empirical methods.

[0068] This invention is applicable to the study of the extrusion process of fluoroplastic valve core blocks by R-type valve seats, and is also applicable to the study of the extrusion process of other non-metallic materials by valve seats of various shapes.

[0069] The present invention provides a finite element calculation system for the width of the fluoroplastic sealing ring of an R-type valve seat, comprising a modeling unit, a setting unit, an analysis unit, and a calculation unit.

[0070] The modeling unit is used to model the sealing pair based on the simulation software ABAQUS and define the interaction between the components in the modeling process; the setting unit is used to set the boundary conditions of the sealing pair and apply a pressure load to the upper end face of the metal valve core block; the analysis unit is used to perform nonlinear analysis of the valve seat and valve core assembly in the closed state using an iterative method; the calculation unit is used to analyze the contact stress between the valve seat and the fluoroplastic valve core block to obtain the sealing band width.

[0071] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0072] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

Claims

1. A finite element calculation method of the width of a fluoroplastic sealing ring of an R-type valve seat, characterized in that, Specifically comprising the following steps: The sealing pair is modeled based on the simulation software ABAQUS, and the interaction of the contact between the components in the modeling is defined; The boundary conditions of the sealing pair are set, and a pressure load is applied to the upper end surface of the metal valve core block; An iterative method is used to analyze the nonlinear state of the valve seat and the valve core assembly in the closed state; The contact stress between the valve seat and the fluoroplastic valve core block is analyzed to obtain the sealing band width; The modeling of the sealing pair based on the simulation software ABAQUS comprises the following specific steps: A two-dimensional axisymmetric line body model is established based on the geometry of the valve seat, and a two-dimensional axisymmetric surface model is established based on the geometry of the valve core assembly, and the valve seat and the metal part of the valve core are set as discrete rigid bodies; The components in the modeling are meshed; The fluoroplastic valve core block is in a compressed state under the medium pressure and spring force in the closed state, the fluoroplastic compression test data is assigned to the fluoroplastic valve core block, and the isotropic bilinear isotropic hardening model and Von Mises yield criterion are used; The definition of the interaction of the contact between the components in the modeling comprises the following steps: The contact between the metal valve core block and the fluoroplastic valve core block is defined as a bound state, the side surface of the metal valve core block facing the fluoroplastic valve core block is the main surface, and the side surface of the fluoroplastic valve core block facing the metal ring valve core block is the slave surface; The contact between the fluoroplastic valve core block and the valve seat is defined as a finite slip contact, the side surface of the valve seat facing the fluoroplastic valve core block is the main surface, and the side surface of the fluoroplastic valve core block facing the valve seat is the slave surface.

2. The finite element calculation method of the width of the R-type valve seat fluoroplastic seal ring as claimed in claim 1, characterized in that: The valve core assembly comprises a metal valve core block and a fluoroplastic valve core block.

3. The finite element calculation method of the width of a R-type valve seat fluoroplastic seal ring as claimed in claim 1, wherein, The components in the modeling are meshed, and for the fluoroplastic valve core block of the valve core assembly, a first-order, axisymmetric hybrid solid element is used, and the area near the valve seat of the fluoroplastic valve core block is meshed densely.

4. The finite element calculation method of the width of a R-type valve seat fluoroplastic seal ring as claimed in claim 1, characterized in that: The friction type between the fluoroplastic valve core block and the valve seat is Coulomb friction.

5. The finite element calculation method of the width of a R-type valve seat fluoroplastic seal ring as claimed in claim 1, wherein, The boundary conditions of the sealing pair are set, and a pressure load is applied to the upper end surface of the metal valve core block, which comprises the following steps: The translational and rotational degrees of freedom of the valve seat in all directions are constrained, and the fixed boundary is set; The resultant force acting on the valve core assembly in the closed state is equivalent to the pressure load on the upper end of the metal valve core block in terms of area, and the pressure load is applied to the upper end surface of the metal valve core block along the normal direction.

6. The finite element calculation method of the width of a R-type valve seat fluoroplastic seal ring as claimed in claim 1, wherein, The nonlinear analysis of the valve seat and the valve core assembly in the closed state is performed by using an iterative method, and the analysis process comprises the following steps: The calculation step is set according to the requirements; Large deformation is set, and the nonlinear analysis is performed by using the complete Newton-Raphson method.

7. The finite element calculation method of the width of a R-type valve seat fluoroplastic seal ring as claimed in claim 1, wherein, The contact stress between the valve seat and the fluoroplastic valve core block is analyzed to obtain the sealing band width, which comprises the following steps: The contact stress between the valve seat and the fluoroplastic valve core is analyzed, and the contact stress values at different positions are derived according to the nodes; The region where the contact pressure is greater than the medium pressure is defined as the annular sealing band, and the difference between the maximum and minimum radial coordinates in this region is the sealing ring width.

8. A finite element calculation system for the width of a R-type seat fluoroplastic seal ring, characterized by, It comprises: A modeling unit for modeling the sealing pair based on the simulation software ABAQUS, and defining the interaction of the contact between the components in the modeling; A setting unit is configured to set boundary conditions of the sealing pair and apply a pressure load on an upper end surface of the metal valve block; An analysis unit is configured to perform a nonlinear analysis on the closed state of the valve seat and the valve block assembly by using an iterative method; A calculation unit is configured to analyze the contact stress between the valve seat and the fluoroplastic valve block to obtain the sealing band width. The modeling of the sealing pair is based on the simulation software ABAQUS, and the specific steps include: A two-dimensional axisymmetric line body model is established based on the geometric shape of the valve seat, a two-dimensional axisymmetric surface body model is established based on the geometric shape of the valve block assembly, and the valve seat and the metal part of the valve block are set as discrete rigid bodies; Grids are divided for each component in the modeling; The fluoroplastic valve block is set to be in a compressed state under the medium pressure and spring force in the closed state, the fluoroplastic compression test data is assigned to the fluoroplastic valve block, and the isotropic bilinear isotropic hardening model and Von Mises yield criterion are used; The interaction between the components in the modeling is defined, specifically including: The contact between the metal valve block and the fluoroplastic valve block is defined as a bound state, the side of the metal valve block facing the fluoroplastic valve block is the main surface, and the side of the fluoroplastic valve block facing the metal ring valve block is the slave surface; The contact between the fluoroplastic valve block and the valve seat is defined as a finite slip contact, the side of the valve seat facing the fluoroplastic valve block is the main surface, and the side of the fluoroplastic valve block facing the valve seat is the slave surface.

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