A valve core and housing two-body wear simulation method

Abstract

The valve core and shell double-body wear simulation method belongs to the technical field of mechanical friction and wear, and relates to a valve core and shell double-body wear simulation method based on Archard wear theory. The method establishes a valve core and shell three-dimensional simulation model based on the matching gap of the guide pair, sets the contact relationship of the valve core and shell as master and slave surfaces, applies spring lateral force load and reciprocating displacement load; a UMESHMOTION subprogram is written to obtain the contact stress and relative slip amount of the model, the wear depth of the valve core and shell nodes is calculated based on the Archard wear theory and the wear coefficient of the material, and the wear direction of the nodes is solved; the software calls the subprogram to control the movement of the model grid nodes to realize the double-body wear simulation of the valve core and shell. The method can realize the double-body wear simulation of the valve core and shell while considering the influence of the shell wear on the contact stress, can be applied to the wear prediction and structure optimization of the valve, and has important practical application significance for improving the guiding performance of the valve.

Description

Technical Field

[0001] This invention belongs to the field of mechanical friction and wear technology, and relates to a method for simulating the wear of a valve core and a housing. Background Technology

[0002] One-way valves perform functions such as reversing, opening and closing, and regulating flow through the relative movement of their components. Their guiding performance directly determines the performance and safety of the equipment. During valve operation, the presence of clearance in the guide pair can easily cause the valve core to deflect, leading to abnormal wear or even jamming at the contact point between the valve core and the housing, ultimately causing overall valve failure. Monitoring the valve's friction and wear process is difficult, the amount of wear is hard to predict, and experiments are expensive, time-consuming, and labor-intensive. To optimize the valve's guiding structure to reduce wear, numerical simulation is needed to simulate valve wear. When using numerical simulation to analyze component wear, two worn components with significantly different elastic moduli can have the component with higher hardness simplified as a rigid body for analysis. However, when the hardness of the valve's guiding wear components is similar, the wear of both components will significantly affect the contact stress; using a rigid body simplification will reduce the accuracy of the simulation.

[0003] Existing technical literature 1, "A Simulation Method for Step-by-Step Coupling of Dry Sliding Friction Thermal Stress Wear" by Gui Liangjin et al. (Patent Publication No. CN104239627B), uses finite element method (FEM) to perform transient heat conduction analysis on the pin and disc to output the temperature field, and stress analysis to output the contact pressure field. Based on temperature, contact stress, and relative slip, it calculates the wear depth of the disc, ultimately realizing the disc's wear. However, this method assumes the pin is a rigid body, only realizing the disc's wear, and cannot analyze the impact of pin wear on the disc, making it difficult to apply to two-body wear. Technical literature 2, "A Method for Determining the Predictive Model of Valve Core and Sleeve Life for Servo Valves" by Zeng Jia et al. (Patent Publication No. CN114321097A), considers erosion wear as the main failure mode of servo valves. It establishes a physical model of erosion wear failure for the valve core and sleeve, and obtains a predictive model of valve core and sleeve wear through servo valve core and sleeve wear tests. This model is only applicable to specific valves with oily fluid media and is not suitable for check valves. Summary of the Invention

[0004] This invention addresses the limitations and defects of existing technologies by proposing a method for simulating the wear of a valve core and its housing. The method first establishes a predictive model of the wear of the valve core and housing. Considering the influence of housing wear on contact stress, a three-dimensional simulation model of the valve core and housing is established based on the fit clearance of the guide pair. The contact relationship between the valve core and housing is set as master-slave surfaces, and spring lateral force loads and reciprocating displacement loads are applied. A UMESHMOTION subroutine is written to obtain the contact stress and relative slip of the model. Based on Archard wear theory and the wear coefficient of the material, the wear depth of the valve core and housing nodes is calculated, and the wear direction of the nodes is solved. The software calls the subroutine to control the movement of the model mesh nodes to achieve the simulation of the wear of the valve core and housing. This method can simulate the wear of the valve core while considering the influence of housing wear on contact stress. It can be applied to valve wear prediction and valve structure optimization, and has significant practical application value for improving the guiding performance of valves.

[0005] The technical solution adopted in this invention is a method for simulating the wear of a valve core and a shell. The method is characterized by obtaining the valve core deflection angle based on the valve's fit clearance, establishing a three-dimensional simulation model of the valve by deflecting the valve core, setting the contact relationship between the valve core and the shell as master and slave surfaces, applying spring lateral force loads and reciprocating displacement loads; writing the UMESHMOTION subroutine to obtain the contact stress and relative slip of the model, calculating the wear depth of the valve core and shell nodes based on Archard wear theory and different wear coefficients, and solving for the wear direction of the nodes; the subroutine controls the movement of the model's mesh nodes, ultimately realizing the simulation of the wear of the valve core and the shell in a two-body manner.

[0006] The specific steps of the method are as follows:

[0007] Step 1: Establish a 3D simulation model of the valve core and housing.

[0008] 1) Constructing the valve assembly model: Extract the features of the one-way valve guide pair to establish a three-dimensional model of the valve. The valve core and the shell have different wear coefficients due to different materials. Set the material properties of the shell and the valve core: the shell material is stainless steel and the valve core material is aluminum. Assemble the valve core and the shell in the assembly module and divide the mesh. The mesh size is 0.1mm and the element type is C3D8. According to the fit clearance, and make the valve core deflect to contact the shell, obtain the valve core deflection angle ∝.

[0009] 2) Establish contact relationship: Establish contact relationship between the contact surfaces of the valve core and the housing. By default, only the slave surface can be worn. First, establish a contact relationship between the housing as the master surface and the valve core as the slave surface, and set the interaction properties of the normal and tangential directions of the contact surfaces. Then, copy the contact relationship and swap the master and slave surface relationships so that the valve core and the housing are mutually master and slave surfaces. Set the normal of the contact surfaces to hard contact and the tangential friction coefficient to 0.6.

[0010] 3) Set constraints, including boundary conditions, lateral force loads, and displacement loads for the model. Simulate and analyze the contact stress and slip at the nodes. The analysis is divided into three steps: loading, reciprocating motion, and unloading. Output variables such as contact stress and slip. Based on the motion of the valve core and the shell, apply a fixed constraint to the lower part of the valve core and apply a reciprocating displacement load of 1 mm to the shell, performing M reciprocating motions. Apply a variable spring load to the shell at 0.1 s intervals. The load variation range of the spring under a 1 mm displacement is ΔF (N), and the variation range of the spring lateral force when the valve core deflects is Δf (N). Create the analysis step.

[0011] Step 2: Write the UMESHMOTION wear subroutine

[0012] A UMESHMOTION subroutine was written to obtain the contact stress and relative slip of the model nodes. Based on Archard wear theory and wear coefficients, the wear depth of the valve core and housing nodes was calculated, the wear direction of the nodes was determined, and the movement of the nodes was realized. The specific process is as follows:

[0013] 1) Calculate wear depth: The subroutine obtains the contact stress and relative slip at the node, and calculates the wear depth at the valve core and housing node based on the classic Archard wear theory. The Archard wear formula is as follows:

[0014]

[0015] Where p is the contact stress on the contact surface; v is the slip rate; K is the wear coefficient of the material; H is the hardness of the softer material, obtained from experimental data; Δh is the wear depth, that is, the wear depth of a node in time Δt is proportional to the contact stress at that point and the relative slip in time Δt.

[0016] 2) Determining the wear direction: For internal nodes, the system uses the node's normal as the wear direction; for boundary nodes, there are two normals. The subroutine obtains the coordinates of the boundary node and the nodes adjacent to its wear direction, decomposes the wear direction formed by the two nodes, and the method for determining the wear direction is as follows:

[0017] ① First, the numbering of the boundary nodes and their adjacent nodes in the wear direction is renumbered in the model;

[0018] ② The subroutine determines whether a node is a boundary node based on its node number. If it is not a boundary node, the normal direction of the node is the wear direction. Otherwise, the subroutine indexes the coordinate values ​​of adjacent nodes, decomposes the wear vector formed by the two nodes along the coordinate axis, and calculates the wear depth along the three coordinate axes. The calculation formula (2) is as follows:

[0019]

[0020] Where H represents the total wear depth; ALOCAL x ALOCAL y ALOCAL z The wear depth is defined in the x, y, and z directions (the coordinate system has the valve core's geometric center as the origin, and the valve core's opening direction as the positive y-axis; a cross-section is created through the origin, perpendicular to the y-axis, and x and z axes are established within the cross-section, pointing outwards; the x, y, and z axes satisfy a right-handed rectangular coordinate system); (x i ,y i ,z i (x) represents the coordinates of the boundary node; i+1 ,y i+1 ,z i+1 ) represents the coordinates of adjacent nodes; dist represents the distance between adjacent points:

[0021]

[0022] Step 3: Control the movement of mesh nodes

[0023] A set of nodes is created for the worn surfaces of the valve core and housing. In the ALE algorithm, the constraint type of the nodes on the worn surfaces of the valve core and housing is set to displacement constraint. The wear region of the valve core and housing is set to adaptive mesh control. Based on the wear depth calculated by the subroutine, the software controls the movement of the nodes. The nodes whose displacement is controlled are those where both the contact stress and relative slip are not zero. The adaptive mesh technology corrects the position of adjacent nodes, updates the finite element model, and performs the wear analysis for the next incremental step until the total time step is reached. The simulation process ends, and the two-body wear simulation of the valve core and housing is finally realized.

[0024] The simulation results are post-processed to extract the nodal coordinates of the valve core shell after dual-body wear and rigid-body wear. The nodal wear depth at the maximum wear depth of the valve core shell after dual-body wear is extracted as a function of time. Comparison diagrams of valve core under dual-body wear and rigid-body wear, cross-sectional diagrams of shell wear, and diagrams of nodal wear depth variation of valve core and shell are plotted respectively. This method can simulate dual-body wear of valve core and shell while considering the influence of shell wear on contact stress.

[0025] The significant effects and benefits of this invention are as follows: This method establishes a three-dimensional contact model between the valve core and the shell based on simulation software. The software calls the UMESHMOTION subroutine to control the movement of the model's mesh nodes, realizing the simulation of wear between the valve core and the shell, thus providing a theoretical model for optimizing valve wear problems. This method can simulate valve core wear while considering the influence of shell wear on contact stress, and can be applied to valve core wear prediction and valve core structure optimization, which has important practical application significance for improving the guiding performance of valves. Attached Figure Description

[0026] Figure 1 —Overall flowchart of numerical simulation method.

[0027] Figure 2 —A three-dimensional geometric model of the valve core housing; where A is the housing and B is the valve core.

[0028] Figure 3 —A simplified 3D simulation model of the valve core housing; where C is the housing simulation model and D is the valve core simulation model.

[0029] Figure 4 —UMESHMOTION subroutine flowchart. Where P(t) and S(t) are the contact stress and slip at time t, S(t+Δt) is the slip at time t+Δt, Δs is the relative slip over time Δt, (x i ,y i ,z i ) represents the coordinates of the node.

[0030] Figure 5 —Schematic diagram of adaptive mesh technology.

[0031] Figure 6 —Comparison of valve core wear between dual-body wear and rigid-body wear; where L1 is the cross-sectional view of valve core wear when the housing is deformable, and L2 is the cross-sectional view of valve core wear when the housing is rigid.

[0032] Figure 7 —Wear section diagram of the casing.

[0033] Figure 8 — A graph showing the variation of wear depth at the valve core housing joints; where L1 is the curve of wear depth at the housing joints over time, and L2 is the curve of wear depth at the valve core joints over time. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail with reference to the technical solutions and accompanying drawings.

[0035] When performing wear simulation analysis on valves using numerical simulation methods, the shell with a large elastic modulus is assumed to be a rigid body, while the influence of shell wear on valve core wear is ignored. To address the limitations and shortcomings of existing technologies, a dual-body wear simulation method for valve core and shell has been invented. This method can simulate the simultaneous wear of the valve core and shell, more closely reflecting the actual wear conditions of dual-body wear.

[0036] The overall process of this simulation method is shown in the appendix. Figure 1 As shown, according to Figure 1 The overall flow of the valve core-shell dual-body wear prediction simulation method is shown. Taking a check valve as an example, the specific implementation process of the invention is explained in detail with the help of simulation software:

[0037] Step 1: Establish a 3D simulation model of the valve core and housing.

[0038] 1) Constructing the valve assembly model: The geometric model of the one-way valve used is attached. Figure 2 As shown, under service conditions, the valve core reciprocates within the housing. The guide pair features consisting of the valve core and housing are extracted from the component module and simplified to obtain the valve simulation model as shown in the attached figure. Figure 3 As shown in Table 1, the housing material is 304 stainless steel, and the valve core material is 5A06 aluminum. The material properties of the housing and valve core are set as shown in Table 1. The components are divided into grids with a grid size of 0.1 mm and a cell type of C3D8. In the assembly module, the valve core and housing are assembled and the valve core is deflected to contact the housing. The valve core deflection angle is obtained as ∝=0.27° based on the mating clearance.

[0039] Table 1. Material properties of the model

[0040]

[0041] 2) Establish contact relationship: Establish contact relationship on the contact surfaces of the valve core and the housing, with the housing as the master surface and the valve core as the slave surface. Copy the established contact relationship and swap the master and slave surfaces so that the valve core and the housing are mutually master and slave surfaces; set the normal of the contact surface to hard contact and the tangential friction coefficient to 0.6.

[0042] 3) Set constraints: Based on the motion patterns of the valve core and the housing, apply a fixed constraint to the lower part of the valve core, apply a reciprocating displacement load of 1mm to the housing, and perform reciprocating motion M=20 times; apply a variable spring load to the housing at 0.1s time intervals, with the load variation range ΔF of the spring under a 1mm displacement being 27N-36N, and the variation range Δf of the spring lateral force when the valve core deflects being 0.127N-0.170N; create an analysis step, which is divided into three analysis steps: loading, reciprocating motion, and unloading, and output variables such as contact stress and slippage.

[0043] Step 2: Write the UMESHMOTION wear subroutine

[0044] 1) Setting the wear coefficient: Due to the different materials used, the valve core and the housing have different wear coefficients. Based on experimental data, the wear coefficient of the valve core is selected as 9.70 × 10⁻⁶. -6 mm 3 / (N·m), the wear coefficient of the shell is 8.63×10 -6 mm 3 The wear coefficient is calculated as / (N·m), and the wear coefficient is magnified by 100 times so that the model's 20 reciprocating motions simulate the valve core's 2000 opening and closing cycles. In the subroutine, when the node number is less than 37260, the wear coefficient of the valve core is used to calculate the wear depth; otherwise, the wear coefficient of the shell is used.

[0045] 2) Calculate the wear depth: as shown in the attached document. Figure 4 The flowchart of the UMESHMOTION subroutine is shown. The subroutine obtains the contact stress P(t) at the node, the slip S(t) at the node within time t, and the slip S(t+Δt) within time t+Δt. The slip is subtracted to obtain the relative slip ΔS of the node within time Δt. Based on the Archard wear theory, the wear depth of the valve core shell at the node is calculated according to formula (1).

[0046] 3) Determine the wear direction: Renumber the boundary nodes and the nodes in their wear directions. Considering that there are a total of 98,728 nodes, the new boundary node numbering starts from 98,729. The node numbering of the adjacent wear direction node is 100 greater than that of the boundary node. According to the set boundary node and adjacent node numbers, when the obtained node number is greater than 98,728, the coordinate values ​​of the node and the adjacent node are obtained. The wear vector formed by the two nodes is decomposed along the coordinate axis direction. The wear depth along the three coordinate axis direction is obtained by formula (2) and formula (3).

[0047] Step 3: Control the movement of mesh nodes

[0048] Create a set of nodes representing the worn surfaces of the valve core and housing. In the ALE algorithm, set the constraint type of the node set to displacement constraint. Configure the wear region of the valve core and housing as an adaptive mesh control system. Based on the wear depth calculated by the subroutine, the software controls the node movement and corrects the node coordinates. (See attached...) Figure 5 The diagram shows the principle of adaptive mesh technology. Adaptive mesh technology corrects the position of adjacent nodes based on the movement distance of the nodes to ensure the correctness of the model; it updates the finite element model and performs the wear analysis of the next incremental step until the total time step is reached, at which point the simulation process ends, and finally realizes the dual-body wear simulation of the valve core and the shell.

[0049] Post-processing was performed on the simulation results to extract the nodal coordinates of the cross-sections of the valve core housing after both-body and rigid-body wear, as shown in the attached figure. Figure 6 Appendix Figure 7 As shown in the figure, the wear depth and width of the valve core using dual-body wear are smaller than those using rigid-body wear. This is because the wear of the housing changes the contact area, resulting in different contact stresses.

[0050] Extract the time-varying value of the nodal wear depth at the maximum wear depth of the valve core housing after dual-body wear, as shown in the attached figure. Figure 8As shown in the figure, the maximum wear depth of the valve core reaches 1.265 μm, while the maximum wear depth of the shell is only 0.087 μm. This is because the wear coefficient of the shell is smaller than that of the valve core, so the wear depth of the shell is also smaller than that of the valve core. In addition, since the total displacement of the joint is equal to the wear displacement plus the displacement caused by elastic deformation, the joint displacement will fluctuate up and down as the joints come into contact and separate.

[0051] This method can simulate the wear of the valve core while taking into account the effect of shell wear on contact stress. It can be applied to the wear analysis of valves and the optimization of valve structure, and has important practical significance for improving the guiding performance of valves.

Claims

1. A method for simulating wear of a valve core and a housing, characterized in that, This method obtains the valve core deflection angle based on the valve's fit clearance, establishes a three-dimensional simulation model of the valve by deflecting the valve core, sets the contact relationship between the valve core and the shell as master and slave surfaces, and applies spring lateral force load and reciprocating displacement load. The UMESHMOTION subroutine was written to obtain the contact stress and relative slip of the model. Based on the Archard wear theory and different wear coefficients, the wear depth of the valve core and the shell nodes were calculated, and the wear direction of the nodes was solved. The subroutine controls the movement of the model mesh nodes, and finally realizes the two-body wear simulation of the valve core and the shell. The specific steps of the method are as follows: Step 1: Establish a 3D simulation model of the valve core and housing. 1) Constructing the valve assembly model: Extract the features of the one-way valve guide pair to establish a 3D model of the valve. The valve core and the shell have different wear coefficients due to different materials. Set the material properties of the shell and the valve core: the shell material is stainless steel and the valve core material is aluminum. Assemble the valve core and the shell in the assembly module and divide the mesh. The mesh size is 0.1mm and the element type is C3D8. According to the fit clearance, and make the valve core deflect to contact the shell, obtain the valve core deflection angle ∝. 2) Establish contact relationship: Establish contact relationship between the contact surfaces of the valve core and the housing. By default, only the slave surface can be worn. First, establish the contact relationship between the housing as the master surface and the valve core as the slave surface, and set the interaction properties of the normal and tangential directions of the contact surfaces. Then, the contact relationship is copied, and the master-slave surface relationship is swapped so that the valve core and the housing are mutually master-slave surfaces; the normal of the contact surface is set to hard contact, and the tangential friction coefficient is set to 0.6; 3) Set constraints, including boundary conditions, lateral force loads, and displacement loads for the model. Simulate and analyze the contact stress and slip at the nodes. The analysis is divided into three steps: loading, reciprocating motion, and unloading. Output the contact stress and slip. Based on the motion of the valve core and the shell, apply a fixed constraint to the lower part of the valve core and apply a reciprocating displacement load of 1 mm to the shell, performing M reciprocating motions. Apply a variable spring load to the shell at 0.1 s intervals. The load variation range of the spring under a 1 mm displacement is ΔF (N), and the variation range of the spring lateral force when the valve core deflects is Δf (N). Create the analysis step. Step 2: Write the UMESHMOTION wear subroutine A UMESHMOTION subroutine was written to obtain the contact stress and relative slip of the model nodes. Based on Archard wear theory and wear coefficients, the wear depth of the valve core and housing nodes was calculated, the wear direction of the nodes was determined, and the movement of the nodes was realized. The specific process is as follows: 1) Calculate wear depth: The subroutine obtains the contact stress and relative slip at the node, and calculates the wear depth at the valve core and housing node based on the classic Archard wear theory. The Archard wear formula is as follows: Where p is the contact stress on the contact surface; v is the slip rate; K is the wear coefficient of the material; H is the hardness of the softer material, obtained from experimental data; Δh is the wear depth, that is, the wear depth of a node in time Δt is proportional to the contact stress at that point and the relative slip in time Δt. 2) Determining the wear direction: For internal nodes, the system uses the node's normal as the wear direction; for boundary nodes, there are two normals. The subroutine obtains the coordinates of the boundary node and the nodes adjacent to its wear direction, decomposes the wear direction formed by the two nodes, and the method for determining the wear direction is as follows: ① First, the numbering of the boundary nodes and their adjacent nodes in the wear direction is renumbered in the model; ② The subroutine determines whether a node is a boundary node based on its node number. If it is not a boundary node, the normal direction of the node is the wear direction. Otherwise, the subroutine indexes the coordinate values ​​of adjacent nodes, decomposes the wear vector formed by the two nodes along the coordinate axis, and calculates the wear depth along the three coordinate axes. The calculation formula (2) is as follows: Where H represents the total wear depth; ALOCAL x ALOCAL y ALOCAL z The wear depth is defined in the x, y, and z directions. The coordinate system has the geometric center of the valve core as the origin and the valve core opening direction as the positive y-axis. A cross-section is created through the origin, perpendicular to the y-axis. Within this cross-section, x and z axes are established, pointing outwards. The x, y, and z axes satisfy a right-handed rectangular coordinate system. (x i, y i, z i (x) represents the coordinates of the boundary node; i+1 ,y i+1 ,z i+1 ) represents the coordinates of adjacent nodes; dist represents the distance between adjacent points: Step 3: Control the movement of mesh nodes A set of nodes is created for the worn surfaces of the valve core and housing. In the ALE algorithm, the constraint type of the nodes on the worn surfaces of the valve core and housing is set to displacement constraint. The wear region of the valve core and housing is set to adaptive mesh control. According to the wear depth calculated by the subroutine, the software controls the movement of the nodes. The nodes whose displacement is controlled are those where both the contact stress and the relative slip are not zero. The adaptive mesh technology corrects the position of adjacent nodes, updates the finite element model, and performs the wear analysis for the next incremental step until the total time step is reached. The simulation process ends, and finally the two-body wear simulation of the valve core and housing is realized. The simulation results are post-processed to extract the nodal coordinates of the valve core shell after dual-body wear and rigid-body wear. The nodal wear depth at the maximum wear depth of the valve core shell after dual-body wear is extracted as a function of time. Comparison diagrams of valve core under dual-body wear and rigid-body wear, cross-sectional diagrams of shell wear, and diagrams of nodal wear depth variation of valve core and shell are plotted respectively. This method can simulate dual-body wear of valve core and shell while considering the influence of shell wear on contact stress.

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