Simulation calibration method for interference assembly and press-in process of cylindrical surface of cast aluminum structure

Abstract

The application discloses a kind of simulation calibration methods of interference assembly press-in process of cast aluminum structure cylindrical surface, using enhanced Lagrange method and the contact surface nonlinear calculation method of finite slip combination, through numerical iteration, the penalty function of contact stiffness is updated ceaselessly, it is helpful to reduce the disease of calculation matrix, improve the success rate of calculation convergence.The application can not only calculate the pressure distribution and axial press-in load of contact surface, calibration maximum load and test maximum load, determine the comprehensive simulation calibration method of contact friction coefficient, material parameter setting, analysis type.According to the stress result calculation safety factor distribution of structure in interference installation process, the structure safety determination feasible scheme in simulation simulation interference assembly process.

Description

Technical Field

[0001] This invention belongs to the field of structural strength simulation technology for cast aluminum structures during interference fit assembly. Specifically, it relates to a simulation calibration method for the pressing process of cylindrical cast aluminum structures with interference fit assembly, which is used to perform structural strength simulation calibration of cylindrical cast aluminum structures during the pressing process of tubular parts with interference fit assembly. Background Technology

[0002] Currently, simulation techniques for interference fits in cast aluminum parts often employ static calculation methods, which only consider the stress state after interference fit without considering the process itself. The advantages are fast calculation speed and ease of adjusting the interference load. The disadvantages are that they cannot calculate load and stress changes during the assembly process, nor the impact of the interference fit on the strength of the cast aluminum structural component itself.

[0003] Invention patent CN104992039 proposes a method for calculating pressure during the hydraulic interference fit of a conical surface. It employs an enhanced Lagrangian method to perform finite element contact calculations on the axial pressing force and radial contact pressure of the conical surface interference fit. The values ​​vary with the amount of insertion during the actual interference fit process. The enhanced Lagrangian method combines the penalty function method and the Lagrangian method. During the calculation, the program starts with the penalty function method, similar to the pure Lagrangian method, continuously updating the penalty function of the contact stiffness until the calculated penetration value is less than the allowable value. This helps reduce ill-conditioned conditions. There are no restrictions on the choice of solver, and the allowable penetration value can be freely controlled. It overcomes the influence of calculations under certain assumptions using the elasticity method. The calculation of axial pressing force and radial contact pressure using the finite element method is more accurate and reliable than the elasticity method. The solved axial pressing force and radial contact pressure can be converted into axial and radial hydraulic pressures using simple theoretical formulas, providing a theoretical basis for determining the required axial and radial hydraulic pressures during the hydraulic interference fit of a conical surface. Summary of the Invention

[0004] To address the aforementioned problems in existing technologies, this invention provides a simulation calibration method for the press-in process of interference fit on the cylindrical surface of cast aluminum structures. It employs an enhanced Lagrangian method combined with a nonlinear calculation method for the contact surface using finite slip. Through numerical iteration, the penalty function of the contact stiffness is continuously updated, which helps reduce ill-conditioned computational matrices and improves the success rate of computational convergence. This invention can not only calculate the pressure distribution and axial press-in load of the contact surface, calibrate the calculated maximum load and the tested maximum load, but also determine the contact friction coefficient, material parameter settings, and analysis type—a comprehensive simulation calibration method. Based on the stress results of the structure during the interference fit process, the safety factor distribution is calculated, and a feasible solution for structural safety is determined through simulation of the interference fit process.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure includes the following steps:

[0007] S1: Draw 3D models of the cast aluminum structure and fittings using 3D drawing software, and import them into finite element preprocessing software;

[0008] S2: Establish finite element models of cast aluminum structures and fittings, and mesh the three-dimensional model;

[0009] S3: In the finite element preprocessor, check whether the interference hole and pipe of the cast aluminum structure are coaxial, and check whether the inner diameter of the hole and the outer diameter of the pipe are consistent with the tolerance zone requirements.

[0010] S4: Set the analysis parameters for interference fit finite element analysis;

[0011] S5: Set the material parameters for cast aluminum structures and fittings;

[0012] S6: Set constraints and apply loads;

[0013] S7: Solve the problem using finite element software;

[0014] S8: Compare the simulation results and test results of the maximum indentation load to verify the accuracy of the simulation calibration results, and then evaluate the strength of the stress results of the cast aluminum structure in step S7.

[0015] Furthermore, in step S2, the cast aluminum structure adopts tetrahedral units, and the pipe fitting adopts hexahedral units.

[0016] Furthermore, in step S2, the meshing of the pipe fitting is performed by using a rotation method to establish a three-dimensional solid mesh model. The inner surface of the mounting hole of the cast aluminum structure is divided with regular right-angled triangular units, and then three-dimensional solid units are generated.

[0017] Further, step S3 specifically involves: according to the tolerance zone of the interference fit and the tolerance zone of the hole, and below the tolerance zone of the pipe, checking the dimensions of the inner diameter of the interference fit hole and the outer diameter of the pipe fitting to ensure the coaxiality of the hole and the pipe, and confirming that the interference fit tolerance zone is consistent with the design requirements.

[0018] Further, step S4 specifically involves: selecting a contact nonlinearity calculation method, setting the initial contact parameters of the interference contact pair, setting the friction coefficient of the interference contact surface to 0.1, setting the contact surface calculation method to the enhanced Lagrangian method, and setting the contact pair to finite slip.

[0019] Furthermore, step S5 specifically involves: the material of the pipe fitting is a linear elastic material, and the elastic modulus and Poisson's ratio are set; the cast aluminum structure is made of a linear elastic material.

[0020] Alternatively, cast aluminum structures can be constructed using elasto-plastic materials, with elasto-plastic stress-strain curve data input.

[0021] Furthermore, step S6 specifically involves: applying constraints to the bottom of the cast aluminum part and applying a load to the pipe; the analysis type is set to large deformation effect.

[0022] Furthermore, in step S6, the applied load type is forced displacement.

[0023] Further, step S7 specifically involves: performing finite element nonlinear contact calculations, and using post-processing software to view the curves of the indentation load and displacement, as well as the contact pressure and cylinder structure stress cloud diagram.

[0024] Compared with the prior art, the technical solution of the present invention has the following differences:

[0025] 1. This invention is a simulation of interference fit on a cylindrical surface, not a simulation of interference fit on a conical surface;

[0026] 2. The finite element algorithm of this invention employs a nonlinear calculation method for the contact surface that combines the enhanced Lagrangian method with finite slip;

[0027] 3. The cast aluminum housing of this invention is made of elasto-plastic material, rather than linear elastic material.

[0028] The present invention has the following beneficial effects:

[0029] This invention employs a refined finite element model of the three-dimensional dimensions of the interference fit component and the mounted component. Following the tolerance zone verification model for interference fit assembly, it utilizes a simulation method combining the enhanced Lagrangian method and the finite slip method to perform finite element nonlinear contact calculations on the interference fit process of cast aluminum parts and hollow cylinders. This allows for the calculation of the variation curves of the indentation load and displacement during the interference fit process, with the indentation load changing with the indentation displacement. The enhanced Lagrangian method continuously updates the penalty function of the contact stiffness until the calculated penetration value is less than the allowable value. This helps reduce ill-conditioned calculation matrices and overcomes the convergence difficulties in large deformation nonlinear finite element calculations. It can efficiently simulate the stress changes of the structural component during the interference fit process, thereby calculating the strength performance of the structural component and providing a design reference for ensuring the strength simulation and optimization of cast aluminum housings during the interference fit process of cooling water pipes. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0031] Figure 1 Mesh generation for the three-dimensional model of the cast aluminum box and water pipes described in this embodiment of the invention;

[0032] Figure 2 The indentation load curves corresponding to different interference fits;

[0033] Figure 3 This is a flowchart of the simulation calibration method for the press-fitting process of the cylindrical surface of the cast aluminum structure described in this invention. Detailed Implementation

[0034] The present invention will now be described in detail with reference to specific examples. These examples will help those skilled in the art to further understand the invention. It should be understood that the specific examples described herein are merely for explaining the invention and are not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention, not the entire structure.

[0035] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or a connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] In this invention, the terms "upper," "lower," "left," and "right," which are explicitly defined and limiting, are discarded. The terms used are based on the range or positional relationships shown in the accompanying drawings and are merely for ease of description and simplification of operation. They do not indicate or imply that the parts or components referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limitations on this invention. Furthermore, "first" and "second" are merely used for descriptive distinction and have no special meaning.

[0037] A simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure includes the following steps:

[0038] S1: Draw 3D models of the cast aluminum structure and fittings using 3D drawing software, and import them into finite element preprocessing software;

[0039] S2: Establish finite element models of cast aluminum structures and fittings, and mesh the three-dimensional model;

[0040] S3: In the finite element preprocessor, check whether the interference hole and pipe of the cast aluminum structure are coaxial, and check whether the inner diameter of the hole and the outer diameter of the pipe are consistent with the tolerance zone requirements.

[0041] S4: Set the analysis parameters for interference fit finite element analysis;

[0042] S5: Set the material parameters for cast aluminum structures and fittings;

[0043] S6: Set constraints and apply loads;

[0044] S7: Solve the problem using finite element software;

[0045] S8: Compare the simulation results and test results of the maximum indentation load to verify the accuracy of the simulation calibration results, and then evaluate the strength of the stress results of the cast aluminum structure in step S7.

[0046] Further, step S1 specifically involves: establishing the mounting surface and fittings of a three-dimensional model of the interference fit of the cast aluminum structure.

[0047] Furthermore, in step S2, the cast aluminum structure adopts tetrahedral units, and the pipe fitting adopts hexahedral units.

[0048] Furthermore, in step S2, the meshing of the pipe fitting is performed by using a rotation method to establish a three-dimensional solid mesh model. The inner surface of the mounting hole of the cast aluminum structure is divided with regular right-angled triangular units, and then three-dimensional solid units are generated.

[0049] Further, step S3 specifically involves: according to the tolerance zone of the interference fit and the tolerance zone of the hole, and below the tolerance zone of the pipe, checking the dimensions of the inner diameter of the interference fit hole and the outer diameter of the pipe fitting to ensure the coaxiality of the hole and the pipe, and confirming that the interference fit tolerance zone is consistent with the design requirements.

[0050] Further, step S4 specifically involves: selecting a contact nonlinearity calculation method, setting the initial contact parameters of the interference contact pair, setting the friction coefficient of the interference contact surface to 0.1, setting the contact surface calculation method to the enhanced Lagrangian method, and setting the contact pair to finite slip.

[0051] Furthermore, step S5 specifically involves: the material of the pipe fitting is a linear elastic material, and the elastic modulus and Poisson's ratio are set; the cast aluminum structure is made of a linear elastic material.

[0052] Alternatively, cast aluminum structures can be constructed using elasto-plastic materials, with elasto-plastic stress-strain curve data input.

[0053] Furthermore, step S6 specifically involves: applying constraints to the bottom of the cast aluminum part and applying a load to the pipe; the analysis type is set to large deformation effect.

[0054] Furthermore, in step S6, the applied load type is forced displacement.

[0055] Further, step S7 specifically involves: performing finite element nonlinear contact calculations, and using post-processing software to view the curves of the indentation load and displacement, as well as the contact pressure and cylinder structure stress cloud diagram.

[0056] Furthermore, step S8 specifically involves: calibrating the simulation results of the interference fit pressing process by comparing the calculation results with the experimental results, and adjusting the simulation parameters and settings to make the simulation results consistent with the experimental results.

[0057] Example 1

[0058] A simulation calibration method for the interference fit pressing process of a cylindrical surface in a cast aluminum structure is described in this embodiment, using the interference fit pressing process of a cast aluminum engine cylinder block in a cooling water pipe as an example. The method includes the following steps:

[0059] Step 1: Create a 3D model of the cast aluminum engine block and water pipe. Create the assembled 3D model of the cast aluminum engine block and water pipe in 3D drawing software and export it in a file format that the finite element software can recognize.

[0060] Step 2: Finite element modeling. Mesh the 3D model and set the element mesh type and mesh size appropriately while ensuring calculation accuracy and saving calculation time.

[0061] Step 3: Check the diameter dimensions of the interference fit hole and the pipe fitting. According to the tolerance zone of the interference fit and the tolerance zone of the hole, under the tolerance zone of the pipe, carefully check the dimensions of the inner diameter of the hole and the outer diameter of the pipe to ensure the coaxiality of the hole and the pipe, and confirm that the interference fit tolerance zone is consistent with the design requirements. It should be noted that if you are calculating the results under different interference fit tolerances, you need to establish different finite element models in step 2.

[0062] Step 4: Set the analysis parameters, select the contact algorithm for interference fit finite element analysis, and select the enhanced Lagrangian method and finite slip method to perform contact nonlinear finite element calculations;

[0063] Step 5: Set material parameters. Set the mechanical property parameters of the engine block, water pipe and press-in block materials respectively, such as elastic modulus, Poisson's ratio, etc.

[0064] Step 6: Set constraints and apply loads. Set constraints at the mating surface of the engine block and cylinder head, and apply forced displacement loads to the press-in block.

[0065] Step 7: Finite element solution. Based on the settings in the finite element preprocessing in Steps 1 to 6, perform finite element nonlinear contact calculation to obtain the entire simulation process and results of the interference fit, and obtain the results of axial pressing force and radial contact pressure during the installation process, as well as the engine cylinder stress results.

[0066] Step 8: Compare the simulation results and test results of the maximum indentation load to verify the accuracy of the simulation calibration results, and then evaluate the strength of the stress results of the cylinder in Step 7.

[0067] In the above technical solution, step 1 is: to establish the mounting surface and pipe of the three-dimensional model of the interference fit of the cast aluminum engine cylinder block, wherein the diameter of the interference fit hole of the cast aluminum engine cylinder block and the outer diameter of the water pipe need to be consistent with the actual size of the interference fit.

[0068] In the above technical solution, step 2 is: to establish a three-dimensional solid mesh model for the water pipe mesh using the rotation method, to divide the inner surface of the mounting hole of the cast aluminum engine cylinder block using regular right-angled triangular units, and then to generate three-dimensional solid units.

[0069] In the above technical solution, step 4 is: setting the initial contact parameters of the interference contact pair, setting the friction coefficient of the interference contact surface to 0.1, setting the contact surface calculation method to the enhanced Lagrange method, and setting the contact pair to finite slip.

[0070] In the above technical solution, step 5 involves: the water pipe being made of a linear elastic material, with the elastic modulus and Poisson's ratio set; the engine block material can be set in two ways: the first method uses a linear elastic material, and the second method uses an elasto-plastic material, with stress-strain curve data input. Specifically, the body is made of die-cast aluminum, the water pipe is made of stainless steel, and the press-in block is made of structural steel, with the die-cast aluminum material inputting an elasto-plastic stress-strain curve.

[0071] In the above technical solution, step 6 is: applying a load of forced displacement.

[0072] In the above technical solution, step 7 is as follows: The calibration of the simulation results of the interference fit pressing process involves comparing the calculated results with the experimental results, and adjusting the simulation parameters and settings to ensure consistency between the simulation results and the experimental results. The calibration parameters in this invention are the maximum load during the pressing process, and the simulation adjustments include the contact surface friction coefficient, material elastic-plastic data, and simulation analysis type.

[0073] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure, characterized in that, Includes the following steps: S1: Draw 3D models of the cast aluminum structure and fittings using 3D drawing software, and import them into finite element preprocessing software; S2: Establish finite element models of cast aluminum structures and fittings, and mesh the three-dimensional model; S3: In the finite element preprocessor, check whether the interference hole and pipe of the cast aluminum structure are coaxial, and check whether the inner diameter of the hole and the outer diameter of the pipe are consistent with the tolerance zone requirements. S4: Set the analysis parameters for interference fit finite element analysis; S5: Set the material parameters for cast aluminum structures and fittings; S6: Set constraints and apply loads; S7: Solve the problem using finite element software; S8: Compare the simulation results and test results of the maximum indentation load to verify the accuracy of the simulation calibration results, and then evaluate the strength of the stress results of the cast aluminum structure in step S7.

2. The simulation calibration method for the press-fit process of a cylindrical surface interference fit in a cast aluminum structure as described in claim 1, characterized in that, In step S2, the cast aluminum structure uses tetrahedral units, and the pipe fittings use hexahedral units.

3. The simulation calibration method for the press-fit process of a cylindrical surface interference fit in a cast aluminum structure as described in claim 1, characterized in that, In step S2, a three-dimensional solid mesh model is established by rotation method for meshing the pipe fittings. The inner surface of the mounting hole of the cast aluminum structure is divided with regular right-angled triangular units, and then three-dimensional solid units are generated.

4. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 1, characterized in that, Specifically, step S3 involves checking the inner diameter of the interference fit hole and the outer diameter of the pipe fitting, within the tolerance zone of the interference fit and the tolerance zone of the hole, to ensure the coaxiality of the hole and the pipe, and to confirm that the interference fit tolerance zone is consistent with the design requirements.

5. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 1, characterized in that, Step S4 specifically involves: selecting a contact nonlinearity calculation method, setting the initial contact parameters of the interference contact pair, setting the friction coefficient of the interference contact surface to 0.1, setting the contact surface calculation method to the enhanced Lagrangian method, and setting the contact pair to finite slip.

6. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 1, characterized in that, Step S5 specifically involves: the pipe fitting is made of a linear elastic material, and the elastic modulus and Poisson's ratio are set; the cast aluminum structure is made of a linear elastic material.

7. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 6, characterized in that, The cast aluminum structure uses an elastic-plastic material; input the elastic-plastic stress-strain curve data.

8. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 1, characterized in that, Specifically, step S6 involves applying a constraint to the bottom of the cast aluminum part and applying a load to the pipe; the analysis type is set to large deformation effect.

9. The simulation calibration method for the press-fit process of an interference fit on a cylindrical surface of a cast aluminum structure as described in claim 8, characterized in that, In step S6, the applied load type is forced displacement.

10. The simulation calibration method for the press-fit process of a cylindrical surface interference fit in a cast aluminum structure as described in claim 1, characterized in that, Step S7 specifically involves: performing finite element nonlinear contact calculations, and using post-processing software to view the curves of the indentation load and displacement, as well as the contact pressure and cylinder structure stress cloud diagram.

Images