Passenger car drive shaft elastomer modal calculation finite element modeling method

Abstract

The application discloses a kind of passenger car transmission shaft elastomer modal calculation finite element modeling method, belong to modeling technical field, the application is simplified to the finite element calculation modal model of transmission shaft of three different universal joint structures, reasonable simplified structure and parameter are given.Test verification shows that it can guarantee the consistency of the first-order bending calculation modal and test modal of transmission shaft, provides reference for the optimization of transmission shaft structure caused by NVH problem using finite element method, provides an ordered finite element calculation different universal joint structure transmission shaft modeling sequence and method, gives reasonable simplified scheme, and parameterizes simplification to different universal joint structure, gives the reference stiffness in different directions, so that calculation and test results can obtain better consistency.For transmission shaft development early stage structure stiffness pre-play provides a kind of feasibility analysis.The application only gives a kind of modeling method, and does not make parameter comparison for subsequent calculation results and test results comparison.

Description

Technical Field

[0001] This invention belongs to the field of modeling technology, specifically a finite element modeling method for modal calculation of the elastic body of a passenger vehicle drive shaft. Background Technology

[0002] With economic development, people's pursuit of quality of life is increasing. Passenger cars have become very common, and people no longer regard them as simple means of transportation, but also have increasingly stringent requirements for their comfort. NVH quality of passenger cars is receiving more and more attention from major domestic OEMs, and NVH control has evolved from early "firefighting" solutions for market products to forward development control. That is, integrating NVH control into every stage of the vehicle development process.

[0003] The driveshaft is a core component of four-wheel drive and rear-wheel drive passenger vehicles, serving as the "main artery" for transmitting vehicle power and is one of the core components of an automobile. Passenger vehicle driveshafts are generally over 1.5 meters long. If the design is unreasonable, fatigue durability and NVH (noise, vibration, and harshness) issues are very likely to occur. The first-order bending mode of the passenger vehicle driveshaft is an important indicator during the forward development of passenger vehicle NVH. Virtual simulation optimization in the early stages of product development is an important means of modal control of the driveshaft assembly. Finite element modeling and optimization analysis are common methods for controlling the modes in the early stages of driveshaft design. However, unreasonable simplification and modeling can lead to incorrect results. This invention parameterizes different simplifications of the driveshaft structure and different connection methods between the driveshaft and components. Experimental verification shows that the error between the calculated results and experimental results is within 2%, indicating that the calculation of the first-order bending mode of the driveshaft assembly using this simplified structure is highly accurate. The calculation model can completely replace experiments in evaluating the first-order bending mode parameters of the driveshaft, which has significant engineering practical value. Summary of the Invention

[0004] To address the above problems, this invention provides a finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft. The invention simplifies the modal models for driveshafts with three different universal joint structures, providing reasonable simplified structures and parameters. Experimental verification shows that it can ensure the consistency between the calculated first-order bending mode and the experimental mode of the driveshaft, providing a reference for optimizing the driveshaft structure using the finite element method to address NVH problems caused by the driveshaft. This method simplifies and parametrically models different parts of the driveshaft when performing modal calculations for driveshafts with different universal joint structures, providing a reliable and effective analysis and modeling tool for modal calculation of the elastic body of the driveshaft.

[0005] The technical solution of this invention is as follows: a finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft, comprising the following steps:

[0006] S1 acquires the geometric model and data of the drive shaft assembly, including: shaft tube, universal joint, splined shaft and flange;

[0007] S2 establishes a finite element model of the drive shaft assembly: the shaft tube is simulated using quadrilateral plate shell elements, the universal joint is simulated using zero-dimensional spring elements, the spline shaft is simulated using hexahedral first-order or tetrahedral second-order solid elements, the flange is simulated using hexahedral first-order or tetrahedral second-order solid elements, and the connection between solid elements and plate shell elements is simulated using massless two-dimensional elements.

[0008] S3 sets the coordinate system, places the model established in step S2 into the corresponding position of the coordinate system, and simulates the connection form of the actual transmission shaft;

[0009] S4 places the spring element into the coordinate system of S3 and defines the orientation and stiffness of the spring element;

[0010] The S5 finite element model is assembled, and rigid constraints are used at both ends of the drive shaft.

[0011] S6 inputs the data from S1 into the model, and the model is now complete.

[0012] Furthermore, in step S1, the data includes: design quality, material grade, and material.

[0013] Furthermore, the material grade includes: material elastic modulus E, material Poisson's ratio μ, and material density ρ.

[0014] Furthermore, in step S2, the solid unit is divided into at least 2 layers of units in the thickness of the split part, the solid unit size is <6mm; the solid unit aspect ratio is <10, the solid unit warpage angle is <10°, the solid unit twist angle is <45°, and the solid unit cone angle is ≥60%.

[0015] Furthermore, in step S2, the solid unit size is 3mm, 95% of the solid units have an aspect ratio <5, 95% of the solid units have a warp angle <7°, 95% of the solid units have a twist angle <30°, and 95% of the solid units have a cone angle >80%.

[0016] Furthermore, in step S2, the shell unit meets the following requirements: number of shell units > 95%, shell unit size < 6mm, shell unit warping angle < 10°, shell unit aspect ratio < 7, shell unit twist angle < 40°, shell unit Jacobian side < 0.3, shell unit taper < 0.8, and maximum shell angle < 135°.

[0017] Furthermore, in step S2, the shell unit meets the following requirements: the shell unit size is 3mm, the warp angle of 95% of the shell unit is <7°, the aspect ratio of 95% of the shell unit is <5, the twist angle of 95% of the shell unit is <30°, the Jacobian side of 95% of the shell unit is <0.7, the taper of 95% of the shell unit is <0.7, and the maximum angle of 95% of the shell unit is <120°.

[0018] Furthermore, in step S4, the axial direction of the transmission shaft tube is X-direction, the direction of the vertical shaft tube parallel to the ground is Y-direction, and the Z-direction is determined by the right-hand rule. K1 to K6 are defined as the translational stiffness in the X, Y, and Z directions and the rotational stiffness in the X, Y, and Z directions, respectively. The units of K1 to K3 are N / mm, and the units of K4 to K6 are N·mm / rad.

[0019] Furthermore, the types of springs include: constant velocity fixed universal joint springs, constant velocity moving universal joint springs, non-constant velocity fixed universal joint springs, and flexible disc universal joint springs. All springs are simulated using massless zero-dimensional elements, and each spring is set with stiffness in six directions from K1 to K6.

[0020] Furthermore, in step S6, after the data is entered into the model, the finite element model is checked, including: checking the geometric cleanup information, ensuring that the finite element model does not contain line or surface geometric information; checking the internal unit connections of the part; checking for duplicate units; checking the material properties of the parts; and checking the quality of the parts, ensuring that the difference from the geometric sample in the 3D modeling software is within 3%.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention provides an ordered finite element method for modeling drive shafts with different universal joint structures, presents a reasonable simplification scheme, and performs parameterized simplification on different universal joint structures, providing reference stiffness in different directions to achieve good consistency between calculation and experimental results. It also provides a feasibility analysis for structural stiffness prediction in the early stages of drive shaft development. This invention only presents one modeling method and does not compare the parameters used in subsequent calculations and experimental results. Attached Figure Description

[0023] Figure 1 This is a schematic diagram showing the connection between the solid unit and the two-dimensional unit of the present invention.

[0024] Figure 2 This is a schematic diagram of the assembly modeling of the present invention.

[0025] Figure 3 This is a flowchart of the present invention.

[0026] In the picture:

[0027] 1-Solid element; 2-Connection node between solid mesh element and plate / shell element; 3-Shaft tube plate / shell element; 4-Two-dimensional element connecting solid element and plate / shell element; 5-Universal joint; 6-Splined shaft; t-Thickness. Detailed Implementation

[0028] It should be noted that in the description of this invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; a connection can be a mechanical connection or an electrical connection; a link can be a direct connection or an indirect connection through an intermediate medium, and 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 according to the specific circumstances.

[0030] A finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft, the specific steps of which are as follows:

[0031] Step 1: Prepare data for finite element modeling and modal analysis of the drive shaft. Detailed three-dimensional geometric parameters of the drive shaft assembly should be provided, and the names of each component should be listed. The geometric model of the drive shaft assembly includes components such as the drive shaft tube, universal joint, and connecting flange.

[0032] Step 2: Obtain the main material parameters of each component of the drive shaft, including the material grade, elastic modulus E, Poisson's ratio μ, and density ρ of each component. Refer to Table 1.

[0033] Table 1 Material Parameter List

[0034]

[0035] Step 3: Establish the finite element model of the drive shaft assembly, and assemble the various components according to the actual situation. Flanges and universal joint shaft heads use tetrahedral second-order solid elements and hexahedral first-order solid elements, while the shaft tube uses quadrilateral shell elements. The connection between solid elements and shell elements uses massless two-dimensional elements. The finite element mesh needs to meet the following requirements:

[0036] Tetrahedral second-order solid elements and hexahedral first-order solid elements should satisfy the following requirements:

[0037] The part should be divided into at least 2 layers of units in the thickness direction. The recommended solid unit size is 3mm and the maximum solid unit size is <6mm.

[0038] 95% of solid elements have an aspect ratio < 5, which does not meet the requirement that the maximum solid element size is < 10;

[0039] 95% of solid elements have a warpage angle <7°, which does not meet the requirement that the maximum warpage angle of solid elements is <10°;

[0040] 95% of solid elements have a twist angle <30°, which does not meet the requirement that the maximum twist angle of solid elements is <45°;

[0041] 95% of solid elements have a cone angle >80%, which does not meet the requirement that the minimum solid element cone angle is ≥60%.

[0042] The quadrilateral plate shell unit should meet the following requirements:

[0043] The number of quadrilateral shell elements is greater than 95%, and the number of triangular shell elements is less than 5%.

[0044] The recommended size for quadrilateral plate housing units is 3mm, and the maximum size for plate housing units is <6mm.

[0045] 95% of the quadrilateral shell units have a warping angle of <7°, and all shell units have a warping angle of <10°;

[0046] 95% of the quadrilateral shell units have an aspect ratio of <5, and all shell units have an aspect ratio of <7.

[0047] 95% of the quadrilateral shell units have a torsion angle of <30°, and all shell units have a torsion angle of <40°;

[0048] 95% of the quadrilateral shell elements have a Jacobian side length of <0.7, and all shell elements have a Jacobian side length of <0.3;

[0049] 95% of the quadrilateral shell units have a taper of <0.7, and all shell units have a taper of <0.8;

[0050] 95% of the quadrilateral shell units have a maximum angle < 120°, which does not meet the requirement that the maximum angle of the shell unit must be less than 135°.

[0051] Step 4: Massless 2D element modeling. During the finite element modeling of the structure, the 2D elements at the connection points are located in the middle of the solid element structure. Massless 2D element modeling reference. Figure 1 .

[0052] Figure 2 The parameters of the virtual plate shell element are as follows: Eb = E, Em = Es = 10% E, TT = t, ρ1 = 0.

[0053] Step 5: Coordinate System and Unit Settings

[0054] A local coordinate system is set for the finite element model. A local coordinate system is set for each universal joint position. For ease of application in engineering, the model unit specifications are shown in Table 2.

[0055] Table 2 Model Units

[0056]

[0057] Step 6: The universal joint uses spring units, and the spring unit stiffness is shown in Table 3. Establish a local coordinate system, with the drive shaft axis as the X-direction, the direction parallel to the ground along the vertical shaft tube as the Y-direction, and the right-hand rule to determine the Z-direction. Define K1 to K6 as the X, Y, Z translational directions and X, Y, Z rotational directions, respectively, where K1 to K3 are in N / mm and K4 to K6 are in N·mm / rad. For different universal joints, spring stiffness constraints are used; stiffness parameters are referenced in Table 1.

[0058] Table 3 Spring Stiffness Parameters

[0059] Simplified spring for constant velocity fixed universal joint <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> 0 <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> Simplified spring of constant velocity universal joint 0 <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> 0 <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> Simplified spring for non-uniform velocity fixed universal joint <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> 0 <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> Flexible disc universal joint Actual measurement <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]> Actual measurement <![CDATA[1E 6 ]]> <![CDATA[1E 6 ]]>

[0060] Step 7: Model assembly. Assemble each component according to the actual structure and simplified method of the drive shaft. Refer to the assembly diagram. Figure 2 .

[0061] Step 8: Rigid constraints are applied to both ends of the drive shaft, refer to... Figure 2 .

[0062] Step 9: After solid mesh modeling is complete, the following checks need to be performed on the finite element model of the part when outputting the model:

[0063] Check the geometry cleanup information; the finite element model does not contain geometric information such as lines and surfaces.

[0064] Inspect the internal unit connections of the part;

[0065] Check for duplicate units;

[0066] Check the material properties of the parts;

[0067] Check the quality and other information of the parts; the difference from the geometric sample in the 3D modeling software should be within 3%.

[0068] Step 10: For the two-dimensional elements of the model shaft tube, assign material name, two-dimensional element thickness, Young's modulus, Poisson's ratio, and density. For solid elements, assign material name, Young's modulus, Poisson's ratio, and density.

[0069] Step 11: Assign the set material parameters to the part properties, and assign the material properties to each component.

[0070] Step 12: Set the calculation range to extract modal parameters within the range of 1Hz to 2000Hz, and set the displacement as the output parameter.

[0071] Step 13: Output the completed finite element model in the file format required by the solver software.

[0072] Step 14: Submit modal calculation to complete the solution of the set modal parameters. The modal frequencies and mode shapes within 2000Hz are identified by the post-processing software, and the modal frequencies, the differences between two adjacent modal frequencies, the mode shapes, and the mode shape descriptions are listed. The modal calculation results of the drive shaft assembly are shown in Table 4.

[0073] Table 4 Modal calculation results of the drive shaft assembly

[0074] 1 2 ……

[0075] This invention patent is a technical means. Steps 1 to 14 and Figure 3 The workflow diagram illustrates the entire work process and sequence. Table 1 records the parameters that different drive shaft design departments need to submit for this invention patent. Table 2 shows the closed units used in the finite element modeling process, providing a reference unit. Table 3 provides a reference that can achieve good consistency between the finite element model calculation results and experimental results.

[0076] The calculation flowchart details the steps of finite element modeling for modal calculation of the transmission shaft's elastic body, a key innovation of this invention. While similar flowcharts exist in reference patents, their descriptions are less detailed and specific. The simplified stiffness parameters of the spring are central to this invention, serving as crucial guarantees for consistency between modal calculation and experimental results. These parameters are key parameters provided in the simplified assembly modeling process for universal joints with different structures, ensuring the accuracy and reliability of the elastic body's modal calculations. The virtual element parameter settings used at the connection points between finite element solid elements and two-dimensional plate / shell elements are unique to this invention.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft, characterized in that, Includes the following steps: S1 acquires the geometric model and data of the drive shaft assembly, including: shaft tube, universal joint, splined shaft and flange; S2 establishes a finite element model of the drive shaft assembly: the shaft tube is simulated using quadrilateral plate shell elements, the universal joint is simulated using spring elements, the spline shaft is simulated using hexahedral first-order or tetrahedral second-order solid elements, the flange is simulated using hexahedral first-order or tetrahedral second-order solid elements, and the connection between solid elements and plate shell elements is simulated using massless two-dimensional elements. The solid unit is divided into at least two layers of units in the thickness of the split part; the solid unit size is <6 mm; the solid unit aspect ratio is <10; the solid unit warpage angle is <10°; the solid unit twist angle is <45°; and the solid unit cone angle is ≥60%. The shell unit meets the following requirements: number of shell units > 95%, shell unit size < 6 mm, shell unit warping angle < 10°, shell unit aspect ratio < 7, shell unit twist angle < 40°, shell unit Jacobian side < 0.3, shell unit taper < 0.8, and maximum shell angle < 135°. S3 sets the coordinate system, places the model established in step S2 into the corresponding position of the coordinate system, and simulates the connection form of the actual transmission shaft; S4 places the spring element into the coordinate system of S3 and defines the orientation and stiffness of the spring element; The spring unit includes: constant velocity fixed universal joint spring, constant velocity moving universal joint spring, non-constant velocity fixed universal joint spring and flexible disk universal joint spring. All springs are simulated using massless zero-dimensional elements, and each spring is set with stiffness in six directions from K1 to K6. The S5 finite element model is assembled, and rigid constraints are used at both ends of the drive shaft. S6 inputs the data from S1 into the model, and the model is now complete.

2. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 1, characterized in that, In step S1, the data includes: design quality, material grade, and material.

3. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 2, characterized in that, The material grade includes: material elastic modulus E, material Poisson's ratio μ, and material density ρ.

4. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 1, characterized in that, In step S2, the solid unit size is 3mm, 95% of the solid units have an aspect ratio <5, 95% of the solid units have a warp angle <7°, 95% of the solid units have a twist angle <30°, and 95% of the solid units have a cone angle >80%.

5. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 1, characterized in that, In step S2, the shell unit meets the following requirements: the shell unit size is 3mm, 95% of the shell unit warping angle is <7°, 95% of the shell unit aspect ratio is <5, 95% of the shell unit twist angle is <30°, 95% of the shell unit Jacobian side is <0.7, 95% of the shell unit taper is <0.7, and 95% of the shell unit maximum angle is <120°.

6. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 1, characterized in that, In step S4, the axial direction of the transmission shaft tube is X-direction, the direction of the vertical shaft tube parallel to the ground is Y-direction, and the Z-direction is determined by the right-hand rule. K1 to K6 are defined as the translational stiffness in the X, Y, and Z directions and the rotational stiffness in the X, Y, and Z directions, respectively. The units of K1 to K3 are N / mm, and the units of K4 to K6 are N·mm / rad.

7. The finite element modeling method for modal calculation of the elastic body of a passenger vehicle driveshaft as described in claim 1, characterized in that, In step S6, after the data is entered into the model, the finite element model is checked, including: checking the geometric cleanup information, ensuring that the finite element model does not contain line or surface geometric information; checking the internal unit connections of the part; checking for duplicate units; checking the material properties of the parts; and checking the part quality information, ensuring that it differs from the geometric sample in the 3D modeling software by no more than 3%.

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