Arbitrary thread form hexahedral mesh modeling method based on parameterized control

Abstract

The invention discloses an arbitrary thread form hexahedral mesh modeling method based on parameterization control, and relates to the technical field of bolt modeling. Decomposing the tooth profile of the complete pitch cycle corresponding to the target tooth angle into a plurality of feature line segments, converting the curve profile corresponding to each feature line segment into a solvable geometrical relationship, and determining a mathematical relationship of any point coordinate on the profile corresponding to each feature line segment; integrating the mathematical relationships corresponding to the feature lines to obtain an external thread curve formula of the target thread angle; parameterizing an external thread curve formula of the target thread angle through an equation driving curve function in SOLIDWORKS software to obtain an external thread profile curve of the target thread angle bolt; and based on the external thread profile curve of the target thread angle bolt, drawing a two-dimensional plane grid of the bolt, and further obtaining a three-dimensional thread hexahedral grid of the target thread angle bolt. By means of the method, modeling of any thread form can be achieved, and the application range of finite element analysis is greatly expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bolt finite element modeling, and particularly relates to a hexahedral mesh modeling method of arbitrary thread form based on parameterized control. BACKGROUND

[0002] At present, the fine and simplified finite element modeling method for bolt connection can consider the contact, friction, gap and other influences between the bolt, nut and connecting piece at the same time, so that the calculation is more accurate. However, in actual engineering, due to the large number of bolt connections and the very small feature size of the bolt, the local mesh is too small, the calculation amount is large, and it is difficult to converge.

[0003] In the prior art, the fine finite element model of bolt connection includes a three-dimensional cylindrical model, an axisymmetric model containing threads (without thread angle) and a three-dimensional spiral model considering thread angle. However, most of the existing hexahedral thread modeling methods are for standard symmetric thread forms (such as 60° arc bottom thread), and the three-dimensional cylindrical model and the axisymmetric model do not consider the spiral angle effect, and can only perform finite element calculation on the bolt, and cannot perform numerical simulation on the bolt loosening. However, the bolt model with spiral angle can better reflect the loosening caused by the relative movement of the bolt and the nut, but the existing method cannot model it efficiently.

[0004] Therefore, how to establish a general thread form modeling method is a technical problem to be solved. SUMMARY

[0005] Therefore, it is necessary to provide a hexahedral mesh modeling method of arbitrary thread form based on parameterized control in view of the above technical problems.

[0006] The present application adopts the following technical solutions: The present application provides a hexahedral mesh modeling method of arbitrary thread form based on parameterized control, comprising: The thread profile of the complete pitch period corresponding to the target thread angle is divided into a plurality of characteristic line segments, and the curve profile corresponding to each characteristic line segment is converted into a solvable geometric relationship, and the mathematical relationship of the coordinates of any point on the profile corresponding to each characteristic line segment is determined. The mathematical relationship of each characteristic line is integrated to obtain the external thread curve formula of the target thread angle; The external thread profile curve of the target thread angle bolt is obtained by parameterizing the external thread curve formula of the target thread angle through the equation-driven curve function in the SOLIDWORKS software. The outer thread profile curve of the target tooth angle bolt is introduced into the HYPERMESH software, and a circular curve is drawn with a preset threshold as a radius; the circular curve and the outer thread profile curve of the target tooth angle bolt form a circular ring; the preset threshold is smaller than the distance from the outer thread profile large diameter of the target tooth angle bolt to the center of the circular ring; A two-dimensional plane grid of the bolt is obtained by drawing the grid inside the circular ring; The two-dimensional plane grid is subjected to translation and rotation operations to obtain a three-dimensional thread hexahedral grid of the target tooth angle bolt.

[0007] Optionally, the target tooth angle is a 75° asymmetric tooth angle; the outer thread curve formula of the 75° asymmetric tooth angle is: wherein, is the distance between the axis and the thread root; is the thread large diameter; is the thread root height; is the pitch; is the polar angle.

[0008] Optionally, the two-dimensional plane grid is subjected to translation and rotation operations to obtain a three-dimensional thread hexahedral grid of the target tooth angle bolt, including: placing the two-dimensional plane grid at z axis = 0 and counterclockwise rotating 2π / θ by the target tooth angle; n translating it to the position of z axis = h and z axis = 0; P / n ; n is the number of layers of the stacked planes in one pitch; P is the pitch; connecting the nodes of the two-dimensional plane grid at z axis = 0 and z axis = P / n to obtain a three-dimensional model with a thickness of P / n ; repeating the establishment of n three-dimensional models with a thickness of P / n ; n stacking the three-dimensional models to obtain a three-dimensional thread hexahedral grid.

[0009] Optionally, the method further includes: according to the number of threads connected by the target tooth angle bolt, the three-dimensional thread hexahedral grid is subjected to translation and replication to obtain a pitch model; constructing a three-dimensional model of the bolt shank and the bolt head; The three-dimensional models of the bolt shank and bolt head, as well as the pitch model, are assembled to obtain the hexahedral mesh model of the target threaded angle bolt.

[0010] Optionally, the method further includes: The interior of the bolt hexahedral mesh model is filled with a transition mesh shaped like a petal at the center.

[0011] This invention provides a device for modeling arbitrary thread profile hexahedral meshes based on parametric control, comprising: The acquisition module is used to decompose the tooth profile of the complete pitch cycle corresponding to the target tooth profile angle into multiple feature line segments, and transform the curve profile corresponding to each feature line segment into a solvable geometric relationship, determine the mathematical relationship of the coordinates of any point on the profile corresponding to each feature line segment, and integrate the mathematical relationship corresponding to each feature line to obtain the external thread curve formula of the target tooth profile angle. The parameterization module is used to parameterize the formula for the external thread curve of the target tooth angle using the equation-driven curve function in SOLIDWORKS software, so as to obtain the external thread profile curve of the bolt with the target tooth angle. The module is used to import the external thread profile curve of the target thread angle bolt into the HYPERMESH software and draw a circular curve with a preset threshold as the radius. The circular curve and the external thread profile curve of the target thread angle bolt form an annulus. The preset threshold is less than the distance between the major diameter of the external thread profile of the target thread angle bolt and the center of the annulus. The internal mesh of the annulus is drawn to obtain the two-dimensional planar mesh of the bolt. The two-dimensional planar mesh is translated and rotated to obtain the three-dimensional thread hexahedral mesh of the target thread angle bolt.

[0012] The present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for modeling arbitrary thread profile hexahedral meshes based on parameterized control.

[0013] The present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for modeling arbitrary thread profile hexahedral meshes based on parameterized control.

[0014] The above-mentioned at least one technical solution adopted in this invention can achieve the following beneficial effects: In this invention, when modeling a target thread angle bolt, the thread profile of the complete pitch period corresponding to the target thread angle is decomposed into multiple feature line segments. The curve profile corresponding to each feature line segment is transformed into a solvable geometric relationship, and the mathematical relationship for the coordinates of any point on the profile corresponding to each feature line segment is determined. Integrating the mathematical relationships corresponding to each feature line segment yields the external thread curve formula for the target thread angle. Then, using the equation-driven curve function in SOLIDWORKS software, the external thread curve formula for the target thread angle is parameterized, thus obtaining the external thread profile curve of the target thread angle bolt. Based on the external thread profile curve of the target thread angle bolt, a three-dimensional thread hexahedral mesh of the target thread angle bolt is constructed. This method, through parameterized control of the curve formula for external threads with arbitrary thread angles, enables accurate modeling of arbitrary thread profiles, greatly expanding the applicability of finite element analysis. Attached Figure Description

[0015] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0016] Figure 1 A schematic diagram of the process for a method of modeling an arbitrary thread profile hexahedral mesh based on parametric control provided by the present invention; Figure 2 A flowchart of a basic method for bolt modeling in FUKUOKA provided by this invention; Figure 3 A schematic diagram of the axial profile of a thread tooth profile provided by the present invention; Figure 4 A schematic diagram of the axial profile of a thread with a 75° asymmetric tooth angle is provided for this invention. Figure 5 A schematic diagram of a thread cross-section along the central axis of a bolt, provided for the present invention; Figure 6 A schematic diagram of the outline of an external thread provided by the present invention; Figure 7 A profile curve of the thread root provided by the present invention; Figure 8 A schematic diagram of the tooth base contour provided by the present invention; Figure 9 A schematic diagram of another thread cross-section along the central axis of the bolt provided by the present invention; Figure 10 A schematic diagram of another thread cross-section along the central axis of the bolt provided by the present invention; Figure 11A schematic diagram of a SOILDWORKS formula modeling interface provided by the present invention; Figure 12 A schematic diagram of a SOILDWORKS formula modeling interface provided by the present invention; Figure 13 A schematic diagram of a ring formed by a circular curve and an external thread profile curve provided by the present invention; Figure 14 A schematic diagram of an external thread planar mesh provided by the present invention; Figure 15 A schematic diagram of a three-dimensional threaded hexahedral mesh provided by the present invention; Figure 16 A schematic diagram of a hexahedral mesh model of a 75° asymmetric tooth profile angle bolt provided by the present invention; Figure 17 A schematic diagram of the transverse cross-section of a bolt head provided for this invention; Figure 18 A schematic diagram of a hexahedral mesh model of a 60° pointed bottom threaded angle bolt provided by the present invention; Figure 19 A schematic diagram of a hexahedral mesh model of a 60° flat-bottomed threaded angle bolt provided by the present invention; Figure 20 A schematic diagram of a hexahedral mesh model of a 90° right-angle threaded corner bolt provided by the present invention; Figure 21 This invention provides a schematic diagram of a computer device for implementing a parametric control-based method for modeling arbitrary thread profile hexahedral meshes. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] Currently, simplified models of bolted connections are mainly divided into beam models and bilinear elastic models. Under lateral loads, the beam model does not exhibit axial dynamic response. Based on this, Luan Yu introduced a nonlinear spring, performed nonlinear modeling, and conducted dynamic experiments to verify more accurate simulation results. Lu Xu, based on the above research, established a simplified model of a three-degree-of-freedom mass-spring system with shear pins and analyzed it. Kang Guidong used PATRAN's Fastener function to simulate bolted connections in structures and analyzed the established model through modal experiments. The results show that the established finite element model can well reflect the dynamic characteristics of the structure. Gray constructed connection constraints between bolts and beams respectively and studied the influence of bolt spacing on the load distribution of multiple bolts.

[0019] In recent years, numerical simulation of the strength and stress distribution of threaded components using the finite element method has seen increasing applications. Detailed modeling of bolted connections has gradually come into focus. Threaded fasteners possess unique mechanical properties, primarily due to the helical structure of the threaded pair. Currently, bolt modeling methods are mainly divided into two types: models with and without threads. Bolts without threads are not the focus of this paper. Two main three-dimensional finite element models are used to study the mechanical properties of threaded joints:

[0020] (1) Free tetrahedron model generated by commercial software.

[0021] Commercial software-generated tetrahedral meshes, due to their geometric complexity, exhibit random mesh scales, shapes, and positions, making them prone to misalignment and deformation. Furthermore, when analyzing threaded fasteners, the stress concentration and contact pressure considerations differ between the finite element models generated by various commercial software programs. Therefore, considering the influence of helix angle on thread characteristics and the complexity of its modeling, it is essential to research a high-precision and easy-to-model thread modeling method.

[0022] (2) FUKUOKA's modeling method for hexahedral precise threads This thread modeling method has not been extended to more thread angles, and the standard 60° rounded bottom thread angle has weak anti-loosening performance. Now, we will promote the thread modeling method pioneered by FUKUOKA, analyzing this modeling approach to extend it to obtain arbitrary bolt thread angles. Taking a relatively complex bolt model with an M10 size and 1.5mm pitch and a 75° asymmetric thread angle—a model with practical production value—as an example, we will elaborate on the modeling process of a 75° asymmetric thread angle bolt.

[0023] 2. The technical content disclosed in the prior art should be objectively evaluated for its defects, problems, and the reasons for these problems; (1) Currently, bolt modeling methods are mainly divided into two types: those with threads and those without. Bolts without threads are not the focus of this paper; bolt modeling methods with threads mainly include...

[0024] Two-dimensional mesh sweeping method: The geometry of a bolt thread can be regarded as the result of sweeping a two-dimensional profile along its axis. A corresponding three-dimensional mesh is generated by "sweeping" or "stretching" an existing two-dimensional mesh along a specific path or direction.

[0025] Mapping method: This method maps an existing mesh onto another geometry through a geometric transformation. In the generation of bolt thread meshes, the mapping method can be used to create complex thread geometries without manually meshing every detail.

[0026] The split thread surface method is particularly suitable for complex thread shapes that are difficult to mesh using traditional methods. The basic idea of ​​the split thread surface method is to divide the surface of the thread into multiple independently processable parts, use the created reference nodes, intersection lines, and planar meshes as boundary conditions to mesh each part separately, and finally recombine these parts into a complete thread mesh.

[0027] FUKUOKA's precise modeling method will be explained in detail below.

[0028] (2) All of these methods have some drawbacks, for example: Two-dimensional mesh sweeping is a simple and effective method for creating threaded hexahedral meshes. It is particularly suitable for bolt models with relatively simple geometry and small variations in cross-sectional area. However, for bolts with drastic or irregular cross-sectional changes, sweeping may be difficult to apply and may fail to capture all important details. After sweeping, the mesh needs to be inspected and optimized to prevent mesh distortion.

[0029] The mapping method (mesh deformation) for creating thread finite element models is a relatively simple way to generate thread meshes. It does not have requirements on the thread profile and can quickly generate thread meshes. However, its thread mesh is based on an internal cylindrical mesh, and complex deformation operations can consume a lot of computational resources, especially when dealing with high-resolution models. The adaptability and accuracy of thread meshes are relatively poor.

[0030] The thread face splitting method is a basic thread mesh generation technique. It can create a hexahedral mesh of the mating body, aligning mesh nodes at the thread mating surfaces, which is more complex than creating a separate thread mesh. This method can perform hexahedral mesh generation for complex thread bodies, improving computational accuracy. However, the processes of splitting the thread face and creating equidistant points are tedious and labor-intensive, requiring multiple repetitions.

[0031] FUKUOKA's precise modeling method for thread structures offers excellent results and high accuracy in analysis. However, it has not been extended to more threaded angle bolts.

[0032] Existing thread modeling methods have the following shortcomings: (1) Problem of insufficient applicability of tooth type Existing methods for modeling hexahedral threads are mostly designed for standard symmetrical thread profiles (such as 60° circular arc bottom threads), making it difficult to extend to arbitrary thread profiles. In engineering, asymmetrical thread profiles (such as 75° asymmetrical thread profiles), sawtooth thread profiles, and trapezoidal thread profiles have higher anti-loosening performance and practical application value, but existing methods cannot efficiently model them. Therefore, how to establish a universal, parameterizable thread profile modeling method is an urgent technical problem to be solved.

[0033] (2) Mesh quality and accuracy issues Commercial software-generated tetrahedral meshes are prone to distortion and misalignment, and their random size leads to inaccurate contact conditions in the meshing zone. This can introduce significant errors in calculations of stress concentration and contact pressure distribution, affecting the reliability of simulation results. A method is needed to generate high-quality hexahedral meshes that ensure uniform and regular meshing in the meshing zone, thereby improving computational accuracy.

[0034] (3) Modeling efficiency and computational cost issues While a detailed 3D helical model can reflect the thread helix angle, the geometric construction and mesh generation process is extremely complex, time-consuming, and inefficient. In practical engineering, the number of bolts is enormous; if each bolt is modeled in detail individually, the computational load is too large, and convergence is difficult, severely limiting engineering applications. Therefore, a fast and automated modeling method is needed to reduce the complexity of manual operations and improve modeling efficiency.

[0035] (4) Problem of insufficient applicability of simulation Simplified models (such as beam models and bilinear elastic models) cannot accurately reflect the stress state and meshing mechanism of threaded pairs, especially failing to accurately simulate thread loosening and anti-loosening performance. This results in a lack of reliable model support for numerical simulation of threaded connections under complex working conditions (lateral vibration, impact loads). Therefore, it is necessary to establish a modeling method that can both reflect the true tooth profile meshing characteristics and be used for large-scale simulations.

[0036] (5) Problems with insufficient model scalability and generality Existing methods lack parametric design capabilities, often requiring modeling from scratch for different thread profiles, making them difficult to generalize and reuse. A reusable modeling platform is lacking when studying thread pairs of different sizes and profiles. There is a need to develop a parametrically controlled modeling method that can flexibly adapt to various thread specifications and thread angles, improving the model's versatility and scalability.

[0037] Based on this, the present invention provides a method for modeling arbitrary thread profile hexahedral meshes based on parametric control. This method can support the modeling of thread pairs with different specifications and arbitrary thread angles, ensure the quality of hexahedral meshes, simplify the modeling process, and improve efficiency and accuracy, thereby providing reliable support for the refined finite element analysis, loosening mechanism research, and anti-loosening performance evaluation of bolted connection structures.

[0038] The method provided by this invention is applicable to the modeling process of arbitrary tooth angles. Taking a thread with a 75° asymmetric tooth angle and its parametric modeling method as an example, it differs from the traditional method of first establishing a geometric model and then meshing it, which has lower accuracy. This method can not only create threads with a 75° asymmetric tooth angle, but also, after extension, can create threads with arbitrary tooth profiles and sizes.

[0039] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] Figure 1 This is a schematic diagram of a method for modeling an arbitrary thread profile hexahedral mesh based on parametric control according to the present invention, which specifically includes the following steps: S101, decompose the tooth profile of the complete pitch period corresponding to the target tooth profile angle into multiple feature line segments, and transform the curve profile corresponding to each feature line segment into a solvable geometric relationship, determine the mathematical relationship of the coordinates of any point on the profile corresponding to each feature line segment; integrate the mathematical relationship corresponding to each feature line to obtain the external thread curve formula of the target tooth profile angle.

[0041] By promoting FUKUOKA's precise thread geometry modeling method, taking a conventional 60° circular arc thread angle as an example, the corresponding bolt is obtained. This modeling approach and the forming process of a conventional 60° circular arc thread angle are analyzed to facilitate its application in obtaining bolt thread angles of arbitrary shapes. The basic method and flow of FUKUOKA bolt modeling are as follows: Figure 2 As shown.

[0042] First, obtain the required thread specification for modeling and compare it with the national standard GBT5782-2000 for hexagonal head bolts. Based on the thread modeling method created by FUKUOKA, derive the curve formula for external threads with arbitrary tooth angles. Specifically, this includes:

[0043] like Figure 3 As shown, Figure 3This is a schematic diagram of the axial profile of a thread profile. The red curve represents the thread profile image, and the vertical axis θ represents a complete pitch of 2π. A, B, C, D, and E represent five nodes of the thread outer profile curve. AB, BD, CD, and DE represent four curve segments with different curvatures. The arc is divided into four segments, each representing a different formula. α and β are derived definitions, mainly expressing this asymmetrical thread angle. The asymmetry is reflected in the horizontal plane; after the root is separated, the upper and lower ends have different angles, and this thread angle is oblique. L1 and L2 are the lengths of this oblique angle, r is the distance of the bolt outer profile from the axis, 2 / D is the distance of the bottom of the thread root from the axis, and d is the major diameter of the thread.

[0044] Depend on Figure 3 It can be seen that angles α and β satisfy: (1) (2) (1) Segment A~B: At point A~B, the polar radius r is a constant value, that is: (3) Where: the polar angle θ1 at point B can be expressed as: (4) (2) Segment B~C: Since the polar radius changes linearly in segment B~C, let the polar radius r and the polar angle θ satisfy the following relationship: (5) It is known that at point B, the following conditions are met: (6) At point C, the following condition is satisfied: (7) Substituting the relation, we can solve for: (8) (9) (3) Segment C~D: Since the polar radius of segment C~D still changes linearly, we still assume that the polar radius and polar angle satisfy the following relationship: (10) Where θ2 is the polar angle corresponding to point D, it can be expressed as: (11) It is known that at point C, the following conditions are met: (12) At point D, the following condition is satisfied: (13) Substituting the above relation, we get: (14) (15) (4) Segment D~E: Since the polar radius is a constant value, therefore: (16) Extreme value analysis Given that d > D, in order to ensure that point B does not coincide with point A, the following must be satisfied: (17) Solving for: (18) Similarly, in order to ensure that point D does not coincide with point E, the following must be satisfied: (19) Solving for: (20) Based on the above formula and geometric relationships, formula (21) can be derived for an external thread with a 75° asymmetric thread angle. The formula for the external thread curve with a 75° asymmetric thread angle is:

[0045] (twenty one) in, This is the distance between the axis and the root of the thread; For the major diameter of the thread; This refers to the height of the thread root. Pitch; This is the polar angle. For example... Figure 4 As shown, Figure 4 This is a schematic diagram of a thread profile with a 75° asymmetric tooth angle.

[0046] In one embodiment, this embodiment provides a specific derivation process: like Figures 5-8 As shown, Figure 5 A schematic diagram of a thread cross-section along the central axis of a bolt, provided for the present invention; Figure 6 A schematic diagram of the outline of an external thread provided by the present invention; Figure 7 Outer contour curve corresponding Figure 6 The red arc in the middle (is the contour curve of the thread root). Figure 8 The right tooth base contour corresponds Figure 5 The thickened black section shows the shape of the tooth base.

[0047] Figure 5 The corresponding formula for the external thread curve is: (twenty two) in, The radius of the tooth root arc, , , , , .

[0048] ① First, investigate Figure 5 Correspondence with formula (22): Figure 7 Outer contour curve corresponding Figure 6 The red arc in the middle (is the contour curve of the thread root). Figure 8 The right tooth base contour corresponds Figure 5 The thickened black section shows the shape of the tooth base. Figure 5 and Figure 6 These represent the distribution characteristics of the thread profile curve in the axial and radial directions, respectively. It is mainly divided into 6 segments: AB, BC, CD, DE, EF, and FG, corresponding to... Figure 5 and Figure 6 It is divided into 6 segments.

[0049] ② Indicate the meaning of each letter: d—Major diameter of the thread (nominal diameter) Figure 6 The diameter of the black circle in the middle; P—Pitch, Figure 5 The height of the middle AG; H—Thread root height; ρ—radius of the tooth root arc; r—the distance between the axis and the root of the thread.

[0050] ③ Derive the formulas for the six curve segments respectively, such as Figure 5 As shown, along θ = π To achieve a symmetrical shape, the derivation of a 6-segment curve can be simplified to a 3-segment curve. Taking the lower half of the symmetrical section as an example: 1) A-B The distance from the major diameter portion of the thread to the axis is 2 / d.

[0051] 2) B-C We need to construct red auxiliary lines, such as Figure 9 As shown. Using similar triangles, the expression for the length of the red auxiliary line is: Since the total distance from the axis is 2 / d, the derived formula is: .

[0052] 3) C - D Parts, such as Figure 10As shown, three auxiliary lines—red, green, and yellow—are constructed. Based on similar triangles and the geometric relationships within triangles and circles, this part of the formula is derived.

[0053] ④ For any thread profile, deduce the source of the formula. Based on the corresponding target thread profile, first draw the following... Figure 5 Based on the above derivation method, the formula for the external thread curve with the target tooth profile angle is derived from the axial tooth profile diagram.

[0054] S102, using the equation-driven curve function in SOLIDWORKS software, the formula for the external thread curve of the target tooth angle is parameterized to obtain the external thread profile curve of the bolt with the target tooth angle.

[0055] The target tooth angle can be any angle and any tooth shape.

[0056] Taking a 75-degree asymmetric thread angle as an example, the equation-driven curve function in SOLIDWORKS software is used to input the derived curve formula in a parametric form to model the external thread profile curve of a 75-degree asymmetric thread angle bolt.

[0057] like Figure 11 As shown, Figure 11 A schematic diagram of the SOILDWORKS formula modeling interface.

[0058] S103, import the external thread profile curve of the target thread angle bolt into the HYPERMESH software, and draw a circular curve with a preset threshold as the radius; the circular curve and the external thread profile curve of the target thread angle bolt form a ring; the preset threshold is less than the distance between the major diameter of the external thread profile of the target thread angle bolt and the center of the ring.

[0059] Import the external thread profile curve of the 75-degree asymmetric thread angle bolt into the HYPERMESH software. For example... Figure 12 As shown, Figure 12 This is a schematic diagram of the profile curve of an M10 external thread. The inner arc curve is the external thread profile curve of the bolt with a precise geometric shape, and the inner circular curve is the major diameter of the bolt as a reference curve.

[0060] In one embodiment, the distance from the major diameter of the external thread profile to the center is 5mm. Therefore, a circular curve with a radius of 3.5mm is drawn to form a ring with the external thread profile curve, as shown below. Figure 13 As shown.

[0061] S104: Draw the internal mesh of the ring to obtain the two-dimensional planar mesh of the bolt; perform translation and rotation operations on the two-dimensional planar mesh to obtain the three-dimensional thread hexahedral mesh of the target thread angle bolt.

[0062] The two-dimensional planar mesh of the bolt is the external thread planar mesh, such as... Figure 14 As shown, Figure 14 This is a schematic diagram of an external thread planar mesh.

[0063] In one embodiment, translating and rotating a two-dimensional planar mesh to obtain a three-dimensional threaded hexahedral mesh of the target threaded angle bolt includes: placing the two-dimensional planar mesh at z-axis = 0 and rotating it counterclockwise by 2π / n Translate it to z axis = P / n Position; set z-axis = 0 and z axis = P / n Connect the nodes of the two-dimensional planar mesh at the specified location to obtain a thickness of... P / n Three-dimensional model; repeatedly build n Each thickness is P / n The three-dimensional model will n The three-dimensional models are superimposed to obtain a three-dimensional spiral hexahedral mesh. n The number of layers in a stacked plane at one pitch; P The pitch is the screw pitch.

[0064] In this embodiment, the helix angle of the thread is accurately simulated on a discrete grid level by spiral motion around the Z-axis (decomposed into "rotation 2π / n" + "translation P / n"). Through tiny rotations and translations in each layer, an accurate spiral surface is finally accumulated, with high geometric fidelity.

[0065] like Figure 15 As shown, Figure 15 This is a schematic diagram of a three-dimensional threaded hexahedral mesh.

[0066] In one embodiment, based on the number of threads in the target threaded angle bolt connection, the three-dimensional thread hexahedral mesh is translated and copied to obtain the pitch model; three-dimensional models of the bolt shank and bolt head are constructed; the three-dimensional models of the bolt shank and bolt head, as well as the pitch model, are assembled to obtain the target threaded angle bolt hexahedral mesh model.

[0067] In this embodiment, by breaking down the complex overall bolt task into several simple sub-tasks, a set of efficient, reliable, and reusable high-quality bolt mesh creation standard processes are provided.

[0068] After drawing the other parts, fill the interior of the bolt with a hexahedral mesh, and then fill the interior of the bolt's hexahedral mesh model with a petal-shaped transition mesh at the center. Using a petal-shaped transition mesh at the center reduces the impact of distorted meshes and reduces the number of meshes, thus improving computational speed.

[0069] like Figure 16 As shown, Figure 16 This is a schematic diagram of a hexahedral mesh model of a 75° asymmetric tooth profile angle bolt. Figure 17 This is a schematic diagram of the transverse cross-section of the bolt head.

[0070] By extending the method of this invention, hexahedral mesh models of 60° pointed-bottom angle bolts, 60° flat-bottom angle bolts, and 90° right-angle angle bolts can also be obtained; for example... Figure 18 , Figure 19 and Figure 20 As shown, Figure 18 This is a schematic diagram of a hexahedral mesh model of a 60° pointed-bottom angle bolt. Figure 19 This is a schematic diagram of a hexahedral mesh model for a 60° flat-bottomed threaded angle bolt. Figure 20 The diagram shows a hexahedral mesh model of a 90° right-angle threaded bolt, where (a) is a schematic diagram of the axial profile of the thread and (b) is a schematic diagram of the pitch model.

[0071] The method provided by this invention has the following advantages: (1) Wider range of applications: Through parametric control, this method can not only model standard symmetrical tooth profiles (such as 60° triangular tooth), but also support asymmetrical tooth profiles, trapezoidal tooth, sawtooth tooth and other special tooth profiles, realize the modeling of arbitrary thread tooth profiles, and greatly expand the scope of application of finite element analysis.

[0072] (2) High mesh quality: The generated thread profiles are all high-quality hexahedral meshes, avoiding the distortion, twisting and size inconsistency problems commonly found in traditional free tetrahedral meshes, thus ensuring the stability and accuracy of simulation calculations. (3) Easy to integrate and automate: This method can be embedded into existing finite element modeling processes or secondary development platforms, and can be combined with batch modeling and automatic calculation to facilitate rapid analysis of bolted connections.

[0073] When applying the parameterized control-based hexahedral mesh modeling method for arbitrary thread profiles provided by this invention, it is not necessary to... Figure 1 The steps shown are executed in sequence. The specific execution order of each step can be determined as needed, and this invention does not impose any restrictions on it.

[0074] The above describes a method for modeling arbitrary thread profile hexahedral meshes based on parametric control, provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding device for modeling arbitrary thread profile hexahedral meshes based on parametric control, the device comprising: The acquisition module is used to decompose the tooth profile of the complete pitch cycle corresponding to the target tooth profile angle into multiple feature line segments, and transform the curve profile corresponding to each feature line segment into a solvable geometric relationship, determine the mathematical relationship of the coordinates of any point on the profile corresponding to each feature line segment, and integrate the mathematical relationship corresponding to each feature line to obtain the external thread curve formula of the target tooth profile angle. The parameterization module is used to parameterize the formula for the external thread curve of the target tooth angle using the equation-driven curve function in SOLIDWORKS software, so as to obtain the external thread profile curve of the bolt with the target tooth angle. The module is used to import the external thread profile curve of the target thread angle bolt into the HYPERMESH software and draw a circular curve with a preset threshold as the radius. The circular curve and the external thread profile curve of the target thread angle bolt form an annulus. The preset threshold is less than the distance between the major diameter of the external thread profile of the target thread angle bolt and the center of the annulus. The internal mesh of the annulus is drawn to obtain the two-dimensional planar mesh of the bolt. The two-dimensional planar mesh is translated and rotated to obtain the three-dimensional thread hexahedral mesh of the target thread angle bolt.

[0075] Specific limitations regarding the parametric control-based arbitrary thread profile hexahedral mesh modeling device can be found in the limitations of the parametric control-based arbitrary thread profile hexahedral mesh modeling method described above, and will not be repeated here. Each module in the aforementioned parametric control-based arbitrary thread profile hexahedral mesh modeling device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0076] The present invention also provides a computer-readable storage medium storing a computer program that can be used to execute the above-described... Figure 1 The provided method is a hexahedral mesh modeling method for arbitrary thread profiles based on parametric control.

[0077] The present invention also provides Figure 21 The schematic diagram of the computer device shown is as follows: Figure 21 As shown, at the hardware level, this computer device includes a processor, internal bus, network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into memory and then executes it to achieve the above.Figure 1 The provided method is a hexahedral mesh modeling method for arbitrary thread profiles based on parametric control.

[0078] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this invention.

Claims

1. A method for modeling arbitrary thread profile hexahedral meshes based on parametric control, characterized in that, include: The tooth profile of the complete pitch period corresponding to the target tooth profile angle is decomposed into multiple feature line segments, and the curve profile corresponding to each feature line segment is transformed into a solvable geometric relationship. The mathematical relationship of the coordinates of any point on the profile corresponding to each feature line segment is determined. The mathematical relationship corresponding to each feature line is integrated to obtain the external thread curve formula of the target tooth profile angle. The formula-driven curve function in SOLIDWORKS software is used to parameterize the formula for the external thread curve of the target tooth angle, thereby obtaining the external thread profile curve of the bolt with the target tooth angle. Import the external thread profile curve of the target thread angle bolt into the HYPERMESH software, and draw a circular curve with a preset threshold as the radius; the circular curve and the external thread profile curve of the target thread angle bolt form an annulus; the preset threshold is less than the distance between the major diameter of the external thread profile of the target thread angle bolt and the center of the circle; Draw the internal mesh of the ring to obtain the two-dimensional planar mesh of the bolt; The two-dimensional planar mesh is translated and rotated to obtain the three-dimensional thread hexahedral mesh of the target tooth profile angle bolt.

2. The method according to claim 1, characterized in that, The target tooth profile angle is a 75° asymmetric tooth profile angle; the formula for the external thread curve with a 75° asymmetric tooth profile angle is: in, This is the distance between the axis and the root of the thread; For the major diameter of the thread; This refers to the height of the thread root. Pitch; It is the polar angle.

3. The method according to claim 1, characterized in that, By performing translation and rotation operations on the two-dimensional planar mesh, a three-dimensional thread hexahedral mesh of the target thread profile bolt is obtained, including: Place the two-dimensional planar mesh at z-axis = 0, and rotate it counterclockwise by 2π / n Translate it to z axis = P / n Location; n The number of layers in a stacked plane at one pitch; P Pitch; Set z-axis = 0 and z axis = P / n Connect the nodes of the two-dimensional planar mesh at the specified location to obtain a thickness of... P / n A three-dimensional model; Repeated creation n Each thickness is P / n The three-dimensional model will n The three-dimensional models are superimposed to obtain a three-dimensional hexahedral thread mesh.

4. The method according to claim 1, characterized in that, The method further includes: Based on the number of threads in the target tooth profile angle bolt connection, the three-dimensional thread hexahedral mesh is translated and copied to obtain the pitch model; Construct three-dimensional models of the bolt shank and bolt head; The three-dimensional models of the bolt shank and bolt head, as well as the pitch model, are assembled to obtain the hexahedral mesh model of the target threaded angle bolt.

5. The method according to claim 4, characterized in that, The method further includes: The interior of the bolt hexahedral mesh model is filled with a transition mesh shaped like a petal at the center.

6. A device for modeling arbitrary thread profile hexahedral meshes based on parametric control, characterized in that, include: The acquisition module is used to decompose the tooth profile of the complete pitch cycle corresponding to the target tooth profile angle into multiple feature line segments, and transform the curve profile corresponding to each feature line segment into a solvable geometric relationship, determine the mathematical relationship of the coordinates of any point on the profile corresponding to each feature line segment, and integrate the mathematical relationship corresponding to each feature line to obtain the external thread curve formula of the target tooth profile angle. The parameterization module is used to parameterize the formula for the external thread curve of the target tooth angle using the equation-driven curve function in SOLIDWORKS software, so as to obtain the external thread profile curve of the bolt with the target tooth angle. The module is used to import the external thread profile curve of the target thread angle bolt into the HYPERMESH software and draw a circular curve with a preset threshold as the radius. The circular curve and the external thread profile curve of the target thread angle bolt form an annulus. The preset threshold is less than the distance between the major diameter of the external thread profile of the target thread angle bolt and the center of the annulus. The internal mesh of the annulus is drawn to obtain the two-dimensional planar mesh of the bolt. The two-dimensional planar mesh is translated and rotated to obtain the three-dimensional thread hexahedral mesh of the target thread angle bolt.

7. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the method as described in any one of claims 1 to 5.

8. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in any one of claims 1 to 5.

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