Parameterization finite element modeling method for bolt connection structure with threaded sleeve

Abstract

The invention provides a parameterization finite element modeling method for a bolt connection structure with a thread sleeve, which comprises the following steps of: establishing a nut and bolt blank model according to determined thread geometrical characteristics of a bolt, a nut and the thread sleeve, and moving finite element nodes of the nut and bolt blank model through a nut and bolt thread mathematical expression, generating thread characteristics of the nut and the bolt; establishing an equal-diameter spiral line along the axial direction of the bolt by taking the starting point of the bolt thread as a starting point; establishing a thread sleeve section plane according to the size of the thread sleeve, and constructing a two-dimensional surface grid unit based on the plane; the two-dimensional face grid units are swept along a spiral line to generate thread sleeve body units, and the thread sleeve body units generated after sweeping are provided with internal thread faces and external thread faces which are matched with bolt external threads and nut internal threads respectively; and establishing a complete bolt-screw sleeve-nut finite element model formed by the head of the bolt and a connected piece. By establishing the finite element models of the bolt, the nut and the thread sleeve, accurate matching between threads can be achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of bolt finite element modeling, and in particular relates to a parametric finite element modeling method for a bolt connection structure with a threaded sleeve. Background Art

[0002] Establishing a high-fidelity finite element model of bolted connections is the premise for conducting research on bolted connections. In existing research, there are some finite element modeling methods for ordinary bolts. However, the bolted connection structure with a threaded sleeve is quite different from that of an ordinary bolt, and the existing modeling methods cannot accurately model the threaded sleeve structure. Summary of the invention

[0003] In view of this, the present application aims to propose a parametric finite element modeling method for a bolt connection structure with a threaded sleeve, so as to solve the problem that the existing modeling methods are unable to carry out accurate finite element modeling of the threaded sleeve structure.

[0004] To achieve the above purpose, the technical solution of this application is implemented as follows: The present application provides a parametric finite element modeling method for a bolt connection structure with a threaded sleeve, comprising: Nut and bolt embryo models are established according to the determined thread geometry features of bolts, nuts and screw sleeves. Finite element nodes of nut and bolt embryo models are moved through mathematical expressions of nut and bolt threads to generate thread features of nuts and bolts. Take the starting point of the bolt thread as the starting point and establish a spiral line of equal diameter along the axial direction of the bolt; A screw sleeve cross-sectional plane is established according to the size of the screw sleeve, and a two-dimensional surface mesh unit is constructed based on the plane; Sweeping the two-dimensional surface mesh unit along the spiral line to generate a screw sleeve body unit, wherein the screw sleeve body unit generated after sweeping has an inner and outer thread surface, and matches the outer thread of the bolt and the inner thread of the nut respectively; The bolt head and connected parts are established to form a complete bolt-sleeve-nut finite element model.

[0005] Furthermore, according to the determined size of the screw sleeve, and the specifications of the nut and the bolt, mathematical expressions of the nuts and bolt threads of corresponding specifications are established, the mathematical expression of the external thread of the bolt corresponds to the mathematical expression of the internal thread of the screw sleeve, and the mathematical expression of the internal thread of the nut corresponds to the mathematical expression of the external thread of the screw sleeve.

[0006] Furthermore, the mathematical expression of the external thread of the bolt is: ; The mathematical expression of the internal thread of the nut is: ; in, , , , , , , , , , , , , , ; In the formula, Indicates the nominal diameter of the bolt. represents the tooth root radius, Indicates the thread working height, represents the radius of the thread feature, Indicates the number of thread layers per unit pitch, Indicates the characteristic radius of the internal thread tooth top. represents the cylindrical coordinate angle of the cross section, Indicates the azimuth after the thread lead angle, Indicates the thread pitch, represents the rotation angle, Indicates the diameter of the thread feature at this angle.

[0007] Further, the thread starting points of the nut and the bolt have the same phase angle.

[0008] Furthermore, when establishing a helix of equal diameter, the helix's rotation direction, pitch, and radius are kept consistent with the outer edge of the bolt thread.

[0009] Further, the step of establishing a cross-sectional plane of the screw sleeve according to the size of the screw sleeve and constructing a two-dimensional surface grid unit based on the plane includes: The keypoint command is used to establish key points of the screw sleeve cross section, and the key points are connected to form a closed cross-sectional plane. The cross-sectional plane is meshed using the surface mesh command of the mesh200 unit to establish a two-dimensional surface mesh for the cross-sectional plane.

[0010] Compared with the prior art, the parametric finite element modeling method of the bolt connection structure with a threaded sleeve described in this application has the following beneficial effects: The parametric finite element modeling method of the bolt connection structure with a threaded sleeve described in the present application can determine the thread geometric characteristics of the bolt, nut and threaded sleeve, and establish finite element models of the bolt, nut and threaded sleeve respectively, and achieve accurate matching between the threads, which is helpful for the subsequent research and use of the bolt connection structure with a threaded sleeve. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A flow chart of a parametric finite element modeling method for a bolt connection structure with a threaded sleeve according to an embodiment of the present application; Figure 2 This is a schematic diagram of the cross-sectional profile of the external thread of the bolt described in the embodiment of the present application; Figure 3 This is a schematic diagram of the variation of r with respect to θ in the cylindrical coordinates of the thread profile described in the embodiment of the present application; Figure 4 A schematic diagram of a cross section and a spiral line of a screw sleeve according to an embodiment of the present application; Figure 5 It is a schematic diagram of a finite element model of a screw sleeve structure described in an embodiment of the present application; Figure 6 A finite element mesh detail cross-sectional view of a complete threaded sleeve structure described in an embodiment of the present application; Figure 7 This is a schematic diagram of the finite element model of the complete threaded sleeve structure described in an embodiment of the present application. DETAILED DESCRIPTION

[0012] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0013] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0014] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0015] See also Figure 1 As shown, this embodiment provides a parametric finite element modeling method for a bolt connection structure with a threaded sleeve, which specifically includes the following steps: Step S101, establishing nut and bolt blank models according to the determined thread geometric features of the bolt, nut and screw sleeve, moving the finite element nodes of the nut and bolt blank models through the mathematical expressions of the nut and bolt threads, and generating the thread features of the nut and bolt.

[0016] Specifically, in this embodiment, the size of the threaded sleeve and the specifications of the nut and bolt are determined according to the GJB 119.4A-2015 specification, and the mathematical expressions of the nut and bolt threads of the corresponding specifications are established. It should be noted that the nut and bolt are not of the same specifications, and the nut specifications are larger than the bolt specifications.

[0017] First, the mathematical expression of the outer surface of the thread is analyzed. Any cross section perpendicular to the bolt axis at the bolt thread (except the undercut groove) has the following characteristics: Figure 2 The shapes shown here show that the cross-sections of the bolts at different locations differ only in Figure 2 On the basis of adding a certain angle, its outer contour line has experienced a complete pitch, and the relationship between the distance r from the bolt axis at different positions and the cylindrical coordinate angle θ of the cross section is as follows Figure 2 shown.

[0018] Assumptions Figure 3 The cross-sectional shape at z=0 is shown, then the outer surface of the thread at z=0 can be expressed by a piecewise function: ; in: , , , , , ; If this section is called the base surface, then another section at a distance z from the base surface has the same shape, but in the same cylindrical coordinates, the profile is rotated around the z axis by an angle. For right-hand threads, the additional rotation angle for: ; The outer surface of a complete single thread can be expressed as: ; in: , , , , , , and the outer surface equation should be periodic: ; Similarly, the helicoid of an internal thread can be expressed as: ; in: , , , , , and the equation is also periodic: .

[0019] In the formula, Indicates the nominal diameter of the bolt. represents the tooth root radius, Indicates the thread working height, represents the radius of the thread feature, Indicates the number of thread layers per unit pitch, Indicates the characteristic radius of the internal thread tooth top. represents the cylindrical coordinate angle of the cross section, Indicates the azimuth after the thread lead angle, Indicates the thread pitch, represents the rotation angle, Indicates the diameter of the thread feature at this angle.

[0020] In the above formula, taking the mathematical expression of the outer surface of the thread as an example, [0, ]、[ , ] indicates the angle range corresponding to the chamfer of the thread root, [ , ] 、[ , ] indicates the angle range corresponding to the oblique line part of the thread, [ , ] indicates the angle range corresponding to the fillet of the thread top.

[0021] Nut and bolt blank models are established. The threads of the blank models do not have thread features. The bolt appearance is a cylindrical hexahedral mesh finite element model, and the nut appearance is a circular hexahedral mesh finite element model. The specific modeling method is: in ANSYS software, first establish key points, connect the key points to form a straight line, rotate the straight line to form a sector arc surface, and stretch the circle to form a cylinder.

[0022] After determining the geometric parameters of the thread, such as the diameter, pitch, and lead angle, the mathematical expression of the thread, such as the helix equation, is used to define the path of the thread. On the blank model of the nut and bolt, the finite element nodes are moved along the thread path to form the side profile of the thread, thereby generating the thread features.

[0023] It should be noted that the established finite element model and geometric model need to be unbound before moving. The command in the ANSYS software is: NUMCMP, NODE MODMSH, DETACH. At the same time, note that the starting points of the nut and bolt threads should have the same phase angle.

[0024] Step S102: Taking the starting point of the bolt thread as the starting point, a helix of equal diameter is established along the axial direction of the bolt.

[0025] Specifically, in this embodiment, taking the starting point of the bolt thread as the starting point, an equal-diameter helix is ​​established along the axial direction of the bolt, and the rotation direction, pitch, and radius of the helix are consistent with the outer edge of the bolt thread; the helix modeling statement is: *SET,PI,3.1415926*SET,R,2.500 *SET,H,0.8*SET,N,6 *SET,ANG1,0 *SET,ANG2,360*10 *SET,HH,H*(ANG2-ANG1) / 360 *SET,DH,HH / (N-1) *SET,DA,(ANG2-ANG1) / (N-1) *DO,I,1,N *SET,XX,R*COS((ANG1+I*DA)*PI / 180) *SET,YY,R*SIN((ANG1+I*DA)*PI / 180)*SET,ZZ,I*DH K,I+10,XX,YY,ZZ *ENDDO BSPLIN,1,2,3,4,5,6.

[0026] Step S103: establishing a cross-sectional plane of the screw sleeve according to the size of the screw sleeve, and constructing a two-dimensional surface grid unit based on the plane.

[0027] Specifically, in this embodiment, the keypoint command is used to establish 6 key points in the screw sleeve cross section (corresponding to Figure 4 The six key points are connected to form a closed cross-sectional plane, and the surface mesh command of the mesh200 unit is used to mesh the cross-sectional plane to establish a two-dimensional surface mesh for the cross-sectional plane.

[0028] Step S104, sweeping the two-dimensional surface mesh unit along the spiral line to generate a screw sleeve body unit, wherein the screw sleeve body unit generated after sweeping has internal and external thread surfaces, and respectively matches with the external thread of the bolt and the internal thread of the nut.

[0029] Specifically, in this embodiment, in the ANSYS software, the process of sweeping a two-dimensional surface mesh along a spiral line to generate a three-dimensional solid element is as follows: like Figure 4 and Figure 5As shown, a sweep path is defined, with the starting and ending points of the spiral line as the starting and ending points of the sweep, and the sweep command is used to sweep the two-dimensional surface mesh along the spiral line to generate a three-dimensional screw sleeve body unit. During the sweeping process, the screw sleeve cross section is controlled to be perpendicular to the spiral line. The screw sleeve unit generated after the sweep has two inner and outer thread surfaces, which match the nut thread and the bolt thread respectively.

[0030] Step S105: Establish the bolt head and the connected parts to form a complete bolt-sleeve-nut finite element model. The complete bolt-sleeve-nut finite element model is as follows: Figure 6 and Figure 7 shown.

[0031] The parametric finite element modeling method of a bolt connection structure with a threaded sleeve described in this embodiment can determine the thread geometric characteristics of the bolt, nut and threaded sleeve, and establish finite element models of the bolt, nut and threaded sleeve respectively, and achieve accurate matching between the threads, which is helpful for subsequent research and use of the bolt connection structure with the threaded sleeve.

[0032] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0033] Although the present application has been described in conjunction with specific embodiments of the present application, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the discussed embodiments.

[0034] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A parametric finite element modeling method for a bolt connection structure with a threaded sleeve, characterized in that: include: Nut and bolt embryo models are established according to the determined thread geometry features of bolts, nuts and screw sleeves. Finite element nodes of nut and bolt embryo models are moved through mathematical expressions of nut and bolt threads to generate thread features of nuts and bolts. Take the starting point of the bolt thread as the starting point and establish a spiral line of equal diameter along the axial direction of the bolt; A screw sleeve cross-sectional plane is established according to the size of the screw sleeve, and a two-dimensional surface mesh unit is constructed based on the plane; Sweeping the two-dimensional surface mesh unit along the spiral line to generate a screw sleeve body unit, wherein the screw sleeve body unit generated after sweeping has an inner and outer thread surface, and matches the outer thread of the bolt and the inner thread of the nut respectively; The bolt head and connected parts are established to form a complete bolt-sleeve-nut finite element model.

2. The method according to claim 1, characterized in that: According to the determined screw sleeve size, and the specifications of the nut and bolt, mathematical expressions of the nuts and bolt threads of corresponding specifications are established, wherein the mathematical expression of the external thread of the bolt corresponds to the mathematical expression of the internal thread of the screw sleeve, and the mathematical expression of the internal thread of the nut corresponds to the mathematical expression of the external thread of the screw sleeve.

3. The method according to claim 2, characterized in that The mathematical expression of the external thread of the bolt is: ； The mathematical expression of the internal thread of the nut is: ； in, , , , , , , , , , , , , , ; In the formula, Indicates the nominal diameter of the bolt. represents the tooth root radius, Indicates the thread working height, represents the radius of the thread feature, Indicates the number of thread layers per unit pitch, Indicates the characteristic radius of the internal thread tooth top. represents the cylindrical coordinate angle of the cross section, Indicates the azimuth after the thread lead angle, Indicates the thread pitch, represents the rotation angle, Indicates the diameter of the thread feature at this angle.

4. The method according to claim 1, characterized in that: The thread starts of the nut and bolt have the same phase angle.

5. The method according to claim 1, characterized in that: When establishing a helix of equal diameter, the helix direction, pitch, and radius are consistent with the outer edge of the bolt thread.

6. The method according to claim 1, characterized in that The step of establishing a screw sleeve cross-sectional plane according to the size of the screw sleeve and constructing a two-dimensional surface grid unit based on the plane includes: The keypoint command is used to establish key points of the screw sleeve cross section, and the key points are connected to form a closed cross-sectional plane. The cross-sectional plane is meshed using the surface mesh command of the mesh200 unit to establish a two-dimensional surface mesh for the cross-sectional plane.

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