JP2014106886A - Tire model creation device, and method and program of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten model creation time while maintaining analysis accuracy.SOLUTION: A boundary line 50 passing an upper side 58A of a bead shape line 58 is set as a boundary between a bead part 54 and a tire body part 56, and a mesh center 74 is set inside the bead shape line 58. On a lower side from the boundary line 50, a critical point 76 for representing a tire member shape line 64 is set, and also, a critical point 78 for representing the bead shape line 58 is set. With the critical points 76 and 78 being base points, toward a tire contour line 62, a mesh line 80 leading to the adjacent tire member shape line 64 is created, and the mesh line 80 is extended until it reaches the tire contour line 62. Also, with the critical points 76 and 78 being the base points, toward the mesh center 74, the mesh line 80 leading to the adjacent tire member shape line 64 or the bead shape line 58 is created, and the mesh line 80 is extended until it reaches the mesh center 74.

Description

  The present invention relates to a tire analysis model creation apparatus, a method and a program for use in evaluating tire characteristics by a finite element method.

  As a method of analyzing the characteristics of the tire by simulation, the tire to be evaluated is approximated by a tire finite element model (tire model) divided into a finite number of elements, and physical properties such as density and elastic modulus are given to each element. A finite element method (FEM) is used in which boundary conditions such as internal pressure and load are given to a tire model, and the deformation state of each element is calculated to simulate the deformation and motion state of the tire.

  In such a finite element model, it is generally said that the triangular element has low analysis accuracy, so that it is required to model it with a square element as much as possible. However, since the tire bead portion has a structure in which a tire member such as a carcass ply is wound around a bead core, modeling all of them with a square element complicates model creation and increases model creation time. End up.

  As a method for creating a tire model around the bead portion, Patent Document 1 discloses that the rim cushion portion and the tire main body portion are individually meshed in order to mesh the portion where the tire contacts the rim in detail (that is, element division). And joining. However, since one tire model needs to be divided, individually meshed, and joined, the analysis result can be influenced by joining conditions.

  Patent Document 2 discloses that a bead core portion constituted by a large element and a portion excluding the bead core constituted by a small element are joined with a constraint condition without sharing a node, and a triangular shape is connected to the bead core portion. Application of the elements is also disclosed. However, since the constraint condition is set between elements having significantly different physical property values, the analysis result can be influenced by the constraint condition.

JP 2006-072893 A JP 2007-216702 A

  The present invention has been made in view of the above points, and it is an object of the present invention to provide a tire model creation device, method and program thereof that can shorten model creation time by introducing a triangular element while maintaining analysis accuracy. .

  A tire model creation device according to the present invention is a tire model creation device for analyzing tire characteristics by simulation; a bead portion including a bead and a tire main body excluding the bead portion based on information on a tire cross-sectional shape A boundary line setting unit that sets a boundary line passing through the upper side of the bead shape line; and a mesh center setting unit that sets a mesh center inside the bead shape line; on the lower side from the boundary line, A critical point setting unit for setting a critical point for expressing a tire member shape line around the bead and setting a critical point for expressing the bead shape line; and a tire contour line based on the critical point Create a mesh line that leads to the adjacent tire member shape line toward the tire contour line A first mesh line creation unit extending the mesh line at: creating a mesh line from the critical point as a base point toward the mesh center to an adjacent tire part shape line or bead shape line; A second mesh line creation unit extending the mesh line to the end; and the bead shape line, the tire member shape line, and the intersection of the tire contour line and the mesh line as nodes, and a finite number of points defined by the nodes. And an element generation unit that generates elements.

  Here, the bead is a bead core. However, when the bead core is covered with a bead cover, the bead core includes a bead core and a bead cover. Further, the upper side of the bead shape line is a side (or a line portion) forming a boundary on the outer side in the tire radial direction of the bead shape line. The lower side refers to the inner side in the tire radial direction.

  According to the present invention, the mesh center is set in the bead, and the bead portion is modeled by the radial mesh line centered on the mesh center, so that a simple logic capable of dealing with various bead shapes is constructed. Thus, the bead portion can be easily modeled, and the model creation time can be shortened without reducing the analysis accuracy.

It is a block diagram of the creation apparatus concerning an embodiment. It is a block diagram of a bead part model creation part of a creation device concerning an embodiment. It is a flowchart of the creation apparatus which concerns on embodiment. It is a flowchart of the bead part model preparation part which concerns on embodiment. It is sectional drawing of the tire bead part which concerns on embodiment. It is the figure which set the boundary line to this bead part. It is the figure which set the critical point in this bead part. It is a figure which shows the state which created the mesh line from a certain critical point to a tire outline. It is a figure which shows the state which created the mesh line from this critical point to a mesh center. It is a figure for demonstrating the method of selecting a critical point. It is a figure which shows the state which created the mesh line which passes along the said selected critical point. It is a figure which shows the state which created the mesh line which passes along all the critical points. It is a figure which shows a bead part model. It is a figure which shows the local node number in each element of a bead part. It is a half sectional view of a tire model. It is a bead part enlarged view of the tire model of the example in rim contact analysis. It is a bead part enlarged view of the tire model of the comparative example in a rim contact analysis.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the tire model creation device 10 according to an embodiment includes an input unit 12, a boundary line setting unit 14, a main body model creation unit 16, a bead part model creation unit 18, and an output unit 20. As shown in FIG. 2, the bead part model creation unit 18 includes a mesh center setting unit 30, a critical point setting unit 32, a critical point selection unit 34, a first mesh line creation unit 36, and a second mesh line creation unit 38. A third mesh line creation unit 40 and an element generation unit 42.

  Note that the creation device 10 can also be realized by using, for example, a general-purpose computer having a mouse and a keyboard as basic hardware. That is, the input unit 12, the boundary line setting unit 14, the main body model creating unit 16, the bead unit model creating unit 18 (in detail, the mesh center setting unit 30, the critical point setting unit 32, the critical point selecting unit 34, the first The mesh line creation unit 36, the second mesh line creation unit 38, the third mesh line creation unit 40, and the element generation unit 42), and the output unit 20 cause the processor mounted on the computer to execute the program. Can be realized. At this time, the creation apparatus 10 may be realized by installing the above program in a computer in advance, or may be stored in a storage medium such as a CD-ROM, or distributed through the network. This program may be realized by appropriately installing it on a computer.

  Hereinafter, the configuration and functions of the above-described units will be described in order.

[1] Input unit 12
The input unit 12 acquires data (tire design information) about the tire including the cross-sectional shape of the pneumatic tire to be created. Specifically, the dimensions, layout, and materials of each tire member such as tire dimensions such as the outer shape and internal structure of the tire, tread rubber, sidewall rubber, belt, carcass ply, bead core, and chacher constituting the tire Physical property values are entered. The input of these pieces of information may be performed using a keyboard, or may be performed through a recording medium such as a CD-ROM, a network, or the like.

[2] Boundary line setting unit 14
The boundary line setting unit 14 sets a boundary line passing through the upper side of the bead shape line based on the information related to the tire cross-sectional shape input by the input unit 12. As shown in FIG. 15, the boundary line 50 is a line that forms a boundary between the bead portion 54 including the bead 52 and the tire main body portion 56 excluding the bead portion 54, and as shown in FIG. The upper side 58A of 58 is set as the boundary line 50.

  The bead 52 is generally composed of a bead core made of steel, and when the bead core is covered with a bead cover, the bead including the bead cover is a bead. The bead shape line 58 is an outline of the bead core in the example of FIG. 5 without the bead cover, and can also be referred to as a bead core shape line. On the other hand, when there is a bead cover, not only the bead core shape line but also the bead cover shape line which is the outline of the bead cover is included in the bead shape line. However, when setting the boundary line, it may be set at the upper side of the bead cover shape line. On the other hand, when the critical point is set by the critical point setting unit 32, both the bead core shape line and the bead cover shape line are set. You only have to set it.

  The upper side 58A of the bead shape line is a side or a line portion (not limited to a straight line) that forms a boundary on the outer side in the tire radial direction of the bead shape line 58. For example, the bead 52 and its diameter You may set to the said boundary line 50 by making the boundary with the bead filler 60 (refer FIG. 5) provided in a direction outer side into the upper side 58A. In addition, it does not specifically limit as a bead shape, For example, various polygons other than a cable shape (circle), a hexagon, and a rectangle are mentioned.

  Although the boundary line 50 may be set only by the upper side 58A of the bead shape line as shown in FIG. 5, in order to clarify the boundary between the tire main body part 56 and the bead part 54, as shown in FIG. It may be set to extend to the contour line 62. In that case, a boundary line 50 that crosses the tire in the thickness direction is created by creating a mesh line extending from the both ends of the upper side 58A to the adjacent tire member shape line 64 and extending the mesh line to the tire contour line 62. Is set. The mesh line is created in the normal direction of the shape line where the respective base points are located, with both ends of the upper side 58A as base points. Here, both ends of the upper side 58A are a critical point located at the end on the tire inner surface side in the upper side 58A and a critical point located at the end on the tire outer surface side. The critical point is a point necessary for expressing the bead shape line 58, and is a change point where the shape changes like a vertex or an inflection point constituting the corner.

  In FIG. 5, reference numeral 66 denotes a carcass ply, reference numeral 68 denotes a chacher, reference numeral 70 denotes a rubber member such as an inner liner or a rim strip, and these are called tire members around the bead 52.

[3] Main body model creation unit 16
The body part model creation part 16 models the tire body part 56 above the boundary line 50 (outside in the tire radial direction) based on the information about the tire cross-sectional shape input by the input part 12. Modeling is to create a finite element model in which the tire cross-sectional shape is divided into finite elements. A method for modeling the tire main body 56 is not particularly limited, and a known method can be employed.

  For example, the tire body part model 72 can be created by sequentially dividing the elements from the tire equator line CL (see FIG. 15) toward the outside in the width direction. At that time, by extending the mesh line from the tire contour line on the tire inner surface side to the tire contour line on the tire outer surface side, the element division can be performed with the intersection point with each tire member as a node, and the element division is defined as the equator line CL. To the boundary line 50, the tire body part model 72 is obtained.

[4] Bead part model creation part 18
The bead part model creation unit 18 models the bead part 54 below the boundary line 50 (inner side in the tire radial direction) based on the information regarding the tire cross-sectional shape input by the input unit 12. As described above, the bead part model creation unit 18 includes the mesh center setting unit 30, the critical point setting unit 32, the critical point selection unit 34, the first mesh line creation unit 36, and the second mesh line creation unit 38. And the third mesh line creation unit 40 and the element generation unit 42 will be described in order.

[5] Mesh center setting unit 30
The mesh center setting unit 30 sets the mesh center 74 inside the bead shape line 58 (see FIG. 7). The mesh center 74 can be set at an appropriate point inside the bead 52, but is preferably set at the center rather than the edge of the bead 52. For example, the center of gravity of the polygon, the center of the circle, the square, An intersection of hexagonal diagonals is conceivable, and the center of gravity is particularly preferable.

[6] Critical point setting unit 32
The critical point setting unit 32 sets a critical point 76 for expressing the tire member shape line 64 (including the tire contour line 62) around the bead 52 on the lower side from the boundary line 50, and the bead shape line. A critical point 78 for expressing 58 is set (see FIG. 7). As the critical point 76 of the tire member shape line 64, the tire members 66, 68, and 70 are connected to each other in addition to a change point where the shape changes like a vertex or an inflection point like the critical point 78 of the bead shape line 58 described above. It may be a boundary point that becomes the boundary of.

[7] Critical point selector 34
The critical point selection unit 34 selects critical points 76 and 78 to be base points when the mesh line is created in the first mesh line creation unit 36 and the second mesh line creation unit 38.

  The critical point selection unit 34 is directed from the tire inner surface side to the tire outer surface side along the tire contour line 62 from the critical point 78A on the tire inner surface side of the bead shape line 58 on the boundary line 50 with the mesh center 74 as the center. Critical points 76 and 78 are sequentially selected in the first direction X (see FIG. 7). For example, for each critical point 76, 78, an angle θ (angle in the first direction X, see FIG. 7) from the critical point 78A centered on the mesh center 74 is calculated, and the angle θ is small. Select in order.

  At that time, even when the critical point selection unit 34 selects the critical point 78 of the bead shape line 58, when the critical point 76 of the tire member shape line 64 exists in the vicinity of the critical point 78, the critical point is selected. Instead of 78, the neighboring critical point 76 is selected. Specifically, when the critical point 76 of the tire member shape line 64 exists within a predetermined angle from the critical point 78 of the bead shape line 58 in the first direction X, the critical point 78 of the bead shape line 58 is replaced. The critical point 76 of the tire member shape line 64 within the predetermined angle is selected.

  For example, in the case shown in FIG. 10, at the critical point 78 of the bead shape line 58 located at the angle θ1 and the critical point 76 of the tire member shape line 64 located at the angle θ2, θ1 is smaller than θ2. Therefore, according to the above basic principle, the critical point 78 located at θ1 is selected. However, in this embodiment, the difference between θ1 and θ2 is smaller than a predetermined value and is small, so the critical point 76 located at θ2 is selected. Thus, by selecting the critical point 76 of the tire member shape line 64 with priority, the critical point of the anisotropic material in which the fibers such as the carcass ply 66 and the chacher 68 are embedded is prioritized. It is easy to avoid the elements of the anisotropic material from being crushed.

[8] First mesh line creation unit 36
The first mesh line creation unit 36 uses the critical points 76 and 78 selected by the critical point selection unit 34 as a base point toward the tire contour line 62 and reaches the adjacent tire member shape line 64 (see FIG. 8). ) And the mesh line 80 is extended to the tire contour line 62.

  Specifically, as shown in FIG. 8, the first mesh line creation unit 36 creates a mesh line 80 in the normal direction of the tire member shape line 64 from the critical points 76 and 78 toward the tire contour line 62. To do. Further, the mesh line 80 is similarly extended in the normal direction using the intersection of the mesh line 80 and the adjacent tire member shape line 64 as a base point. This is repeated until the tire contour line 62 is reached. Thereby, the mesh line 80 extending from the selected critical points 76 and 78 to the tire contour line 62 is completed.

  However, if it is not appropriate to create the mesh line 80 in the normal direction, for example, when passing through an acute angle portion such as a tire toe, the mesh in the direction that bisects the angle formed by the tire member shape line 64 A line 80 is defined to be created. Whether or not it is appropriate may be determined based on whether or not the size of the included angle formed by the tire member shape line 64 and having the critical point as a vertex is equal to or less than a predetermined angle.

  Further, when the critical point 76 of the tire member shape line 64 exists within a predetermined allowable range (angle) with respect to the normal direction, the mesh line is avoided in order to avoid creating an unnecessarily thin element. 80 is connected to the critical point 76.

[9] Second mesh line creation unit 38
As shown in FIG. 9, the second mesh line creation unit 38 uses the critical points 76 and 78 selected by the critical point selection unit 34 as base points toward the mesh center 74 and adjacent tire part shape lines 64 or bead shapes. A mesh line 80 reaching the line 58 is created, and the mesh line 80 is extended to reach the mesh center 74.

  Specifically, the second mesh line creation unit 38 creates a mesh line 80 in the normal direction of the tire member shape line 64 from the critical point 76 toward the mesh center 74, and a tire adjacent to the mesh line 80. Similarly, the mesh line 80 is extended in the normal direction using the intersection with the member line 64 as a base point. This is repeated until the bead shape line 58 is reached, and finally tied to the mesh center 74. The critical point 78 of the bead shape line 58 extends from the critical point 78 to the mesh center 74 by extending the mesh line 80. Thereby, the mesh line 80 extending from the selected critical points 76 and 78 to the mesh center 74 is completed.

  Similarly to the first mesh line creation unit 36, the second mesh line creation unit 38 bisects the angle formed by the tire member shape line 64 when it is not appropriate to create the mesh line 80 in the normal direction. A mesh line 80 is created in the direction. Further, when other critical points 76 and 78 exist within a predetermined allowable range (angle) with respect to the normal direction, the mesh line 80 is connected to the critical points 76 and 78.

[10] Third mesh line creation unit 40
The third mesh line creation unit 40 is configured to divide the mesh line 82 (see FIG. 13) when an element created by two adjacent mesh lines 80 extending from the mesh center 74 is larger than a predetermined element size. Insert).

  Specifically, when the angle formed by the two mesh lines 80 and 80 in the bead-shaped line 58 is equal to or larger than a predetermined value, the mesh line 80 is divided so as to divide the elements formed by the two mesh lines 80 and 80. Insert. As an insertion method, each mesh segment of the bead shape line 58 and the tire member shape line 64 sandwiched between the two mesh lines 80 and 80 is divided into a plurality of equal intervals (for example, bisected). A line 82 is created. The mesh line 82 is created until reaching the tire contour line 62 from the mesh center 74.

[11] Element generation unit 42
The element generation unit 42 uses the intersection points of the mesh lines 80 and 82 created as described above and the bead shape line 58, the tire member shape line 64, and the tire contour line 62 as nodes to define a finite number of elements defined by the nodes. 85 is generated. Each element 85 is defined by four nodes, that is, four nodes are defined in the order of local node numbers at the time of element generation. Thereby, the tire model which divided | segmented the tire cross section into the finite number of elements is obtained.

  By the way, a tire is a composite of fiber and rubber. Reinforcing materials such as belts, carcass plies, and chachers are like a fiber topped with rubber and are anisotropic. Therefore, in setting elements, it is necessary to be aware of anisotropy. When evaluating the analysis results, connectivity can be considered for each element, but a series of anisotropic material elements can be handled easily at the time of setting and evaluation if the connectivity is aligned. That is, it is useful to align the directions of the corresponding local node numbers at the time of element definition (for example, align the directions of “node 1-node 2”).

  Therefore, in this embodiment, the element generation unit 42 corresponds to the local region corresponding to the same direction (first direction X) around the mesh center 74 in the bead portion 54 below the boundary line 50 as shown in FIG. Nodes of each element 85 are defined so as to have node numbers 1 to 4. That is, when the four nodes defining the element 85 are designated in the order of the local node numbers, this order is set so as to be in the same direction around the mesh center 74. Specifically, the bead 52 is expressed by a triangular element in which the side on the bead shape line 58 becomes “node 1-node 2” in the first direction X. Therefore, the local node numbers of the mesh center 74 are the nodes 3 and 4. For the tire members 66, 68, and 70 wound around the bead 52, elements are defined according to the elements of the bead 52. That is, the elements of the tire members 66, 68, and 70 around the bead 52 are expressed by elements such that the side far from the mesh center 74 becomes “node 1-node 2” in the first direction X. In FIG. 14, “1” to “4” are local node numbers, “1” is node 1, “2” is node 2, “3” is node 3, and “4” is node 4. means.

  When modeling the tire body 56, it is preferable to align the directions of the corresponding local node numbers when generating the elements. In the present embodiment, the bead part model creating unit 18 sets the node on the side closer to the tire equator line CL on the tire inner surface side to the local node number “1” in each element of the tire main body model 72, and counterclockwise from here. By defining the nodes, the direction of “node 1-node 2” on the tire inner surface side of each element is the direction indicated by the arrow Y in FIG.

  For anisotropic tire members such as the carcass ply 66 and the chacher 68, in the portion wound up on the outer surface side of the tire, the nodes above the boundary line 50 are nodes in the order of local node numbers according to the elements of the bead part model 84. 15 is defined such that the direction of “node 1-node 2” on the tire outer surface side of each element is the direction indicated by arrow Z in FIG.

[12] Output unit 20
The output unit 20 outputs the tire model (tire cross section model, 2D model) obtained as described above. The tire model can be output by being displayed on a display or printed by a printer.

  Next, the operation state of the tire model creation device 10 according to the present embodiment will be described based on the flowcharts of FIGS. 3 and 4.

  In step S1, the input unit 12 acquires tire design information including a cross-sectional shape of a pneumatic tire to be created.

  Next, in step S <b> 2, the boundary line setting unit 14 sets the upper side 58 </ b> A of the bead shape line 58 to the boundary line 50 around the bead unit 54 illustrated in FIG. 5 using the acquired information. In this example, as shown in FIG. 6, by creating mesh lines that reach the tire contour line 62 from both ends of the upper side 58A, a boundary line 50 that crosses the tire in the thickness direction is set. Then, the process proceeds to step S3.

  In step S <b> 3, the main body model creation unit 16 models the tire main body 56 above the boundary line 50 based on the information acquired by the input unit 12. That is, the tire body part model 72 is created. Then, the process proceeds to step S4.

  In step S <b> 4, the bead part model creating unit 18 models the bead part 54 below the boundary line 50 based on the information acquired by the input unit 12. That is, the bead part model 84 is created.

  Specifically, as shown in FIG. 4, first, in step S11, the mesh center setting unit 30 sets the mesh center 74 inside the bead shape line 58 (see FIG. 7). Then, the process proceeds to step S12.

  In step S12, the critical point setting unit 32 sets the critical point 76 of the tire member shape line 64 and sets the critical point 78 of the bead shape line 58 below the boundary line 50 as shown in FIG. To do. Then, the process proceeds to step S13.

  In step S <b> 13, the critical point selection unit 34 selects critical points 76 and 78 that are base points when the mesh line 80 is created. The critical points 76 and 78 are basically selected sequentially from the critical point 78A on the tire inner surface side on the boundary line 50 in the first direction X. Therefore, first, the critical point 78A of the boundary line 50 is selected. Then, the process proceeds to step S14.

  In step S14, the first mesh line creation unit 36 uses the critical points 76 and 78 selected by the critical point selection unit 34 as a base point toward the tire contour line 62 and reaches the adjacent tire member shape line 64. And the mesh line 80 is extended to the tire contour line 62. However, since the mesh line has already been created as the boundary line 50 at the critical point 78A selected first, the process proceeds to the next step S15.

  In step S15, the second mesh line creation unit 38 uses the critical points 76 and 78 selected by the critical point selection unit 34 as base points toward the mesh center 74 to the adjacent tire part shape line 64 or bead shape line 58. A mesh line 80 is created, and the mesh line 80 is extended to the mesh center 74. At the first selected critical point 78A, a mesh line 80 extending from the critical point 78A to the mesh center 74 is created as shown in FIG. Then, the process proceeds to step S16.

  In step S16, the critical point selection unit 34 determines whether or not the mesh line 80 has been created for all critical points 76 and 78, and if not, the process proceeds to step S13. In step S13, the critical point selection unit 34 selects the next critical points 76 and 78. Here, the critical point 76 on the tire member shape line 64 shown in FIG. 8 is selected. Next, in step S14, the first mesh line creation unit 36 creates a mesh line 80 from the critical point 76 to the tire contour line 62 as shown in FIG. Thereafter, in step S15, the second mesh line creation unit 38 extends the mesh line 80 from the critical point 76 to the mesh center 74 as shown in FIG. In this case, in this example, the mesh line 80 passes through a critical point 78 on the bead-shaped line 58 and then is connected to the mesh center 74.

  Then, the process proceeds to step S13 again through step S16, and the next critical points 76 and 78 are selected. At this time, in this example, as shown in FIG. 10, the critical point 78 at the angle θ1 and the critical point 76 at the angle θ2 are smaller than a predetermined value, so that the critical point located at θ2 Point 76 is selected. In step S14, the first mesh line creation unit 36 creates a mesh line 80 that reaches the critical point 76 on the tire contour line 62 with the critical point 76 as a base point, as shown in FIG. Thereafter, in step S15, the second mesh line creation unit 38 creates the mesh line 80 from the critical point 76 toward the mesh center 74 and connects it to the mesh center 74 as shown in FIG. Then, the process proceeds to step S16.

  In this manner, steps S13 to S16 are repeated until the mesh line 80 is created for all critical points 76 and 78, and the model shown in FIG. 12 is obtained. And if it determines with the mesh line 80 having been created by all the critical points 76 and 78, it will progress to step S17.

  In step S17, the third mesh line creation unit 40 determines whether or not the element that will be formed by the two mesh lines 80 is larger than a predetermined element size. 3, the third mesh line creation unit 40 inserts a mesh line 82 so as to divide the element as shown in FIG. 13. Then, the process proceeds to step S19. On the other hand, if there is no element larger than the predetermined element size in step S17, the process proceeds directly to step S19 without passing through step S18.

  In step S19, the element generation unit 42 uses the intersections of the mesh lines 80 and 82, the bead shape line 58, the tire member shape line 64, and the tire contour line 62 as nodes, and a finite number of elements defined by the nodes. 85 is generated (see FIG. 14). Thereby, the bead part model 84 is completed and step S4 is complete | finished. As described above, the modeling (element division) of the entire tire is completed, and the process proceeds to step S5.

  In step S5, the output unit 20 outputs the tire model obtained as described above.

  According to the present embodiment as described above, the mesh center 74 is taken in the bead 52, and the bead 52 is expressed by a triangular element by the radial mesh lines 80 and 82 centered on the mesh center 74. Shapes can be easily modeled with the same logic. Further, since the bead portion 54 has a structure in which a carcass ply 66 and a chacher 68 are wound around the bead 52, various mesh lines 80 and 82 are generated by generating radial images from the mesh center 74 defined in the bead 52. The original tire structure can be reproduced as much as possible in accordance with the bead shape, and the elements can be generated efficiently. It is also easy to change the fineness of the mesh only in the necessary part.

  In addition, the definition of the anisotropic material elements such as the carcass ply 66 and the chacher 68 wound around the bead 52 can be easily unified, and the evaluation of the result becomes easy. That is, the fiber elements such as the carcass ply 66 and the chacher 68 have a structure wound around the bead 52. When the nodes are defined in order of the local node numbers by meshing the beads 52 in a radial manner, a series of fiber elements are formed. It becomes easy to align the direction of. By aligning the directions of the fiber elements, it becomes easy to evaluate values affected by anisotropy such as cord tension, and the result processing can be easily programmed.

  Further, priority is given to the critical points 76 and 78, particularly the critical point 76 of the tire member shape line 64, and a mesh line 80 is created in the normal direction from the critical points 76 and 78 toward the tire contour line 62 and the mesh center 74. By doing so, an element as close to a regular square as possible can be generated particularly for anisotropic materials such as fiber elements. Therefore, the analysis accuracy can be increased.

  On the other hand, in general, the analysis accuracy of the triangular element is low, the beat 52 that introduces the triangular element is usually made of steel, and is harder and less deformed than the surrounding materials such as rubber, nylon, and textiles. The disadvantages of being a triangular element are considered to be minimal.

  In order to confirm this point, a rim contact 2D analysis was performed. In the analysis, the tire model having the bead part model 84 of the embodiment shown in FIG. 16 and the tire model having the bead part model of the comparative example shown in FIG. 17 are contacted so that the bead part fits the rim flange 90. Let me analyze the difference between the two. Here, the difference between the two tire models is whether the bead, that is, the bead core is composed of a triangular element (Example) or a square element (Comparative Example), and the node coordinate values are exactly the same. The tire shape, rim shape, material properties, boundary conditions, and analysis conditions were set to be the same. As a result of the analysis, the example in which the bead core is composed of triangular elements was completely the same in the elements other than the bead core up to the displacement coordinates of the nodes, as compared to the comparative example in which the bead core was composed of square elements. Therefore, there was no difference in analysis accuracy between the two.

  As described above, according to the present embodiment, tire modeling can be facilitated with simple logic, and model creation time can be reduced without degrading analysis accuracy.

  In the above embodiment, when modeling the bead portion 54, the mesh line 80 is created first toward the tire contour line 62 for each critical point 76, 78, and then toward the mesh center 74. The mesh line 80 was created. However, the mesh line 80 may be created first toward the mesh center 74 and then the mesh line 80 may be created toward the tire contour line 62. In the above embodiment, the mesh line creation to the tire contour line 62 and the mesh line creation to the mesh center 74 are performed for each of the critical points 76 and 78. First, the tire contour line is started from all the critical points 76 and 78. The mesh line 80 may be created toward 62, and then the mesh line 80 may be created toward the mesh center 74. Conversely, the mesh line 80 may be created toward the tire contour line 62 after the mesh line 80 is created from the critical points 76 and 78 toward the mesh center 74 first.

  Moreover, although the said embodiment demonstrated the case where a two-dimensional tire model was created, a three-dimensional tire model may be created. When creating a three-dimensional tire model, the two-dimensional tire model obtained above is developed in the tire circumferential direction and divided into elements at predetermined intervals in the circumferential direction to create a three-dimensional tire model can do.

  Moreover, although the said embodiment demonstrated the case where the bead 52 consisted only of a bead core, it can apply similarly also about the structure provided with the bead cover surrounding a bead core. In that case, since the bead cover is made of rubber and has different physical properties from the bead core, the element is also divided between the outer shape line of the bead cover made of a thin film and the outer shape line of the bead core. Divide at 82.

  The tire model obtained by the above can be used when analyzing the tire characteristics by simulation, giving physical properties such as density and elastic modulus to each element, giving boundary conditions such as internal pressure and load to the tire model, By calculating the deformation state of the element, the deformation and motion state of the tire can be simulated.

  Although one embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 ... Tire model creation apparatus 14 ... Boundary line setting part 30 ... Mesh center setting part 32 ... Critical point setting part 34 ... Critical point selection part 36 ... 1st mesh line creation part 38 ... 2nd mesh line creation part 40 ... 3rd Mesh line creation unit 42 ... element generation unit 50 ... boundary line 52 ... bead 54 ... bead part 56 ... tire main body 58 ... bead shape line 58A ... upper side 62 ... tire contour line 64 ... tire member shape line 66 ... carcass ply 68 ... Chaer 74 ... Mesh center 76, 78 ... Critical point 80, 82 ... Mesh line 85 ... Element X ... First direction

Claims (6)

A tire model creation device for analyzing tire characteristics by simulation,
Based on information on the tire cross-sectional shape, as a boundary between the bead part including the bead and the tire main body part excluding the bead part, a boundary line setting part that sets a boundary line passing through the upper side of the bead shape line;
A mesh center setting unit for setting a mesh center inside the bead shape line;
On the lower side from the boundary line, a critical point setting unit for setting a critical point for expressing the tire member shape line around the bead and setting a critical point for expressing the bead shape line;
Using the critical point as a base point, creating a mesh line leading to an adjacent tire member shape line toward the tire contour line, and extending the mesh line until reaching the tire contour line;
Creating a mesh line reaching the adjacent tire part shape line or bead shape line from the critical point toward the mesh center, and extending the mesh line until reaching the mesh center; ,
An element generation unit that generates a finite number of elements defined by the nodes, with the bead shape line, the tire member shape line, and the intersection of the tire contour line and the mesh line as nodes.
A tire model creation device comprising: A third mesh line creation unit that inserts a mesh line so as to divide an element created by the two mesh lines when an angle formed by two adjacent mesh lines extending from the mesh center is equal to or larger than a predetermined value. The tire model creation device according to claim 1, wherein: A critical point selection unit that selects a critical point as a base point in the first mesh line creation unit and the second mesh line creation unit, the tire having the bead shape line on the boundary line with the mesh center as a center A critical point selection unit that sequentially selects a critical point from a critical point on the inner surface side in a first direction from the tire inner surface side to the tire outer surface side along the tire contour line, the critical point selection unit including the bead shape; When the critical point of the tire member shape line exists within a predetermined angle from the critical point of the line toward the first direction, the tire member shape line within the predetermined angle instead of the critical point of the bead shape line The tire model creation device according to claim 1 or 2, wherein a critical point is selected. The element generation unit defines a node of each element so as to have a corresponding local node number in the same direction around the mesh center in a bead portion below the boundary line. The tire model device according to any one of? A tire model creation method for analyzing tire characteristics by simulation,
Based on information on the tire cross-sectional shape, as a boundary between the bead part including the bead and the tire main body part excluding the bead part, a boundary line setting step for setting a boundary line passing through the upper side of the bead shape line;
A mesh center setting step for setting a mesh center within the bead shape line;
On the lower side from the boundary line, a critical point setting step for setting a critical point for expressing the tire member shape line around the bead and setting a critical point for expressing the bead shape line;
A first mesh line creation step of creating a mesh line that reaches an adjacent tire member shape line toward the tire contour line with the critical point as a base point, and extends the mesh line until the tire contour line;
A second mesh line creation step of creating a mesh line that reaches an adjacent tire part shape line or bead shape line toward the mesh center with the critical point as a base point, and extends the mesh line to the mesh center; ,
A tire model creation method comprising: A program for creating a tire model for analyzing tire characteristics by simulation,
On the computer,
Based on information on the tire cross-sectional shape, as a boundary between the bead part including the bead and the tire main body part excluding the bead part, a boundary line setting function for setting a boundary line passing through the upper side of the bead shape line;
A mesh center setting function for setting a mesh center inside the bead shape line;
On the lower side from the boundary line, a critical point setting function for setting a critical point for expressing the tire member shape line around the bead and setting a critical point for expressing the bead shape line;
Using the critical point as a base point, creating a mesh line that reaches an adjacent tire member shape line toward a tire contour line, and a first mesh line creation function that extends the mesh line until reaching the tire contour line;
A second mesh line creation function for creating a mesh line reaching an adjacent tire part shape line or bead shape line toward the mesh center from the critical point, and extending the mesh line to the mesh center; ,
Tire model creation program to realize

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