Finite element-based testing device and method for breaking force of tire bead wire ring

Abstract

The present invention provides a finite element-based testing device and method for the breaking force of a tire bead wire ring. The device comprises an annular mold and a bead wire ring cross-section acting force extractor; the outer surface of the annular mold is provided with a mold groove, and the mold groove is used for accommodating a bead wire ring; the inner surface of the annular mold is provided with a load surface, and the load surface is used for expanding the annular mold to apply a breaking force to the bead wire ring; the bead wire ring cross-section acting force extractor is used for reading the acting force on a cross-section of the bead wire ring and testing the breaking force of the bead wire ring. In the present invention, the annular mold is expanded to apply an acting force to a bead wire ring, to simulate service conditions of the bead wire ring and more accurately evaluate the breaking force of the bead wire ring; by applying annular expansion displacement fields to the bottom surface of the annular mold and imposing displacement constraints on the annular mold, deviation of the annular mold is restricted.

Description

A finite element based tire bead breaking force testing device and method TECHNICAL FIELD

[0001] The present application relates to the field of tire detection technology, and particularly relates to a finite element based tire bead breaking force testing device and method. BACKGROUND

[0002] The tire bead is a main load-bearing component in a tire and is a circular ring with multiple steel wires in cross section. The bead breaking force is an important indicator of product performance, but it is very difficult to test. Since the shape of the bead is a circular ring, the test must be assisted by a mold. The bead breaking force experiment currently usually adopts a combined fan-shaped mold to expand outward and break or two half-circle molds to stretch and break at both ends. However, both of these test machines are limited by the size of the mold and cannot test all sizes of beads, so finite element simulation is a better method to solve this problem.

[0003] The difficulty of finite element simulation of the bead lies in the application of load. The bead structure is complex, so it is not possible to directly apply surface forces such as force or pressure to the bead. Only by applying body forces such as ring gravity can the load be applied.

[0004] However, the way of applying body forces has the following defects: 1. The inner layer of the bead is subjected to the pressure of the rim in the tire, and the remaining steel wires are subjected to the pressure of the inner layer of the steel wire, which is different from the form of body force; 2. Due to the complexity of the structure of the bead, the mass in the ring direction is not completely uniform, so the application of body force will cause the position of the bead to shift, so the simulation of the breaking force of the bead must also be assisted by a mold. However, a new problem arises. If a combined fan-shaped mold is used, stress concentration will occur at both sides of a single mold, that is, at the two boundaries of the fan-shaped mold, which will affect the results of the analysis. If a ring-shaped closed mold is used, the modeling method of expanding and supporting the bead by thermal expansion or upsetting can solve the problem of stress concentration, but it will produce the same problem as applying body force. Due to uneven stress, the position of the entire model will shift. SUMMARY

[0005] The present application aims to overcome the deficiencies in the prior art and provide a finite element based tire bead breaking force testing device and method.

[0006] To solve the prior art problems, in a first aspect, the application discloses a tire bead breaking force testing device based on finite elements, which comprises a ring-shaped mold and a bead cross-section force extractor, an outer surface of the ring-shaped mold is provided with a mold groove body, and the mold groove body is used for assembling a bead; an inner surface of the ring-shaped mold is provided with a load surface, the load surface is used for expanding the ring-shaped mold to exert a breaking force on the bead; and the bead cross-section force extractor is used for reading the action force of the bead cross section to test the breaking force of the bead.

[0007] Further, a side surface of the ring-shaped mold is provided with a constraint surface, and the constraint surface is used for limiting the movement of the ring-shaped mold.

[0008] Further, the bead cross-section force extractor is provided with a plurality of grid nodes, the grid nodes comprise steel wire circumferential grid nodes and steel wire cross-section internal grid nodes; the steel wire circumferential grid nodes are uniformly distributed on the circumference of the steel wire of the bead; and the steel wire cross-section internal grid nodes are uniformly distributed in the cross section of the steel wire.

[0009] Further, the number of the steel wire circumferential grid nodes and the steel wire cross-section internal grid nodes is 8.

[0010] Further, a cylindrical coordinate system is further included, wherein a Z axis is perpendicular to the plane where the ring-shaped mold is located, and the load surface exerts a displacement load on an R axis to expand the ring-shaped mold.

[0011] Further, a constraint line is arranged on the outside of the ring-shaped mold, and the constraint line is used for limiting the movement of the ring-shaped mold.

[0012] Further, a rectangular coordinate system is further included, wherein a Z axis is perpendicular to the plane where the ring-shaped mold is located, and the load surface exerts a displacement field in two perpendicular directions in the plane where the ring-shaped mold is located to expand the ring-shaped mold.

[0013] Further, the displacement field in the two perpendicular directions is expressed as u x and u y ; u x =u cos(arctan(Y / X))*X / |X|; u y =u sin(arctan(Y / X))*X / |X|;

[0014] In the formula, u is the displacement of the bead expansion, X and Y are displacement field parameters.

[0015] In a second aspect, correspondingly, the application further provides a tire bead breaking force testing method based on finite elements, which comprises the following steps.

[0016] According to the bead, a corresponding closed ring-shaped mold is established;

[0017] putting the bead into the groove of the annular mold, applying displacement constraint to one side or the bottom side of the annular mold which is perpendicular to the annular surface;

[0018] applying annular expansion displacement load or displacement field to the annular mold, expanding the annular mold outwardly until the bead is broken, and extracting the force of any section of the bead to obtain the breaking force of the bead.

[0019] The present application has the beneficial effects of:

[0020] (1) applying force to the bead through annular mold expansion to simulate the working condition of the bead and more accurately judge the breaking force of the bead;

[0021] (2) applying annular expansion displacement field to the bottom surface of the annular mold to constrain the displacement of the annular mold and limit the deviation of the annular mold. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1 is a schematic diagram of the bead breaking force testing device based on finite elements in the present application under the column coordinate axis;

[0023] Fig. 2 is a schematic diagram of the bead breaking force testing device based on finite elements in the present application under the rectangular coordinate axis;

[0024] Fig. 3 is a schematic diagram of the groove structure of the annular mold in the present application;

[0025] Fig. 4 is a schematic diagram of the bead cross-section grid node in the present application.

[0026] Reference signs: 1, bead; 2, annular mold; 3, mold groove body; 4, load surface; 5, constraint surface; 6, column coordinate axis; 7, bead cross-section force extractor; 8, displacement load; 9, constraint line; 10, rectangular coordinate system; 11, displacement field; 21, steel wire; 22, bead circumferential grid node; 23, bead cross-section internal grid node. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings. The following examples are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0028] Example 1, as shown in Fig. 1, the present example introduces a tire bead breaking force testing device based on finite elements, which comprises:

[0029] bead 1, which is the object of analysis;

[0030] steel wire 21, which is used to form the bead 1;

[0031] annular mold 2, which is a closed ring and applies breaking load to the bead 1;

[0032] Mold groove 3, provided on the outer surface of the ring mold 2, used to assemble the steel wire ring 1, and the shape is matched with the steel wire ring;

[0033] Load surface 4, provided on the inner surface of the ring mold 2;

[0034] Constraint surface 5, provided on one side of the ring mold 2, used to limit the movement of the ring mold 2;

[0035] Column coordinate axis 6, the coordinate axis of the model, the Z axis is perpendicular to the plane where the ring mold 2 is located;

[0036] Steel wire ring cross-section force extractor 7, used to extract the cross-section force of the steel wire ring.

[0037] In this embodiment, the contact between the steel wires 21 is not penetrable, the friction coefficient is the actual parameter, the contact between the steel wire ring 1 and the ring mold 2 is not penetrable, and the friction coefficient is zero. In order to ensure the accuracy of the analysis, the grid nodes on the circular cross-section of the steel wire 21 are as follows: the radius of the steel wire is r, the center of the circle is (0, 0), the node (0, r) on the circumference of the circle is taken as the starting point, and 8 steel wire circumferential grid nodes 22 are uniformly arranged at intervals; 8 steel wire circular cross-section internal grid nodes 23 are arranged inside the circular cross-section, which are (-0.5r, 0.5r), (0.5r, 0.5r), (0.5r, -0.5r), (-0.5r, -0.5r), (-0.6r, 0), (0.6r, 0), (0, 0.6r) and (0, -0.6r). The grid length in the length direction of the steel wire 21 is 0.5r-5r, and the total number of grid nodes of the steel wire ring 1 is not less than 500,000 and not more than 2,000,000.

[0038] In this embodiment, the ring mold 2 is made of elastic material, and the elastic modulus is greater than that of the steel wire ring 1. The displacement load 8 on the R axis is applied to the load surface 4 to make the ring mold 2 expand, and the steel wire ring cross-section force extractor 7 reads the force of the steel wire ring cross-section to test the breaking force of the steel wire ring 2.

[0039] Example two, based on the same inventive concept as example one, in this embodiment, the constraint of the ring mold 2 is realized by applying a constraint line 9 on the constraint line 9; the constraint line (9) is provided on the outer side of the ring mold 2.

[0040] Example three, based on the same inventive concept as example one, in this embodiment, the displacement load applied to the load surface 4 is applied in the rectangular coordinate system 10, and the specific method is to apply two vertical displacement fields 11 in the plane where the ring mold 2 is located on the load surface 4, and the formula is: x u = u cos(arctan(Y / X))*X / |X| (1) u y= u sin(arctan(Y / X)) * X / |X| (2)

[0041] where u is the displacement of the bead expansion, u x and u y are the displacement fields in two perpendicular directions, and X and Y are the displacement field parameters.

[0042] In an embodiment, a finite element based bead break force testing method is provided. For a specific bead, a corresponding closed ring mold is established, and the outer diameter of the mold groove is slightly smaller than the inner diameter of the bead. The bead is placed in the groove of the mold, and a displacement constraint perpendicular to the ring surface is applied to one side or the bottom edge of the side of the ring mold, and the model is constrained in the direction perpendicular to the displacement surface. A ring-shaped displacement field is applied to the bottom surface of the mold ring, which has two effects: one is to expand the ring mold outward to break the bead and test the break force, and the other is to apply a specific displacement constraint to the mold to limit the deviation of the mold. The force acting on the arbitrary cross section of the bead is extracted, and the force acting on the bead during the expansion of the mold is obtained, and the break force of the bead is analyzed by using the finite element method.

[0043] It should be noted that the relational terms such as first and second and the like are used only to differentiate one entity or action from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or actions. In addition, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In the drawings of the present application, the filling pattern is only for distinguishing the layers and does not have any other limitation.

[0044] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A finite element based tire bead break force testing apparatus, characterized by, The application relates to a device for testing the breaking force of a steel wire ring, which comprises a ring-shaped mould (2) and a steel wire ring cross-section force extractor (7), wherein the outer surface of the ring-shaped mould (2) is provided with a mould groove (3) for assembling the steel wire ring (1); the inner surface of the ring-shaped mould (2) is provided with a load surface (4) for expanding the ring-shaped mould (2) to exert a breaking force on the steel wire ring (1); and the steel wire ring cross-section force extractor (7) is used for reading the force of the cross section of the steel wire ring (1) and testing the breaking force of the steel wire ring (1).

2. The finite element based tire bead break force testing apparatus of claim 1, wherein, The side surface of the ring-shaped mould (2) is provided with a constraint surface (5) for limiting the movement of the ring-shaped mould (2).

3. The finite element based tire bead break force testing apparatus of claim 1, wherein, The steel wire ring cross-section force extractor (7) is provided with a plurality of grid nodes, wherein the grid nodes comprise steel wire circumferential grid nodes (22) and steel wire cross-section internal grid nodes (23); the steel wire circumferential grid nodes (22) are uniformly distributed on the circumference of the steel wire (21) of the steel wire ring (1); and the steel wire cross-section internal grid nodes (23) are uniformly distributed in the cross section of the steel wire (21).

4. The finite element based tire bead break force testing apparatus of claim 3, wherein, The number of the steel wire circumferential grid nodes (22) and the steel wire cross-section internal grid nodes (23) is 8.

5. The finite element based tire bead break force testing apparatus of claim 1, wherein, A column coordinate axis (6) is further included, wherein the Z axis is perpendicular to the plane where the ring-shaped mould (2) is located, and the load surface (4) exerts a displacement load (8) on the R axis to expand the ring-shaped mould (2).

6. The finite element based tire bead break force testing apparatus of claim 1, wherein, The outer side of the ring-shaped mould (2) is provided with a constraint line (9) for limiting the movement of the ring-shaped mould (2).

7. The finite element based tire bead break force testing apparatus of claim 1, wherein, A rectangular coordinate system (10) is further included, wherein the Z axis is perpendicular to the plane where the ring-shaped mould (2) is located, and the load surface (4) exerts a displacement field (11) in two perpendicular directions in the plane where the ring-shaped mould (2) is located to expand the ring-shaped mould (2).

8. The finite element based tire bead break force testing apparatus of claim 7, wherein, Two perpendicular displacement fields are represented as u x and u y ; u x = u cos(arctan(Y / X))*X / |X|; u y = u sin(arctan(Y / X))*X / |X| In the formula, u is the displacement of the expansion of the steel wire ring, and X and Y are displacement field parameters.

9. A finite element based method for testing the breaking force of a tire bead, characterized in that, The application further relates to a method for testing the breaking force of a steel wire ring, which comprises the following steps: establishing a corresponding closed ring-shaped mould according to the steel wire ring; placing the steel wire ring in the groove of the ring-shaped mould, exerting displacement constraint on one side surface or the bottom side of the ring-shaped mould, which is perpendicular to the ring surface; exerting a ring-shaped expansion displacement load or displacement field on the ring-shaped mould to expand the ring-shaped mould outward until the steel wire ring is broken; reading the force of any cross section of the steel wire ring to obtain the breaking force of the steel wire ring.

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