Method for determining structural parameters of radial tire bead and radial tire bead

Abstract

The invention belongs to the technical field of radial aircraft tires, and particularly relates to a method for determining structural parameters of a radial tire bead and the radial tire bead. According to the method, the flexural neutral layer of the flexural beam of the tire bead section is introduced into the method for determining the structural parameters of the radial tire bead, and the flexural neutral layer at the tire bead of the radial tire is obtained by adopting a calculation method of an area weighted average method; then the distance between the midpoint of the intersection interface of the positive wrapping cord thread and the tire bead reinforcing rubber and the Y axis is designed to be equal to the distance between the bending neutral layer and the Y axis, and the obtained structural parameters of the radial tire bead can improve the fatigue performance of the tire bead, so that cracks and delamination of rubber at the tire bead and the cord thread in overload sliding of the radial tire are effectively avoided. Meanwhile, the invention provides a method for positively designing the tire bead of the radial tire by adopting an iteration method, so that the design efficiency of the tire bead of the radial tire is greatly improved, and the method has wide industrial application value.

Description

Technical Field

[0001] The invention belongs to the technical field of radial aircraft tires, and in particular relates to a method for determining structural parameters of a radial tire bead and a radial tire bead. Background Art

[0002] With the development of aerospace technology, high requirements are placed on radial aircraft tires, such as high load bearing, fatigue resistance and light weight.

[0003] However, in recent years, 80% of the damage to radial aircraft tires during overload taxiing in dynamic simulation tests is as follows: Figure 1 The damage to the interface between the cord and rubber shown in the figure restricts the improvement of the performance of radial aviation tires. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the structural parameters of a radial tire bead and a radial tire bead. The structural parameters of the radial tire bead obtained by the method provided by the present invention can effectively improve the fatigue performance of the bead and prevent delamination of the rubber and cord at the bead, thereby solving the problem of delamination of the bead cord and rubber interface commonly occurring in radial aviation tires during overload sliding in dynamic simulation tests.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for determining structural parameters of a radial tire bead, comprising the following steps:

[0007] (1) The bead structure of a radial tire is modeled by using the equal area method to obtain a simplified model, wherein the simplified model includes: a bead reinforcing rubber in the shape of a parallelogram, a positive cord in the shape of a parallelogram, a reverse cord in the shape of a parallelogram and a rectangle, a apex rubber in the shape of a right triangle, and a sealing layer rubber in the shape of a rectangle;

[0008] (2) establishing a two-dimensional coordinate system with the edge of the sealant layer in the simplified model that is away from the wire ring and does not contact the turn-up cord as the coordinate origin and the long side of the rectangle of the sealant layer in the simplified model as the Y axis;

[0009] (3) In the two-dimensional coordinate system:

[0010] The distance x between the bending neutral layer and the Y axis in the simplified model is calculated according to formula 1;

[0011]

[0012] In formula 1: E r1 is the elastic modulus of the tire bead reinforcement rubber, E r2is the elastic modulus of the apex, E r3 is the elastic modulus of the sealing layer glue, E r4 is the elastic modulus of the positive cord, E r5 is the elastic modulus of the turn-up cord, S y1 To simplify the static moment of the tire bead reinforcement rubber on the Y axis in the model, S y2 To simplify the static moment of the triangle rubber on the Y axis in the model, S y3 To simplify the static moment of the sealant layer on the Y axis in the model, S y4 To simplify the static moment of the positive cord about the Y axis in the model, S y5 is the static moment of the turn-up cord to the Y axis in the simplified model, A1 is the area of ​​the bead reinforcement rubber in the simplified model; A2 is the area of ​​the apex rubber in the simplified model; A3 is the area of ​​the sealing layer rubber in the simplified model; A4 is the area of ​​the positive cord in the simplified model; A5 is the area of ​​the turn-up cord in the simplified model;

[0013] Then, it is determined whether the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, wherein x0 is the distance between the midpoint of the intersection interface between the bead reinforcement rubber and the positive cord in the simplified model and the Y axis;

[0014] When the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, step (5) is executed;

[0015] When the distances x and x0 between the bending neutral layer and the Y axis in the simplified model are not equal, executing step (4);

[0016] (4) modifying the simplified model, wherein the modification comprises: modifying the model parameters of at least one of the bead reinforcement rubber, the front cord, the back cord, the apex rubber and the sealing layer rubber in the simplified model, wherein the model parameters include elastic modulus information and / or graphic size information; and then executing step (3);

[0017] (5) Obtaining structural parameters of the radial tire bead, wherein the structural parameters of the radial tire bead include: elastic modulus information and graphic size information of the bead reinforcing rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model.

[0018] Preferably, in step (4), the correction is: modifying the elastic modulus information of the positive cord in the simplified model, and modifying the graphic size information of the bead reinforcing rubber, the positive cord, the reverse cord, the apex rubber and the sealing layer rubber in the simplified model;

[0019] In step (1), the construction is as follows: simplifying the shape of the bead reinforcing rubber in the bead located on the upper part of the radial tire wire ring into a parallelogram, simplifying the shape of the positive cord into a parallelogram, simplifying the shape of the reverse cord into a parallelogram and a rectangle, simplifying the shape of the apex rubber into a right triangle, and simplifying the shape of the sealing layer rubber into a rectangle; the absolute value of the area change rate of the bead reinforcing rubber, positive cord, reverse cord, apex rubber and sealing layer rubber before and after the simplified model is constructed is ≤5%.

[0020] Preferably, the elastic modulus of the apex rubber, the elastic modulus of the sealing layer rubber, the elastic modulus of the positive cord and the elastic modulus of the reverse cord are uniaxial tensile moduli.

[0021] Preferably, the elastic modulus of the apex glue and the elastic modulus of the sealing layer glue adopt the tensile elastic modulus when the strain is 1.

[0022] Preferably, the method for determining the tensile elastic modulus when the strain is 1 comprises the following steps:

[0023] The sample of the apex glue or the sealing layer glue is stretched in a tensile testing machine until the apex glue or the sealing layer glue breaks, and a tensile stress-strain curve is obtained;

[0024] According to the compressive stress-strain curve, the tensile elastic modulus when the strain is 1 is calculated by formula 2;

[0025]

[0026] In formula 2: σ1 is the stress value when the strain is 1, ε1=1.

[0027] Preferably, the elastic modulus of the tire bead reinforcing rubber is a compressive elastic modulus.

[0028] Preferably, the compressive elastic modulus is the compressive elastic modulus when the strain is -0.4.

[0029] Preferably, the method for determining the compressive elastic modulus when the strain is -0.4 comprises the following steps:

[0030] The tire bead reinforcement rubber sample is placed in a compression tester for compression until the strain reaches 25% or the compression force reaches 18 kN, and a compression stress-strain curve is obtained;

[0031] According to the compressive stress-strain curve, the compressive elastic modulus when the strain is -0.4 is calculated by formula 3;

[0032]

[0033] In formula 3: σ -0.4is the stress value when the strain is -0.4, ε -0.4 =-0.4.

[0034] Preferably, the elastic modulus of the front cord and the elastic modulus of the back cord are the tensile elastic modulus when the strain is 0.1.

[0035] Preferably, the method for determining the tensile elastic modulus when the strain is 0.1 comprises the following steps:

[0036] The stress-strain performance test of the cord was carried out according to GB / T 9101-2017 "Nylon 66 dipped cord fabric" and GB / T 32108-2015 "Test methods for tensile properties of dipped cords, yarns and cords", and the stress-strain curve of the cord fabric was obtained;

[0037] According to the stress-strain curve of the cord fabric, the tensile elastic modulus when the strain is 0.1 is calculated by formula 4;

[0038]

[0039] In formula 4: σ 0.1 is the stress value when the strain is 0.1, ε 0.1 =0.1.

[0040] The present invention provides a radial tire bead, and the structural parameters of the radial tire bead are determined by the method described in the above technical solution.

[0041] The present invention provides a method for determining the structural parameters of a radial tire bead. Figure 1The main reason for the damage of the interface between the cord (positive cord) and the rubber (bead reinforcement rubber) shown is that a large amount of deformation occurs at the interface between the cord and the rubber when the bead is subjected to reciprocating bending loads. The present invention finds that in the bending deformation model of the bead, there is a bending neutral layer that is neither pulled nor compressed, which can prevent the bead cord and the rubber from deforming. Therefore, the present invention proposes the concept of a radial tire bead bending neutral layer to solve the common problem of delamination of the bead cord and rubber interface in the overload sliding of the dynamic simulation test of the radial aircraft tire. The present invention introduces the bead bending neutral layer into the method for determining the structural parameters of the radial tire bead, adopts the area weighted average method to calculate the bending neutral layer at the radial tire bead, and then designs the distance between the midpoint of the intersection interface of the positive cord and the bead reinforcing rubber and the Y axis to be equal to the distance between the bending neutral layer and the Y axis (that is, the interface between the bead reinforcing rubber and the positive cord is set at the bending neutral layer position), and the obtained structural parameters of the radial tire bead can improve the fatigue performance of the bead, thereby effectively avoiding cracks and delamination between the rubber and the cord at the bead of the radial tire during overload sliding. At the same time, the present invention adopts an iterative method to provide a method for forward designing the bead of a radial tire, which greatly improves the design efficiency of the radial tire bead and has a wide range of industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a radial tire bead crack;

[0043] Figure 2 It is a simplified schematic diagram of the tire bead;

[0044] Figure 3 This is the force analysis diagram of the model;

[0045] Figure 4 The shape and size of the I-type cutter;

[0046] Figure 5 is the tensile stress-strain curve;

[0047] Figure 6 is the compression stress-strain curve of rubber;

[0048] Figure 7 is the tensile stress-strain curve of the cord;

[0049] Figure 8 A flow chart of a method for determining structural parameters of a radial tire bead provided by the present invention;

[0050] Fig. 9 This is a simplified schematic diagram of an aviation tire in an embodiment;

[0051] Fig.10 is a schematic diagram of the tire bead size after adjustment in the embodiment;

[0052] In the figure: 1 is the positive cord, 2 is the reverse cord, 3 is the apex rubber, 4 is the sealing layer rubber, and 5 is the tire bead reinforcement rubber. DETAILED DESCRIPTION

[0053] The present invention provides a method for determining structural parameters of a radial tire bead, comprising the following steps:

[0054] (1) The bead structure of a radial tire is modeled by using the equal area method to obtain a simplified model, wherein the simplified model includes: a bead reinforcing rubber in the shape of a parallelogram, a positive cord in the shape of a parallelogram, a reverse cord in the shape of a parallelogram and a rectangle, a apex rubber in the shape of a right triangle, and a sealing layer rubber in the shape of a rectangle;

[0055] (2) establishing a two-dimensional coordinate system with the edge of the sealant layer in the simplified model that is away from the wire ring and does not contact the turn-up cord as the coordinate origin and the long side of the rectangle of the sealant layer in the simplified model as the Y axis;

[0056] (3) In the two-dimensional coordinate system:

[0057] The distance x between the bending neutral layer and the Y axis in the simplified model is calculated according to formula 1;

[0058]

[0059] In formula 1: E r1 is the elastic modulus of the tire bead reinforcement rubber, E r2 is the elastic modulus of the apex, E r3 is the elastic modulus of the sealing layer glue, E r4 is the elastic modulus of the positive cord, E r5 is the elastic modulus of the turn-up cord, S y1 To simplify the static moment of the tire bead reinforcement rubber on the Y axis in the model, S y2 To simplify the static moment of the triangle rubber on the Y axis in the model, S y3 To simplify the static moment of the sealant layer on the Y axis in the model, S y4 To simplify the static moment of the positive cord about the Y axis in the model, S y5 is the static moment of the turn-up cord to the Y axis in the simplified model, A1 is the area of ​​the bead reinforcement rubber in the simplified model; A2 is the area of ​​the apex rubber in the simplified model; A3 is the area of ​​the sealing layer rubber in the simplified model; A4 is the area of ​​the positive cord in the simplified model; A5 is the area of ​​the turn-up cord in the simplified model;

[0060] Then, it is determined whether the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, wherein x0 is the distance between the midpoint of the intersection interface between the bead reinforcement rubber and the positive cord in the simplified model and the Y axis;

[0061] When the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, step (5) is executed;

[0062] When the distances x and x0 between the bending neutral layer and the Y axis in the simplified model are not equal, executing step (4);

[0063] (4) modifying the simplified model, wherein the modification comprises: modifying the model parameters of at least one of the bead reinforcement rubber, the front cord, the back cord, the apex rubber and the sealing layer rubber in the simplified model, wherein the model parameters include elastic modulus information and / or graphic size information; and then executing step (3);

[0064] (5) Obtaining structural parameters of the radial tire bead, wherein the structural parameters of the radial tire bead include: elastic modulus information and graphic size information of the bead reinforcing rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model.

[0065] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0066] In the present invention, the radial tire bead is preferably a radial aircraft tire bead. In the present invention, the cross-sectional schematic diagram of the radial tire bead is as follows: Figure 2 As shown in the left figure, the tire bead reinforcement rubber contacts the wheel rim and is a compression material. The apex rubber is placed on the top of the wire ring and is a tension material. The sealant rubber contacts the internal air to ensure the air tightness inside the tire and is a tension material. The positive cord is the cord that wraps from the outside of the tire to the inside and does not need to wrap over the top of the wire ring. The reverse cord is the cord that wraps from the inside of the tire to the outside and needs to wrap over the top of the wire ring to ensure that the cord can be stably stressed. Figure 2 In the left figure, all materials are irregular in shape, which is not conducive to the subsequent calculation of the bead's neutral bending layer. Therefore, the present invention uses the equal area method to construct a model (i.e., simplify the process) for the bead cross-section structure located on the upper part of the radial tire bead to obtain a simplified model. In the present invention, the simplified model has a neutral bending layer.

[0067] In the present invention, if Figure 2As shown in the right figure in , the present invention constructs a model of the radial tire bead structure using the area equality method to obtain a simplified model, and the simplified model includes: a bead reinforcing rubber in the shape of a parallelogram, a positive cord in the shape of a parallelogram, a reverse cord in the shape of a parallelogram and a rectangular, a apex rubber in the shape of a right triangle, and a sealing layer rubber in the shape of a rectangle. In a specific embodiment of the present invention, from the outside to the inside of the radial tire bead, the simplified model includes in sequence: a bead reinforcing rubber in the shape of a parallelogram, a positive cord in the shape of a parallelogram, a reverse cord in the shape of a parallelogram, a apex rubber in the shape of a right triangle, a reverse cord in the shape of a rectangle, and a sealing layer rubber in the shape of a rectangle.

[0068] In the present invention, the model is constructed as follows: the shape of the bead reinforcing rubber in the bead located on the upper part of the radial tire wire ring is simplified to a parallelogram, the shape of the positive cord is simplified to a parallelogram, the shape of the reverse cord is simplified to a parallelogram and a rectangle, the shape of the apex rubber is simplified to a right triangle, and the shape of the sealing layer rubber is simplified to a rectangle. In the present invention, the absolute value of the area change rate of the bead reinforcing rubber, the positive cord, the reverse cord, the apex rubber and the sealing layer rubber before and after the model is constructed (i.e., simplified processing) is preferably ≤5%. Figure 2 It is a schematic diagram of the model construction of the tire bead cross-section structure located on the upper part of the radial tire wire ring according to the present invention.

[0069] like Figure 3 The model force analysis diagram shown is Figure 3 The "M" in the simplified model represents the bending moment. After obtaining the simplified model, the present invention uses the edge of the sealant layer in the simplified model that is away from the wire ring and does not contact the turn-up cord as the coordinate origin, and uses the rectangular long side of the sealant layer in the simplified model as the Y axis to establish the following Figure 3 The two-dimensional coordinate system shown.

[0070] After establishing the two-dimensional coordinate system, the present invention, in the two-dimensional coordinate system:

[0071] The distance between the bending neutral layer and the Y axis in the simplified model is calculated according to Formula 1;

[0072]

[0073] In formula 1: E r1 is the elastic modulus of the tire bead reinforcement rubber, E r2 is the elastic modulus of the apex, E r3 is the elastic modulus of the sealing layer glue, E r4 is the elastic modulus of the positive cord, E r5 is the elastic modulus of the turn-up cord, S y1To simplify the static moment of the tire bead reinforcement rubber on the Y axis in the model, S y2 To simplify the static moment of the triangle rubber on the Y axis in the model, S y3 To simplify the static moment of the sealant layer on the Y axis in the model, S y4 To simplify the static moment of the positive cord about the Y axis in the model, S y5 is the static moment of the turn-up cord about the Y-axis in the simplified model; A1 is the area of ​​the bead reinforcement rubber in the simplified model; A2 is the area of ​​the apex rubber in the simplified model; A3 is the area of ​​the sealing layer rubber in the simplified model; A4 is the area of ​​the positive cord in the simplified model; A5 is the area of ​​the turn-up cord in the simplified model.

[0074] In the present invention, S y5 To simplify the static moment of the turn-up cord about the Y axis in the model, that is, S y5 To simplify the model, the sum of the static moments of the turn-up cord with a parallelogram shape and the turn-up cord with a rectangular shape about the Y axis.

[0075] In the present invention, A5 is the area of ​​the turn-up cord in the simplified model, that is, A5 is the sum of the areas of the turn-up cord in the shape of a parallelogram and the turn-up cord in the shape of a rectangle with respect to the Y axis in the simplified model.

[0076] In the present invention, the determination of the bead bending neutral layer position is mainly related to the elastic modulus of the bead material, the static moment of the material in the compressive direction and the cross-sectional area of ​​the material, so the present invention uses formula 1 to calculate the bending neutral layer position. In the present invention, since the rubber material in the bead of the radial tire (including bead reinforcing rubber, apex rubber and sealing layer rubber) is anisotropic material, the bead reinforcing rubber is in a compressive state in most cases, and the apex rubber and the sealing layer rubber are in a tensile state, the bead reinforcing rubber adopts a compression modulus, and the apex rubber and the sealing layer rubber adopt a tensile modulus.

[0077] In the present invention, the elastic modulus of the apex rubber, the elastic modulus of the sealing layer rubber, the elastic modulus of the positive cord and the elastic modulus of the turn-up cord are preferably uniaxial tensile moduli. The elastic modulus of the apex rubber and the elastic modulus of the sealing layer rubber are preferably the tensile elastic modulus when the strain is 1. The elastic modulus of the positive cord and the elastic modulus of the turn-up cord are preferably the tensile elastic modulus when the strain is 0.1. The elastic modulus of the bead reinforcing rubber is preferably the compressive elastic modulus. The compressive elastic modulus is preferably the compressive elastic modulus when the strain is -0.4.

[0078] In the present invention, the method for determining the tensile elastic modulus when the strain is 1 preferably comprises the following steps:

[0079] The sample of the apex glue or the sealing layer glue is stretched in a tensile testing machine until the apex glue or the sealing layer glue breaks, and a tensile stress-strain curve is obtained;

[0080] According to the compressive stress-strain curve, the tensile elastic modulus when the strain is 1 is calculated by formula 2;

[0081]

[0082] In formula 2: σ1 is the stress value when the strain is 1, ε1=1.

[0083] In the present invention, the sample of the apex rubber or the sealing layer rubber is stretched in a tensile testing machine until the apex rubber or the sealing layer rubber breaks, and a tensile stress-strain curve is obtained. In the present invention, the sample of the apex rubber or the sealing layer rubber is preferably vulcanized into a sheet sample using a flat vulcanizer, and the sheet sample is preferably cut using an I-type cutter. During the cutting, the length direction of the sample of the apex rubber or the sealing layer rubber is parallel to the length direction of the sample. The sample of the apex rubber or the sealing layer rubber is preferably in a dumbbell shape, and the number is preferably 3. In the present invention, the structural schematic diagram of the I-type cutter is as shown in the figure Figure 4 As shown. The present invention preferably clamps the sample of the apex rubber or the sealing layer rubber symmetrically on the upper and lower clamps of the tensile testing machine, and then fixes the extensometer on the marking lines at both ends of the narrow and long part, wherein the spacing between the marking lines is 25mm; then the tensile testing machine is started, and the stretching is preferably to stretch the clamp at a rate of 200mm / min±20mm / min until the rubber breaks. In a specific embodiment of the present invention, the tensile stress-strain curve of the sample of the apex rubber or the sealing layer rubber is calculated as follows Figure 5 shown.

[0084] In the present invention, the apex rubber or the sealing layer rubber is a highly nonlinear large deformation elastic body, and the strain at the apex rubber or the sealing layer rubber of the radial tire bead (especially the radial aircraft tire bead) is often not more than 1, so the present invention obtains a tensile stress-strain curve;

[0085] According to the compressive stress-strain curve, the tensile elastic modulus when the strain is 1 is calculated by formula 2;

[0086]

[0087] In formula 2: σ1 is the stress value when the strain is 1, ε1=1.

[0088] In the present invention, the method for determining the compressive elastic modulus when the strain is -0.4 preferably comprises the following steps:

[0089] The tire bead reinforcement rubber sample is placed in a compression tester for compression until the strain reaches 25% or the compression force reaches 18 kN, and a compression stress-strain curve is obtained;

[0090] According to the compressive stress-strain curve, the compressive elastic modulus when the strain is -0.4 is calculated by formula 3;

[0091]

[0092] In formula 3: σ -0.4 is the stress value when the strain is -0.4, ε -0.4 =-0.4.

[0093] The present invention places the tire bead reinforcement rubber sample in a compression testing machine for compression until the strain reaches 25% or the compression force reaches 18kN, and obtains a compression stress-strain curve. In the present invention, the tire bead reinforcement rubber sample is in the shape of a cylinder, and the diameter of the tire bead reinforcement rubber sample is preferably 29.0mm±0.5mm, and the height is preferably 12.5mm±0.5mm. The tire bead reinforcement rubber sample is preferably prepared by a molding method, and the surface of the tire bead reinforcement rubber sample is preferably flat, and the upper and lower surfaces are parallel to each other. The present invention preferably places the assembly of the tire bead reinforcement rubber sample into the center of the compression testing machine, and the compression is preferably to compress the tire bead reinforcement rubber sample at a speed of 10mm / min until the strain reaches 25% or the compression force reaches 18kN. In a specific embodiment of the present invention, the compression stress-strain curve is as follows Figure 6 According to the compressive stress-strain curve, the present invention calculates the compressive elastic modulus when the strain is -0.4 by formula 3.

[0094] In the present invention, the method for determining the tensile elastic modulus when the strain is 0.1 preferably comprises the following steps:

[0095] The stress-strain performance test of the cord was carried out according to GB / T 9101-2017 "Nylon 66 dipped cord fabric" and GB / T 32108-2015 "Test methods for tensile properties of dipped cords, yarns and cords", and the stress-strain curve of the cord fabric was obtained;

[0096] According to the stress-strain curve of the cord fabric, the tensile elastic modulus when the strain of the positive cord or the reverse cord is 0.1 is calculated by formula 4;

[0097]

[0098] In formula 4: σ 0.1 is the stress value when the strain is 0.1, ε 0.1 =0.1.

[0099] In a specific embodiment of the present invention, the stress-strain curve of the cord fabric is as follows: Figure 7 shown.

[0100] After obtaining the distance x between the bending neutral layer and the Y axis in the simplified model, the present invention then determines whether the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, where x0 is the distance between the midpoint of the intersection interface between the tire bead reinforcement rubber and the positive cord in the simplified model and the Y axis.

[0101] In the present invention, when the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, the structural parameters of the bead of the radial tire are obtained, and the structural parameters of the bead of the radial tire include: when the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, the elastic modulus information and graphic size information of the bead reinforcement rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model.

[0102] In the present invention, when the distance x between the bending neutral layer and the Y axis in the simplified model is not equal to x0, the present invention modifies the model parameters of at least one of the bead reinforcement rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model, and the model parameters include elastic modulus information and / or graphic size information.

[0103] In the present invention, the correction is preferably: modifying the elastic modulus information of the positive cord in the simplified model, and modifying the graphic size information of the bead reinforcement rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model.

[0104] In the present invention, when the distance x between the bending neutral layer in the simplified model and the Y axis is less than x0, the correction is preferably: increasing the elastic modulus information of the positive cord, increasing the thickness of the tire bead reinforcement rubber, reducing the thickness of the positive cord, increasing the thickness of the reverse cord, reducing the thickness of the apex rubber, and increasing the thickness of the sealing layer rubber.

[0105] In the present invention, when the distance x between the bending neutral layer in the simplified model and the Y axis is greater than x0, the correction is preferably: reducing the elastic modulus information of the positive cord, reducing the thickness of the tire bead reinforcement rubber, increasing the thickness of the positive cord, reducing the thickness of the reverse cord, increasing the thickness of the apex rubber, and reducing the thickness of the sealing layer rubber.

[0106] The thickness of the tire bead reinforcing rubber is the length of the short side of the parallelogram forming the tire bead reinforcing rubber in the simplified model. The thickness of the positive cord is the length of the short side of the parallelogram forming the positive cord in the simplified model. The thickness of the turn-up cord is the length of the short side of the parallelogram forming the turn-up cord in the simplified model and the length of the wide side of the rectangle forming the turn-up cord in the simplified model. The thickness of the apex rubber is the length of the short straight side of the right triangle forming the apex rubber in the simplified model. The thickness of the sealant rubber is the length of the wide side of the rectangle forming the sealant rubber in the simplified model.

[0107] After modifying the model parameters of at least one of the bead reinforcement rubber, the front cord, the reverse cord, the apex rubber and the sealing layer rubber in the simplified model, the present invention repeats the above steps of "in the two-dimensional coordinate system: calculating the distance between the bending neutral layer and the Y axis in the simplified model according to Formula 1" and "then judging whether the distances x and x0 between the bending neutral layer and the Y axis in the simplified model are equal", and iterates until the distances x and x0 between the bending neutral layer and the Y axis in the simplified model are equal, thereby obtaining the structural parameters of the bead of the radial tire.

[0108] The present invention provides a radial tire bead, and the structural parameters of the radial tire bead are determined by the method described in the above technical solution.

[0109] The present invention proposes the concept of a radial aircraft tire bead bending neutral layer for the first time, in order to solve the common problem of delamination between the bead cord and the rubber interface of radial aircraft tires during overload sliding in dynamic simulation tests. The present invention introduces the cross-section bending beam bending neutral layer calculation method into the radial tire bead design for the first time, and proposes a method for forward design of the radial tire bead, which greatly improves the iterative efficiency of the radial tire bead design.

[0110] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0111] The method for determining the structural parameters of the bead of a radial tire provided in the following embodiments includes a bead simplification method, a bead structure calculation method, and a bead material parameter determination method. The steps include: first roughly drawing a bead structure schematic diagram, and then simplifying the bead structure using the area equality method to make the simplified bead diagram into a regular shape that is easy to calculate. Then calculate the elastic modulus, cross-sectional area, and static moment of each material, and bring them into the area weighted average formula to calculate the bending neutral layer position of the bead, and finally obtain the final bead structure diagram after multiple iterations.

[0112] Figure 8 A flow chart of a method for determining structural parameters of a radial tire bead provided by the present invention, Figure 8"Adjusting the neutral layer position" is the step to correct the simplified model.

[0113] Example 1

[0114] This embodiment provides a method for determining the structural parameters of a radial aircraft tire bead, and the flow chart is as follows: Figure 8 As shown. In this embodiment, the following should be drawn first: Figure 2 The structural schematic diagram of the radial aircraft tire bead is shown in the middle left figure, and then the cross-sectional structure of the bead located on the upper part of the radial tire wire ring is modeled by the area equality method (i.e., simplified processing) to obtain a simplified model. The simplified processing is: the shape of the bead reinforcing rubber in the bead located on the upper part of the radial tire wire ring is simplified to a parallelogram, the shape of the positive cord is simplified to a parallelogram, the shape of the reverse cord is simplified to a parallelogram and a rectangle, the shape of the triangle rubber is simplified to a right triangle, and the shape of the sealing layer rubber is simplified to a rectangle, as shown in the figure Figure 2 As shown in the right figure of the figure. In this embodiment, the area change rate of the bead reinforcing rubber, the front cord, the back cord, the apex rubber and the sealing layer rubber before and after the simplified treatment is ≤5%.

[0115] After obtaining the simplified model, this embodiment uses the edge of the sealant layer in the simplified model that is away from the wire ring and does not contact the turn-up cord as the coordinate origin, and uses the rectangular long side of the sealant layer in the simplified model as the Y axis to establish the following Figure 3 The two-dimensional coordinate system shown.

[0116] Then measure the elastic modulus of the rubber (bead reinforcement rubber, triangular cross and sealing layer rubber) and cords (positive cords and reverse cords) used in the bead;

[0117] Among them, the elastic modulus of the apex rubber and the elastic modulus of the sealing layer rubber adopt the tensile elastic modulus when the strain is 1. The elastic modulus of the positive cord and the elastic modulus of the reverse cord adopt the tensile elastic modulus when the strain is 0.1. The elastic modulus of the bead reinforcement rubber adopts the compressive elastic modulus when the strain is preferably -0.4.

[0118] The method for determining the elastic modulus of the apex glue or the elastic modulus of the sealing layer glue includes:

[0119] Use a flat vulcanizer to vulcanize sheet samples. The samples are dumbbell-shaped. There are 3 samples. Use an I-type cutter to cut (make the length of the sample parallel to the length of the sample) to obtain dumbbell-shaped samples. Figure 4 As shown:

[0120] Clamp the sample symmetrically on the upper and lower clamps of the tensile testing machine, and then fix the extensometer on the marking lines at both ends of the narrow and long part (the spacing between the marking lines is 25mm); start the testing machine and stretch the clamps at a rate of 200mm / min±20mm / min until the rubber breaks. The rubber tensile stress-strain curve is calculated as follows: Figure 5 As shown:

[0121] The elastic modulus of the apex rubber or the sealing layer rubber is a highly nonlinear large deformation elastic body, and the strain at the bead rubber of the radial aircraft tire is often not more than 1. Therefore, the elastic modulus of the apex rubber or the sealing layer rubber is calculated using Formula 2:

[0122]

[0123] In formula 2: σ1 is the stress value when the strain is 1, ε1 = 1;

[0124] Methods for determining the elastic modulus of the tire bead reinforcement include:

[0125] The rubber material compression specimen of the tire bead reinforcement is a cylinder with a diameter of 29.0mm±0.5mm and a height of 12.5mm±0.5mm. The specimen is prepared by molding, and its surface should be flat and the upper and lower surfaces should be parallel to each other. Place the specimen assembly in the center of the compression tester and compress the specimen at a speed of 10mm / min until the strain reaches 25% or the compression force reaches 18kN. The compression stress-strain curve is shown in Figure 6 As shown, the rubber compression modulus should be calculated using Formula 3:

[0126]

[0127] In formula 3: σ -0.4 is the stress value when the strain is -0.4, ε -0.4 =-0.4;

[0128] Methods for determining the elastic modulus of the positive cord or the reverse cord include:

[0129] The stress-strain performance test of the cord was carried out according to GB / T 9101-2017 "Nylon 66 dipped cord fabric" and GB / T 32108-2015 "Test methods for tensile properties of dipped cords, yarns and cords". The stress-strain curve is as follows: Figure 7 As shown, the cord modulus should be calculated using Formula 4:

[0130]

[0131] In formula 4: σ 0.1 is the stress value when the strain is 0.1, ε 0.1 =0.1.

[0132] exist Figure 3 The cross-sectional area and static moment of the rubber and cord are measured and calculated in the two-dimensional coordinate system shown. Fig. 9 This is a simplified model diagram of a radial aircraft tire. The calculation formula for the static moment of rubber and cord is: Static moment = A × Y c , A is the area of ​​the material, Yc is the distance from the centroid of the material to the Y axis, and the calculated dimensions and parameters of the simplified model of a radial aircraft tire are shown in Table 1.

[0133] Table 1 Dimensional parameters of a simplified model of a radial aircraft tire

[0134] <![CDATA[E r1 ]]> <![CDATA[E r2 ]]> <![CDATA[E r3 ]]> <![CDATA[E r4 ]]> <![CDATA[E r5 ]]> 7.25 4.0 0.956 1300 1300 <![CDATA[S y1 ]]> <![CDATA[S y2 ]]> <![CDATA[S y3 ]]> <![CDATA[S y4 ]]> <![CDATA[S y5 ]]> 9884 2232 31 1024 2160 <![CDATA[A1]]> <![CDATA[A2]]> <![CDATA[A3]]> <![CDATA[A4]]> <![CDATA[A5]]> 416 248 62 64 252

[0135] Substituting the parameters in Table 1 into Formula 1, we get the result x = 10.17 mm. Fig. 9 The distance x0 between the midpoint of the interface where the bead reinforcement rubber and the positive cord intersect and the Y axis is measured. x0 = 17.2 mm, x ≠ x0, so the bead structure is adjusted. The schematic diagram of the adjusted bead size is as follows Fig.10 The calculated and adjusted tire bead size parameters are shown in Table 2.

[0136] Table 2 Bead size parameters after adjustment

[0137] <![CDATA[E r1 ]]> <![CDATA[E r2 ]]> <![CDATA[E r3 ]]> <![CDATA[E r4 ]]> <![CDATA[E r5 ]]> 7.25 4 0.956 6000 1300 <![CDATA[S y1 ]]> <![CDATA[S y2 ]]> <![CDATA[S y3 ]]> <![CDATA[S y4 ]]> <![CDATA[S y5 ]]> 10166 1488 139.5 450 1960 <![CDATA[A1]]> <![CDATA[A2]]> <![CDATA[A3]]> <![CDATA[A4]]> <![CDATA[A5]]> 480 186 93 31 189

[0138] Then substitute the parameters in Table 2 into Formula 1 to obtain the bending neutral layer x, x = 12.22 mm, from Fig.10 The distance x0 between the midpoint of the interface where the bead reinforcement rubber and the positive cord intersect and the Y axis is measured, x0=13mm, x-x0≤1mm. Due to the limitations of the aircraft tire manufacturing process, a process error of 1mm is allowed.

[0139] The interface is located at the bending neutral layer. The tire bead structure is redrawn according to the bending neutral layer x, and the final tire bead structure diagram can be obtained after two or three iterations.

[0140] As can be seen from the above embodiments, the present invention provides a novel tire bead design method based on a material weighted average algorithm. The method uses an area weighted average method to calculate the bending neutral layer at the bead of a radial tire, and then sets the interface between the rubber and the cord at the bending neutral layer position, thereby improving the fatigue performance of the bead and preventing the rubber and the cord from delaminating at the bead. The method can effectively improve the fatigue performance at the bead of a radial aircraft tire and greatly improve the efficiency of the bead structure of an aircraft tire.

[0141] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for determining structural parameters of a radial tire bead, characterized in that: The following steps are involved: (1) The bead structure of a radial tire is modeled by using the equal area method to obtain a simplified model, wherein the simplified model includes: a bead reinforcing rubber in the shape of a parallelogram, a positive cord in the shape of a parallelogram, a reverse cord in the shape of a parallelogram and a rectangle, a apex rubber in the shape of a right triangle, and a sealing layer rubber in the shape of a rectangle; (2) establishing a two-dimensional coordinate system with the edge of the sealant layer in the simplified model that is away from the wire ring and does not contact the turn-up cord as the coordinate origin and the long side of the rectangle of the sealant layer in the simplified model as the Y axis; (3) In the two-dimensional coordinate system: The distance x between the bending neutral layer and the Y axis in the simplified model is calculated according to formula 1; In formula 1: E r1 is the elastic modulus of the tire bead reinforcement rubber, E r2 is the elastic modulus of the apex, E r3 is the elastic modulus of the sealing layer glue, E r4 is the elastic modulus of the positive cord, E r5 is the elastic modulus of the turn-up cord, S y1 To simplify the static moment of the tire bead reinforcement rubber on the Y axis in the model, S y2 To simplify the static moment of the triangle rubber on the Y axis in the model, S y3 To simplify the static moment of the sealant layer on the Y axis in the model, S y4 To simplify the static moment of the positive cord about the Y axis in the model, S y5 is the static moment of the turn-up cord to the Y axis in the simplified model, A1 is the area of ​​the bead reinforcement rubber in the simplified model; A2 is the area of ​​the apex rubber in the simplified model; A3 is the area of ​​the sealing layer rubber in the simplified model; A4 is the area of ​​the positive cord in the simplified model; A5 is the area of ​​the turn-up cord in the simplified model; Then, it is determined whether the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, wherein x0 is the distance between the midpoint of the intersection interface between the bead reinforcement rubber and the positive cord in the simplified model and the Y axis; When the distance x between the bending neutral layer and the Y axis in the simplified model is equal to x0, step (5) is executed; When the distances x and x0 between the bending neutral layer and the Y axis in the simplified model are not equal, executing step (4); (4) modifying the simplified model, wherein the modification comprises: modifying the model parameters of at least one of the bead reinforcement rubber, the front cord, the back cord, the apex rubber and the sealing layer rubber in the simplified model, wherein the model parameters include elastic modulus information and / or graphic size information; and then executing step (3); (5) Obtaining structural parameters of the radial tire bead, wherein the structural parameters of the radial tire bead include: elastic modulus information and graphic size information of the bead reinforcing rubber, positive cord, reverse cord, apex rubber and sealing layer rubber in the simplified model.

2. The method for determining the structural parameters of a radial tire bead according to claim 1, characterized in that: In step (4), the correction is: modifying the elastic modulus information of the positive cord in the simplified model, and modifying the graphic size information of the bead reinforcement rubber, the positive cord, the reverse cord, the apex rubber and the sealing layer rubber in the simplified model; In step (1), the model is constructed as follows: the shape of the bead reinforcing rubber in the bead located on the upper part of the radial tire wire ring is simplified to a parallelogram, the shape of the positive cord is simplified to a parallelogram, the shape of the turn-up cord is simplified to a parallelogram and a rectangle, the shape of the apex rubber is simplified to a right triangle, and the shape of the sealing layer rubber is simplified to a rectangle; the absolute value of the area change rate of the bead reinforcing rubber, positive cord, turn-up cord, apex rubber and sealing layer rubber before and after the simplified model is constructed is ≤5%.

3. The method for determining the structural parameters of a radial tire bead according to claim 1, characterized in that: The elastic modulus of the apex rubber, the elastic modulus of the sealing layer rubber, the elastic modulus of the front cord and the elastic modulus of the reverse cord are uniaxial tensile moduli.

4. The method for determining the structural parameters of a radial tire bead according to claim 3, characterized in that: The elastic modulus of the apex glue and the elastic modulus of the sealing layer glue adopt the tensile elastic modulus when the strain is 1.

5. The method for determining the structural parameters of the radial tire bead according to claim 4, characterized in that: The method for determining the tensile elastic modulus when the strain is 1 comprises the following steps: The sample of the apex glue or the sealing layer glue is stretched in a tensile testing machine until the apex glue or the sealing layer glue breaks, and a tensile stress-strain curve is obtained; According to the compressive stress-strain curve, the tensile elastic modulus when the strain is 1 is calculated by formula 2; In formula 2: σ1 is the stress value when the strain is 1, ε1=1.

6. The method for determining the structural parameters of a radial tire bead according to claim 1, characterized in that: The elastic modulus of the tire bead reinforcing rubber is a compressive elastic modulus.

7. The method for determining the structural parameters of a radial tire bead according to claim 6, characterized in that: The compressive elastic modulus is the compressive elastic modulus when the strain is -0.

4.

8. The method for determining the structural parameters of a radial tire bead according to claim 7, characterized in that: The method for determining the compressive elastic modulus when the strain is -0.4 comprises the following steps: The tire bead reinforcement rubber sample is placed in a compression tester for compression until the strain reaches 25% or the compression force reaches 18 kN, and a compression stress-strain curve is obtained; According to the compressive stress-strain curve, the compressive elastic modulus when the strain is -0.4 is calculated by formula 3; In formula 3: σ -0.4 is the stress value when the strain is -0.4, ε -0.4 =-0.

4.

9. The method for determining the structural parameters of a radial tire bead according to claim 3, characterized in that: The elastic modulus of the front cord and the elastic modulus of the turn-up cord are the tensile elastic modulus when the strain is 0.

1.

10. A radial tire bead, characterized in that: The structural parameters of the radial tire bead are determined by the method described in any one of claims 1 to 9.

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