A method for constructing a crack propagation rate model of spliced rubber

Abstract

The present invention provides a method for constructing a crack propagation rate model of spliced rubber. By splicing a first sample piece and a second sample piece and forming a test crack, the present invention constructs a crack propagation scenario at the material interface, thereby reproducing the mechanical environment of interface crack propagation during the actual use of a tire. Subsequently, by collecting the stress-strain curves of each tensile cycle, the crack propagation rate of each cycle group and the maximum strain in the cycle group are obtained. Finally, by combining the crack propagation rates and the maximum strains of multiple cycle groups, a first coefficient and a second coefficient are calculated to correct the initial model, and a model of the crack propagation rate of the spliced rubber material formed by combining the first sample piece and the second sample piece is reconstructed to accurately characterize the crack propagation at the interface of the spliced rubber. The newly constructed model can significantly reduce errors, thereby improving the accuracy of tire fatigue life assessment.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber material testing, and in particular to a method for constructing a crack propagation rate model of spliced rubber. Background Art

[0002] Rubber is a key material for tires, and the crack propagation rate at its interface is a major indicator of tire performance, directly affecting the fatigue life of tires.

[0003] In most cases, the fatigue crack path of tires extends along the rubber interface between adjacent components, and the crack propagation rate determines the service life. Therefore, studying the crack propagation rate between the interfaces of rubber materials with different components is of great significance for improving the fatigue life of tires.

[0004] However, existing testing methods only target the crack propagation rate of a single rubber material. In actual applications, tire fatigue cracks often extend along the interfaces of different rubber materials. Existing methods cannot accurately characterize the interface behavior, and the traditional crack propagation model based on tearing energy has significant errors in the interface expansion scenario, especially when the tearing energy is large, resulting in poor fitting effect and poor accuracy in evaluating the fatigue life of tires. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide.

[0006] In a first aspect, an embodiment of the present invention provides a method for constructing a crack propagation rate model of spliced rubber, and the method is as follows:

[0007] Obtain a first sample piece and a second sample piece;

[0008] Splice and bond the first sample piece and the second sample piece to obtain a target sample piece;

[0009] Cut the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece;

[0010] Under preset experimental parameter conditions, perform a crack tensile test on the test crack on the test sample piece to obtain a test result; wherein, the test result at least includes the stress-strain curve of each tensile cycle;

[0011] For each cycle group, calculate the crack propagation rate after the tensile test of the cycle group based on the stress-strain curve and determine the maximum strain corresponding to the cycle group; wherein, the cycle group includes a first number of tensile cycles;

[0012] Substitute all the crack propagation rates and maximum strains into the initial model to calculate the first coefficient and the second coefficient;

[0013] Determine the crack growth rate model according to the first coefficient, the second coefficient and the initial model.

[0014] Combined with the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect. The steps of splicing the first sample piece and the second sample piece and bonding them to obtain the target test piece include:

[0015] Freeze the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge;

[0016] Splice the first bonding edge and the second bonding edge and perform vulcanization treatment to obtain the target test piece.

[0017] Combined with the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect. The steps of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge include:

[0018] With a freezing depth of 20 to 30 mm, put the edges of the first sample piece and the second sample piece into liquid nitrogen and freeze for 15 to 20 minutes to obtain the first sample piece with the first bonding edge and the second sample piece with the second bonding edge.

[0019] Combined with the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect. The steps of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge further include:

[0020] Put the first sample piece and the second sample piece into a vulcanization mold and splice the first bonding edge and the second bonding edge, and perform vulcanization for 30 minutes under the conditions of 150 °C and 10 Mpa to obtain a pre-connected sample piece;

[0021] Cool the pre-connected sample piece to room temperature to obtain the target sample piece.

[0022] Combined with the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect. The steps of cutting the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece include:

[0023] Cut the target sample piece to obtain a pure shear specimen with the junction of the first sample piece and the second sample piece at the center;

[0024] Cut the edge of the pure shear specimen along the junction of the first sample piece and the second sample piece to obtain the test sample piece;

[0025] Among them, the length of the test crack is 25 mm.

[0026] Combined with the first aspect, the embodiment of the present invention provides the first possible implementation manner of the first aspect. The thickness of the first sample piece is the same as that of the second sample piece, and is greater than or equal to 1.5 mm and less than or equal to 2 mm.

[0027] Combined with the first aspect, the embodiments of the present invention provide a first possible implementation manner of the first aspect, where the first sample piece and the second sample piece are mixed rubbers of two different types of rubber materials.

[0028] Combined with the first aspect, the embodiments of the present invention provide a first possible implementation manner of the first aspect, where the first sample piece and the second sample piece are rectangular structures with the same size and shape.

[0029] Combined with the first aspect, the embodiments of the present invention provide a first possible implementation manner of the first aspect, where the crack propagation rate model is 。

[0030] In a second aspect, the present application provides a method for calculating the crack propagation rate of spliced rubber, and the method includes:

[0031] Obtaining the maximum strain corresponding to each cycle group in the crack tensile test of the target spliced rubber;

[0032] Combining the maximum strain and the provided crack propagation rate model to calculate the target crack propagation rate of the spliced rubber.

[0033] The embodiments of the present invention bring the following beneficial effects:

[0034] The present invention provides a method for constructing a crack propagation rate model of spliced rubber.

[0035] In the present invention, by splicing the first sample piece and the second sample piece and forming a test crack, a crack propagation scenario at the material interface is directly constructed, thereby reproducing the mechanical environment of interface crack propagation during the actual use of the tire. Subsequently, by collecting the stress-strain curves of each tensile cycle, the crack propagation rate of each cycle group and the maximum strain in the cycle group are obtained. Finally, combining the crack propagation rates and maximum strains of multiple cycle groups, the first coefficient and the second coefficient are calculated to correct the initial model, and a crack propagation rate model of the spliced rubber material formed by combining the first sample piece and the second sample piece is reconstructed to accurately characterize the crack propagation at the interface of the spliced rubber. The newly constructed model can significantly reduce errors, thereby improving the accuracy of tire fatigue life assessment.

[0036] Other features and advantages of the present invention will be described in the subsequent description, and, in part, will be obvious from the description, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the description, the claims, and the drawings.

[0037] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically given below, and in conjunction with the accompanying drawings, the detailed description is as follows. Brief Description of the Drawings

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic flowchart of a method for constructing a one - pattern expansion rate model of spliced rubber provided in Embodiment 1 of the present invention. Specific Embodiments

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present invention.

[0041] For the convenience of understanding this embodiment, the application scenarios and design concepts of the embodiments of this application will be briefly introduced.

[0042] In most cases, the fatigue crack path of a tire extends along the rubber interface between adjacent components. The speed of crack propagation determines the service life. However, the current rubber fatigue crack propagation rate experiments only test the crack propagation rate of a single rubber material, and the relationship model between the crack propagation rate and the tearing energy is not applicable to the crack propagation rate between the interfaces of spliced rubber. When calculating the crack propagation rate through the traditional relationship model between the crack propagation rate and the tearing energy, the greater the tearing energy received by the spliced rubber, the greater the error. Therefore, the present invention proposes a method for constructing a crack propagation rate model of spliced rubber.

[0043] Embodiment 1

[0044] Combined with Figure 1 , this embodiment provides a method for constructing a crack propagation rate model of spliced rubber, and the method is as follows:

[0045] S100, Obtain a first sample piece and a second sample piece.

[0046] S200, Splice and bond the first sample piece and the second sample piece to obtain a target sample piece.

[0047] S300, Cut the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece.

[0048] S400. Under the condition of preset experimental parameters, a crack tensile test is carried out on the test crack on the test sample to obtain the test results. Among them, the test results at least include the stress-strain curve of each tensile cycle.

[0049] S500. For each cycle group, based on the stress-strain curve, calculate the crack growth rate after the cycle group tensile test and determine the maximum strain corresponding to the cycle group. Among them, the cycle group includes a first number of tensile cycles.

[0050] S600. Substitute all the crack growth rates and maximum strains into the initial model to calculate the first coefficient and the second coefficient.

[0051] S700. According to the first coefficient, the second coefficient and the initial model, determine the crack growth rate model.

[0052] Specifically, in this embodiment, first, the first sample and the second sample are combined to form a test crack, so as to construct a crack growth scenario of the material interface of the spliced rubber, thereby reproducing the mechanical environment of the interface crack growth during the actual use of the tire.

[0053] Subsequently, by collecting the stress-strain curve of each tensile cycle, the crack growth rate of each cycle group and the maximum strain in the cycle group are obtained.

[0054] Among them, the preset experimental parameters in this embodiment include the frequency and strain range of the reciprocating tensile motion. The frequency is specifically 3 - 8 Hz, and the strain range is 10% - 50%.

[0055] Moreover, in this embodiment, one tensile cycle is 600 reciprocating tensile motions, and one cycle group includes 800 tensile cycles. During the crack tensile test, the stress-strain curve of each tensile cycle is recorded by the experimental equipment.

[0056] In addition, after each tensile cycle ends, a photo is taken of the tip of the test crack. According to the taken photo, calculate the length of the crack growth in each tensile cycle, and then divide it by the number of times of the tensile cycle, which is the crack growth rate corresponding to the tensile cycle.

[0057] Finally, combining the crack growth rates and maximum strains of multiple cycle groups, calculate the first coefficient and the second coefficient to correct the initial model, and reconstruct the model of the crack growth rate of the spliced rubber material formed by the combination of the first sample and the second sample to accurately characterize the crack growth of the interface of the spliced rubber. The constructed new model can significantly reduce the error, thereby improving the accuracy of tire fatigue life assessment.

[0058] In this embodiment, step S200, the step of splicing the first sample piece and the second sample piece and bonding them to obtain the target test piece includes:

[0059] S210, freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge.

[0060] S220, splicing the first bonding edge and the second bonding edge and performing a vulcanization treatment to obtain the target test piece.

[0061] In this embodiment, first, the edges of the first sample piece and the second sample piece are frozen, so that the elastic modulus at the frozen edges of the first sample piece and the second sample piece is increased, avoiding dislocation caused by the material rebounding at room temperature.

[0062] Subsequently, through the vulcanization process, the first bonding edge and the second bonding edge of the first sample piece and the second sample piece are bonded, and chemical cross-linking occurs at the bonding position of the first sample piece and the second sample piece. The bonding strength at the bonding position is relatively high, thus ensuring that the crack propagates along the preset path.

[0063] Among them, step S210, the step of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge includes:

[0064] S211, with a freezing depth of 20 mm to 30 mm, putting the edges of the first sample piece and the second sample piece into liquid nitrogen and freezing for 15 minutes to 20 minutes to obtain the first sample piece with the first bonding edge and the second sample piece with the second bonding edge.

[0065] To ensure that the frozen area can cover the edge areas of the first sample piece and the second sample piece, so that the widths of the first bonding edge and the second bonding edge can resist tensile stress, it is necessary to ensure that the freezing depth of the first sample piece and the second sample piece is not less than 20 mm. In this embodiment, the freezing depth is specifically 25 mm. At this freezing depth and a freezing duration of 15 to 20 minutes for the first sample piece and the second sample piece, the temperature of the rubber can be reduced below the glass transition temperature, enabling the first sample piece and the second sample piece to be fully tempered, thus avoiding rebounding during splicing.

[0066] In this embodiment, step S210, the step of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge further includes:

[0067] S212, putting the first sample piece and the second sample piece into a vulcanization mold and splicing the first bonding edge and the second bonding edge, and performing vulcanization at 150 °C and 10 Mpa for 30 min to obtain a pre-connected sample piece.

[0068] S213, cooling the pre-connected sample piece to room temperature to obtain the target sample piece.

[0069] In an environment of 150°C, the vulcanizing agent can be activated to promote the cross-linking reaction of rubber molecular chains, enabling the first bonding edge and the second bonding edge to achieve a firm bond.

[0070] Moreover, in this embodiment, during the vulcanization process, the vulcanization pressure is maintained at 10 MPa, which can eliminate the interfacial voids between the first sample piece and the second sample piece, further improving the uniformity of the bond and avoiding local stress concentration in the overall bonded part.

[0071] In this embodiment, step S300, the step of cutting the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece, includes:

[0072] S310, cutting the target sample piece to obtain a pure shear specimen with the junction of the first sample piece and the second sample piece at the center.

[0073] S320, cutting the edge of the pure shear specimen along the junction of the first sample piece and the second sample piece to obtain a test sample piece.

[0074] Among them, the length of the test crack is 25 mm.

[0075] To ensure the accuracy of each group of test data, in this embodiment, the target test piece is cut to ensure the accuracy of each test.

[0076] Specifically, the test sample piece formed by the building materials in this embodiment is 150 mm long and 25 mm wide, and the junction line of the first sample piece and the second sample piece is parallel to the long side and located at the midline of the wide side. In this structure, the crack propagation path can be controlled by the interface, and at the same time, the interference of geometric deviation to the test results can be eliminated.

[0077] In addition, the length of the test crack in this embodiment is 25 mm, which can ensure that the tip of the test crack is in a pure shear stress field, avoiding the fracture of the test sample piece during the tensile test.

[0078] It should be noted here that in this embodiment, the thickness of the first sample piece is the same as that of the second sample piece, and is greater than or equal to 1.5 mm and less than or equal to 2 mm.

[0079] Within this thickness range, it can avoid the edge warping or local tearing of the first sample piece and the second sample piece due to being too thin, and at the same time, it can also prevent non-uniform deformation caused by being too thick.

[0080] Moreover, in this embodiment, the first sample piece and the second sample piece are mixed rubbers of two different types of rubber materials.

[0081] Under the condition that the first sample piece and the second sample piece adopt heterogeneous rubber materials, the authenticity of the simulated tire interface can be further ensured, thereby improving the matching degree between the experimental data and the actual working conditions.

[0082] It should be noted that in this embodiment, the first sample piece and the second sample piece are rectangular structures with the same size and shape.

[0083] Specifically, in this embodiment, both the first sample piece and the second sample piece are rectangular sample pieces of 165 mm × 75 mm. The two sample pieces with the same size can eliminate the interference of geometric differences on the tensile strain, thereby further ensuring the accuracy of the test.

[0084] Moreover, in this embodiment, the first bonding edge and the second bonding edge are respectively the long sides of the first sample piece and the second sample piece.

[0085] In addition, in this embodiment, in the crack tensile test in step S400, first, the test sample piece is placed in the fixture. The upper fixture clamps one side of the first sample piece away from the second sample piece. At the same time, the lower fixture clamps one side of the second sample piece away from the first sample piece. Subsequently, the upper fixture and the lower fixture are driven to perform a reciprocating stretching action along the width direction of the test sample piece.

[0086] It should be noted that the widths of the test sample pieces clamped by the upper fixture and the lower fixture are the same, that is, the clamping depths are the same, so as to ensure that the stress during stretching can be evenly distributed.

[0087] Moreover, the ratio of the distance between the upper fixture and the lower fixture (i.e., the height of the effective test area) to the test sample piece is not less than 10, to avoid unexpected fracture caused by instability. At the same time, the tip stress field of the test crack under this condition is closer to the theoretical model.

[0088] In this embodiment, the crack growth rate model is .

[0089] Wherein, is the crack growth rate, is the maximum strain per turn, and a and b are is the parameter for linear fitting with 1 + i.e., the first coefficient and the second coefficient.

[0090] This embodiment uses to replace the tearing energy variable, thereby avoiding the influence of the interface bonding strength and the strain field mutation in the traditional model. The goodness of fit is higher than that of the traditional model, and the model error is reduced, especially suitable for the high-load working conditions of tires.

[0091] Specifically, in this embodiment, the finally constructed crack growth rate model of the spliced rubber is .

[0092] Embodiment 2

[0093] This embodiment provides a method for calculating the crack growth rate of spliced rubber, and the method includes:

[0094] Obtain the maximum strain corresponding to each cycle group in the crack tensile test of the target spliced rubber.

[0095] Combine the maximum strain with the crack propagation rate model provided in Example 1 to calculate the target crack propagation rate of the spliced rubber.

[0096] In this embodiment, after obtaining the maximum strain corresponding to each cycle group, substituting the maximum strain into the crack propagation rate model constructed in Example 1 can quickly calculate the crack propagation rate of the target spliced rubber. That is, by obtaining the , and substituting it into the crack propagation rate model constructed in Example 1, that is , the can be obtained through calculation. The calculation is simple, fast, and has high accuracy.

[0097] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the above-described systems and devices can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0098] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0099] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0100] Finally, it should be noted that the above embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A method for constructing a crack propagation rate model of spliced rubber, characterized in that, The method is as follows: Obtain a first sample piece and a second sample piece; Splice and bond the first sample piece and the second sample piece to obtain a target sample piece; Cut the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece; Under preset experimental parameter conditions, perform a crack tensile test on the test crack on the test sample piece to obtain a test result; wherein, the test result at least includes a stress-strain curve for each tensile cycle; For each cycle group, calculate the crack propagation rate after the tensile test of the cycle group based on the stress-strain curve and determine the maximum strain corresponding to the cycle group; wherein, the cycle group includes a first number of the tensile cycles; Substitute all the crack propagation rates and the maximum strains into an initial model to calculate a first coefficient and a second coefficient; Determine the crack propagation rate model according to the first coefficient, the second coefficient and the initial model; The initial model is , where is the crack propagation rate, is the maximum strain per turn, and a and b are for linear fitting with 1 + parameters, namely the first coefficient and the second coefficient.

2. The method according to claim 1, wherein The step of splicing the first sample piece and the second sample piece and bonding them to obtain a target test piece includes: Freeze the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge; Splice the first bonding edge and the second bonding edge and perform a vulcanization treatment to obtain the target test piece.

3. The method according to claim 2, wherein The step of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge includes: With a freezing depth of 20 mm to 30 mm, place the edges of the first sample piece and the second sample piece into liquid nitrogen and freeze for 15 minutes to 20 minutes to obtain a first sample piece with the first bonding edge and a second sample piece with the second bonding edge.

4. The method according to claim 3, characterized in that, The step of freezing the edges of the first sample piece and the second sample piece to form a first bonding edge and a second bonding edge further includes: Place the first sample piece and the second sample piece into a vulcanization mold and splice the first bonding edge and the second bonding edge, and perform vulcanization for 30 min under the conditions of 150 °C and 10 Mpa to obtain a pre-connected sample piece; Cool the pre-connected sample piece to room temperature to obtain the target sample piece.

5. The method according to claim 1, wherein The step of cutting the target sample piece to obtain a test sample piece with a test crack formed at the junction of the first sample piece and the second sample piece includes: Cut the target sample piece to obtain a pure shear specimen with the junction of the first sample piece and the second sample piece located at the center; Cut the edges of the pure shear specimen along the junction of the first sample piece and the second sample piece to obtain the test sample piece; Wherein, the length of the test crack is 25 mm.

6. The method according to claim 1, wherein The thickness of the first sample piece is the same as the thickness of the second sample piece, and is greater than or equal to 1.5 mm and less than or equal to 2 mm.

7. The method according to claim 1, characterized in that, The first sample piece and the second sample piece are mixed rubbers of two different types of rubber materials.

8. The method according to claim 1, wherein The first sample piece and the second sample piece are rectangular structures with the same size and shape.

9. A method for calculating the crack growth rate of spliced rubber, characterized in that, The method includes: Obtain the maximum strain corresponding to each cycle group in the crack tensile test of the target spliced rubber; Combined with the maximum strain and the crack propagation rate model as described in any one of claims 1-8, calculate the target crack propagation rate of the spliced rubber.

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