Finite element analysis and evaluation method for reducing tire sidewall cracks

Abstract

The invention provides a finite element analysis and evaluation method for reducing tire sidewall cracks. The finite element analysis and evaluation method comprises the following steps: S10, acquiring hyperelastic constitutive parameters and fatigue grade coefficients of different types of sidewall rubber materials; s20, building a sidewall pattern model, building a font model based on the obtained rubber material parameters, and obtaining a plurality of different model schemes; different loading conditions are set, and the stress deformation conditions of the tire side wall of the tire under different conditions are simulated; s30, performing non-linear statics general simulation analysis on stretching and shearing working conditions aiming at the stress deformation of the sidewall under different loading working conditions, and calculating to obtain a stress gradient and an associated fatigue damage value; s40, the risk degrees of different model schemes are judged according to the obtained stress gradients and the associated fatigue damage values, and a double-low-risk scheme is selected according to the risk degrees; and if the double-low-risk scheme does not exist, the design is optimized through result analysis, and the steps S10-S40 are repeated until the double-low-risk scheme is obtained. According to the method, the problem of predictive quantitative evaluation of the tire sidewall crack risk is solved.

Description

Technical Field

[0001] This invention relates to the field of tire simulation design technology, and in particular to a finite element analysis and evaluation method for reducing tire sidewall cracks. Background Technology

[0002] During tire use, various types of cracks can easily appear on the tire sidewall. One typical type of crack is located at the edge or corner of the pattern on the tire sidewall. If not dealt with in time, the crack will expand and damage the tire's airtightness, which can lead to a tire blowout in severe cases, endangering driving safety.

[0003] For the aforementioned types of sidewall cracks, there are two traditional evaluation methods. One relies on actual road testing or market feedback, which has a long evaluation cycle and makes timely adjustments difficult. The other, with the development of computer and simulation technologies, utilizes finite element simulation to predict sidewall stress in the early stages of new product development. Currently, the existing simulation analysis method involves first establishing a two-dimensional axisymmetric model of the tire, and then using the *SYMMETRIC MODEL GENERATION,REVOLVE command to convert the two-dimensional model into a three-dimensional model to analyze the stress distribution of the entire sidewall. This method can predict the stress on the entire sidewall, but it cannot analyze the stress at the subtle edges of the lettering and pattern designs on the sidewall. These areas often have significantly different stress levels than the rest of the sidewall due to the raised and recessed edges of the patterns, leading to cracks that affect tire quality and lifespan.

[0004] In view of this, this invention is hereby proposed. Summary of the Invention

[0005] To address the shortcomings of the aforementioned technologies, this invention provides a finite element analysis and evaluation method for reducing tire sidewall cracks. This method constructs a simplified simulation model that differs only in the sidewall pattern. It simulates radial loads and driving / braking conditions under static tensile and shear conditions, quantifies fatigue risk by combining rubber fatigue level classification, and predicts the risk of cracks based on the maximum stress gradient and maximum associated fatigue damage value at key locations such as font and pattern corners. The prediction accuracy exceeds 90%. This method can efficiently guide the optimization of sidewall pattern structures, significantly shorten the R&D cycle, and improve tire R&D efficiency and safety.

[0006] The specific details of the technical solution provided by this invention are as follows:

[0007] A finite element analysis evaluation method for reducing tire sidewall cracks includes:

[0008] S10. Obtain the hyperelastic constitutive parameters and fatigue grade coefficients of different types of tire sidewall rubber materials;

[0009] S20. Establish a tire sidewall pattern model, and establish a font model and obtain various different model schemes based on the rubber parameters obtained in step S10.

[0010] Different loading conditions are set to simulate the sidewall stress and deformation of the tire under different conditions;

[0011] S30. For the stress deformation of the tire sidewall under different loading conditions in step S20 above, perform nonlinear static general simulation analysis of tensile and shear conditions respectively, and calculate and obtain stress gradient and associated fatigue damage value.

[0012] S40. Determine the risk level of different model schemes based on the obtained stress gradient and associated fatigue damage values, and select the low-risk scheme as the safe design scheme based on the risk level.

[0013] If no dual-low-risk solution exists, optimize the design through result analysis and repeat steps S10-S40 until a dual-low-risk solution is obtained.

[0014] Furthermore, the hyperelastic constitutive parameters of different types of tire sidewall compounds were obtained, including:

[0015] Select the sidewall rubber material, prepare standard samples, and conduct hyperelastic uniaxial cyclic tensile tests using a universal tensile testing machine to obtain stress-strain curves;

[0016] The static stress limit threshold is obtained from the stress-strain curve; the obtained stress-strain curve is preprocessed and then fitted to obtain the hyperelastic constitutive parameters of each rubber compound.

[0017] Furthermore, the fatigue grade coefficients for different types of tire sidewall rubber compounds were obtained, including:

[0018] Different types of tire sidewall rubber samples were prepared. By using a laboratory fatigue testing machine, the periodic tensile stress experienced by rubber products in actual use was simulated, and the number of cycles experienced by different rubber samples before fracture was obtained.

[0019] By using a flexural testing machine, the periodic shear stress experienced by rubber products in actual use was simulated, and the number of times the primary crack initiation occurred in different rubber samples was obtained.

[0020] The relative order is determined based on the number of cycles and the number of primary cracks of different rubber compounds;

[0021] The fatigue grade coefficients of different rubber compounds are obtained by assigning grade values ​​based on their relative order.

[0022] Furthermore, step S20 involves obtaining various different model schemes, including:

[0023] The font protrusion thickness and corner curvature radius are used as variable parameters. After binding the rubber parameters, they are imported into the finite element analysis software, and static displacement loads are applied to form a variety of combined model schemes.

[0024] Furthermore, the different loading conditions include planar tensile loading, first shear motion loading, and second shear motion loading;

[0025] The planar tensile loading includes tensile motions in the vertical and horizontal directions, respectively, on the node sets of the front and right sides of the tire sidewall, simulating the radial and circumferential stress conditions of the tire sidewall.

[0026] The first and second shear motion loading include: fixing the bottom of the base model, and forming shear motion by vertical and horizontal stretching, both of which act on the node set on the front side of the tire side. The difference is that the first and second shear motions have opposite stretching directions in the horizontal direction.

[0027] Furthermore, the calculation of the stress gradient includes:

[0028] ;;

[0029] in, The maximum stress value at the critical location, in MPa; The minimum stress value at the critical location is expressed in MPa.

[0030] Furthermore, the calculation of the associated fatigue damage value includes:

[0031] ;

[0032] in, This is the maximum stress value at the key location in the simulation; is the static stress limit threshold of the rubber compound; n0 is the number of normal cycles the tire withstands under this stress, calculated by back-calculating from 10,000 kilometers of driving mileage using tires of the same specification; K is the fatigue level coefficient, and N0 is the basic cycle coefficient of the rubber compound.

[0033] Furthermore, step S40, which determines the risk level of different model schemes based on the obtained stress gradient and associated fatigue damage values, includes:

[0034] Obtain the maximum stress gradient R under the three loading conditions for each model scheme. max And the maximum associated fatigue damage value D max ;

[0035] According to R max D max The magnitude of the value determines the risk level, which can be any one of high risk, medium risk, or low risk.

[0036] Furthermore, high risk is R max ≥3.50 and D max ≥0.058; medium risk is 3.30≤R max <3.50 and 0.05≤D max <0.058; Low risk is R max <3.30 and D max <0.05.

[0037] Furthermore, in step S40, the design optimization through result analysis includes reducing the font height and / or increasing the radius of curvature at key font positions; the font height is the thickness of the font protrusion relative to the sidewall substrate, and the key font positions are the corners of the font.

[0038] Compared with the prior art, the present invention has the following beneficial technical effects:

[0039] A simplified simulation model with only different sidewall patterns was constructed. Radial load and driving and braking conditions were simulated under static tension and shear conditions. Fatigue risk was quantified by combining the fatigue level classification of rubber materials. Based on the maximum stress gradient and maximum associated fatigue damage value at key locations such as the corners of the font pattern, the risk of cracking under two indicators was predicted with an accuracy rate of over 90%. This method can efficiently guide the optimization of sidewall pattern structure, significantly shorten the R&D cycle, and improve tire R&D efficiency and safety.

[0040] Based on the superelastic cyclic tensile test and fatigue test of the rubber compound, the rubber compound with better tear resistance and fatigue resistance can be screened out. Combined with model analysis for structural optimization, the service life of the tire sidewall can be extended, reducing the frequency of tire replacement due to tire aging and cracks, and reducing the probability of traffic accidents caused by sudden tire failure during vehicle operation.

[0041] By using simulation models to identify high-risk design schemes for stress gradient and / or fatigue damage in advance, low-risk schemes for both stress gradient and associated fatigue damage values ​​can be prioritized in actual production. This reduces the risk of sidewall cracks from the design stage and avoids the risk of tire failures such as cord exposure and bulging caused by structural or material problems after the tire is put into use, thereby improving product performance and quality. Attached Figure Description

[0042] Figure 1 This is a model diagram of the tire sidewall font G in this invention;

[0043] Figure 2 This is a schematic diagram of planar stretching loading of the font model in this invention;

[0044] Figure 3This is a schematic diagram of the first shearing motion loading of the font model in this invention;

[0045] Figure 4 This refers to the second shearing motion loading of the font model in this invention;

[0046] Figure 5 This is a stress distribution diagram under tensile conditions for Scheme 4 in this invention;

[0047] Figure 6 This is a stress distribution diagram under tensile conditions for Scheme 9 in this invention;

[0048] Figure 7 This is a flowchart illustrating the implementation of the method of the present invention;

[0049] Figure 8 This is a schematic diagram of the radial force on the tire in this invention;

[0050] Figure 9 This is a schematic diagram of the circumferential force on the tire in this invention;

[0051] Figure 10 This is a schematic diagram of a crack in the lettering on the tire sidewall, with a lettering height of 0.7mm and a radius of curvature of 0mm.

[0052] Figure 11 This is a schematic diagram of the tire sidewall model of Scheme 1 of the present invention;

[0053] Figure 12 This is a schematic diagram of the tire sidewall model of Scheme 6 of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0055] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0056] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0057] Combined with appendix Figure 1-12 As shown, a finite element analysis evaluation method for reducing tire sidewall cracks includes:

[0058] S10. Obtain the hyperelastic constitutive parameters and fatigue grade coefficients of different types of tire sidewall rubber materials;

[0059] S20. Establish a tire sidewall pattern model, and establish a font model and obtain various different model schemes based on the rubber parameters obtained in step S10.

[0060] Different loading conditions are set to simulate the sidewall stress and deformation of the tire under different conditions;

[0061] S30. For the stress deformation of the tire sidewall under different loading conditions in step S20 above, perform nonlinear static general simulation analysis of tensile and shear conditions respectively, and calculate and obtain stress gradient and associated fatigue damage value.

[0062] S40. Determine the risk level of different model schemes based on the obtained stress gradient and associated fatigue damage values, and select the low-risk scheme as the safe design scheme based on the risk level.

[0063] If no dual-low-risk solution exists, optimize the design through result analysis and repeat steps S10-S40 until a dual-low-risk solution is obtained.

[0064] Obviously, this invention first constructs a simplified simulation model of different sidewall patterns (including fonts, patterns, etc.), and then simplifies the simulation of radial loading and driving braking conditions of the tire through a dual-mode working condition design of "static tension + static shear". Combined with the rubber fatigue level classification method, fatigue risk is quantified, and the dual-index risk degree of crack risk at key positions of the font pattern on the sidewall is predicted, so as to optimize the sidewall pattern design in a timely manner until a dual low-risk solution is obtained.

[0065] With a low-risk prediction accuracy rate of over 90%, it shortens the R&D cycle and significantly improves tire R&D efficiency and safety.

[0066] In some embodiments, obtaining the hyperelastic constitutive parameters of different types of sidewall rubber compounds includes:

[0067] Select the sidewall rubber material, prepare standard samples, and conduct hyperelastic uniaxial cyclic tensile tests using a universal tensile testing machine to obtain stress-strain curves;

[0068] The static stress limit threshold is obtained from the stress-strain curve; the obtained stress-strain curve is preprocessed and then fitted to obtain the hyperelastic constitutive parameters of each rubber compound.

[0069] For example, the test steps for the hyperelastic constitutive parameters of different types of tire sidewall rubber are as follows:

[0070] S10-10, Clamping the sample

[0071] Install the specimen in the upper and lower clamps of the testing machine, use an extensometer to fix it in the gauge length of the specimen, and ensure that the specimen is centered to avoid off-center loading. Otherwise, additional bending stress will be generated, resulting in asymmetrical stress and strain data and distorted experimental data.

[0072] S10-11, Manual Reset

[0073] After the sample is installed, manually reset the stress and strain to zero.

[0074] S10-12, Preloading

[0075] Set an appropriate preload speed to prevent overshoot and callback due to excessive speed, and to prevent curve fluctuations due to excessive slowness, thus affecting test efficiency.

[0076] Set an appropriate preload force value so that the specimen can straighten as soon as possible, while ensuring that the specimen does not undergo too much deformation in its initial state.

[0077] S10-13, Automatic Balancing

[0078] Once the preloaded force value is reached, the high-precision universal testing machine triggers the automatic balancing function to eliminate any slight slack or gap that may still exist in the entire system (sample, fixture, sensor, lead screw). The instantaneously read force value (which may be a small positive or negative value) is identified as the new zero point. All slack or gap is eliminated, and the test starts from a stable true zero point.

[0079] S10-14, Uniaxial Cyclic Tension

[0080] The deformation of the rubber compound in the tire is generally between 20% and 100% as the maximum strain under load. To eliminate the Mullins effect, the energy loss caused by internal friction tends to stabilize after 3-8 cycles. The slower the loading speed, the better, as it can reflect the entropy elasticity of hyperelasticity. To further eliminate the influence of creep, the load is briefly maintained after the maximum strain to observe or eliminate the influence of instantaneous creep on the unloading curve.

[0081] Two types of sidewall rubber compounds, A and B, were selected for hyperelastic uniaxial cyclic tensile testing and fitting. The hyperelastic constitutive parameters of the Yeoh model were obtained by fitting, and the static stress limit threshold of each rubber compound was determined from the stress-strain curves.

[0082] Table 1 Comparison of Constitutive Parameters of Superelastic Rubber Compounds

[0083] Rubber Static stress limit threshold / MPa C10 C20 C30 A 0.20 0.4904 -0.0914 0.02161 B 0.24 0.5539 -0.1336 0.00324

[0084] As can be seen from the static stress limit thresholds in Table 1 above, the static stress limit thresholds for sidewall compounds A and B are 0.20 MPa and 0.24 MPa, respectively. The stress limit threshold of compound A is lower than that of compound B.

[0085] In some embodiments, obtaining the fatigue grade coefficients of different types of tire sidewall rubber compounds includes:

[0086] Different types of tire sidewall rubber samples were prepared. By using a laboratory fatigue testing machine, the periodic tensile stress experienced by rubber products in actual use was simulated, and the number of cycles experienced by different rubber samples before fracture was obtained.

[0087] By using a flexural testing machine, the periodic shear stress experienced by rubber products in actual use was simulated, and the number of times the primary crack initiation occurred in different rubber samples was obtained.

[0088] The relative order is determined based on the number of cycles and the number of primary cracks of different rubber compounds;

[0089] The fatigue grade coefficients of different rubber compounds are obtained by assigning grade values ​​based on their relative order.

[0090] The following are exemplary test procedures and related test data for fatigue and flexure tests:

[0091] The fatigue test was conducted in accordance with GB / T 1688-2008 "Determination of tensile fatigue of vulcanized rubber".

[0092] S10-20. Sample preparation: Use standard dumbbell-shaped samples (Type 1), which are punched from finished products or test pieces. The sample thickness is 2.0±0.2mm.

[0093] S10-21 Conditioning: The sample shall be conditioned at a standard laboratory temperature (usually 23±2°C) for at least 3 hours;

[0094] S10-22. Measuring the gauge length: Mark the initial gauge length of 25 mm on the sample;

[0095] S10-23. Install the specimen: Clamp the specimen vertically in the upper and lower clamps of the testing machine, ensuring alignment and avoiding the application of additional stress;

[0096] S10-24. Set test conditions: Frequency: 5Hz, Dynamic strain amplitude: Strain is 100%;

[0097] S10-25. Start the test: Start the testing machine and perform periodic tensile testing at the set strain range;

[0098] S10-26. Record the results: When the specimen completely breaks, the testing machine will stop automatically and the number of cycles will be recorded.

[0099] The flexure test was conducted according to the Demesia type flexure crack test method specified in GB 13934-2006 standard.

[0100] S10-30, Sample preparation: Cut the rubber sample into strips of a specific size;

[0101] S10-31. Specimen installation: Install the specimen onto the Demosia flexure testing machine, which consists of a fixed upper clamp and a reciprocating lower clamp. The specimen is vertically clamped between the two clamps.

[0102] S10-32, Flexural test: Start the testing machine, and the lower clamp will carry the lower half of the specimen in a continuous reciprocating motion (usually up and down). This reciprocating motion causes the specimen to be bent and straightened repeatedly, forming a constant flexural strain. The test will stop and be observed after a preset number of flexural cycles.

[0103] S10-33. Result Evaluation: Referring to the specific provisions of the degree of cracking and crack width grade in Table 2, observe whether cracks appear on the sample and the grade of cracking after the preset number of flexing cycles. The specific observation and measurement can be carried out with the help of a magnifying glass. Finally, record the number of times grade one cracking occurs.

[0104] Table 2. Crack Degree and Crack Width Grades

[0105] Crack width grade Degree and characteristics of cracking Crack width / mm Level 0 There were no cracks; they were not visible even with a 20x magnifying glass. 0 Level 1 Slight cracks, tiny cracks, easily visible with a magnifying glass, and clearly visible to the naked eye. <0.1

[0106] Table 3 Comparison of Fatigue Grade Parameters of Rubber Compounds

[0107] Rubber Tension fatigue resistance cycles Number of first-order flexural cracks Fatigue level coefficient K A <![CDATA[14×10 4 Next <![CDATA[40×10 4 Next 1.0 B <![CDATA[20×10 4 Next <![CDATA[60×10 4 Next 1.2

[0108] From Table 3 above, we can see that the fatigue grade coefficient K of rubber compound A is 1.0 and the fatigue grade coefficient K of rubber compound B is 1.2. Therefore, the fatigue resistance of rubber compound B is better than that of rubber compound A.

[0109] The following model scheme is designed based on the hyperelastic constitutive parameters and fatigue grades (rubber parameters) of rubber compounds A and B.

[0110] In some embodiments, obtaining multiple different model schemes in step S20 includes:

[0111] The font protrusion thickness and corner curvature radius are used as variable parameters. After binding the rubber parameters, they are imported into the finite element analysis software, and static displacement loads are applied to form a variety of combined model schemes.

[0112] Furthermore, the different loading conditions include planar tensile loading, first shear motion loading, and second shear motion loading;

[0113] The planar tensile loading includes tensile motions in the vertical and horizontal directions, respectively, on the node sets of the front and right sides of the tire sidewall, simulating the radial and circumferential stress conditions of the tire sidewall.

[0114] The first and second shear motion loading include: fixing the bottom of the base model, and forming shear motion by vertical and horizontal stretching, both of which act on the node set on the front side of the tire side. The difference is that the first and second shear motions have opposite stretching directions in the horizontal direction.

[0115] For example, the tire sidewall pattern model scheme and static loading condition design are as follows:

[0116] S201. Establish the tire sidewall pattern model: The model consists of two parts: the tire sidewall base and the font pattern, as shown in the attached figure. Figure 1 As shown, a convex or concave model of the tire sidewall lettering and pattern is designed and established according to the size of the tire sidewall lettering and pattern. The mesh size in Hypermesh is 0.5mm, and the element type is C3D6H / C3D8H. Node sets are defined on the front, back, left, and right sides of the tire sidewall matrix, and the load is applied to these four node sets.

[0117] S202, Font “G” Model and Scheme: The thickness of the base adhesive is 4.5mm. The font adopts an upward convex design. The thickness of the convexity is a design variable. The radius of curvature of the key position of the “G” is also a variable. After associating the adhesive parameters, it is imported into Abaqus software. Static displacement load is applied to form a combination scheme of “6 schemes + 3 adhesives = 9 groups”. The specific model scheme is shown in Table 4 below.

[0118] Table 4 Model Scheme Table

[0119] plan Rubber Font embossing thickness / mm Corner curvature radius / mm 1 A 0.7 R0 2 A 0.5 R0 3 A 0.3 R0 4 A 0.7 R1.5 5 A 0.5 R1.5 6 A 0.3 R1.5 7 B 0.7 R0 8 B 0.5 R0 9 B 0.3 R0

[0120] S203. Set the loading conditions to simulate the actual stress conditions on the tire sidewall:

[0121] a) Planar stretching simulation: as shown in the appendix Figure 2As shown, through vertical and horizontal stretching motions, the node sets on the front side and the node sets on the right side are applied respectively to simulate the radial and circumferential stress conditions of the tire sidewall. Displacement control simulates the actual strain. A displacement of 2.0 mm is applied in both directions. The displacement amount is determined based on the deformation of the tire sidewall rubber of the same specification tire under the corresponding working conditions.

[0122] b) Shear motion simulation: as shown in the appendix Figure 3 and 4 As shown, the bottom of the fixed base model is subjected to shearing motion through vertical and horizontal stretching, which acts on the node set on the front side. This corresponds to the tire sidewall deformation during braking and driving, with a vertical displacement of 2.0 mm and a horizontal displacement of ±2.0 mm applied.

[0123] In some embodiments, in step S30, the general-purpose large-scale software Abaqus is used to perform nonlinear static general simulation analysis of tensile and shear conditions, and to calculate the stress gradient R and the associated fatigue damage value D. The calculation of the stress gradient includes:

[0124] ;

[0125] in, The maximum stress value at the critical location, in MPa; The minimum stress value at the critical location is expressed in MPa.

[0126] Furthermore, the calculation of the associated fatigue damage value includes:

[0127] ;

[0128] in, This is the maximum stress value at the key location in the simulation; is the static stress limit threshold of the rubber compound; n0 is the number of normal cycles the tire withstands under this stress, calculated by back-calculating from 10,000 kilometers of driving mileage using tires of the same specification; K is the fatigue level coefficient, and N0 is the basic cycle coefficient of the rubber compound.

[0129] It should be noted that the stress gradient reflects the degree of local stress concentration, while the associated fatigue damage value reflects the cumulative damage potential. By constructing two quantitative evaluation indicators, the stress gradient and the associated fatigue damage value, the risk of tire sidewall cracks can be quantitatively determined.

[0130] In some embodiments, the step S40 of determining the risk level of different model schemes based on the obtained stress gradient and associated fatigue damage values ​​includes:

[0131] Obtain the maximum stress gradient R under the three loading conditions for each model scheme. max And the maximum associated fatigue damage value D max ;

[0132] According to R max D max The magnitude of the value determines the risk level, which can be any one of high risk, medium risk, or low risk.

[0133] Furthermore, high risk is R max ≥3.50 and D max ≥0.058; medium risk is 3.30≤R max <3.50 and 0.05≤D max <0.058; Low risk is R max <3.30 and D max <0.05. The risk assessment of the entire model scheme must simultaneously ensure R... max D max Both values ​​fall within the risk range.

[0134] When assessing the risk levels of stress gradient R and associated fatigue damage value D separately, the following assessment criteria must be followed:

[0135] If R max If R is ≥3.50, then R is considered high-risk; if R is ≤3.30, then R is considered high-risk. max If R < 3.50, then R is considered a risk level. max If the value is less than 3.30, then R is considered low risk;

[0136] If D max If the value is ≥0.058, then D is considered high-risk; if 0.05≤D max If <0.058, then risk is determined in D. max If the value is less than 0.05, then D is considered to be of low risk.

[0137] Through the simulation calculation and analysis in steps S30-S40, the simulation analysis results of schemes 1-9 are shown in Table 5.

[0138] The risk assessment criteria are based on the stress gradient Rmax and the associated fatigue damage value Dmax. The simulation analysis results in the table below show the dual risk criteria for nine schemes. Scheme 9 is a low-risk scheme and can be adopted in actual production design. If no dual low-risk scheme appears in the design, the design can be further optimized and analyzed by repeating steps S10-S40 through result analysis.

[0139] Table 5 Simulation Analysis Results

[0140] plan Rubber Font height (mm) radius of curvature (mm) Rshear1 Rshear2 Rstretch Rmax R Risk Assessment Dshear1 Dshear2 Dstretch Dmax D Risk Assessment Option 1 A 0.70 R0 3.736 4.298 3.627 4.298 High risk 0.057 0.052 0.064 0.064 High risk Option 2 A 0.50 R0 3.311 3.502 2.934 3.502 High risk 0.053 0.047 0.059 0.059 High risk Option 3 A 0.30 R0 2.369 2.345 2.163 2.369 Low risk 0.048 0.043 0.055 0.055 Medium risk Option 4 A 0.70 R1.5 3.643 4.139 2.964 4.139 High risk 0.056 0.051 0.063 0.063 High risk Option 5 A 0.50 R1.5 3.127 3.280 2.428 3.280 Low risk 0.052 0.047 0.059 0.059 High risk Option 6 A 0.30 R1.5 1.984 2.210 1.781 2.210 Low risk 0.047 0.043 0.055 0.055 Medium risk Option 7 B 0.70 R0 3.777 4.247 3.625 4.247 High risk 0.043 0.039 0.050 0.050 Medium risk Option 8 B 0.50 R0 3.309 3.500 2.936 3.500 Medium risk 0.040 0.035 0.046 0.046 Low risk Option 9 B 0.30 R0 2.368 2.343 2.168 2.368 Low risk 0.036 0.033 0.039 0.039 Low risk

[0141] Furthermore, in step S40, the design optimization through result analysis includes reducing the font height and / or increasing the radius of curvature at key font positions; the font height is the thickness of the font protrusion relative to the sidewall substrate, and the key font positions are the corners of the font.

[0142] For example, in the "G" font model of the tire sidewall, the font height is the primary influencing factor; the smaller the height, the lower the risk. Reducing the font height can lower the risk value. The radius of curvature at key locations is a secondary influencing factor; the larger the radius, the lower the risk due to stress gradient, but this needs to be combined with the associated fatigue damage value for joint judgment. The rubber compound has a relatively small impact on the risk level. A low-risk approach using both stress gradient Rmax and associated fatigue damage value Dmax serves as a safe design scheme, thereby reducing the risk of sidewall cracks.

[0143] Compared with the prior art, the above embodiments of the present invention have the following beneficial technical effects:

[0144] A simplified simulation model with only different sidewall patterns was constructed. Radial load and driving and braking conditions were simulated under static tension and shear conditions. Fatigue risk was quantified by combining the fatigue level classification of rubber materials. Based on the maximum stress gradient and maximum associated fatigue damage value at key locations such as the corners of the font pattern, the risk of cracking under two indicators was predicted with an accuracy rate of over 90%. This method can efficiently guide the optimization of sidewall pattern structure, significantly shorten the R&D cycle, and improve tire R&D efficiency and safety.

[0145] Based on the superelastic cyclic tensile test and fatigue test of the rubber compound, the rubber compound with better tear resistance and fatigue resistance can be screened out. Combined with model analysis for structural optimization, the service life of the tire sidewall can be extended, reducing the frequency of tire replacement due to tire aging and cracks, and reducing the probability of traffic accidents caused by sudden tire failure during vehicle operation.

[0146] By using simulation models to identify high-risk design schemes for stress gradient and / or fatigue damage in advance, low-risk schemes for both stress gradient and associated fatigue damage values ​​can be prioritized in actual production. This reduces the risk of sidewall cracks from the design stage and avoids the risk of tire failures such as cord exposure and bulging caused by structural or material problems after the tire is put into use, thereby improving product performance and quality.

[0147] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A finite element analysis and evaluation method for reducing tire sidewall cracks, characterized in that, include: S10. Obtain the hyperelastic constitutive parameters and fatigue grade coefficients of different types of tire sidewall rubber materials; S20. Establish a tire sidewall pattern model, and establish a font model and obtain various different model schemes based on the rubber parameters obtained in step S10. Different loading conditions are set to simulate the sidewall stress and deformation of the tire under different conditions; S30. For the stress deformation of the tire sidewall under different loading conditions in step S20 above, perform nonlinear static general simulation analysis of tensile and shear conditions respectively, and calculate and obtain stress gradient and associated fatigue damage value. S40. Determine the risk level of different model schemes based on the obtained stress gradient and the associated fatigue damage value, and select the low-risk scheme as the safe design scheme based on the risk level. If no dual-low-risk solution exists, optimize the design through result analysis and repeat steps S10-S40 until a dual-low-risk solution is obtained.

2. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 1, characterized in that, The acquisition of hyperelastic constitutive parameters for different types of tire sidewall rubber materials includes: Select the sidewall rubber material, prepare standard samples, and conduct hyperelastic uniaxial cyclic tensile tests using a universal tensile testing machine to obtain stress-strain curves; The static stress limit threshold is obtained from the stress-strain curve; the obtained stress-strain curve is preprocessed and then fitted to obtain the hyperelastic constitutive parameters of each rubber compound.

3. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 2, characterized in that, The fatigue grade coefficients for different types of tire sidewall rubber materials include: Different types of tire sidewall rubber samples were prepared. By using a laboratory fatigue testing machine, the periodic tensile stress experienced by rubber products in actual use was simulated, and the number of cycles experienced by different rubber samples before fracture was obtained. By using a flexural testing machine, the periodic shear stress experienced by rubber products in actual use was simulated, and the number of times the primary crack initiation occurred in different rubber samples was obtained. The relative order is determined based on the number of cycles and the number of primary cracks of different rubber compounds; The fatigue grade coefficients of different rubber compounds are obtained by assigning grade values ​​based on their relative order.

4. The finite element analysis and evaluation method for reducing tire sidewall cracks according to any one of claims 1-3, characterized in that, Step S20 involves obtaining various model schemes, including: The font protrusion thickness and corner curvature radius are used as variable parameters. After binding the rubber parameters, they are imported into the finite element analysis software, and static displacement loads are applied to form a variety of combined model schemes.

5. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 4, characterized in that, The different loading conditions include planar tensile loading, first shear motion loading, and second shear motion loading; The planar tensile loading includes tensile motions in the vertical and horizontal directions, respectively, on the node sets of the front and right sides of the tire side, simulating the radial and circumferential stress conditions of the tire side. The first and second shear motion loading include: fixing the bottom of the base model, and forming shear motion by vertical and horizontal stretching, both of which act on the node set on the front side of the tire side. The difference is that the first and second shear motions have opposite stretching directions in the horizontal direction.

6. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 5, characterized in that, The calculation of the stress gradient includes: ； in, The maximum stress value at the critical location, in MPa; The minimum stress value at the critical location is expressed in MPa.

7. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 6, characterized in that, The calculation of the associated fatigue damage value includes: ； in, This is the maximum stress value at the key location in the simulation; is the static stress limit threshold of the rubber compound; n0 is the number of normal cycles the tire withstands under this stress, calculated by back-calculating from 10,000 kilometers of driving mileage using tires of the same specification; K is the fatigue level coefficient, and N0 is the basic cycle coefficient of the rubber compound.

8. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 5, characterized in that, Step S40, which determines the risk level of different model schemes based on the obtained stress gradient and the associated fatigue damage value, includes: Obtain the maximum stress gradient R under the three loading conditions for each model scheme. max And the maximum associated fatigue damage value D max ; According to R max D max The magnitude of the value determines the risk level, which can be any one of high risk, medium risk, or low risk.

9. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 8, characterized in that, The high risk is R max ≥3.50 and D max ≥0.058; the medium risk is 3.30≤R max <3.50 and 0.05≤D max <0.058; the low risk is R max <3.30 and D max <0.

05.

10. The finite element analysis and evaluation method for reducing tire sidewall cracks according to claim 9, characterized in that, Step S40 involves optimizing the design through result analysis, including reducing font height and / or increasing the radius of curvature at key font positions. The font height is the thickness of the font protrusion relative to the tire sidewall substrate, and the key position of the font is the corner of the font.

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