Method and apparatus for testing carcass stresses

Abstract

The application provides a kind of carcass stress test method and device, it is related to the technical field of tire, the carcass stress test method provided by the embodiment of the application comprises the following steps: providing a tire bead portion, the tire bead portion is the portion between the portion and the upper side of tire contact portion with rim;A stress sensor is arranged at the predicted point inside the tire bead portion;The tire bead portion includes the first end close to the bead and the second end away from the bead;Maintain the first end as a whole fixedly;Maintain the end face of second end fixed and the outer side fixedly unmoved;Resistance F1 is applied to the inner side surface of second end;Pressure F2 is applied to the inner side surface of tire bead portion between the first end and second end, and the value of stress sensor is obtained.

Description

Technical Field

[0001] This invention relates to the field of tire technology, and in particular to a method and apparatus for testing tire stress. Background Technology

[0002] The tire bead area (below the horizontal axis of the cross-section, the contact area between the bead and the rim) is subjected to complex multi-directional stresses, which can easily lead to stress concentration, resulting in deformation of the steel wire bead, cracking of the rubber, or even tire blowout failure. Furthermore, the mechanical properties of this area directly affect the tire's durability and high-speed safety.

[0003] Currently, the industry relies on finite element simulation, bench testing, or whole vehicle testing for mechanical analysis of the tire bead area. Finite element simulation is highly dependent on material constitutive models and simplified boundary conditions, making it difficult to accurately simulate the nonlinear contact behavior between rubber, steel wire, and rim (such as the interface slippage between the steel wire ring and the triangular rubber).

[0004] Currently, industry standard test specimens can only characterize the properties of homogeneous materials and cannot characterize the multi-material composite structural characteristics of the rim region, leading to a mismatch between laboratory data and actual working conditions. Existing tensile testing machines can only apply unidirectional loads, while the rim actually bears combined radial and axial loads, and there is a lack of testing devices that can simultaneously simulate rim assembly constraints and loads. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for testing tire carcass stress, so as to alleviate the technical problem that the load is singular and the testing apparatus cannot simulate composite load when analyzing the mechanical properties of the tire carcass in the camber region in the prior art.

[0006] An embodiment of the present invention provides a method for testing tire carcass stress, comprising the following steps: A tire bead portion is provided, the tire bead portion being the portion of the tire between the rim contacting part and the upper tire sidewall; a stress sensor is provided at a prediction point inside the tire bead portion; the tire bead portion includes a first end near the bead and a second end away from the bead; Keep the first end fixed as a whole; Keep the end face and outer surface of the second end fixed; apply resistance F1 to the inner surface of the second end. Pressure F2 is applied to the inner side of the tire bead portion at a position between the first and second ends, and the value of the stress sensor is obtained.

[0007] Furthermore, the fetal opening portion includes an upper triangular adhesive; stress sensors are provided at the four vertices of the upper triangular adhesive.

[0008] Furthermore, the frequency of the applied pressure F2 is adjustable.

[0009] Furthermore, the magnitude of the resistance F1 is adjustable.

[0010] Secondly, the present invention provides a tire stress testing device for implementing the above-described tire stress testing method.

[0011] Furthermore, the tire stress testing device includes a flange constraint assembly, a deformation control mechanism, and a composite load simulation device, wherein the flange constraint assembly is used to keep the first end fixed as a whole. The deformation control mechanism is used to keep the end face and outer surface of the second end fixed; and to apply resistance F1 to the inner surface of the second end. The composite load simulation device is used to apply pressure F2 to the inner side of the tire bead portion at a position between the first end and the second end, and to obtain the value of the stress sensor.

[0012] Furthermore, the rim restraint assembly includes a first clamp for clamping or releasing the first end.

[0013] Furthermore, the first clamp includes a first fixing base, the first fixing base having a first supporting surface supporting the outer side of the first end, and a second supporting surface supporting the end face of the first end; Along a direction perpendicular to the first support surface, a first pressure plate is slidably connected to the first fixed base. The first pressure plate is parallel to the first support surface and forms a first clamping space to accommodate the first end. A screw is threaded onto the first fixed base, and the bottom end of the screw is directly opposite the side of the first pressure plate that is away from the first support surface, so that the screw can drive the first pressure plate to move toward or away from the first support surface.

[0014] Furthermore, the deformation control mechanism includes a second fixed base, the second fixed base having a third supporting surface supporting the outer side of the second end, and a fourth supporting surface supporting the end face of the second end, the third supporting surface and the fourth supporting surface being used to prevent the tire bead portion from deforming along its length direction. Along a direction perpendicular to the third support surface, a second pressure plate is slidably connected to the second fixed base. The second pressure plate is parallel to the third support surface and forms a second clamping space to accommodate the second end. A sliding rod is slidably connected to the second fixed seat. The bottom end of the sliding rod is directly opposite the side of the second pressure plate that is away from the third support surface, so that the sliding rod can drive the second pressure plate to move toward or away from the third support surface. A resistance source is connected to the top of the slide bar.

[0015] Furthermore, the resistance source includes multiple counterweights, which are detachably connected to the slide bar.

[0016] The tire stress testing method provided in this embodiment of the invention includes the following steps: providing a tire bead portion, wherein the tire bead portion is the part of the tire between the part that contacts the rim and the upper sidewall; a stress sensor is provided at a predicted point inside the tire bead portion; the tire bead portion includes a first end close to the bead and a second end away from the bead; keeping the first end fixed as a whole; keeping the end face and outer surface of the second end fixed; applying a resistance F1 to the inner surface of the second end; applying a pressure F2 to the inner surface of the tire bead portion at a position between the first end and the second end, and obtaining the value of the stress sensor.

[0017] This testing method only tests the target portion; therefore, a complete tire is not required. The portion used is the part of the tire between the rim contact area and the upper sidewall, referred to as the tire bead portion. In actual testing, because the tire is subjected to the combined force of the vehicle's load and internal air pressure, and because a steel wire ring is installed inside the rim contact area, the part in contact with the rim is almost completely fixed. Therefore, to fully simulate actual operating conditions, before testing, the first end needs to be kept entirely fixed to simulate the situation where the first end is fixed by the rim and steel wire ring; the end face and outer surface of the second end need to be kept fixed to simulate radial load; resistance F1 is applied to the inner surface of the second end to simulate the combined force of the vehicle's load and internal air pressure. Under fixed conditions, this combined force is a constant value, and the inner surface of the second end can overcome this resistance F1 and deform upwards during the test. This situation corresponds to the deformation that occurs between the tire carcass below the tire contact area and the tire bead portion when the tire is in actual driving. Then, a pressure F2 is applied to the inner surface of the tire bead portion between the first and second ends to simulate axial load, and the stress sensor values ​​are obtained to simulate the tire's internal inflation pressure. Finally, by placing stress sensors at predicted points inside the tire bead portion, the tire carcass stress at the predicted points is monitored, the stress conditions (tension / compression) of different parts of the tire carcass are analyzed, and damage sites are predicted, thereby guiding subsequent tire structure design and manufacturing processes. By optimizing the tire carcass reverse-wrapping structure and reducing the pressure on the reverse-wrapping side of the tire carcass, combined with the working conditions of tire cavity pressure and bead support, the stress analysis is directly linked to durability improvement. By reducing the shear force amplitude, tire fatigue damage is indirectly reduced, thus improving durability. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the bead portion of the tire being tested in the tire stress testing method provided in this embodiment of the invention. Figure 2 This is a schematic diagram of the tire bead portion testing process in the tire stress testing method provided in this embodiment of the invention; Figure 3 This is a schematic diagram of the wheel flange constraint assembly in the tire stress testing device provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the deformation control mechanism in the tire stress testing device provided in an embodiment of the present invention; Figure 5 This is a cross-sectional view of an existing tire.

[0020] Icons: 1-Sidewall rubber; 2-Upper triangular rubber; 3-Lower triangular rubber; 4-Tire body; 5-Reverse-wrapped tire body; 6-Sidewall filler rubber; 7-Inner liner rubber; 8-Stress sensor; 9-Wheel flange constraint assembly; 10-Deformation control mechanism; 11-Composite load simulation device; 12-First fixed seat; 13-First support surface; 14-Second support surface; 15-First pressure plate; 16-Screw; 17-Second fixed seat; 18-Third support surface; 19-Fourth support surface; 20-Second pressure plate; 21-Slide rod; 22-Resistance source. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figures 1-4 As shown, the tire stress testing method provided in this embodiment of the invention includes the following steps: like Figure 1 As shown, a tire bead portion is provided. This tire bead portion is not a complete tire, but rather a part of the tire. The tire bead portion is the part of the tire between the portion that contacts the rim and the upper sidewall (the portion between the tread and the horizontal axis). Figure 5As shown. For ease of explanation, assume that the tire bead portion includes a first end near the bead ( Figure 1 The right end of the middle) and the second end away from the child mouth ( Figure 1 (Left end of the middle). Specifically, it includes a sidewall rubber 1, an upper triangular rubber 2, and a lower triangular rubber 3 connected along the length direction; a tire body 4 covering the inside of the sidewall rubber 1, the upper triangular rubber 2, and the lower triangular rubber 3; and a reverse-wrapped side tire body 5 that wraps around the lower triangular rubber 3 from the first end and covers the outside. The reverse-wrapped side tire body 5 is connected to the tire body 4 (the reverse-wrapped side tire body 5 is formed by the reverse extension of the tire body 4 at the end of the triangular rubber 3, that is, the reverse-wrapped side tire body 5 and the tire body 4 are an integral structure); a sidewall filler rubber 6 covering the outside of the reverse-wrapped side tire body 5; and an inner liner rubber 7 covering the inside of the tire body.

[0023] Stress sensors 8 are installed at the predicted points inside the tire bead portion. In this embodiment, four stress sensors 8 are installed. The stress sensors 8 are also installed at the four vertices of the upper triangular rubber 2.

[0024] Of course, the stress sensor 8 can also be placed in other locations. The stress sensor 8 is inserted inside the tire bead portion during its fabrication.

[0025] Before the test, keep the first end fixed; keep the end face and outer side of the second end fixed; apply resistance F1 to the inner side of the second end; during the test, apply pressure F2 to the inner side of the tire bead at the position between the first end and the second end, and obtain the value of stress sensor 8.

[0026] This testing method only tests the target portion; therefore, a complete tire is not required. The portion used is the part of the tire between the rim contact area and the upper sidewall, referred to as the tire bead portion. In actual testing, because the tire is subjected to the combined force of the vehicle's load and internal air pressure, and because a steel wire ring is installed inside the rim contact area, the rim contact area is almost completely fixed. Therefore, to fully simulate actual operating conditions, before testing, the first end needs to be kept entirely fixed to simulate the situation where the first end is fixed by the rim and steel wire ring; the end face and outer surface of the second end need to be fixed to simulate radial load; resistance F1 is applied to the inner surface of the second end to simulate the combined force of the vehicle's load and internal air pressure. Under fixed conditions, this combined force is a constant value, and the inner surface of the second end can overcome this resistance F1 and deform upwards during the test. This situation corresponds to the deformation that occurs between the tire carcass below the tire contact area and the tire bead portion when the tire is in actual driving. Then, pressure F2 is applied to the inner surface of the tire bead portion between the first and second ends to simulate axial load, and the value of stress sensor 8 is obtained to simulate the tire's internal inflation pressure. Finally, by setting stress sensors 8 at predicted points inside the tire bead portion, the tire stress at the predicted points is monitored, the stress conditions (tension / compression) of different parts of the tire body are analyzed, and the damage sites are predicted, thereby guiding subsequent tire structure design and manufacturing processes.

[0027] The applied pressure F2 has an adjustable frequency, which is adjusted according to the frequency of the tire entering and exiting the ground. When the tire is in contact with the ground and when it is not in contact with the ground, the force on the tire body is different. The adjustable frequency is set to simulate the rolling process of car tires on the ground at different driving speeds.

[0028] The resistance F1 is adjustable. The value of F2 can be adjusted according to tire pressure and load requirements. Resistance F1 should be generated during tire inflation or loading. Correspondingly, the counterweight of the resistance source in the device is adjusted according to F1. The value of F1 can be determined first through simulation, based on the simulated force predictions of the tire's contact with and without contact after inflation and / or loading. Then, the number / weight of the resistance source counterweights is adjusted according to F1, the actual force on the tire is tested, and the stress data from the sensors is read, thereby simulating vehicles with different tire pressures and loads.

[0029] Before physical testing, the tire bead can be modeled first, and then the first end can be fixed and the second end constrained to conduct a simulation test to obtain the optimal parameters. Then, the model can be materialized and tested using a testing device.

[0030] For example, setting the range of applied pressure F2—simulating the force per unit area under internal pressure (e.g., kPa•m). 2Equal to 1000N. The internal pressure of the tire when inflated is 830kPa, and the inner surface area of ​​the tire is 81.4m². 2 The force per unit area is 830,000 N / m 2 ).

[0031] The frequency of the applied pressure F2 is consistent with the tire's contact patch frequency, ranging from 4-15Hz. The frequency varies depending on the driving speed and tire outer diameter: 100km / h, 1125mm outer diameter, frequency 7.86Hz; 120km / h, 1125mm outer diameter, frequency 9.43Hz; 60km / h, 1085mm outer diameter, frequency 4.89Hz; 80km / h, 1085mm outer diameter, frequency 6.52Hz; 100km / h, 1085mm outer diameter, frequency 8.15Hz; 160km / h, 1085mm outer diameter, frequency 13.04Hz; 180km / h, 1085mm outer diameter, frequency 14.67Hz.

[0032] The rubber modulus range of the constrained area (lower triangular rubber 3) is 25-40.

[0033] The rubber modulus range for the active zone (carcass, upper triangle, and reverse-wrapped side carcass) is M: 7.5-15.

[0034] Thickness range (distance of translation of the tire body on the reverse side): Δh = 1-5mm.

[0035] The minimum stress amplitude of Δh and the reverse side of the tire carcass satisfies the following relationship: lg(Δh)=A S 11 3 +B S 11 2 +C S 11 +D Specific implementation: A negative amplitude indicates compression.

[0036] lg(Δh) = -0.1553 S 11 3 +1.1797 S 11 2 -1.7976 S 11 +1.148

[0037] In preferred embodiment 2, the compressive stress amplitude on the reverse-wrapped tire carcass is minimized.

[0038]

[0039] The relative height change of the reverse-side tire body (i.e., the relative height between the reverse-side tire body and the tire body at the calves' end; when the height of the reverse-side tire body = the height of the tire body at the calves' end, the relative height is 1; when the height of the reverse-side tire body = 1 / 2 the height of the tire body at the calves' end, the relative height is 1 / 2): Preferred Example 6 Optimal parameters are obtained through simulation, which are then used for physical manufacturing.

[0040] The above method can be implemented using the following tire stress testing device.

[0041] like Figures 1-4 As shown, the tire stress testing device includes a flange constraint assembly 9, a deformation control mechanism 10, and a composite load simulation device 11. The flange constraint assembly 9 is used to keep the first end fixed as a whole; the deformation control mechanism 10 is used to keep the end face and outer surface of the second end fixed; a resistance F1 is applied to the inner surface of the second end; the composite load simulation device 11 is used to apply pressure F2 to the inner surface of the tire bead portion at a position between the first end and the second end, and to obtain the value of the stress sensor 8.

[0042] The composite load simulation device 11 is located between the wheel flange constraint module and the deformation control mechanism 10, and includes a force application component that can output a normal distributed load (applying vertical pressure F2 to simulate inflation pressure).

[0043] The rim restraint assembly 9 includes a first clamp, which is used to clamp or release the first end, thereby completely fixing the first end in place. The first clamp is specifically positioned to the right of the lower triangular rubber 3.

[0044] Specifically, such as Figure 3 As shown, the first fixture includes a first fixed base 12, which remains stationary during testing. The first fixed base 12 has a first support surface 13 that supports the outer side of the first end, and a second support surface 14 that supports the end face of the first end. The first support surface 13 and the second support surface 14 are vertically arranged in an "L" shape.

[0045] Along a direction perpendicular to the first support surface 13, a first pressure plate 15 is slidably connected to the first fixed base 12. The first pressure plate 15 can move toward or away from the first support surface 13. The first pressure plate 15 is parallel to the first support surface 13 and forms a first clamping space to accommodate the first end.

[0046] A screw 16 is threaded onto the first fixed base 12. The bottom end of the screw 16 is directly opposite the side of the first pressure plate 15 that is away from the first support surface 13, so that the screw 16 can drive the first pressure plate 15 to move toward or away from the first support surface 13.

[0047] Before testing, loosen screw 16, move the first pressure plate 15 upward, insert the first end into the first receiving space, and make the end face of the first end abut against the second support surface 14. Then tighten screw 16, screw 16 presses down on the first pressure plate 15, the first pressure plate 15 and the first support surface 13 press and fix the first end, and the first end cannot move at all during the test.

[0048] like Figure 4 As shown, the deformation control mechanism 10 includes a second fixed base 17, which has a third support surface 18 supporting the outer side of the second end and a fourth support surface 19 supporting the end face of the second end. The third support surface 18 and the fourth support surface 19 are used to prevent the tire bead portion from deforming along its length. A second pressure plate 20 is slidably connected to the second fixed base 17 in a direction perpendicular to the third support surface 18. The second pressure plate 20 is parallel to the third support surface 18 and forms a second clamping space to accommodate the second end. A slide rod 21 is slidably connected to the second fixed base 17. The bottom end of the slide rod 21 faces the side of the second pressure plate 20 that is away from the third support surface 18, so that the slide rod 21 can drive the second pressure plate 20 to move toward or away from the third support surface 18. A resistance source 22 is connected to the top of the slide rod 21.

[0049] The portion clamped by the third support surface 18 and the second pressure plate 20 is the part to the left of the upper triangular rubber 2 (excluding the area where the upper triangular rubber 2 is located). Similar to the first fixed seat 12, the third support surface 18 on the second fixed seat 17 supports the outer side of the second end, and the fourth support surface 19 is perpendicular to the third support surface 18. The third support surface 18 and the fourth support surface 19 clamp the tire bead portion from both ends in the length direction to prevent the tire bead portion from deforming along its length direction. After adding the resistance source 22 to the upper end of the slide rod 21, a certain amount of resistance F1 can be provided, and this resistance F1 can be overcome. That is, during the test, under the action of pressure F2, the inner side of the second end can deform, that is, the inner side of the second end pushes the slide rod 21 upward and overcomes the resistance F1 to deform upward; in addition, if F2 decreases, the resistance F1 that the inner side of the second end needs to overcome decreases. At this time, the slide rod moves downward, which has a controlling effect on the end face deformation of the second end, simulating the tire grounding and non-grounding situations. This situation is also the same as the actual working condition, that is, the tire body below the contact patch of the tire can deform relative to the tire bead. The resistance source 22 includes multiple counterweights, which are detachably connected to the slide bar 21. Depending on the vehicle model, different weights of counterweights are applied to the slide bar. The first end, which is pressed by the second pressure plate 20, simulates the situation where it is connected to the tire body below the contact patch of the tire.

[0050] After testing, based on the data obtained, a quantitative evaluation index for stress amplitude was established: a mathematical model of constraint conditions and stress distribution was established, and the stress distribution mode was changed (from overall deformation to local stress regulation) through a specific combination of fixed constraints and load loading. Design parameters for the carcass inverted wrap structure based on stress amplitude optimization were proposed, such as inverted wrap height, thickness of each rubber layer, and specific modulus gradient design range.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing tire carcass stress, characterized in that, Including the following steps: A tire bead portion is provided, the tire bead portion being the portion of the tire between the rim contact portion and the upper tire sidewall; a stress sensor (8) is provided at a prediction point inside the tire bead portion; the tire bead portion includes a first end close to the bead and a second end away from the bead; Keep the first end fixed as a whole; Keep the end face and outer surface of the second end fixed; apply resistance F1 to the inner surface of the second end. Pressure F2 is applied to the inner side of the tire bead portion at a position between the first end and the second end, and the value of the stress sensor (8) is obtained.

2. The method for testing tire stress according to claim 1, characterized in that, The fetal opening portion includes an upper triangular adhesive (2); stress sensors (8) are provided at the four vertices of the upper triangular adhesive (2).

3. The method for testing tire stress according to claim 1, characterized in that, The frequency of pressure F2 application is adjustable.

4. The method for testing tire stress according to claim 1, characterized in that, The magnitude of the resistance F1 is adjustable.

5. A tire carcass stress testing device, characterized in that, Used to implement the tire stress testing method according to any one of claims 1-4.

6. The tire carcass stress testing device according to claim 5, characterized in that, The tire stress testing device includes a flange constraint assembly (9), a deformation control mechanism (10), and a composite load simulation device (11). The flange constraint assembly (9) is used to keep the first end fixed. The deformation control mechanism (10) is used to keep the end face and outer surface of the second end fixed; and to apply resistance F1 to the inner surface of the second end. The composite load simulation device (11) is used to apply pressure F2 to the inner side of the tire bead portion at a position between the first end and the second end, and to obtain the value of the stress sensor (8).

7. The tire stress testing device according to claim 6, characterized in that, The rim restraint assembly (9) includes a first clamp for clamping or releasing the first end.

8. The tire carcass stress testing device according to claim 7, characterized in that, The first clamp includes a first fixed base (12), the first fixed base (12) having a first support surface (13) supporting the outer side of the first end, and a second support surface (14) supporting the end face of the first end. Along a direction perpendicular to the first support surface (13), a first pressure plate (15) is slidably connected to the first fixed base (12). The first pressure plate (15) is parallel to the first support surface (13) and forms a first clamping space to accommodate the first end. A screw (16) is threaded onto the first fixed base (12). The bottom end of the screw (16) is directly opposite the side of the first pressure plate (15) that is away from the first support surface (13), so that the screw (16) can drive the first pressure plate (15) to move toward or away from the first support surface (13).

9. The tire carcass stress testing device according to claim 8, characterized in that, The deformation control mechanism (10) includes a second fixed seat (17), the second fixed seat (17) having a third support surface (18) supporting the outer side of the second end, and a fourth support surface (19) supporting the end face of the second end, the third support surface (18) and the fourth support surface (19) being used to prevent the tire bead portion from deforming along its length. Along a direction perpendicular to the third support surface (18), a second pressure plate (20) is slidably connected to the second fixed seat (17). The second pressure plate (20) is parallel to the third support surface (18) and forms a second clamping space to accommodate the second end. A slide rod (21) is slidably connected to the second fixed seat (17). The bottom end of the slide rod (21) is directly opposite the side of the second pressure plate (20) that is away from the third support surface (18), so that the slide rod (21) can drive the second pressure plate (20) to move toward or away from the third support surface (18). The top of the slide bar (21) is connected to a resistance source (22).

10. The tire carcass stress testing device according to claim 9, characterized in that, The resistance source (22) includes multiple counterweights, which are detachably connected to the slide bar (21).

Images