Rubber mount fatigue crack propagation analysis method and fatigue life prediction method

Abstract

The invention discloses a rubber mount fatigue crack propagation analysis method and a fatigue life prediction method, and belongs to the technical field of rubber mounts. The method comprises the following steps: acquiring rubber parameters required by simulation for manufacturing the rubber suspension, and performing a fatigue test on a crack propagation testing machine by using a rubber pure shear sample with a single-side notch to obtain critical tearing energy; a rubber suspension finite element model is constructed through an Abaqus finite element method, and a local fatigue dangerous point area of the rubber suspension is analyzed and determined; the relation between the precrack propagation and the rubber suspension rigidity is obtained by establishing a precrack model and performing simulation analysis on the rubber precrack propagation.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubber mounts, and more specifically, relates to a method for analyzing fatigue crack propagation and a method for predicting fatigue life of a rubber mount. Background Art

[0002] As an important part of the powertrain mounting system, the rubber mount is composed of key parts such as a rubber main spring, a metal inner core, and a metal outer sleeve. The metal inner sleeve, the rubber main spring, and the metal outer sleeve are bonded together through vulcanization. This structure is not only simple and clear, but also has a simple manufacturing process, greatly improving production efficiency, and the rubber mount has extremely high cost performance. First of all, compared with hydraulic mounts and other mounting systems with complex structures, the rubber mount has lower material costs, and due to its simple structure, the processing and assembly processes are also more efficient; this gives the rubber mount an obvious price advantage and can meet the cost control requirements of automobile manufacturers; at the same time, the rubber mount has stable and reliable performance and can meet the use requirements of the automobile under various working conditions. Secondly, the rubber mount has extremely strong adaptability. The rubber material has good elastic and damping properties and can effectively isolate and reduce the vibration and noise generated by the powertrain; whether it is on urban roads or off-road driving, the rubber mount can maintain good performance and ensure the smoothness and comfort of the vehicle. In addition, the rubber mount also has strong durability and anti-aging ability and can maintain stable performance during long-term use.

[0003] However, the fatigue failure of the rubber mount is often difficult to detect. Once it fails, the consequences are extremely serious, posing a potential safety hazard to driving and even threatening the life safety of passengers. For this reason, Ding Xing et al. proposed a multi-axial fatigue crack propagation method based on crack energy density in the article "Research on Static and Dynamic Characteristics and Fatigue Life Prediction of a Rubber Mount for a Certain Automobile Powertrain" (May 2021), and used Fe-safe software to build a fatigue simulation model to complete life prediction; Chinese Patent CN119354700A discloses a method for testing rubber fatigue crack propagation, which includes: obtaining a test piece of a rubber sample to be tested and the calendering direction of the test piece; based on the calendering direction, determining the test tensile direction; based on the test tensile direction, performing a crack tensile test on the test piece to obtain a test result. This patent realizes multi-directional crack tensile testing of the test piece of the rubber material and can select the optimal tensile direction for tensile testing from it.

[0004] Based on a comprehensive analysis of the above-disclosed content, although the fatigue cracks of the rubber mount can be initially analyzed, the accuracy of the analysis of fatigue crack propagation of the rubber mount still needs to be further improved. Summary of the Invention

[0005] 1. Problems to be Solved

[0006] In view of the technical problems existing in the prior art, the present invention provides a method for analyzing fatigue crack propagation and a method for predicting fatigue life of a rubber mount. By simulating crack propagation, the remaining fatigue life of the rubber mount can be accurately evaluated, and the safe use performance of the rubber mount can be improved.

[0007] 2. Technical solution

[0008] To solve the above problems, the technical solutions adopted by the present invention are as follows:

[0009] Fatigue failure of rubber materials is usually caused by the gradual expansion of microcracks initiated by internal defects under cyclic fatigue loads, which may ultimately lead to the complete impairment of the functions of rubber components or rapid instability. Understanding the fatigue crack propagation characteristics of rubber materials is crucial for predicting various performances of rubber mounts under fatigue loads.

[0010] The first aspect of the present invention provides a method for analyzing fatigue crack propagation of a rubber mount, including the steps of:

[0011] Obtain the rubber parameters for manufacturing the rubber mount required for simulation, use a rubber pure shear specimen with a single-edge notch, conduct a fatigue test on a crack propagation testing machine to obtain the critical tearing energy;

[0012] Construct a finite element model of the rubber mount by the Abaqus finite element method, and analyze and determine the local fatigue critical point area of the rubber mount;

[0013] By establishing a prefabricated crack model and simulating the propagation of the prefabricated crack in the rubber, the relationship between the propagation of the prefabricated crack and the stiffness of the rubber mount is obtained.

[0014] The change in the total strain energy at the crack tip of the rubber pure shear specimen is: δU = -Wh 0 lδc, where h0 is the height of the specimen, W represents the strain energy density of the rubber material, U is the strain energy reduced inside the rubber when the crack interface expands by a unit area, l represents the length of the rubber material, and δc represents the crack size at the crack opening of the rubber material.

[0015] The tearing energy at the crack tip of the rubber pure shear specimen is given by the formula: It can be seen that the tearing energy acting on the crack tip of the pure shear specimen is independent of the crack size and is only related to the specimen size and the degree of deformation. Therefore, using a rubber pure shear specimen can quickly and effectively obtain the crack propagation characteristic data of the rubber material, accurately evaluate the remaining fatigue life of the rubber mount, with the accuracy improved by at least more than 1%, thereby improving the safe use performance of the rubber mount.

[0016] According to any embodiment of the first aspect of the object of the present invention, in order to ensure that the effective area of the rubber specimen is in a pure shear state, the rubber specimen needs to meet a relatively large aspect ratio. The width l0 of the rubber pure shear specimen is 140, the height h0 is 10, the thickness d is 2, and the length of the prefabricated crack c0 is 20, with the unit being mm for all.

[0017] According to any embodiment of the first aspect of the object of the present invention, in the fatigue test step of the crack propagation testing machine, the test temperature is 23 ± 2 °C, the loading frequency is 4 Hz, the axial tension is 0 - 5 mm, and it is cyclically loaded 500 times. The crack lengths of the specimens and the stress-strain test data under different cycle numbers are summarized to obtain the critical tearing energy.

[0018] According to any embodiment of the first aspect of the object of the present invention, in actual use, cracks may appear in multiple parts of the rubber mount due to the action of fatigue loads. Among them, the formation and propagation speed of cracks at the failure hot spot position of the rubber mount are faster, which will cause the rubber mount to fail. To more efficiently analyze the performance changes of the rubber mount caused by fatigue crack propagation, it is necessary to find a suitable dangerous position of the rubber mount as the crack propagation area. Through a large number of tests, it is found that under the action of V-direction fatigue loads, the rubber mount is extremely likely to generate fatigue cracks at or near this position or area, and the crack generation methods are the same, so that the position of local cracks in the rubber mount and the prevention and control methods can be determined.

[0019] Therefore, in order to obtain the distribution and change of stress and strain within the cycle period of the rubber mount under the action of V-direction loads, in the step of analyzing and determining the local fatigue dangerous point area of the rubber mount, displacement loads of ±6 mm are respectively applied to the finite element model of the rubber mount, so as to obtain the fatigue failure dangerous point area of the rubber mount under the action of V-direction loads in the local coordinate system.

[0020] According to any embodiment of the first aspect of the object of the present invention, based on the above strain results and Saint-Venant's principle (Saint-Venant's principle is that if the forces acting on a small surface of an elastic body are replaced by a statically equivalent force system acting on the same surface, this replacement only causes significant stress changes on the local surface, and its influence can be ignored at places farther than the linear dimension of the stress change surface), on the tensile side of the rubber specimen, the areas 2 mm to the left and right of the prefabricated crack are selected as the dangerous fatigue point areas.

[0021] According to any embodiment of the first aspect of the object of the present invention, in the step of establishing the prefabricated crack model, the angles of the prefabricated cracks are respectively -10°, -5°, 0°, 5°, 10°; and the crack lengths are respectively 0.2 mm, 0.6 mm, 1 mm.

[0022] According to any embodiment of the first aspect of the object of the present invention, in the step of establishing the prefabricated crack model, after creating the crack, it is necessary to assemble the crack with the local fatigue dangerous point area of the rubber mount, and at the same time use "Creat Crack" in the "Interaction" module, and the type is selected as "XFEM".

[0023] Due to the singularity at the crack tip, by performing mesh refinement on the area near the prefabricated crack, higher calculation accuracy can be obtained, thereby controlling the error within a reasonable range and avoiding the problem of model non-convergence under large deformations. The rubber body in the prefabricated crack area is re-meshed.

[0024] According to any embodiment of the first aspect of the object of the present invention, in the step of simulating and analyzing and verifying the propagation of the prefabricated crack, the prefabricated crack is in a vertical position with respect to the rubber block of the rubber mount. Taking this position as the starting position of crack deflection, the deflection angle of the crack is recorded as 0°. In addition, clockwise deflection is negative, and the prefabricated crack is deflected by 5° and 10° respectively; counterclockwise deflection is positive, and it is deflected by 5° and 10° respectively; the crack is assembled with the model in Creo10.0, and the assembled body is input into Abaqus for finite element analysis.

[0025] According to any embodiment of the first aspect of the object of the present invention, with the deflection crack angle being 0°, the crack propagation process is analyzed at the 10th analysis step, the 20th analysis step, and the 40th analysis step respectively. Among them, when analyzing the crack propagation process, the model cracks along the prefabricated crack angle at the 10th analysis step; as the analysis step increases, the crack completely breaks along the prefabricated crack at the 20th analysis step, and the crack propagates at the 40th analysis step. After that, as the position load further increases, the crack length of the crack propagation increases.

[0026] The second aspect of the present invention provides a method for predicting the fatigue life of a rubber mount. According to the rubber mount fatigue crack propagation analysis method described in the first aspect, cracks with different angles and lengths are prefabricated in the fatigue dangerous point area to obtain the influence law of crack propagation on the stiffness of the rubber mount, and the remaining fatigue life of the rubber mount is predicted.

[0027] 3. Beneficial effects

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The method of the present invention predicts in advance the catastrophic failure that may occur during the use of the rubber mount by simulating the crack propagation of the rubber mount, and accurately predicts the remaining fatigue life of the rubber mount, enabling preventive measures to be taken and replacement plans to be arranged, such as timely replacing the rubber mount components, thereby ensuring driving safety, avoiding waste of resources caused by premature replacement, and also preventing vehicle failures due to untimely maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The technical solutions of the present invention will be further described in detail below with reference to the drawings and embodiments. However, it should be understood that these drawings are only designed for explanatory purposes and thus do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0031] Figure 1 Rubber pure shear specimen and dimensional drawing of an embodiment of the present invention;

[0032] Figure 2 Physical drawing of a crack with a single-sided notch in an embodiment of the present invention;

[0033] Figure 3 Variation of crack length with fatigue cycle number in an embodiment of the present invention;

[0034] Figure 4 Variation of tearing energy with fatigue cycle number in an embodiment of the present invention;

[0035] Figure 5 Result of strain analysis nephogram of the rubber mount in an embodiment of the present invention;

[0036] Figure 6 Partial mesh refinement drawing of the finite element model of the rubber mount in an embodiment of the present invention;

[0037] Figure 7 Diagram of the deflection angle of a prefabricated crack in the fatigue danger area in an embodiment of the present invention;

[0038] Figure 8 PHILSM diagram of crack propagation in an embodiment of the present invention;

[0039] Figure 9 Diagrams of different prefabricated crack propagation angles in an embodiment of the present invention;

[0040] Figure 10 Curve of the variation relationship between the deflection angle of the prefabricated crack and the stiffness in an embodiment of the present invention;

[0041] Figure 11 Curve of the variation relationship between the deflection angle of the prefabricated crack and the remaining fatigue life in an embodiment of the present invention;

[0042] Figure 12 Length diagram of prefabricated cracks in the fatigue danger area of the embodiment of the present invention;

[0043] Figure 13 Diagram of different prefabricated crack propagation lengths in the embodiment of the present invention;

[0044] Figure 14 Curve of the relationship between the crack propagation length and the prefabricated crack length in the embodiment of the present invention;

[0045] Figure 15 Curve of the relationship between the crack propagation length and the stiffness in the embodiment of the present invention;

[0046] Figure 16 Curve of the relationship between the crack propagation length and the remaining fatigue life in the embodiment of the present invention. Detailed implementation manners

[0047] The following detailed description of the exemplary embodiments of the present invention refers to the accompanying drawings, which form a part of the description, and in which the exemplary embodiments in which the present invention can be implemented are shown by way of example. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be achieved and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed present invention, but is merely for purposes of illustration and does not limit the description of the features and characteristics of the present invention, to set forth the best mode of carrying out the present invention, and to be sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is defined only by the appended claims.

[0048] The following detailed description and exemplary embodiments of the present invention can be better understood in conjunction with the accompanying drawings, in which the elements and features of the present invention are identified by reference numerals.

[0049] The method for predicting the fatigue life of the rubber mount of the present invention includes the steps of: according to the rubber mount fatigue crack propagation analysis method, prefabricating cracks with different angles and lengths in the fatigue danger point area, obtaining the influence law of the crack propagation on the stiffness of the rubber mount, and predicting the remaining fatigue life of the rubber mount; wherein the rubber mount fatigue crack propagation analysis method includes the steps of: obtaining the rubber parameters for manufacturing the rubber mount required for simulation, using a rubber pure shear specimen with a single-edge notch, performing a fatigue test on a crack propagation testing machine to obtain the critical tearing energy; constructing a finite element model of the rubber mount by the Abaqus finite element method, analyzing and determining the local fatigue danger point area of the rubber mount; by establishing a prefabricated crack model and simulating the propagation of the prefabricated crack in the rubber, obtaining the relationship between the propagation of the prefabricated crack and the stiffness of the rubber mount.

[0050] The change in the total strain energy at the crack tip of a pure shear rubber specimen is: δU = -Wh 0 lδc, where h0 is the height of the specimen, W represents the strain energy density of the rubber material, U is the strain energy reduced inside the rubber when the crack interface expands by a unit area, l represents the length of the rubber material, and δc represents the crack size at the crack initiation of the rubber material.

[0051] The tearing energy at the crack tip of a pure shear rubber specimen is given by the formula: It can be seen from this that the tearing energy acting on the crack tip of a pure shear specimen is independent of the crack size and is only related to the specimen size and the degree of deformation. Therefore, using a pure shear rubber specimen can quickly and effectively obtain data on the crack propagation characteristics of rubber materials.

[0052] To ensure that the effective area of the specimen is in a pure shear state, the specimen needs to meet a large aspect ratio. In this embodiment, the width l0 of the pure shear rubber specimen used is 140, the height h0 is 10, the thickness d is 2, and the length of the prefabricated crack c0 is 20, with all units in mm, as Figure 1 shown.

[0053] Use a pure shear specimen with a single-edge notch, as Figure 2 shown, and conduct tests on a crack propagation testing machine (using the rubber tensile testing machine M-100 / M-3000 under Kayr). The test conditions are within a temperature range of 23 ± 2 °C, a loading frequency of 4 Hz, an axial tension of 0 - 5 mm, and 500 cycles of cyclic loading. Summarize the specimen crack length and stress-strain test data under different numbers of cycles, and obtain the critical tearing energy Tc according to this.

[0054] Referring to the test method of the prior art (such as the test method proposed by Bai Yu of Central South University), during the fatigue test, the minimum strain h of the fatigue cyclic load is constantly 0, and the maximum strain of the cyclic load decreases linearly with the increase in the number of fatigue cycles. Among them, the strain peak starts from 0.60 and gradually decreases to 0.10 with the number of fatigue cycles. After the test, the relationships between the crack propagation length and the tearing energy and the number of fatigue cycles are obtained, as Figure 3 、 Figure 4 shown.

[0055] According to the pure shear test of the rubber material, the test data related to the crack propagation fatigue test are obtained, as shown in Table 1-1.

[0056] Table 1-1 Rubber material crack propagation material parameters

[0057]

[0058]

[0059] In actual use, cracks may occur in multiple parts of the rubber mount due to the action of fatigue loads. Among them, the cracks at the failure hot spot positions of the rubber mount form and propagate faster, which will cause the rubber mount to fail. To more efficiently analyze the performance changes of the rubber mount caused by fatigue crack propagation, it is necessary to find the appropriate dangerous positions of the rubber mount as the crack propagation regions.

[0060] In this embodiment, in order to be able to determine the stress-strain distribution and change conditions of the rubber mount during the cyclic period under the V-direction load, it is necessary to obtain the fatigue failure dangerous point region of the rubber mount under the V-direction load in the local coordinate system. Displacement loads of ±6 mm are applied to the finite element model of the rubber mount respectively. The results of the strain analysis nephogram of the rubber mount are shown in Figure 5 .

[0061] From the results of the strain finite element analysis of the rubber mount under the V-direction cyclic load, when the V-direction amplitude of the rubber mount reaches the amplitude value, the principal strain in the same direction as the V-direction amplitude in the main spring rubber block reaches the maximum value of 0.3371 at node number 584, and the direction of the maximum principal strain is the same as the direction of the V-direction amplitude. Similarly, under the V-direction fatigue loads with different amplitudes, the positions and directions of the maximum principal strain of the rubber mount show similarity. Based on the strain results and Saint-Venant's principle, the fatigue dangerous point region is further determined: on the tensile side, the regions 2 mm to the left and right of the prefabricated crack are selected as the dangerous fatigue point regions.

[0062] In the step of establishing the prefabricated crack model, the angles of the prefabricated cracks are -10°, -5°, 0°, 5°, and 10° respectively; the crack lengths are 0.2 mm, 0.6 mm, and 1 mm respectively. When calculating the crack propagation, the crack does not need to be assigned relevant material properties and meshed, but it is necessary to set the crack propagation criterion for the material of the rubber mount, that is, the rubber material. Based on the energy release rate parameters under different fracture moduli of the energy release rate, the critical tearing energy of the rubber material is set. After creating the crack, it is necessary to assemble the crack with the position of the fatigue dangerous point of the rubber mount, and at the same time use "Creat Crack" in the "Interaction" module, and the type is selected as "XFEM".

[0063] However, due to the singularity at the crack tip, by subdividing the mesh of the region near the prefabricated crack, higher calculation accuracy can be obtained, so that the error can be controlled within a reasonable range and the problem of model non-convergence under large deformations can be avoided. The rubber body in the prefabricated crack region is remeshed, as shown in Figure 6 the local mesh subdivision diagram of the finite element model of the rubber mount shown, and the mesh within the white frame is the target subdivision mesh.

[0064] Furthermore, as shown in Figure 7As shown, the crack is perpendicular to the rubber block of the rubber mount at this time. Taking this position as the starting position of crack deflection, the deflection angle of the crack is recorded as 0°. In addition, clockwise deflection is negative. The prefabricated crack is deflected by 5 degrees and 10 degrees respectively; counterclockwise deflection is positive, and it is deflected by 5° and 10° respectively. The crack and the model are assembled in Creo 10.0, and the assembled body is input into Abaqus for finite element analysis.

[0065] In this embodiment, with the deflection crack angle being 0°, the crack propagation process is analyzed. At the 10th analysis step, the model cracks along the prefabricated crack angle. As the analysis step increases, the crack completely fractures along the prefabricated crack at the 20th analysis step. At the 40th analysis step, the crack propagates. Thereafter, as the position load further increases, the crack length of the crack propagation increases, as Figure 8 is the PHILSM diagram of crack propagation when the prefabricated crack deflection angle is 0°. It is obtained that as the size of the crack propagation increases, the strain of the rubber mount increases, and the remaining fatigue life decreases significantly.

[0066] Furthermore, the other 4 groups of models are processed in the same way to obtain the prefabricated crack propagation diagrams under displacement loads respectively, as Figure 9 are the crack propagation diagrams of 5 groups of prefabricated cracks at different deflection angles, and the relationship curves of the rubber mount stiffness and the remaining fatigue life can be calculated respectively as the prefabricated crack deflection angle changes.

[0067] Combined with Figure 10 shown, when the deflection angle is negative, the stiffness increases with the increase of the angle. When the deflection angle is -10°, the stiffness of the rubber mount is 462.53 N / mm; when the deflection angle is -5°, the stiffness of the rubber mount is 463.30 N / mm; when the prefabricated crack angle is 0°, the stiffness value is the largest at this time, which is 463.41 N / mm; as the deflection angle increases in the positive direction, the stiffness value gradually decreases. From the above analysis, it can be seen that after the crack exists, compared with the stiffness value of the initial model of 474.81 N / mm, the stiffness value decreases, and the maximum decrease is 2.4%. The reason for the analysis is that the crack length of the crack propagation increases and the decrease amplitude in the positive direction of deflection is faster than that in the negative direction.

[0068] It should be noted that from Figure 11From the curve of the prefabricated crack deflection angle and the remaining fatigue life, it can be obtained that when the prefabricated crack deflection angle is in the negative direction, as the deflection angle increases, the remaining fatigue life of the rubber mount gradually decreases. When the deflection angle is 0°, the remaining fatigue life is 387,384 times, and the remaining fatigue life value is the smallest at this time; when the prefabricated crack deflection angle is in the positive direction, as the deflection angle increases, the remaining fatigue life of the rubber mount gradually increases. When the deflection angle is 10°, the remaining fatigue life is 500,972 times. The reason is that as the displacement load increases, the crack propagation length also increases. In this state, the number of working cycles to reach this state increases, and the remaining fatigue life value accumulates and increases.

[0069] As Figure 12 shown, the length of the inserted prefabricated crack and the prefabricated crack in the vertical direction of the rubber block of the rubber mount. Different lengths of cracks are used in this direction, and there are 3 groups of cracks with lengths of 0.2 mm, 0.6 mm, and 1 mm respectively.

[0070] In this embodiment, from left to right are the crack propagation diagrams when the prefabricated crack lengths are 1 mm, 0.6 mm, and 0.2 mm respectively. As Figure 13 shown, the figure intercepted is the crack propagation state diagram on the outer diameter of the rubber mount when the crack propagates. Selecting the crack propagation diagram in this direction can calculate the relationship between the crack propagation length and the prefabricated crack length.

[0071] Furthermore, it can be obtained from Figure 13 that as the prefabricated crack length increases, the crack propagation length also increases. And as Figure 14 is the change relationship curve between the crack propagation length and the prefabricated crack length. It can be obtained that the relationship between the two is positively correlated. Among them, when the prefabricated crack length is 0.2 mm, the crack propagation length is 2.54558 mm; when the length is 0.6 mm, the crack propagation length is 4.24264 mm; when the length is 1 mm, the crack propagation length is 8.77033 mm, showing an approximate 2-fold relationship.

[0072] In this embodiment, in order to obtain the influence law of crack propagation on the stiffness of the rubber mount, as Figure 15 shown, as the prefabricated crack length increases, the stiffness gradually decreases and the change amplitude increases. When the prefabricated crack length is 1 mm, the stiffness value of the rubber mount is the smallest, which is 457.31 N / mm. Compared with the stiffness value before the crack exists, the stiffness value decreases, and it decreases by 3.69%. The longer the crack propagation length, the more obvious the decrease in the stiffness value. As Figure 16As shown, the longer the prefabricated crack length, the greater the remaining fatigue life, and it shows a gradually increasing trend. When the prefabricated crack length is 0.2 mm, the remaining fatigue life of the rubber mount is 411,525 times at this time; when the prefabricated crack length is 1 mm, the remaining fatigue life of the rubber mount is 551,043 times at this time.

[0073] It is obtained that the longer the prefabricated crack length, the greater the strain at the crack, the greater the strain, the smaller the fatigue life, and the influence law of the increase in the cumulative remaining fatigue life value. Combining this law, the remaining fatigue life of the rubber mount can be predicted. By simulating the crack propagation of the rubber mount, the possible catastrophic failure of the rubber mount during use can be predicted in advance; the remaining fatigue life of the rubber mount can be predicted more accurately, and preventive measures and replacement plans can be taken, such as timely replacing the rubber mount parts, so as to ensure driving safety, avoid waste of resources caused by premature replacement, and at the same time prevent vehicle failures caused by untimely maintenance.

[0074] The above schematically describes the present invention and its implementation manners. This description is not restrictive, and what is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments to this technical solution without creative work without departing from the gist of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for analyzing fatigue crack growth of a rubber suspension, characterized in that: The following steps are involved: (1) Obtaining the rubber parameters of the rubber suspension material, performing fatigue tests on a rubber pure shear specimen with a single-side notch, and determining the critical tear energy; (2) The finite element model of the rubber suspension is established by using the Abaqus finite element method, and the displacement load is applied to determine the local fatigue danger point area; (3) A prefabricated crack model with different angles and lengths was established to simulate and analyze the crack propagation process and obtain the correlation between crack propagation and rubber suspension stiffness.

2. The method for analyzing fatigue crack growth of a rubber suspension according to claim 1, characterized in that: The dimensions of the rubber pure shear specimen are 140 mm in width, 10 mm in height, and 2 mm in thickness, and the length of the prefabricated crack is 20 mm.

3. The method for analyzing fatigue crack growth of a rubber suspension according to claim 2, characterized in that: The fatigue test conditions are as follows: temperature 23±2° C., loading frequency 4 Hz, axial tensile displacement 0-5 mm, and cyclic loading 500 times. The critical tearing energy is calculated by recording the crack length and stress-strain data at different numbers of cycles.

4. The method for analyzing fatigue crack growth of a rubber suspension according to claim 1, characterized in that: In step (2), a V-direction displacement load of ±6 mm is applied to the rubber suspension finite element model. Based on the strain distribution and Saint-Venant's principle, an area 2 mm to the left and right of the prefabricated crack is selected as a fatigue danger point.

5. The rubber suspension fatigue crack growth analysis method according to claim 1, characterized in that: In step (3), the angle of the prefabricated crack is -10°, -5°, 0°, 5° or 10°, and the length is 0.2 mm, 0.6 mm or 1 mm.

6. The method for analyzing fatigue crack growth of a rubber suspension according to claim 5, characterized in that: When establishing the prefabricated crack model, the "XFEM" type crack is created through the "Interaction" module of Abaqus, and the crack is assembled with the fatigue danger point area.

7. The method for analyzing fatigue crack growth of a rubber mount according to claim 1, characterized in that: In step (3), the initial position of the prefabricated crack is perpendicular to the rubber block, and the crack deflection angle is defined as 0°; by deflecting by -5°, -10° clockwise and 5°, 10° counterclockwise, the crack propagation behavior under different deflection angles is analyzed.

8. The rubber suspension fatigue crack growth analysis method according to claim 7, characterized in that: With the deflection crack angle of 0°, the crack propagation process is analyzed at the 10th, 20th and 40th analysis steps respectively.

9. A method for predicting fatigue life of a rubber suspension, characterized in that: The following steps are involved: Based on the fatigue crack growth analysis method described in any one of claims 1 to 8, cracks of different angles and lengths are preset in the fatigue danger point area, and the remaining fatigue life is predicted in combination with the influence of crack growth on the rubber suspension stiffness.

10. The method for predicting the fatigue life of a rubber mount according to claim 9, characterized in that: The prediction method verifies the accuracy of the life model by comparing finite element simulation data with test data.

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