Method for judging fatigue resistance of ms adhesive

Abstract

This invention relates to a method for determining the fatigue resistance of MS adhesive. The method includes: (1) preparing a shear sample of MS adhesive and testing the shear strength of MS adhesive; (2) determining the safe stress value for permanent service life of MS adhesive based on the shear strength obtained from step (1) and the following formula (I): safe stress value = shear strength × K1, formula (I); where 0 < K1 ≤ 0.12; (3) combining the set stress value of actual working conditions, making the following determination: when the set stress value is less than or equal to the safe stress value obtained from step (2), MS adhesive can be safely applied to the actual working conditions; when the set stress value is greater than the safe stress value obtained from step (2), there is a safety hazard when MS adhesive is applied to the actual working conditions. The method of this invention can intuitively, simply and reliably determine the fatigue resistance of MS adhesive.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and more specifically to a method for determining the fatigue resistance of MS adhesive. Background Technology

[0002] MS adhesive is short for silane-modified polyether adhesive. It is a one- or two-component elastic sealant primarily based on MS polymers, combined with fillers, plasticizers, and other functional additives. It is a new generation of building sealant developed after silicone sealant (SR) and polyurethane sealant (PU). It is mainly used in bonding, filling, sealing, waterproofing, and reinforcement in building engineering and decoration. As people's understanding of the advantages of MS adhesive deepens, its application in refrigerated trucks, containers, and elevator industries is also expanding. With the continuous advancement of MS adhesive research, its mechanical strength has significantly improved, becoming comparable to that of polyurethane sealants. It also boasts significant advantages in environmental protection, flame retardancy, and weather resistance, leading to its increasing application in industries such as rail transportation, automobiles, aviation, and wind power. These fields require adhesives with high safety standards. Research on the fatigue resistance of standard bonded components using MS adhesive products can provide accurate data support for component design when MS adhesive is applied in actual working conditions.

[0003] Currently, the national standard for determining the fatigue performance of adhesives is GB / T 27595. This standard specifies various technical terms and related parameter settings for the fatigue behavior of adhesives when the fatigue test specimen is a shear test piece. The adhesives involved in the standard are high-strength products (such as epoxy adhesives), and there are no requirements for the adhesive joint thickness. MS adhesive, as an elastic adhesive sealant, has a significant strength difference compared to high-strength epoxy resin products. When used for bonding and sealing under actual working conditions, there are specific requirements for adhesive thickness. For example, the rail transit standard DIN 6701-3 clearly stipulates that the adhesive test specimen must meet certain adhesive length and adhesive thickness requirements.

[0004] When MS adhesive is applied in actual working conditions, such as in rail transportation, automobiles, and aviation, the application area requires the adhesive to meet certain force values ​​to ensure a certain level of safety. Existing technologies often require multiple simulations of fatigue test curves based on the MS adhesive and working conditions to ensure it meets these force requirements. This process is complex, time-consuming, and involves high power consumption and economic costs for fatigue testing machines. This invention, referencing national standards, studies the fatigue performance of MS adhesive products. Through research on the fatigue behavior of MS adhesive sealants, it explores a new, simple, and reliable method for determining the fatigue performance of MS adhesives. This method provides an intuitive, simple, and reliable assessment of the fatigue resistance of MS adhesives, addressing the problems and deficiencies of existing simulation methods. Summary of the Invention

[0005] This invention provides a method for determining the fatigue resistance of MS adhesive, which is intuitive, simple and reliable for determining the fatigue resistance of MS adhesive.

[0006] This invention relates to a method for determining the fatigue resistance of MS adhesive, the method comprising the following steps:

[0007] (1) Prepare shear samples of MS adhesive and test the shear strength of MS adhesive;

[0008] (2) Determine the safe stress value for the permanent service life of the MS adhesive based on the shear strength obtained from step (1) and the following formula (Ⅰ).

[0009] Safety stress value = shear strength × K1, Equation (Ⅰ);

[0010] Where 0 < K1 ≤ 0.12;

[0011] (3) Based on the set stress value under actual working conditions, the following judgment is made:

[0012] When the set stress value is less than or equal to the safe stress value obtained from step (2), the MS adhesive can be safely applied to the actual working condition;

[0013] When the set stress value is greater than the safe stress value obtained from step (2), there is a safety hazard when the MS adhesive is applied to the actual working condition.

[0014] Optionally, the shear strength of the MS adhesive is 1.0 MPa to 3.5 MPa.

[0015] Optionally, in step (1), when preparing the shear sample of MS adhesive and testing the shear strength of MS adhesive, the process shall be carried out in accordance with standard DIN6701-3.

[0016] Optionally, when testing the shear strength of the MS adhesive, the bonding length of the shear sample is 12-22 mm, the bonding width is 22-27 mm, the bonding thickness is 3-6.5 mm, and the tensile rate is 18-35 mm / min.

[0017] Optionally, the shear strength of the MS adhesive is the average shear strength after 5 to 10 tests.

[0018] Optionally, the MS adhesive has a permanent service life: the shear fatigue number of the MS adhesive sample is greater than or equal to 10. 7 .

[0019] Optionally, 0.08≤K1≤0.11; K1 is preferably 0.09.

[0020] Optionally, when the MS adhesive can be safely applied to the actual working conditions, the method further includes the following steps after step (3):

[0021] (4) Calculate the safety factor according to the following formula (II):

[0022] Safety factor = safety stress value ÷ set stress value, Equation (II).

[0023] Optionally, when 1 ≤ safety factor < 10, the MS adhesive has a first-level safety factor when applied to the actual working condition; when 10 ≤ safety factor < 20, the MS adhesive has a second-level safety factor when applied to the actual working condition; and when 20 ≤ safety factor < 30, the MS adhesive has a third-level safety factor when applied to the actual working condition.

[0024] Optionally, when 30 ≤ safety factor < 40, the MS adhesive has a level four safety factor when applied to the actual working conditions; when 40 ≤ safety factor < 50, the MS adhesive has a level five safety factor when applied to the actual working conditions.

[0025] Beneficial effects:

[0026] This invention provides a simple and quick method for determining the fatigue resistance of MS adhesive. The shear strength of the MS adhesive is tested, and then the safe stress value for the permanent service life of the MS adhesive is calculated. Based on the relationship between the set stress value and the safe stress value in actual working conditions, it can be reliably determined whether the MS adhesive can be safely used in actual working conditions. Attached Figure Description

[0027] Figure 1 The fatigue test SN curve for sample 1;

[0028] Figure 2 This is the fatigue test SN curve of sample 2;

[0029] Figure 3 This is the fatigue test SN curve of sample 3;

[0030] Figure 4 It is the fatigue test SN curve of competitor product 1;

[0031] Figure 5 It is the fatigue test SN curve of competitor product 2. Detailed Implementation

[0032] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.

[0033] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0034] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0035] This invention relates to a method for determining the fatigue resistance of MS adhesive, the method comprising the following steps:

[0036] (1) Prepare shear samples of MS adhesive and test the shear strength of MS adhesive;

[0037] (2) Determine the safe stress value for the permanent service life of the MS adhesive based on the shear strength obtained from step (1) and the following formula (Ⅰ).

[0038] Safety stress value = shear strength × K1, Equation (Ⅰ);

[0039] Where 0 < K1 ≤ 0.12;

[0040] (3) Based on the set stress value under actual working conditions, the following judgment is made:

[0041] When the set stress value is less than or equal to the safe stress value obtained from step (2), the MS adhesive can be safely applied to the actual working condition;

[0042] When the set stress value is greater than the safe stress value obtained from step (2), there is a safety hazard when the MS adhesive is applied to the actual working condition.

[0043] It should be noted that in actual working conditions, such as the use of adhesives for windows in rail transit vehicles, the adhesives used need to meet certain stress values ​​to ensure safe operation. For example, trains and automobiles are designed with specific stress values ​​for certain working conditions, and these design values ​​are the set stress values ​​for actual working conditions. Therefore, when the actual working conditions are determined, the set stress value can be obtained by referring to the design values ​​for those actual working conditions. For example, the set stress value for the first window working condition is 1.0 MPa, meaning the maximum stress value in that condition is 1.0 MPa. Whether a certain MS adhesive can be used safely and sustainably under such conditions often requires technicians to conduct multiple fatigue test simulations of the SN curve for that MS adhesive to make a judgment.

[0044] The inventors of this application have innovatively discovered through long-term research and development that, by first testing the shear strength of the MS adhesive and then calculating the safe stress value according to the above formula (Ⅰ), for example, 0.5 MPa, the MS adhesive can achieve its permanent service life under a stress of less than or equal to 0.5 MPa. In other words, the safe stress value represents the maximum stress value at which the MS adhesive can have a permanent service life. Since the safe stress value of 0.5 MPa for the MS adhesive is less than the set stress value of 1.0 MPa for the operating condition, the MS adhesive cannot reach its permanent service life when used under the condition of 0.6-1.0 MPa, thus posing a safety risk.

[0045] Conversely, for example, if the set stress value for the second window working condition is 1.5 MPa, meaning the maximum stress value in this condition is 1.5 MPa, the following determination is made regarding whether a certain MS adhesive can be safely applied to this condition: First, test the shear strength of the MS adhesive. Calculate the safe stress value for the MS adhesive to have a permanent service life according to the above formula (Ⅰ). This indicates that the MS adhesive can achieve a permanent service life when used under a stress of less than or equal to 2.0 MPa. In other words, the safe stress value represents the maximum stress value at which the MS adhesive can have a permanent service life. Since the safe stress value of the MS adhesive, 2.0 MPa, is greater than the set stress value of 1.5 MPa for this condition, and the MS adhesive can have a permanent service life under a stress value of less than or equal to 2.0 MPa, it is even more likely to achieve a permanent service life under a stress of less than or equal to 1.5 MPa. Therefore, the MS adhesive can be safely applied to this condition.

[0046] In summary, this invention provides a simple, reasonable, and reliable method for determining the fatigue resistance of MS adhesive. It does not require extensive fatigue testing and curve simulation. By testing shear strength and calculating the safe stress value, and comparing the safe stress value with the set stress value of the actual working condition, it is possible to quickly determine whether the MS adhesive can be safely applied to the working condition. The determination process is simple and fast, and the determination result is reliable.

[0047] According to a specific embodiment of the method of the present invention, the shear strength of the MS adhesive is 1.0 MPa to 3.5 MPa.

[0048] According to a specific embodiment of the method of the present invention, in step (1), when preparing the shear sample of MS adhesive and testing the shear strength of MS adhesive, the method is performed in accordance with standard DIN 6701-3.

[0049] According to a specific embodiment of the method of the present invention, when testing the shear strength of the MS adhesive, the bonding length of the shear sample is 12-22 mm, the bonding width is 22-27 mm, the bonding thickness is 3-6.5 mm, and the tensile rate is 18-35 mm / min.

[0050] It should be noted that MS adhesive is an elastic bonding sealant. In actual application conditions, when stress is applied, there is also a certain displacement change. Its fatigue performance is significantly different compared with high-strength, high-modulus epoxy resin adhesives. The fatigue performance determination method of this invention has the advantages of reliability, simplicity, and speed. However, the determination method of this invention has its own applicable scope. First, the adhesive used for determination must be MS adhesive. Second, MS adhesive with a shear strength in the range of 1.0 MPa to 3.5 MPa is more suitable.

[0051] According to a specific embodiment of the method of the present invention, the shear strength of the MS adhesive is the average shear strength after 5 to 10 tests.

[0052] It should be noted that this application, referencing national standards, sets corresponding mean parameters and a stress ratio R of 0.1, to study the stress fatigue performance of MS adhesives with shear strengths (e.g., adhesive thickness 5 mm, adhesive length 20 mm, adhesive width 25 mm) ranging from 1.0 MPa to 3.5 MPa. The relevant laws governing stress fatigue of MS adhesives within this strength range were investigated, and a new method applicable to the stress fatigue performance assessment of MS adhesives was invented. Compared with the national standard method, this method is simpler, more intuitive, and more reliable.

[0053] According to another specific embodiment of the method described in this invention, the MS adhesive has a permanent service life:

[0054] The MS adhesive shear sample had a fatigue number greater than or equal to 10. 7 .

[0055] It should be noted that, firstly, the MS adhesive has a permanent service life, meaning that the shear fatigue number of the MS adhesive sample is greater than or equal to 10. 7 That is, the shear sample of the MS adhesive has an abscissa greater than or equal to 10 in the fatigue test SN curve. 7 Secondly, the shear fatigue number of the MS adhesive sample is greater than or equal to 10. 7 The specifications and fabrication of the sheared specimens of the MS adhesive are in accordance with standard DIN 6701-3. Therefore, the bonding length of the sheared specimens of the MS adhesive can be 12-22 mm, the bonding width can be 22-27 mm, and the bonding thickness can be 3-6.5 mm.

[0056] It should be noted that, in the process of researching the method for determining the fatigue resistance of MS adhesive, the inventors of this application selected three MS adhesive samples with significant differences in mechanical strength: Sample 1, Sample 2, and Sample 3. They also selected two other samples, namely, two competing products: Competitor 1 (domestic) and Competitor 2 (imported). Sample 1, Sample 2, and Sample 3 can be MF1502, MF1506F, and MF1506 from Zhengzhou Zhongyuan Silande High-Tech Co., Ltd., respectively; Competitor 1 and Competitor 2 can be 7937D from a domestic manufacturer and 7008 from an imported manufacturer, respectively.

[0057] First, shear specimens were prepared and tested according to standard DIN 6701-3. Several shear specimens with a bonding thickness of 5 mm, a bonding length of 20 mm, and a bonding width of 25 mm were prepared for each of the five types of samples. The shear strength and elongation at maximum strength of each of the five types of samples were tested at a tensile rate of 30 mm / min. The test results are shown in Table 1.

[0058] Table 1

[0059]

[0060] Then, based on the shear specimens prepared according to the above standard DIN 6701-3, when performing stress fatigue tests on MS adhesive, referring to the mean value method in GB / T 27595 standard, with a fixed test frequency of 10Hz and a stress ratio of 0.1, the mean stress was selected or set to 0.13 times, 0.12 times, 0.11 times, 0.10 times, and 0.09 times the shear strength of the corresponding sample, respectively. After determining the mean, the amplitude was calculated when the stress ratio R was 0.1. The test results of the above 5 samples (samples 1-3, competitors 1 and 2) are shown in the following tables.

[0061] Sample 1 underwent fatigue testing and SN curve simulation according to GB / T 27595 standard. The fatigue counts or service counts for Sample 1 at average stress values ​​of 0.13, 0.12, 0.11, 0.10, and 0.09 times the shear strength are shown in Table 2 below. The SN curve for Sample 1 when undergoing fatigue performance testing according to national standards is as follows. Figure 1 As shown, Figure 1 The SN curve for fatigue testing of sample 1. Figure 1 It can be seen that when the average stress is ≤0.15MPa (0.1 times the shear strength), the service life (fatigue cycles) of sample 1 can reach 10. 7 At this point, the sample 1 is in the durability zone, meaning that the sample has a permanent service life.

[0062] Table 2 Fatigue test results for Sample 1 at different mean values.

[0063]

[0064] Note: The fatigue count in the table is the median of 3 tests.

[0065] Sample 2 was tested using the same method as Sample 1. The fatigue cycles or service cycles of Sample 2 at average stress values ​​of 0.13, 0.12, 0.11, 0.10, and 0.09 times the shear strength are shown in Table 3 below. The fatigue test SN curves of Sample 2 are shown below. Figure 2 When the average stress is ≤0.24MPa (0.11 times the shear strength), the service life (fatigue cycles) of sample 2 can reach 10. 7 Sample 2 is in the durability zone, meaning it has a permanent service life.

[0066] Table 3 Fatigue test results for Sample 2 at different mean values.

[0067]

[0068] Note: The fatigue count in the table is the median of 3 tests.

[0069] Sample 3 was tested using the same method as Sample 1. The fatigue cycles or service cycles of Sample 3 at average stress values ​​of 0.13, 0.12, 0.11, 0.10, and 0.09 times the shear strength are shown in Table 4 below. The fatigue test SN curves of Sample 3 are shown below. Figure 3 When the average stress is ≤0.297MPa (0.09 times the shear strength), the service life (fatigue cycles) of sample 3 can reach 10. 7 Sample 3 is in the durability zone, meaning it has a permanent service life.

[0070] Table 4. Fatigue test results for sample 3 at different mean values.

[0071]

[0072] Note: The fatigue count in the table is the median of 3 tests.

[0073] Competitor 1 was tested using the same method as Sample 1. The fatigue cycles or service cycles of Competitor 1 at average stress values ​​of 0.13, 0.12, 0.11, 0.10, and 0.09 times the shear strength are shown in Table 5 below. The fatigue test SN curves of Competitor 1 are shown below. Figure 4 When the average stress is ≤0.171MPa (0.09 times the shear strength), the service life (fatigue cycles) of competitor product 1 can reach 10. 7 The sample of competitor product 1 is in the durability zone, meaning that the sample has a permanent service life.

[0074] Table 5. Fatigue test results of competitor product 1 at different mean values.

[0075]

[0076] Note: The fatigue count in the table is the median of 3 tests.

[0077] Competitor Product 2 was tested using the same method as Sample 1. The fatigue cycles or service cycles of Competitor Product 2 at average stress values ​​of 0.13, 0.12, 0.11, 0.10, and 0.09 times the shear strength are shown in Table 6 below. The SN curves of the fatigue test for Competitor Product 2 are shown below. Figure 5 As shown, when the average stress is ≤0.21MPa (0.1 times the shear strength), the service life (fatigue cycles) of competitor product 2 can reach 10. 7 The sample of competitor product 2 is in the durability zone, meaning that the sample has a permanent service life.

[0078] Table 6. Fatigue test results of competitor product 2 at different mean values.

[0079]

[0080] Note: The fatigue count in the table is the median of 3 tests.

[0081] It should be noted that, in addition to the five groups of samples mentioned above, the inventors of this application have also conducted extensive research and concluded that MS adhesive with a shear strength of 1.0 MPa to 3.5 MPa has a permanent service life when the stress value is less than or equal to the safe stress value, and the service life (fatigue cycles) of MS adhesive is greater than or equal to 10. 7 Wherein, the safe stress value = shear strength × K1, 0 < K1 ≤ 0.1. Then, by comparing the set stress value under the actual working conditions with the calculated safe stress value of the MS adhesive, it is easy, quick and reliable to determine whether the MS adhesive can be safely used under the working conditions.

[0082] According to a specific embodiment of the method of the present invention, 0.08≤K1≤0.11; K1 is preferably 0.09.

[0083] It should be noted that in the stress fatigue test, when using 0.09 times the shear strength as the mean and the stress ratio R is 0.1, the shear specimens of MS adhesive with different force values ​​can all reach the ultimate fatigue cycle of 10 million (10 7The test results of the dumbbell specimens (GB / T 528) of several samples (Table 7) show that Sample 1, Sample 2, and Competitor 2 reached their ultimate fatigue cycles under stress values ​​of 0.1, 0.11, and 0.1 times the average shear strength, respectively. Sample 3 and Competitor 1 reached their ultimate fatigue cycles under stress values ​​of 0.09 times the average shear strength. Analysis of the test results (Table 7) of the Type 2 dumbbell specimens of these samples shows that Sample 1 dumbbell has the highest elongation at break among the five samples, indicating better elasticity. While the tensile strength of Sample 2 and Competitor 2 dumbbells is weaker than that of Sample 3, their 100% modulus (100% elongation at a given elongation in Table 7) is comparable to that of Sample 3. Under force-controlled fatigue test conditions, the displacement displayed by the displacement sensor for sample 3 changed continuously. This was mainly because the maximum value of the displacement parameter increased continuously with the increase of the number of fatigue cycles (as shown in Table 8). That is, under the continuous stress fatigue test conditions of the elastic MS rubber, the elastic rubber underwent creep due to continuous stress. In order to reach the set force value, the displacement of the elastic rubber continuously increased. However, when the elastic rubber modulus is high, the creep phenomenon is not obvious. Therefore, under stress fatigue test conditions, the creep displacement is less affected by the continuous increase of the number of fatigue cycles. Thus, the MS rubber with a higher modulus has better stress fatigue performance.

[0084] Table 7. Tensile results of the Type 2 dumbbell samples (tensile rate: 200 mm / min)

[0085]

[0086] Table 8 shows the maximum displacement parameter variation of sample 3 at 0.11 times the mean shear strength.

[0087]

[0088] Based on the above, when MS adhesives with shear strength ranging from 1.0 MPa to 3.5 MPa undergo fatigue testing, under the condition that the average safe stress is 0.09 times the average shear strength and the stress ratio is 0.1, MS adhesives within this stress range have a permanent service life. That is, when the stress value is less than or equal to 0.09 times the shear strength, the MS adhesive has a permanent service life. Then, based on the relationship between the set stress value under actual working conditions and 0.09 times the shear strength (safe stress value), it can be determined whether the MS adhesive can be safely used under that actual working condition.

[0089] In practical applications, the safety stress value of MS adhesive K1 times, such as 0.09 times the shear strength, can be calculated to easily and quickly determine whether the safety factor set for the application area is met.

[0090] Two MS adhesive products were selected: Sample 4 and Competitor 3. Several shear specimens were prepared. The shear specimens of Sample 4 and Competitor 3 were subjected to 56 cycles of D4 curve aging test (ISO 9142) and 1000 hours of salt spray aging test, respectively. After the environmental aging period, the specimens were taken out and equilibrated under standard conditions for 24 hours. Their shear strength was tested at a tensile rate of 30 mm / min. The fatigue test frequency was fixed at 10 Hz, the stress ratio R was 0.1, and the average stress was 0.09 times the shear strength. The number of fatigue cycles was tested. The test results are shown in Table 9 below.

[0091] Table 9. Test results for Sample 4 and Competitor 3

[0092]

[0093]

[0094] As can be seen from the above, using the method of this invention, the fatigue cycles of sample 4 and competitor 3 under standard shear conditions and after environmental aging both reached the limit fatigue cycle. Application examples demonstrate that this method can be used to determine the fatigue resistance of MS adhesive. This indicates that, in actual use, even after exposure to wind, sun, and salt spray aging, when the MS adhesive sample is used within the range of the safe stress value calculated by shear strength × K1 (i.e., less than or equal to the safe stress value), it can still have a permanent service life, i.e., a service life or fatigue cycle of 10. 7 Therefore, the method of the present invention can reliably determine whether a certain MS adhesive can be safely used in actual working conditions.

[0095] According to a preferred embodiment of the method of the present invention, when the MS adhesive can be safely applied to the actual working conditions, the method further includes the following steps after step (3):

[0096] (4) Calculate the safety factor according to the following formula (II):

[0097] Safety factor = safety stress value ÷ set stress value, Equation (II).

[0098] It should be noted that the MS adhesive with a larger safety factor calculated according to the above formula (II) has higher safety when applied to the actual working conditions. The MS adhesive can be used more safely in actual working conditions. Therefore, MS adhesive with a larger safety factor is preferred.

[0099] Preferred embodiments of the method according to the present invention:

[0100] When 1 ≤ safety factor < 10, MS adhesive has a level 1 safety factor when applied to the actual working conditions.

[0101] When 10 ≤ safety factor < 20, MS adhesive has a level 2 safety factor when applied to the actual working conditions.

[0102] When 20 ≤ safety factor < 30, MS adhesive has a three-level safety factor when applied to the actual working conditions.

[0103] It should be noted that in actual working conditions, safety markings can be placed near the MS adhesive application environment. For example, marking the MS adhesive fatigue resistance performance assessment level three safety factor around the MS adhesive on the car window can facilitate inspection.

[0104] Preferred embodiments of the method according to the present invention:

[0105] When 30 ≤ safety factor < 40, MS adhesive has a safety factor of level four when applied to the actual working conditions.

[0106] When 40 ≤ safety factor < 50, MS adhesive has a safety factor of five when applied to the actual working conditions.

[0107] It should be noted that the safety level gradually increases from Level 1, Level 2, ... up to Level 5. In addition, when the safety level is between 50 and 100, it can be defined as the super safety level, etc.

[0108] The present invention will be further described in detail below through examples, but this does not limit the present invention. Unless otherwise specified, all reagents and other materials used in the following examples can be commercially available finished products.

[0109] Five MS adhesives: Sample 1, Sample 2, and Sample 3 are MF1502, MF1506F, and MF1506 from Zhengzhou Zhongyuan Silande High-Tech Co., Ltd., respectively; Competitor 1 and Competitor 2 are 7937D from a domestic manufacturer and 7008 from an imported company, respectively.

[0110] Example 1

[0111] (1) The shear strength of five MS adhesive samples, namely Sample 1, Sample 2, Sample 3, Competitor 1, and Competitor 2, was tested. Several shear specimens with a bonding thickness of 5 mm, a bonding length of 20 mm, and a bonding width of 25 mm were prepared for each of the five samples. The shear strength and elongation at maximum strength of the five sample shear specimens were tested at a tensile rate of 30 mm / min according to DIN 6701-3. The test results are shown in Table 1 above.

[0112] (2) Calculate the safe stress values ​​for the five samples when they have the ultimate fatigue life as follows:

[0113] The safe stress value of sample 1 = shear strength of sample 1 × 0.09 = 0.135 MPa;

[0114] The safe stress value of sample 2 = shear strength of sample 2 × 0.09 = 0.198 MPa;

[0115] The safe stress value of sample 3 = shear strength of sample 3 × 0.09 = 0.297 MPa;

[0116] The safe stress value of competitor 1 = shear strength of competitor 1 × 0.09 = 0.171 MPa;

[0117] The safe stress value of competitor product 2 = shear strength of competitor product 2 × 0.09 = 0.189 MPa.

[0118] (3) The above five MS adhesive samples were used in the working conditions of rail vehicles. The safe stress values ​​of the ultimate fatigue life of Sample 1, Sample 2, Sample 3, Competitor 1 and Competitor 2 in actual working conditions were 0.135MPa, 0.198MPa, 0.297MPa, 0.171MPa and 0.189MPa, respectively. By comparing the safe stress value of the ultimate fatigue life of each MS adhesive sample with the set stress value of the working condition and calculating the safety factor, it was determined whether the MS adhesive could meet the usage requirements of the working condition. If the design of a certain bonding part requires the use of MS adhesive, and its design stress value (set stress value) is 0.16MPa, when selecting from the above five adhesives, the safety factor of Sample 1 is <1 and it is not suitable for bonding of this part (the set stress value of this working condition is greater than the safe stress value of Sample 1). Therefore, there is a safety risk when Sample 1 is used in this working condition. The set stress value for this working condition is less than the safe stress value of the remaining four samples. Therefore, MS adhesives of the four samples other than sample 1 can be safely used in this working condition. However, among the remaining four samples, the safety factor of sample 3 calculated according to the above formula (II) is significantly higher than that of the other three samples. Therefore, when selecting adhesives, MS adhesive of sample 3 is preferred for this working condition.

[0119] Comparative Example 1

[0120] To determine whether the five samples in Example 1 are safe for use in the rail vehicle operating conditions described in Example 1, fatigue testing was conducted using SN curve simulation according to standard GB / T27595-2011. At a testing frequency of 10Hz, the time required for 1 million cycles was 27.8 hours (1.16 days), and for 10 million cycles, it was 11.6 days. A 2-ton fatigue testing machine consumes 1000 kWh of electricity per day. Each fitted curve requires at least 12 fatigue test samples, meaning that fitting each SN curve takes at least 30 days and consumes 30,000 kWh of electricity. Fatigue testing on the five samples and fitting the results showed that the fitting results were basically consistent with the results determined by the method in Example 1, indicating that the shear sample has permanent fatigue life when the stress value is approximately 0.09 times the shear strength. However, this method is time-consuming and consumes a lot of electricity, and the test data still needs analysis and processing.

[0121] As can be seen from the results of Example 1 and Comparative Example 1 above, the result of the determination based on the method of this application in Example 1 is basically consistent with the determination result made by SN curve simulation of fatigue test in Comparative Example 1. However, the determination method of Comparative Example 1 is time-consuming and consumes a lot of electricity.

[0122] In the description of this application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this application. They are only for the convenience of describing this application 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 limitations on this application.

[0123] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0124] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.

Claims

1. A method for determining the fatigue resistance of MS adhesive, characterized in that, The method includes the following steps: (1) Prepare shear samples of MS glue and test the shear strength of MS glue; (2) Determine the safe stress value for the permanent service life of the MS adhesive based on the shear strength obtained from step (1) and the following formula (Ⅰ). Safety stress value = shear strength × K1, Equation (Ⅰ); Where 0 < K1 ≤ 0.12; (3) Based on the set stress value under actual working conditions, the following judgment is made: When the set stress value is less than or equal to the safe stress value obtained from step (2), the MS adhesive can be safely applied to the actual working condition; When the set stress value is greater than the safe stress value obtained from step (2), there is a safety hazard when the MS adhesive is applied to the actual working condition.

2. The method according to claim 1, characterized in that, The shear strength of the MS adhesive is 1.0 MPa to 3.5 MPa.

3. The method according to claim 1, characterized in that, In step (1), when preparing the shear sample of MS adhesive and testing the shear strength of MS adhesive, the standard DIN 6701-3 shall be followed.

4. The method according to claim 3, characterized in that, When testing the shear strength of the MS adhesive, the bonding length of the shear sample is 12~22mm, the bonding width is 22~27mm, the bonding thickness is 3~6.5mm, and the tensile rate is 18~35mm / min.

5. The method according to claim 3, characterized in that, The shear strength of the MS adhesive is the average shear strength after 5 to 10 tests.

6. The method according to claim 1, characterized in that, The MS adhesive has a permanent service life: The MS adhesive shear sample had a fatigue number greater than or equal to 10. 7 .

7. The method according to claim 1 or 6, characterized in that, 0.08≤K1≤0.11。 8. The method according to claim 1, characterized in that, When the MS adhesive can be safely applied to the actual working conditions, the method further includes the following steps after step (3): (4) Calculate the safety factor according to the following formula (II): Safety factor = safety stress value ÷ set stress value, Equation (II).

9. The method according to claim 8, characterized in that: When 1 ≤ safety factor < 10, MS adhesive has a level 1 safety factor when applied to the actual working conditions. When 10 ≤ safety factor < 20, MS adhesive has a level 2 safety factor when applied to the actual working conditions. When 20 ≤ safety factor < 30, MS adhesive has a three-level safety factor when applied to the actual working conditions.

10. The method according to claim 9, characterized in that: When 30 ≤ safety factor < 40, MS adhesive has a safety factor of level four when applied to the actual working conditions. When 40 ≤ safety factor < 50, MS adhesive has a safety factor of five when applied to the actual working conditions.

11. The method according to claim 7, characterized in that, K1 is 0.09.

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