Tension testing system for structural adhesive

Abstract

The invention relates to the technical field of adhesives, in particular to a tensile test system for a structural adhesive, which is characterized in that a first sample group and a second sample group are prepared through a sample preparation unit; aiming at a plurality of sample subgroups in the sample group, standard tension test, dynamic tension test and cyclic tension test are respectively carried out through the standard test unit, the dynamic test unit and the cyclic test unit, and the data acquisition unit acquires test data in the tension test process in real time; in addition, the intelligent control unit controls the tension testing machine in the corresponding tension test through the standard tension increasing rate, the dynamic tension increasing rate and the circulating tension increasing rate; the intelligent control unit also controls the temperature of a test environment, and tension tests are carried out under different temperature conditions; the data analysis unit analyzes the tension test data to obtain a tension test result; the intelligent tension test system provided by the invention has high flexibility and adaptability, and can obtain a more accurate tension test result.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to a tensile testing system for structural adhesives. Background Art

[0002] Structural adhesives are an indispensable component in industrial applications and are widely used in aerospace, automotive manufacturing, construction engineering and other fields. Their main function is to connect various structural materials and withstand important mechanical loads. In order to ensure that structural adhesives meet safety and performance standards, they must pass rigorous tensile tests to verify their load-bearing capacity and durability.

[0003] There are related studies on the tensile test of structural adhesives in the prior art. For example, a Chinese patent with publication number CN115753594A provides a high-strength structural adhesive tensile test method and device based on multi-material analysis. First, the bonding method and the thickness of the bonding layer of the target material are determined, and the target material is bonded according to the bonding method to obtain the bonding material; the material elastic modulus of the bonding material is determined according to the material deformation degree index of the bonding material; then the material tensile capacity test is performed to obtain the material tensile strength, and the material yield strength of the bonding material is determined according to the material plasticity index; finally, the tensile performance of the high-strength structural adhesive is determined according to the material elastic modulus, the material tensile strength and the material yield strength using a preset finite element model.

[0004] However, the current tensile testing of structural adhesives mostly relies on traditional mechanical operations, and the setting and adjustment of test parameters and test equipment cannot flexibly adapt to structural adhesives with different properties, and therefore cannot improve the accuracy of the test.

[0005] In order to solve the above problems, a tensile testing system for structural adhesives is proposed. Summary of the invention

[0006] The purpose of the present invention is to provide a tensile test system for structural adhesives, comprising an initialization unit, a standard test unit, a dynamic test unit, a cyclic test unit, a data acquisition unit, an intelligent control unit and a data analysis unit; the initialization unit records sample data of the tensile test; the standard tensile test, the dynamic tensile test and the cyclic tensile test are respectively performed by the standard test unit, the dynamic test unit and the cyclic test unit; the data acquisition unit collects test data in real time during the tensile test; in addition, the intelligent control unit calculates the standard tensile increase rate, the dynamic tensile increase rate and the cyclic tensile increase rate to control the tensile testing machine in the corresponding tensile test; at the same time, the intelligent control unit also controls the test environment temperature and performs the tensile test under different temperature conditions; the data analysis unit analyzes the sample data and the test data to obtain the tensile test results; the present invention provides an intelligent tensile test system, which has high flexibility and adaptability and can obtain more accurate tensile test results.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A tensile testing system for structural adhesives, comprising:

[0009] A sample preparation unit, for preparing samples for tensile testing of structural adhesives, including a first sample group and a second sample group;

[0010] Standard test unit, which performs standard tensile test at a standard rate of increase of tensile force;

[0011] Dynamic test unit, which performs dynamic tensile test by dynamic tensile force increasing rate;

[0012] Cyclic test unit, which performs cyclic tensile tests at different tensile levels;

[0013] A data acquisition unit collects tension test data in real time, including standard test data, dynamic test data and cycle test data; the standard test data and dynamic test data include the real-time tension of the testing machine, the real-time relative displacement of the fixture and the real-time slope of the tension displacement curve; the cycle test data includes the real-time number of cycles at each tension level; the tension test data also includes the real-time ambient temperature;

[0014] An intelligent control unit comprises a standard control module, a dynamic control module and a cycle control module; wherein the standard control module controls the constant standard tension increase rate to perform the standard tension test; the dynamic control module calculates the dynamic tension increase rate in real time, controls the variable dynamic tension increase rate to perform the dynamic tension test; the cycle control module controls the corresponding cycle tension increase rate at different tension levels to perform the cycle tension test;

[0015] The data analysis unit analyzes the tensile test data to obtain tensile test results under different temperature conditions, including the tensile strength, fatigue life and tensile shear strength of the structural adhesive.

[0016] Preferably, the first sample group includes N1 first samples with the same parameters; the second sample group includes N2 second samples with the same parameters; the first sample group is divided into a first subgroup of first samples, a second subgroup of first samples and a third subgroup of first samples; the second sample group is divided into a first subgroup of second samples and a second subgroup of second samples; the first subgroup of first samples is used to perform the standard tensile test, the second subgroup of first samples is used to perform the dynamic tensile test, and the third subgroup of first samples is used to perform the cyclic tensile test to obtain tensile strength and fatigue life; the first subgroup of second samples is used to perform the standard tensile test and, and the second subgroup of second samples is used to perform the dynamic tensile test to obtain tensile shear strength.

[0017] Preferably, during the standard tensile test and the dynamic tensile test, the data acquisition unit records M tensile values ​​and M relative displacement values ​​per second to obtain a tensile value group and a relative displacement value group; the tensile value group and the relative displacement value group are filtered to remove noise, and the average values ​​are calculated as the real-time tensile force and the real-time relative displacement per second, respectively; the real-time slope is calculated according to the real-time tensile force and the real-time relative displacement to obtain the standard test data and the dynamic test data.

[0018] Preferably, the specific steps of the dynamic control module calculating the dynamic tension increase rate in real time include:

[0019] Setting an adjustment period of the dynamic tension increase rate;

[0020] Calculating the change rate of the dynamic test data within the adjustment period to obtain a first change rate, including a tension change rate, a relative displacement change rate, and a slope change rate;

[0021] Calculate a first adjustment factor for each adjustment period according to the first change rate;

[0022] Setting an adjustment threshold, comparing the first adjustment factor with the adjustment threshold, and calculating an adjustment coefficient;

[0023] The dynamic tension increase rate in the next adjustment period is calculated according to the adjustment coefficient.

[0024] Preferably, the adjustment threshold is set according to standard test data, and the specific steps include:

[0025] Analyze the standard test data in the entire standard tensile test process to obtain first time series data, including tensile time series data, relative displacement time series data and slope time series data;

[0026] Extracting data in the last adjustment period from the first time series data, and calculating a second change rate;

[0027] calculating a second adjustment factor according to the second change rate;

[0028] The adjustment threshold is set according to the second adjustment factor.

[0029] Preferably, when performing a dynamic tension test, the standard tension increase rate is used as the dynamic tension increase rate in the first adjustment period to calculate the dynamic tension increase rate in the second adjustment period.

[0030] Preferably, the specific steps of the cyclic tensile test include:

[0031] Set the maximum tension at each tension level;

[0032] Select a cyclic loading method and determine a tension ratio; the tension ratio is the ratio of the minimum tension to the maximum tension at each tension level;

[0033] Determining the minimum tension at each tension level according to the tension ratio;

[0034] At each tension level, the specimen is repeatedly loaded and unloaded until the specimen fails. The specific steps include:

[0035] S1. Stretch the sample through a testing machine;

[0036] S2. When the tensile force of the testing machine reaches the maximum tensile force at each tensile force level, the tensile force begins to be reduced;

[0037] S3. When the tensile force of the testing machine reaches the minimum tensile force at each tensile force level, a cycle ends;

[0038] S4. Repeat steps S1, S2 and S3 until the specimen fails.

[0039] Preferably, the maximum tension at each tension level is set according to the dynamic test data, and the specific steps include: analyzing the dynamic test data during the entire dynamic tension test process to extract the stress-strain curve of the sample; identifying the key change stages of the structural adhesive according to the stress-strain curve, including the elastic stage, yield stage and fracture stage of the sample; and setting the maximum tension at different tension levels according to the maximum stress of the key change stage.

[0040] Preferably, the cyclic tension increase rate at different tension levels is selected according to the dynamic test data and the dynamic tension increase rate, and the specific steps include: analyzing the dynamic test data in the entire dynamic tension test process to obtain second time series data; extracting tension time series data in the second time series data; analyzing the tension time series data, extracting the tension in the first second and the tension in the last second in each adjustment period, and obtaining the tension range; analyzing the tension range where the maximum tension at each tension level is located, and then determining the corresponding adjustment period; selecting the dynamic tension increase rate in the corresponding adjustment period as the cyclic tension increase rate at each tension level.

[0041] Preferably, the test environment temperature is adjusted by the intelligent control unit, and the standard tensile test, the dynamic tensile test and the cyclic tensile test are performed under different temperature conditions.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. A comprehensive structural adhesive tensile test system is proposed, integrating multiple functional units. Through real-time data acquisition, the system can accurately record key parameters such as tension and displacement, ensuring the accuracy and timeliness of the test data; the introduction of the intelligent control unit enables the system to automatically adjust the tension increase rate and test environment temperature according to different test requirements, greatly improving the accuracy and adaptability of the test; the data analysis unit can comprehensively analyze various test data and calculate the tensile strength, fatigue life and tensile shear strength of structural adhesives under different temperature conditions. The system can comprehensively evaluate the performance of structural adhesives and enhance the reliability and accuracy of test results.

[0044] 2. Dynamic tension increase rate adjustment method, by setting the adjustment cycle, real-time calculation of the change rate of key test data, and the introduction of adjustment factors and adjustment thresholds to dynamically adjust the tension increase rate; by analyzing the change rates of multiple test data, the system can fully consider the dynamic response of structural adhesives, thereby more accurately controlling the test process; in addition, by setting the adjustment threshold, the system can timely adjust the tension increase rate, which not only ensures the effectiveness of the test, but also reduces the risk of premature failure of the specimen; this method enhances the adaptability of the test system to the different characteristics of structural adhesives and improves the accuracy of the tension test results.

[0045] 3. The cyclic tensile test method first analyzes the stress-strain characteristics of the structural adhesive through standard tensile tests and dynamic tensile tests, and then sets the key parameters of the cyclic test based on these characteristics, including the maximum and minimum tensile forces at different tensile levels, and automatically selects the most suitable tensile increase rate for each tensile level based on the dynamic test data; this method achieves a precise match between the test parameters and the characteristics of the test object, ensuring that the test process can comprehensively and accurately evaluate the fatigue performance of the structural adhesive, and provides reliable data support for the performance testing of structural adhesives in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A schematic diagram of the structure of a tensile testing system for a structural adhesive provided by an embodiment of the present invention;

[0047] Figure 2 A schematic diagram of a first sample provided by an embodiment of the present invention;

[0048] Figure 3 A side view of a second sample provided by an embodiment of the present invention;

[0049] Figure 4 A top view of a second sample provided by an embodiment of the present invention;

[0050] In the figure: 1. first substrate plate; 2. second substrate plate; 3. glue coating area. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Structural adhesives play a key role in modern industry. For example, in the aerospace field, structural adhesives are widely used to connect aircraft fuselages, wings and internal structures, which need to withstand extreme temperature changes and continuous vibration stress; the automotive manufacturing industry uses structural adhesives to connect body panels and strengthen vehicle structures; in construction projects, structural adhesives are used for glass curtain wall installation, bridge component connection, etc. These applications require structural adhesives to have excellent performance. Accurate tensile test data can not only help accurately evaluate the performance of structural adhesives, but also promote technological innovation and sustainable development of related industries.

[0053] The present invention provides a tensile testing system for structural adhesives, which can accurately and comprehensively perform tensile testing on structural adhesives. The effectiveness of the present invention will be described below using two embodiments.

[0054] Embodiment 1

[0055] See also Figure 1 The present application embodiment provides a tensile testing system for a structural adhesive for a rigid material A, comprising:

[0056] A sample preparation unit, for preparing samples for tensile testing of structural adhesives, including a first sample group and a second sample group;

[0057] Standard test unit, which performs standard tensile test at a standard rate of increase of tensile force;

[0058] Dynamic test unit, which performs dynamic tensile test by dynamic tensile force increasing rate;

[0059] Cyclic test unit, which performs cyclic tensile tests at different tensile levels;

[0060] A data acquisition unit collects tension test data in real time, including standard test data, dynamic test data and cycle test data; the standard test data and dynamic test data include the real-time tension of the testing machine, the real-time relative displacement of the fixture and the real-time slope of the tension displacement curve; the cycle test data includes the real-time number of cycles at each tension level; the tension test data also includes the real-time ambient temperature;

[0061] An intelligent control unit comprises a standard control module, a dynamic control module and a cycle control module; wherein the standard control module controls the constant standard tension increase rate to perform the standard tension test; the dynamic control module calculates the dynamic tension increase rate in real time, controls the variable dynamic tension increase rate to perform the dynamic tension test; the cycle control module controls the corresponding cycle tension increase rate at different tension levels to perform the cycle tension test;

[0062] The data analysis unit analyzes the tensile test data to obtain tensile test results under different temperature conditions, including the tensile strength, fatigue life and tensile shear strength of the structural adhesive.

[0063] The embodiment of the present application provides a comprehensive structural adhesive tensile testing system, which comprehensively evaluates the performance of structural adhesives through three tensile testing methods: standard, dynamic and cyclic; the data acquisition unit collects test data in real time to ensure the accuracy and timeliness of the test data; the intelligent control unit adjusts the rate of increase of tension according to different test requirements to improve the accuracy and adaptability of the test; the data analysis unit comprehensively analyzes various test data, calculates the tensile shear strength, tensile strength and fatigue life of the structural adhesive under different temperature conditions, and provides a comprehensive basis for the evaluation of the structural adhesive; the initialization, testing, data acquisition, control and analysis functions are integrated into one system to improve the test efficiency and data consistency.

[0064] Further, the first specimen group includes N1 first specimens with the same parameters; the second specimen group includes N2 second specimens with the same parameters; the first specimen group is divided into a first subgroup of first specimens, a second subgroup of first specimens and a third subgroup of first specimens; the second specimen group is divided into a first subgroup of second specimens and a second subgroup of second specimens; the first subgroup of first specimens is used to perform the standard tensile test, the second subgroup of first specimens is used to perform the dynamic tensile test, and the third subgroup of first specimens is used to perform the cyclic tensile test to obtain tensile strength and fatigue life; the first subgroup of second specimens is used to perform the standard tensile test and, and the second subgroup of second specimens is used to perform the dynamic tensile test to obtain tensile shear strength.

[0065] In the present embodiment, the first sample is a colloid sample, see Figure 2 ; The second specimen is a single lap specimen, see Figure 3 and Figure 4, showing the side view and top view of the single lap specimen respectively; the colloid specimen is made by pouring liquid structural adhesive into a mold and curing it; the single lap specimen is made by making a type A rigid material into a first substrate plate 1 and a second substrate plate 2 of the same size, overlapping and bonding one end portion of the two substrate plates, and then curing it, and it is necessary to ensure that the coating area and coating thickness of the coating area 3 of each single lap specimen are the same; when the colloid specimen is subjected to a tensile test, the standard tensile increase rate is set to 25N / s; when the single lap specimen is subjected to a tensile test, the standard tensile increase rate is set to 40N / s; some data of the standard tensile test and dynamic tensile test results of the structural adhesive for type A rigid material under different temperature conditions are shown in Table 1.

[0066] Table 1 Results of standard tensile test and dynamic tensile test under different temperature conditions

[0067] Temperature / ℃ Tensile shear strength / MPa Tensile strength / MPa 10 4.29 28.65 20 5.65 34.72 30 6.91 38.58 40 3.87 19.36

[0068] By using different types of specimens for specific tests, different performance indicators of structural adhesives can be evaluated more accurately. The consistency of specimen preparation methods and specimen parameters ensures the repeatability and comparability of test results.

[0069] Furthermore, during the standard tensile test and the dynamic tensile test, the data acquisition unit records M tensile values ​​and M relative displacement values ​​per second to obtain a tensile value group and a relative displacement value group; the tensile value group and the relative displacement value group are filtered to remove noise, and the average values ​​are calculated as the real-time tensile force and the real-time relative displacement per second respectively; the real-time slope is calculated according to the real-time tensile force and the real-time relative displacement to obtain the standard test data and the dynamic test data; the formula for calculating the real-time slope is:

[0070]

[0071] Among them, F i (t), s i (t) and k i (t) represent the tension of the testing machine at the tth second in the ith adjustment cycle, the relative displacement of the fixture and the slope of the tension-displacement curve.

[0072] By filtering to remove noise, the accuracy and reliability of the data are improved, and the average value is calculated as the test data at the current time point to reduce data redundancy and facilitate subsequent analysis.

[0073] Furthermore, the specific steps of the dynamic control module calculating the dynamic tension increase rate in real time include:

[0074] Setting an adjustment period of the dynamic tension increase rate;

[0075] The change rate of the dynamic test data within the adjustment period is calculated to obtain a first change rate, including a tension change rate, a relative displacement change rate and a slope change rate, and the calculation formula is:

[0076]

[0077] Among them, F i (t last ),s i (t last ) and k i (t last ) represent the tension, relative displacement and slope in the last second of the i-th adjustment cycle respectively; F i (1)s i (1) and k i (1) respectively represent the tension, relative displacement and slope in the first second of the i-th adjustment cycle; ΔF i , Δs i and Δk i They represent the tension change rate, relative displacement change rate and slope change rate of the i-th adjustment cycle respectively;

[0078] The first adjustment factor of each adjustment period is calculated according to the first change rate, and the calculation formula is:

[0079] R i =w1*|ΔF i |+w2*|Δs i |+w3*|Δk i |;

[0080] Among them, R i represents the first adjustment factor of the ith adjustment period; w1, w2 and w3 represent weight coefficients, which need to be determined through experiments;

[0081] Setting the adjustment threshold Comparing the first adjustment factor with the adjustment threshold and calculating an adjustment coefficient includes:

[0082] If R i Less than The adjustment coefficient calculation formula is:

[0083]

[0084] If R i Not less than The adjustment coefficient calculation formula is:

[0085]

[0086] Among them, β and γ represent weight coefficients, which need to be determined through experiments;

[0087] The dynamic tension increase rate in the next adjustment period is calculated according to the adjustment coefficient, and the calculation formula is:

[0088]

[0089] in, It represents the rate of increase of dynamic tension in the i-th adjustment cycle.

[0090] By real-time calculation and adjustment of the dynamic tension increase rate, the test process can adapt to the dynamic changes in the performance of structural adhesives; according to the change rates of multiple parameters, the response characteristics of structural adhesives are fully considered; by setting adjustment thresholds and adjustment factors, intelligent tension increase rate adjustment is achieved to improve test accuracy; by setting weight coefficients, the influence of each parameter can be adjusted according to the characteristics of different materials.

[0091] Furthermore, the adjustment threshold is set according to standard test data, and the specific steps include:

[0092] Analyze the standard test data in the entire standard tensile test process to obtain first time series data, including tensile time series data, relative displacement time series data and slope time series data;

[0093] Extracting data in the last adjustment period from the first time series data, and calculating a second change rate;

[0094] calculating a second adjustment factor according to the second change rate;

[0095] The adjustment threshold is set according to the second adjustment factor. In the embodiment of the present application, 80% of the fracture factor is selected as the adjustment threshold.

[0096] The accuracy of the dynamic test process is improved by setting the adjustment thresholds by analyzing the standard test data; setting the thresholds according to the actual performance of each specimen enables the tensile test system to adapt to different batches or types of structural adhesives.

[0097] Furthermore, when performing the dynamic tension test, the standard tension increase rate is used as the dynamic tension increase rate in the first adjustment period to calculate the dynamic tension increase rate in the second adjustment period.

[0098] Correlating the standard tensile test with the dynamic tensile test parameters ensures continuity and consistency throughout the test process and provides a stable reference point for subsequent adjustments to the dynamic tensile increase rate.

[0099] Furthermore, the specific steps of the cyclic tensile test include:

[0100] Set the maximum tension at each tension level;

[0101] Select a cyclic loading method and determine a tension ratio; the tension ratio is the ratio of the minimum tension to the maximum tension at each tension level;

[0102] Determining the minimum tension at each tension level according to the tension ratio;

[0103] At each tension level, the specimen is repeatedly loaded and unloaded until the specimen fails. The specific steps include:

[0104] S1. Stretch the sample through a testing machine;

[0105] S2. When the tensile force of the testing machine reaches the maximum tensile force at each tensile force level, the tensile force begins to be reduced;

[0106] S3. When the tensile force of the testing machine reaches the minimum tensile force at each tensile force level, a cycle ends;

[0107] S4. Repeat steps S1, S2 and S3 until the specimen fails.

[0108] The cyclic loading methods include stretch-compression loading, stretch-stretch loading and stretch-only loading. The embodiment of the present application selects the stretch-only loading method, and the tension ratio is 0, that is, the minimum tension is 0; the tension ratio of the stretch-compression loading method is -1, that is, when the tension of the testing machine is reduced to 0, the sample is compressed until the pressure is equal to the maximum tension to end a cycle; the tension ratio of the stretch-stretch loading method is a decimal between 0 and 1, that is, a cycle is ended before the tension of the testing machine is reduced to 0.

[0109] In the implementation of this application, when the cyclic tensile test is performed under different temperature conditions, the maximum tensile force at each tensile level is different, as shown in Table 2 for details.

[0110] Table 2 Maximum tensile force at each tensile force level under different temperature conditions

[0111]

[0112] By setting different tension levels, the fatigue performance of structural adhesives can be comprehensively evaluated. By recording the number of cycles before the specimen fails, reliable data is provided for fatigue life prediction of structural adhesives. Cyclic testing under different temperature conditions helps to evaluate the long-term performance of structural adhesives in various environments.

[0113] Furthermore, the maximum tension at each tension level is set according to the dynamic test data, and the specific steps include: analyzing the dynamic test data during the entire dynamic tension test process to extract the stress-strain curve of the sample; identifying the key change stages of the structural adhesive according to the stress-strain curve, including the elastic stage, yield stage and fracture stage of the sample; and setting the maximum tension at different tension levels according to the maximum stress of the key change stage.

[0114] By analyzing the dynamic test data and setting the maximum tensile force at different tensile levels, it can be ensured that the test covers all key stages of the structural adhesive, making the subsequent cyclic tensile test more targeted.

[0115] Furthermore, the cyclic tension increase rate under different tension levels is selected according to the dynamic test data and the dynamic tension increase rate, and the specific steps include: analyzing the dynamic test data in the entire dynamic tension test process to obtain second time series data; extracting tension time series data in the second time series data; analyzing the tension time series data, extracting the tension in the first second and the tension in the last second in each adjustment period, and obtaining the tension range; analyzing the tension range where the maximum tension under each tension level is located, and then determining the corresponding adjustment period; selecting the dynamic tension increase rate in the corresponding adjustment period as the cyclic tension increase rate under each tension level.

[0116] By automatically selecting the most suitable tension increase rate for each tension level, the error that may be caused by manual setting is reduced. At the same time, reusing the data of dynamic tests reduces the time and resources required for cyclic test parameter setting.

[0117] Furthermore, the test environment temperature is adjusted by the intelligent control unit, and the standard tensile test, the dynamic tensile test and the cyclic tensile test are performed under different temperature conditions.

[0118] By testing under various temperature conditions, the performance of structural adhesives in various environments can be comprehensively evaluated, which improves the reliability of the test results and their practical application value.

[0119] Embodiment 2

[0120] The embodiment of the present application provides a tensile testing system for a structural adhesive for a type B rigid material, including:

[0121] A sample preparation unit, for preparing samples for tensile testing of structural adhesives, including a first sample group and a second sample group;

[0122] Standard test unit, which performs standard tensile test at a standard rate of increase of tensile force;

[0123] Dynamic test unit, which performs dynamic tensile test by dynamic tensile force increasing rate;

[0124] Cyclic test unit, which performs cyclic tensile tests at different tensile levels;

[0125] A data acquisition unit collects tension test data in real time, including standard test data, dynamic test data and cycle test data; the standard test data and dynamic test data include the real-time tension of the testing machine, the real-time relative displacement of the fixture and the real-time slope of the tension displacement curve; the cycle test data includes the real-time number of cycles at each tension level; the tension test data also includes the real-time ambient temperature;

[0126] An intelligent control unit comprises a standard control module, a dynamic control module and a cycle control module; wherein the standard control module controls the constant standard tension increase rate to perform the standard tension test; the dynamic control module calculates the dynamic tension increase rate in real time, controls the variable dynamic tension increase rate to perform the dynamic tension test; the cycle control module controls the corresponding cycle tension increase rate at different tension levels to perform the cycle tension test;

[0127] The data analysis unit analyzes the tensile test data to obtain tensile test results under different temperature conditions, including the tensile strength, fatigue life and tensile shear strength of the structural adhesive.

[0128] Further, the first specimen group includes N1 first specimens with the same parameters; the second specimen group includes N2 second specimens with the same parameters; the first specimen group is divided into a first subgroup of first specimens, a second subgroup of first specimens and a third subgroup of first specimens; the second specimen group is divided into a first subgroup of second specimens and a second subgroup of second specimens; the first subgroup of first specimens is used to perform the standard tensile test, the second subgroup of first specimens is used to perform the dynamic tensile test, and the third subgroup of first specimens is used to perform the cyclic tensile test to obtain tensile strength and fatigue life; the first subgroup of second specimens is used to perform the standard tensile test and, and the second subgroup of second specimens is used to perform the dynamic tensile test to obtain tensile shear strength.

[0129] In the embodiment of the present application, the first sample is a colloid sample; the second sample is a single lap sample; the colloid sample is made by pouring a liquid structural adhesive into a mold and curing it; the single lap sample is made by making a type B rigid material into a first substrate plate and a second substrate plate of the same size, overlapping and bonding one end portion of the two substrate plates, and then curing it, and it is necessary to ensure that the coating area and coating thickness of each single lap sample are the same; when the colloid sample is subjected to a tensile test, the standard tensile increase rate is set to 25N / s; when the single lap sample is subjected to a tensile test, the standard tensile increase rate is set to 40N / s; some data of the standard tensile test and dynamic tensile test results of the structural adhesive for type B rigid material under different temperature conditions are shown in Table 3.

[0130] Table 3 Results of standard tensile test and dynamic tensile test under different temperature conditions

[0131]

[0132] Furthermore, during the standard tensile test and the dynamic tensile test, the data acquisition unit records M tensile values ​​and M relative displacement values ​​per second to obtain a tensile value group and a relative displacement value group; the tensile value group and the relative displacement value group are filtered to remove noise, and the average values ​​are calculated as the real-time tensile force and the real-time relative displacement per second respectively; the real-time slope is calculated according to the real-time tensile force and the real-time relative displacement to obtain the standard test data and the dynamic test data; the formula for calculating the real-time slope is:

[0133]

[0134] Among them, F i (t), s i (t) and k i (t) represent the tension of the testing machine at the tth second in the ith adjustment cycle, the relative displacement of the fixture and the slope of the tension-displacement curve.

[0135] Furthermore, the specific steps of the dynamic control module calculating the dynamic tension increase rate in real time include:

[0136] Setting an adjustment period of the dynamic tension increase rate;

[0137] The change rate of the dynamic test data within the adjustment period is calculated to obtain a first change rate, including a tension change rate, a relative displacement change rate and a slope change rate, and the calculation formula is:

[0138]

[0139] Among them, F i (tlast ),s i (t last ) and k i (t last ) represent the tension, relative displacement and slope in the last second of the i-th adjustment cycle respectively; F i (1)s i (1) and k i (1) respectively represent the tension, relative displacement and slope in the first second of the i-th adjustment cycle; ΔF i , Δs i and Δk i They represent the tension change rate, relative displacement change rate and slope change rate of the i-th adjustment cycle respectively;

[0140] The first adjustment factor of each adjustment period is calculated according to the first change rate, and the calculation formula is:

[0141] R i =w1*|ΔF i |+w2*|Δs i |+w3*|Δk i |;

[0142] Among them, R i represents the first adjustment factor of the ith adjustment period; w1, w2 and w3 represent weight coefficients, which need to be determined through experiments;

[0143] Setting the adjustment threshold Comparing the first adjustment factor with the adjustment threshold and calculating an adjustment coefficient includes:

[0144] If R i Less than The adjustment coefficient calculation formula is:

[0145]

[0146] If R i Not less than The adjustment coefficient calculation formula is:

[0147]

[0148] Among them, β and γ represent weight coefficients, which need to be determined through experiments;

[0149] The dynamic tension increase rate in the next adjustment period is calculated according to the adjustment coefficient, and the calculation formula is:

[0150]

[0151] Among them, v if It represents the rate of increase of dynamic tension in the i-th adjustment cycle.

[0152] Furthermore, the adjustment threshold is set according to standard test data, and the specific steps include:

[0153] Analyze the standard test data in the entire standard tensile test process to obtain first time series data, including tensile time series data, relative displacement time series data and slope time series data;

[0154] Extracting data in the last adjustment period from the first time series data, and calculating a second change rate;

[0155] calculating a second adjustment factor according to the second change rate;

[0156] The adjustment threshold is set according to the second adjustment factor. In the embodiment of the present application, 80% of the fracture factor is selected as the adjustment threshold.

[0157] Furthermore, when performing the dynamic tension test, the standard tension increase rate is used as the dynamic tension increase rate in the first adjustment period to calculate the dynamic tension increase rate in the second adjustment period.

[0158] Furthermore, the specific steps of the cyclic tensile test include:

[0159] Set the maximum tension at each tension level;

[0160] Select a cyclic loading method and determine a tension ratio; the tension ratio is the ratio of the minimum tension to the maximum tension at each tension level;

[0161] Determining the minimum tension at each tension level according to the tension ratio;

[0162] At each tension level, the specimen is repeatedly loaded and unloaded until the specimen fails. The specific steps include:

[0163] S1. Stretch the sample through a testing machine;

[0164] S2. When the tensile force of the testing machine reaches the maximum tensile force at each tensile force level, the tensile force begins to be reduced;

[0165] S3. When the tensile force of the testing machine reaches the minimum tensile force at each tensile force level, a cycle ends;

[0166] S4. Repeat steps S1, S2 and S3 until the specimen fails.

[0167] The cyclic loading methods include stretch-compression loading, stretch-stretch loading and stretch-only loading. The embodiment of the present application selects the stretch-only loading method, and the tension ratio is 0, that is, the minimum tension is 0; the tension ratio of the stretch-compression loading method is -1, that is, when the tension of the testing machine is reduced to 0, the sample is compressed until the pressure is equal to the maximum tension to end a cycle; the tension ratio of the stretch-stretch loading method is a decimal between 0 and 1, that is, a cycle is ended before the tension of the testing machine is reduced to 0.

[0168] In the implementation of this application, when the cyclic tensile test is performed under different temperature conditions, the maximum tensile force at each tensile level is different, as shown in Table 4 for details.

[0169] Table 4 Maximum tensile force at each tensile force level under different temperature conditions

[0170]

[0171] Furthermore, the maximum tension at each tension level is set according to the dynamic test data, and the specific steps include: analyzing the dynamic test data during the entire dynamic tension test process to extract the stress-strain curve of the sample; identifying the key change stages of the structural adhesive according to the stress-strain curve, including the elastic stage, yield stage and fracture stage of the sample; and setting the maximum tension at different tension levels according to the maximum stress of the key change stage.

[0172] Furthermore, the cyclic tension increase rate under different tension levels is selected according to the dynamic test data and the dynamic tension increase rate, and the specific steps include: analyzing the dynamic test data in the entire dynamic tension test process to obtain second time series data; extracting tension time series data in the second time series data; analyzing the tension time series data, extracting the tension in the first second and the tension in the last second in each adjustment period, and obtaining the tension range; analyzing the tension range where the maximum tension under each tension level is located, and then determining the corresponding adjustment period; selecting the dynamic tension increase rate in the corresponding adjustment period as the cyclic tension increase rate under each tension level.

[0173] Furthermore, the test environment temperature is adjusted by the intelligent control unit, and the standard tensile test, the dynamic tensile test and the cyclic tensile test are performed under different temperature conditions.

[0174] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A tensile testing system for structural adhesives, characterized in that: include: A sample preparation unit, for preparing samples for tensile testing of structural adhesives, including a first sample group and a second sample group; Standard test unit, which performs standard tensile test at a standard rate of increase of tensile force; Dynamic test unit, which performs dynamic tensile test by dynamic tensile force increasing rate; Cyclic test unit, which performs cyclic tensile tests at different tensile levels; A data acquisition unit collects tension test data in real time, including standard test data, dynamic test data and cycle test data; the standard test data and dynamic test data include the real-time tension of the testing machine, the real-time relative displacement of the fixture and the real-time slope of the tension displacement curve; the cycle test data includes the real-time number of cycles at each tension level; the tension test data also includes the real-time ambient temperature; An intelligent control unit comprises a standard control module, a dynamic control module and a cycle control module; wherein the standard control module controls the constant standard tension increase rate to perform the standard tension test; the dynamic control module calculates the dynamic tension increase rate in real time, controls the variable dynamic tension increase rate to perform the dynamic tension test; the cycle control module controls the corresponding cycle tension increase rate at different tension levels to perform the cycle tension test; The data analysis unit analyzes the tensile test data to obtain tensile test results under different temperature conditions, including the tensile strength, fatigue life and tensile shear strength of the structural adhesive.

2. A tensile testing system for structural adhesives according to claim 1, characterized in that: The first sample group includes N1 first samples with the same parameters; the second sample group includes N2 second samples with the same parameters; the first sample group is divided into a first subgroup of first samples, a second subgroup of first samples and a third subgroup of first samples; the second sample group is divided into a first subgroup of second samples and a second subgroup of second samples; the first subgroup of first samples is used to perform the standard tensile test, the second subgroup of first samples is used to perform the dynamic tensile test, and the third subgroup of first samples is used to perform the cyclic tensile test to obtain the tensile strength and fatigue life; the first subgroup of second samples is used to perform the standard tensile test and, and the second subgroup of second samples is used to perform the dynamic tensile test to obtain the tensile shear strength.

3. A tensile testing system for structural adhesives according to claim 1, characterized in that: During the standard tensile test and the dynamic tensile test, the data acquisition unit records M tensile values ​​and M relative displacement values ​​per second to obtain a tensile value group and a relative displacement value group; The tension value group and the relative displacement value group are filtered to remove noise, and average values ​​are calculated as the real-time tension and the real-time relative displacement per second respectively; the real-time slope is calculated according to the real-time tension and the real-time relative displacement to obtain the standard test data and the dynamic test data.

4. A tensile testing system for structural adhesives according to claim 1, characterized in that: The specific steps of the dynamic control module calculating the dynamic tension increase rate in real time include: Setting an adjustment period of the dynamic tension increase rate; Calculating the change rate of the dynamic test data within the adjustment period to obtain a first change rate, including a tension change rate, a relative displacement change rate, and a slope change rate; Calculate a first adjustment factor for each adjustment period according to the first change rate; Setting an adjustment threshold, comparing the first adjustment factor with the adjustment threshold, and calculating an adjustment coefficient; The dynamic tension increase rate in the next adjustment period is calculated according to the adjustment coefficient.

5. A tensile testing system for structural adhesives according to claim 4, characterized in that: The adjustment threshold is set according to standard test data, and the specific steps include: Analyze the standard test data in the entire standard tensile test process to obtain first time series data, including tensile time series data, relative displacement time series data and slope time series data; Extracting data in the last adjustment period from the first time series data, and calculating a second change rate; calculating a second adjustment factor according to the second change rate; The adjustment threshold is set according to the second adjustment factor.

6. A tensile testing system for structural adhesives according to claim 4, characterized in that: When performing the dynamic tension test, the standard tension increase rate is used as the dynamic tension increase rate in the first adjustment period to calculate the dynamic tension increase rate in the second adjustment period.

7. A tensile testing system for structural adhesives according to claim 1, characterized in that: The specific steps of cyclic tensile testing include: Set the maximum tension at each tension level; Select a cyclic loading method and determine a tension ratio; the tension ratio is the ratio of the minimum tension to the maximum tension at each tension level; Determining the minimum tension at each tension level according to the tension ratio; At each tension level, the specimen is repeatedly loaded and unloaded until the specimen fails. The specific steps include: S1. Stretch the sample through a testing machine; S2. When the tensile force of the testing machine reaches the maximum tensile force at each tensile force level, the tensile force begins to be reduced; S3. When the tensile force of the testing machine reaches the minimum tensile force at each tensile force level, a cycle ends; S4. Repeat steps S1, S2 and S3 until the specimen fails.

8. A tensile testing system for structural adhesives according to claim 7, characterized in that: The maximum tension at each tension level is set according to the dynamic test data. The specific steps include: analyzing the dynamic test data during the entire dynamic tension test process to extract the stress-strain curve of the sample; identifying the key change stages of the structural adhesive according to the stress-strain curve, including the elastic stage, yield stage and fracture stage of the sample; and setting the maximum tension at different tension levels according to the maximum stress of the key change stage.

9. A tensile testing system for structural adhesives according to claim 1, characterized in that: The cyclic tension increase rate under different tension levels is selected according to the dynamic test data and the dynamic tension increase rate, and the specific steps include: analyzing the dynamic test data in the entire dynamic tension test process to obtain second time series data; extracting tension time series data in the second time series data; analyzing the tension time series data, extracting the tension in the first second and the tension in the last second in each adjustment period, and obtaining the tension range; analyzing the tension range where the maximum tension under each tension level is located, and then determining the corresponding adjustment period; selecting the dynamic tension increase rate in the corresponding adjustment period as the cyclic tension increase rate under each tension level.

10. A tensile testing system for structural adhesives according to claim 1, characterized in that: The test environment temperature is adjusted by the intelligent control unit, and the standard tensile test, the dynamic tensile test and the cyclic tensile test are performed under different temperature conditions.

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