Strain rate sensitive foam material dynamic-static bearing force ratio test method and dynamic bearing force tester

Abstract

This invention provides a method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials and a dynamic bearing capacity tester. The method includes: conducting a quasi-static bearing capacity test on the strain rate-sensitive foam material, with the counting formula for the quasi-static bearing capacity being: ; conducting a dynamic bearing capacity test on the strain rate-sensitive foam material, calculating the impact bearing capacity of the material according to the following formula: Impact bearing capacity (MPa) = Maximum impact force N / (Sample area MM2 × strain), and taking the average value of the impact bearing capacity values ​​of three samples as the dynamic bearing capacity value of the sample in MPa; calculating the dynamic-to-static bearing capacity ratio: Dynamic-to-static bearing capacity ratio = Dynamic bearing capacity / Quasi-static bearing capacity; by introducing calculation formulas for calculating the quasi-static bearing capacity and dynamic bearing capacity of strain rate-sensitive foam materials, the static and dynamic parameter performance of the tested strain rate-sensitive foam material can be accurately calculated using the above calculation formulas, providing accurate and reliable parameters for the use of strain rate-sensitive foam materials.

Description

Technical Field

[0001] This invention relates to the field of strain rate-sensitive foam material testing technology, specifically to a strain rate-sensitive method for testing the dynamic-to-static bearing capacity ratio of foam materials and a dynamic bearing capacity tester. Background Technology

[0002] Strain rate sensitive foam materials are those whose stress-strain response is not constant; it changes significantly with the rate of external stretching (or compression), such as polymers (e.g., plastics, rubber) and asphalt.

[0003] To understand the performance of strain rate-sensitive foam materials, static and dynamic tests are required. Static tests (such as tensile tests at constant and slow speeds) can only obtain data points at a single speed, which cannot fully describe the complex behavior of the material under different service conditions. Dynamic tests, on the other hand, obtain data at different speeds by changing the load applied to the material, thus simulating various working conditions in the real world.

[0004] In existing technologies, the dynamic and static load-bearing capacity ratio test of strain rate-sensitive foam materials introduces different systematic errors and assumptions due to the different test methods and principles used, resulting in certain deviations in the accuracy and reliability of the test data obtained after the test. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an accurate and reliable method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials, as well as a dynamic bearing capacity tester.

[0006] To achieve the above objectives, the following technical solution is adopted: Firstly, this application provides a method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials, wherein the method for testing the dynamic-to-static bearing capacity ratio is as follows: For strain rate-sensitive foam materials undergoing quasi-static bearing capacity testing, the counting formula for quasi-static bearing capacity is as follows: , where F is the force that the specimen withstands when it generates compressive strain, in Newtons; A is the cross-sectional area of ​​the specimen facing the indenter, in square millimeters; ϵ is the compressive strain; E is the compressive bearing capacity, in MPa; For strain rate sensitive foam materials, dynamic bearing capacity tests are conducted, and the impact bearing capacity of the material is calculated according to the following formula: Impact bearing capacity (MPa) = Maximum impact force N / (sample area MM2 × strain). The average value of the impact bearing capacity of three samples is taken as the dynamic bearing capacity value of the sample in MPa. Calculation of dynamic and static bearing capacity ratio: Dynamic bearing capacity ratio = Dynamic bearing capacity / Quasi-static bearing capacity.

[0007] Furthermore, the dynamic load-bearing capacity test of strain rate-sensitive foam materials includes the following steps: S1. Sample pre-clamping; S2. Adjust the tester according to the set parameters; S3. Each specimen is impacted only once, and the number of specimens for normal testing is at least three. S4. Three standard specimens, one side of each impact compression specimen, and read the maximum force value.

[0008] Furthermore, in step S3 above, during the process of adjusting the impact speed of the sample in the impact test, one sample can be used first. If the standard speed is not reached after adjusting more than two samples, wait 45 minutes before testing again.

[0009] Furthermore, in step S1 above, the sample adopts a cylindrical shape and is pre-compressed to a set strain and held for more than 5 minutes using a double-sided clamp.

[0010] Furthermore, the test procedure for quasi-static load-bearing capacity testing of strain rate-sensitive foam materials is as follows: A1. Place the sample directly under the indenter; A2. Compress the specimen until the required strain position is reached, record the force value at this point, and calculate the quasi-static bearing capacity according to the counting formula for quasi-static bearing capacity.

[0011] Furthermore, in step A2 above, the sample is compressed at a speed of 0.6 mm / min.

[0012] Secondly, this application also provides a dynamic bearing capacity tester for implementing the dynamic bearing capacity test in the strain rate sensitive dynamic-static bearing capacity ratio test method for foam materials as described in claim 1 above. The dynamic bearing capacity tester includes a support base, an upper cover plate, a lower cover plate, and an impact head. The lower cover plate is horizontally fixedly installed at the top of the support base. A lower sensor for collecting the magnitude of the impact load borne by the support base is installed on the support base. The upper cover plate is horizontally positioned above the lower cover plate. A locking screw is provided between the outer edges of the upper cover plate and the lower cover plate. A space for horizontally placing a sample is formed between the upper cover plate and the lower cover plate. The impact head is positioned above the upper cover plate. An upper sensor for collecting the magnitude of the force on the impact head is provided on the impact head.

[0013] Furthermore, the upper sensor is a strain gauge sensor, and the lower sensor is a piezoelectric sensor.

[0014] Compared with existing technologies, the beneficial technical effects of this solution are as follows: By introducing calculation formulas for the quasi-static bearing capacity and dynamic bearing capacity of strain rate-sensitive foam materials, respectively, the static and dynamic parameter performance of the tested strain rate-sensitive foam materials can be accurately calculated using the above-mentioned calculation formulas, providing accurate and reliable parameters for the use of strain rate-sensitive foam materials. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the test procedure for dynamic load-bearing capacity testing of strain rate-sensitive foam materials in the embodiments of this application.

[0016] Figure 2 This is a schematic diagram of the test procedure for conducting quasi-static bearing capacity tests on the strain rate-sensitive foam material in the embodiments of this application.

[0017] Figure 3 This is a schematic diagram of the dynamic bearing capacity tester in the embodiments of this application.

[0018] In the picture: 100-Dynamic Load Capacity Tester; 200-sample; 10-Support base; 20-lower sensor; 30 - Lower cover plate; 40 - Top cover plate; 50 - Locking screw; 60-Impact head. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] This embodiment provides a method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials. The method for testing the dynamic-to-static bearing capacity ratio is as follows: For strain rate-sensitive foam materials undergoing quasi-static bearing capacity testing, the counting formula for quasi-static bearing capacity is as follows: , where F is the force that the specimen withstands when it generates compressive strain, in Newtons; where parameter A is the cross-sectional area of ​​the specimen facing the indenter, in square millimeters; ϵ is the compressive strain; and E is the compressive bearing capacity, in MPa; For strain rate-sensitive foam materials, dynamic bearing capacity tests are conducted. The impact bearing capacity of the material is calculated according to the following formula: Impact bearing capacity (MPa) = Maximum impact force N / (sample area MM2 × strain). The average value of the impact bearing capacity of three samples is taken as the dynamic bearing capacity value of the sample in MPa. The dynamic-static bearing capacity ratio is calculated as follows: Dynamic-static bearing capacity ratio = Dynamic bearing capacity / Quasi-static bearing capacity.

[0021] By introducing calculation formulas for the quasi-static bearing capacity and dynamic bearing capacity of strain rate-sensitive foam materials, respectively, the static and dynamic parameter performance of the tested strain rate-sensitive foam materials can be accurately calculated using the above-mentioned calculation formulas, providing accurate and reliable parameters for the use of strain rate-sensitive foam materials.

[0022] Reference Figure 1 In this embodiment, the dynamic load-bearing capacity test of strain rate-sensitive foam material includes the following steps: S1. Sample pre-clamping; The sample adopts a cylindrical shape and is pre-compressed to a set strain and held for more than 5 minutes using a double-sided clamp.

[0023] S2. Adjust the tester according to the set parameters; S3. Each specimen is impacted only once, and the number of specimens for normal testing is at least three. During the impact test, one sample can be used first to adjust the impact speed. If the standard speed is not reached after adjusting more than two samples, wait 45 minutes before testing again.

[0024] S4. Three standard specimens, one side of each impact compression specimen, and read the maximum force value.

[0025] Thus, according to the counting formula for impact bearing capacity, impact bearing capacity (MPa) = maximum impact force N / (sample area MM2 × strain), and taking the average value of the three sample values ​​in step S4 as the maximum impact force, and substituting it into the above calculation formula for impact bearing capacity, the dynamic bearing capacity value of the sample in MPa can be obtained.

[0026] Reference Figure 2 As shown, the test procedure for quasi-static load-bearing capacity testing of strain rate-sensitive foam materials is as follows: A1. Place the sample directly under the indenter; A2. Compress the specimen (compress the specimen at a speed of 0.6 mm / min) until the required strain position is reached, record the force value at this point, and calculate the quasi-static bearing capacity according to the counting formula of quasi-static bearing capacity counting.

[0027] When conducting dynamic-to-static bearing capacity ratio tests on strain rate-sensitive foam materials, the parameters of the testing instrument need to be set. The parameter settings for the testing instrument are shown in Table 1 and Table 2 below: Table 1 Table 2 Reference Figure 3 As shown, this embodiment also provides a dynamic bearing capacity tester 100 for implementing the dynamic bearing capacity test in the above-mentioned strain rate sensitive foam material dynamic-static bearing capacity ratio test method. The dynamic bearing capacity tester 100 includes a support base 10, an upper cover plate 40, a lower cover plate 30, and an impact head 60. The lower cover plate 30 is horizontally fixedly installed on the top of the support base 10. A lower sensor 20 for collecting the magnitude of the impact load borne by the support base 10 is installed on the support base 10. In some embodiments, the lower sensor 20 is a piezoelectric sensor. The upper cover plate 40 is horizontally positioned above the lower cover plate 30. A locking screw 50 is provided between the outer edges of the upper cover plate 40 and the lower cover plate 30. A receiving space for horizontally placing the sample is formed between the upper cover plate 40 and the lower cover plate 30. The impact head 60 is positioned above the upper cover plate 40. An upper sensor for collecting the magnitude of the force borne by the impact head 60 is provided on the impact head 60. The upper sensor can be a strain gauge sensor.

[0028] During the test, the vertical distance between the upper cover plate 40 and the lower cover plate 30 can be changed by adjusting the locking screw 50 to rotate forward or backward, thereby adjusting the pre-compression amount of the sample.

[0029] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials, characterized in that, The method for testing the ratio of dynamic to static bearing capacity is as follows: For strain rate-sensitive foam materials undergoing quasi-static bearing capacity testing, the counting formula for quasi-static bearing capacity is as follows: , where F is the force that the specimen withstands when it generates compressive strain, in Newtons; A is the cross-sectional area of ​​the specimen facing the indenter, in square millimeters; ϵ is the compressive strain; E is the compressive bearing capacity, in MPa; For strain rate-sensitive foam materials undergoing dynamic load-bearing capacity testing, the impact load-bearing capacity is calculated using the following formula: Impact load-bearing capacity (MPa) = Maximum impact force (N) / (sample area (mm)) 2 × strain), and the average value of the impact bearing capacity of the three specimens is taken as the dynamic bearing capacity value of the specimen in MPa; Calculation of dynamic and static bearing capacity ratio: Dynamic bearing capacity ratio = Dynamic bearing capacity / Quasi-static bearing capacity.

2. The method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials according to claim 1, characterized in that, The dynamic load-bearing capacity test of strain rate-sensitive foam materials includes the following steps: S1. Sample pre-clamping; S2. Adjust the tester according to the set parameters; S3. Each specimen is impacted only once, and the number of specimens for normal testing is at least three. S4. Three standard specimens, each impact compression specimen on one side and read the maximum force value.

3. The method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials according to claim 2, characterized in that, In step S3 above, during the process of adjusting the impact speed of the sample in the impact test, one sample can be used first. If the standard speed is not reached after adjusting more than two samples, wait 45 minutes before testing again.

4. A method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials according to claim 2 or 3, characterized in that, In step S1 above, the sample adopts a cylindrical shape and is pre-compressed to a set strain and held for more than 5 minutes using a double-sided clamp.

5. The method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials according to claim 1, characterized in that, The test procedure for quasi-static load-bearing capacity testing of strain rate-sensitive foam materials is as follows: A1. Place the sample directly under the indenter; A2. Compress the specimen until the required strain position is reached, record the force value at this point, and calculate the quasi-static bearing capacity according to the counting formula for quasi-static bearing capacity.

6. The method for testing the dynamic-to-static bearing capacity ratio of strain rate-sensitive foam materials according to claim 5, characterized in that, In step A2 above, the sample is compressed at a speed of 0.6 mm / min.

7. A dynamic bearing capacity testing instrument for performing the dynamic bearing capacity test in the strain rate-sensitive dynamic-static bearing capacity ratio test method for foam materials as described in claim 1, characterized in that, The dynamic load-bearing capacity tester includes a support base, an upper cover plate, a lower cover plate, and an impact head. The lower cover plate is horizontally fixed at the top of the support base. A lower sensor for collecting the magnitude of the impact load borne by the support base is installed on the support base. The upper cover plate is horizontally positioned above the lower cover plate. A locking screw is provided between the outer edges of the upper and lower cover plates. A space for horizontally placing the sample is formed between the upper and lower cover plates. The impact head is positioned above the upper cover plate, and an upper sensor for collecting the magnitude of the force applied to the impact head is provided on the impact head.

8. A dynamic bearing capacity testing instrument according to claim 7, characterized in that, The upper sensor is a strain gauge sensor, and the lower sensor is a piezoelectric sensor.

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