A material mechanics performance auxiliary testing device for liquid environment

Abstract

The application belongs to the technical field of material mechanical property testing equipment, and discloses a material mechanical property auxiliary testing device for liquid environment, which comprises an electric lifting platform fixed on a testing machine working platform, a bath on the top end of the electric lifting platform, and a concave-shaped beam composed of two curved cantilever beams, a gap is formed between the two curved cantilever beams for the bath to lift and avoid, the cross beam extends to the inside of the bath and is installed with a lower clamp, an upper clamp is connected with a force sensor through an extension rod, an industrial camera is placed in front of the sample, a telecentric lens is assembled, and is used for non-contact deformation measurement; a data acquisition card collects force signals, controls the lifting of the lifting platform, and cooperates with the testing machine through I / O triggering; and an upper computer is responsible for data processing and control. The lifting bath is used for realizing free switching of liquid and non-liquid environment, the video extensometer is combined to meet the small force value testing requirement of low-strength materials, and the application is suitable for long-term fatigue mechanical property testing.

Description

Technical Field

[0001] This invention belongs to the technical field of material mechanical property testing equipment, and in particular relates to an auxiliary testing device for material mechanical properties in a liquid environment. Background Technology

[0002] Electronic dynamic fatigue testing machines are widely used for fatigue testing of various components and materials. They employ linear motors to drive the fixture movement, eliminating the need for a hydraulic power source and offering advantages such as small size, easy maintenance, and strong compatibility. In the field of materials testing, materials such as hydrogels, biomaterials, and organic gels can only maintain stable performance over extended periods in a liquid environment. Furthermore, these materials have relatively low strength and require small loads during testing, making it impossible to install contact extensometers to measure strain. Given these characteristics, electronic dynamic fatigue testing machines cannot directly meet the testing needs of such materials. Currently, the mainstream solution involves adding a bath to the bottom of the lower fixture of the testing machine. The lower fixture support column and the bottom of the bath require a movable dynamic seal connection, resulting in a complex structure with high sealing requirements and significant challenges in automation development. Summary of the Invention

[0003] The purpose of this invention is to provide an auxiliary testing device for the mechanical properties of materials in a liquid environment, so as to solve the problems existing in the prior art.

[0004] To achieve the above objectives, this invention provides an auxiliary testing device for the mechanical properties of materials in a liquid environment. It is applied to the mechanical property testing of low-strength materials such as hydrogels, biomaterials, and organic gels in a liquid environment, and is particularly suitable for long-cycle fatigue mechanical property testing. Specifically, it includes a force sensor, an extension rod, an upper clamp, a U-shaped beam, a lower clamp, a bath, and an electric lifting platform. The force sensor is connected between the moving end of the testing machine and the extension rod, and the upper clamp is installed at the end of the extension rod. The electric lifting platform is fixed at the center of the testing machine's working platform. The bath is installed at the top of the electric lifting platform. The bath is raised and lowered under the drive of the electric lifting platform to switch between liquid and non-liquid environments. The U-shaped beam is composed of two curved cantilever beams. The two curved cantilever beams are respectively fixed to the working platform of the testing machine on both sides of the bath. A gap is formed between the two curved cantilever beams to allow the bath to rise and fall. The two curved cantilever beams are connected by a crossbeam that extends into the interior of the bath. The lower clamp is installed at the top of the crossbeam, and the sample is fixed between the upper clamp and the lower clamp.

[0005] Optionally, the curved cantilever beam consists of a support column and two crossbeams, with the support column and the crossbeams being fixedly connected by bolts.

[0006] Optionally, an industrial camera is also included, which is positioned in front of the sample and equipped with a telecentric lens for non-contact precision measurement of sample deformation.

[0007] Optionally, it also includes a data acquisition card and a host computer. The data acquisition card is connected to the force sensor and the electric lifting platform respectively, and the host computer is connected to the industrial camera and the data acquisition card via a bus.

[0008] Optionally, a light source is also included, which is connected to a universal adjustment rod and can be switched to a front lighting mode or a back lighting mode; in the front lighting mode, two light sources illuminate the two sides in front of the bathtub; in the back lighting mode, one light source illuminates the back of the bathtub.

[0009] On the other hand, to achieve the above objectives, the present invention provides a method for testing the mechanical properties of materials in a liquid environment, applied to the aforementioned auxiliary testing device for the mechanical properties of materials in a liquid environment, comprising:

[0010] S1: Lower the bath, install the sample, and make markings on the sample;

[0011] S2: Raise the bath to completely immerse the sample in the liquid, and adjust the field of view and light source of the industrial camera;

[0012] S3: Load the sample cyclically according to the set program, and at the same time use the industrial camera to capture and calculate the deformation data of the sample throughout the process.

[0013] S4: Lower the bath to expose the sample to the air, load the sample monotonically according to the set program, and use the industrial camera to capture and calculate the deformation data of the sample throughout the process.

[0014] S5: Repeat steps S3 to S4 until the specimen fails due to fatigue.

[0015] S6: Lower the bath and remove the sample.

[0016] The technical effects of this invention are as follows:

[0017] (1) The U-shaped beam has a simple structure and no sealing requirement: The U-shaped beam has good support rigidity, and compared with the traditional design of the lower support column passing through the bath, there is no need to consider the influence of sealing. The structure is simple and easy to modify the original testing machine.

[0018] (2) Freely switch between liquid and non-liquid environments to eliminate interference: The bath can be automatically raised and lowered. When fatigue testing is carried out, the material can be kept in a liquid environment without affecting the change of material properties. When mechanical property testing is required, the bath can be raised to reduce the influence of liquid viscosity during testing and eliminate the buoyancy effect caused by the upper clamp rising and falling in the liquid.

[0019] (3) Solve the problem of testing small load materials with high precision: The industrial camera is used as a video extensometer to complete the strain detection of the sample, and the small-range force sensor can realize the measurement of small force values.

[0020] (4) Fast image and data processing speed to meet real-time requirements: Industrial camera images are processed in real time, and only the corresponding deformation data is saved instead of the images, which meets the requirements of monitoring the entire fatigue test process. Images will only be stored if necessary.

[0021] (5) The light source angle can be freely adjusted, which is highly flexible: the light source is connected to the universal adjustment rod, which can adjust the illumination angle in different directions. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0024] Figure 1 This is a schematic diagram of the auxiliary testing system for material mechanical properties in a liquid environment, as described in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the main structure of the experimental device in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the front illumination method test in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of the back-illumination test in an embodiment of the present invention.

[0028] Labeling Explanation: 1. Main structure of auxiliary testing device; 11. Force sensor; 12. Extension rod; 13. Upper clamp; 14. U-shaped beam; 15. Lower clamp; 16. Bath; 17. Electric lifting platform; 2. Industrial camera; 3. Data acquisition card; 4. Host computer; 5. Amplifier; 6. Driver; 7. Front light source; 8. Back light source; 9. Sample; 10. Moving end of testing machine. Detailed Implementation

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] Example 1

[0033] like Figure 1 - Figure 4 As shown, this embodiment provides an auxiliary testing device for the mechanical properties of materials in a liquid environment, including a main structure 1, an industrial camera 2, a data acquisition card 3, and a host computer 4. The main structure 1 is primarily used for clamping the sample 9, loading it into the liquid environment, and measuring the load on the sample 9. The industrial camera 2 is installed directly in front of the sample 9 for measuring the deformation of the sample 9 during the test. The data acquisition card 3, as the control core of the entire system, has three main functions:

[0034] 1. The signal from the force sensor 11, amplified by the amplifier 5, is collected and transmitted to the host computer 4 to be converted into a load value;

[0035] 2. Receive instructions from host computer 4 and control the raising and lowering of the lifting platform via driver 6;

[0036] 3. By triggering each other with the main unit of the testing machine through digital I / O signals, the auxiliary testing system and the testing machine in this embodiment can achieve coordinated control.

[0037] The host computer 4 is connected to the industrial camera 2 and the data acquisition card 3 via a USB bus. As the control and interaction center of the auxiliary test system in this embodiment, it is responsible for various data processing and storage, instruction reception and distribution, information input and display, and other functions.

[0038] The feasible auxiliary test device main structure 1 is the main structure of the material mechanical property test device for liquid environment, and its structure is shown in the attached figure. Figure 2 As shown, the force sensor 11 is connected between the moving end 10 of the testing machine and the extension rod 12, and the upper clamp 13 is connected to the extension rod 12, maintaining overall axial alignment. The electric lifting platform 17 is fixed at the center of the testing machine's working platform, and the bath 16 is installed at the top of the electric lifting platform 17. The bath 16 rises and falls through the electric lifting platform 17, realizing the switching between liquid and non-liquid environments. The U-shaped beam 14 is a U-shaped structure composed of two curved cantilever beams. The curved cantilever beam consists of one support column and two crossbeams, which are fixed together by bolts. The gap between the two supports allows the bath 16 to be raised and lowered without obstruction. The two curved cantilever beams are fixed at the left and right ends of the testing machine's working platform, i.e., the two sides of the bath 16, and are connected to the two small supports by a long crossbeam. The long crossbeam has a straight slot in the center, which can be connected to the lower clamp 15. The long crossbeam in the middle of the U-shaped beam 14 extends into the bath 16, and the lower clamp 15 is installed at the top of the long crossbeam in the middle of the U-shaped beam 14. The sample 9 is fixed between the upper clamp 13 and the lower clamp 15.

[0039] By employing a specially designed U-shaped beam 14, the lifting and lowering process of the bath 16 is ensured to be undisturbed, thereby facilitating the switching of the sample 9 between liquid and non-liquid environments. This design has no dynamic sealing requirements, a simple structure, is easy to modify and upgrade, and the supporting structure of the U-shaped beam 14 has good frame rigidity.

[0040] Feasible, the industrial camera 2 is mounted directly in front of the specimen 9 to achieve precise measurement of the deformation of the specimen 9. The industrial camera 2 is equipped with a telecentric lens to eliminate perspective errors and ensure the accuracy of deformation measurement. During testing, marking points need to be made on the surface of the specimen 9, and the displacement of the marking points is tracked by the camera to calculate the relevant deformation data.

[0041] In this embodiment, an industrial camera 2 is used as a video extensometer to solve the problem of not being able to install a contact extensometer to measure strain in materials with small loads. The light source can be easily switched between front illumination and back illumination modes depending on the type of sample 9. The camera completes calibration for both liquid and non-liquid environments and can automatically switch calibration parameters during the test.

[0042] Based on technologies such as real-time image processing of industrial camera 2, electric lifting of bath 16 and interactive triggering of I / O ports, the complex process of material fatigue testing in liquid environment can be automated.

[0043] It is feasible that the host computer 4 program can control the lifting of the electric lifting platform 17 via buttons, and at the same time display the force value data sent by the force sensor 11 in real time. The industrial camera 2 also communicates with the host computer 4 via USB bus and outputs relevant deformation data.

[0044] In practice, data acquisition card 3 controls the electric lifting platform 17 to lift the bath 16 by sending pulse signals. The signal from force sensor 11 is amplified by signal amplifier 5 and transmitted to the host computer 4 via data acquisition card 3. In addition, the host computer 4 achieves synchronous control with the testing machine controller via data acquisition card 3.

[0045] It is feasible to connect the light source to a universal adjustment rod to adjust the illumination angle in different directions. During illumination, either front illumination or back illumination can be used as needed; front illumination is recommended for opaque samples, while back illumination is recommended for transparent samples. Front illumination uses two light sources directly facing the two sides in front of the octagonal bath 16, as shown in the attached diagram. Figure 3 As shown, this method can also effectively reduce the impact of reflected light on the camera; the back-illumination method uses a light source directly facing the back of the bath 16 to illuminate it, which provides better contrast for transparent samples, as shown in the attached diagram. Figure 4 As shown.

[0046] Based on the above-described apparatus, this embodiment provides a method for testing the mechanical properties of materials in a liquid environment, specifically including:

[0047] S1: Lower the bath 16 to the bottom, exposing the upper clamp 13 and lower clamp 15 to facilitate the installation of the sample 9. Adjust the height of the upper clamp 13 to a suitable position. Mark the middle area of ​​the sample 9, usually by creating digital speckle patterns, or by setting a pair of circular markers at certain intervals along the length of the sample. Then install the sample 9 between the upper and lower clamps 15.

[0048] S2: Raise the bath 16 to completely submerge the sample 9 in the liquid, which can be water, alcohol, or an organic solvent, leaving space for the sample 9 to stretch. Adjust the field of view and orientation of the industrial camera 2 to align it with the sample 9 to be tested, and adjust the light source for illumination;

[0049] S3: Load the sample 9 cyclically according to the set program (such as a sine wave with a frequency of 1Hz, an amplitude of 5mm, and an initial phase of -90°) until the specified number of times is reached. During this process, the industrial camera 2 captures and calculates the deformation data of the sample 9 throughout the process.

[0050] S4: Lower the bath 16 to expose the sample 9 to the air environment. Monotonically load the sample 9 according to the set program (e.g., speed of 5 mm / min, stroke of 10 mm). During this process, the industrial camera 2 also captures and calculates the deformation data of the sample 9. After loading is completed, unload the sample 9 to the initial position according to the loading speed. Note: Loading the sample 9 in the air eliminates the influence of liquid adhesion and fixture buoyancy changes on small force values.

[0051] S5: Repeat steps S3 to S4 until specimen 9 fails due to fatigue.

[0052] S6: Lower the bath 16, remove the sample, and the test is complete.

[0053] In summary, this embodiment achieves free switching between liquid and non-liquid environments through a lifting bath, eliminating the need for dynamic seals, and features a simple structure. Combined with a video extensometer, it meets the requirements for testing small force values ​​in low-strength materials and is suitable for long-term fatigue mechanical property testing.

[0054] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An auxiliary testing device for the mechanical properties of materials in a liquid environment, characterized in that, The system includes a force sensor (11), an extension rod (12), an upper clamp (13), a U-shaped beam (14), a lower clamp (15), a bath (16), and an electric lifting platform (17). The force sensor (11) is connected between the moving end (10) of the testing machine and the extension rod (12), and the upper clamp (13) is installed at the end of the extension rod (12). The electric lifting platform (17) is fixed at the center of the testing machine's working platform, and the bath (16) is installed at the top of the electric lifting platform (17). Driven by the lifting mechanism, the liquid environment and non-liquid environment are switched. The U-shaped beam (14) is composed of two curved cantilever beams. The two curved cantilever beams are respectively fixed on the working platform of the test machine on both sides of the bath (16). A gap is formed between the two curved cantilever beams for the bath (16) to lift and avoid. The two curved cantilever beams are connected by a crossbeam. The crossbeam extends into the bath (16). The lower clamp (15) is installed on the top of the crossbeam. The sample (9) is fixed between the upper clamp (13) and the lower clamp (15).

2. The auxiliary testing device for material mechanical properties in a liquid environment according to claim 1, characterized in that, The curved cantilever beam consists of a support column and two crossbeams, with the support column and the crossbeams being fixedly connected by bolts.

3. The auxiliary testing device for material mechanical properties in a liquid environment according to claim 1, characterized in that, It also includes an industrial camera (2), which is positioned in front of the sample (9) and is equipped with a telecentric lens for non-contact precision measurement of the deformation of the sample (9).

4. The auxiliary testing device for the mechanical properties of materials in a liquid environment according to claim 3, characterized in that, It also includes a data acquisition card (3) and a host computer (4). The data acquisition card (3) is connected to the force sensor (11) and the electric lifting platform (17) respectively. The host computer (4) is connected to the industrial camera (2) and the data acquisition card (3) via a bus.

5. The auxiliary testing device for the mechanical properties of materials in a liquid environment according to claim 1, characterized in that, It also includes a light source, which is connected to a universal adjustment rod and can be switched to a front lighting mode or a back lighting mode; in the front lighting mode, two light sources illuminate the two sides in front of the bathtub (16); in the back lighting mode, one light source illuminates the back of the bathtub (16).

6. A method for testing the mechanical properties of materials in a liquid environment, applied to the auxiliary testing device for the mechanical properties of materials in a liquid environment as described in any one of claims 1-5, characterized in that, include: S1: Lower the bath (16), install the sample (9) and make markings on the sample (9); S2: Raise the bath (16) to completely immerse the sample (9) in the liquid, and adjust the field of view and light source of the industrial camera (2); S3: Load the sample (9) cyclically according to the set program, and at the same time use the industrial camera (2) to capture and calculate the deformation data of the sample (9) throughout the process. S4: Lower the bath (16) to expose the sample (9) to the air, load the sample (9) monotonically according to the set program, and use the industrial camera (2) to capture and calculate the deformation data of the sample (9) throughout the process. S5: Repeat steps S3 to S4 until the specimen (9) fails due to fatigue. S6: Lower the bath (16) and remove the sample (9).

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