Freeze-thaw test device for testing composite material sheet

Abstract

The utility model discloses a device for testing the freeze thawing test of a composite material sheet, which comprises a test piece box and a test piece fixed connecting part, the structure of the test piece box is matched with a test piece placing container, the upper end of a shell is provided with an upper opening, the test piece fixed connecting part is sleeved on the outer side of the test piece box; a clamping groove for fixing the composite material sheet at the middle part between the outer side of the side wall of the test piece box and the inner side of the side wall of the test piece placing container is formed in the test piece fixing and connecting part, and the clamping groove is clamped with the composite material sheet. According to the utility model, the position of the composite material sheet can be limited, the test piece is prevented from moving or inclining, water can be uniformly attached and dispersed on the surface of the test piece and in the test piece, the phenomenon that the test piece is not completely frozen or ablated in the freezing and ablating stages can be prevented, and the test piece is not completely frozen or ablated. The test result of the composite material under the freezing and thawing condition is simulated to the greatest extent.

Description

Technical Field

[0001] The utility model relates to the technical field of experimental devices, in particular to a device for testing freeze-thaw experiments of composite material sheets. Background Art

[0002] The global climate is changeable, especially in the cold and temperate zones. Materials often face cyclical changes from low temperatures in winter to below zero degrees and warming in spring. This freeze-thaw cycle will have a significant impact on building materials and engineering structures. Many infrastructures, building structures, pavement materials, pipeline systems, etc. need to withstand the test of harsh climatic conditions, especially the performance maintenance in freezing environments, to ensure safety and stability during long-term service. With the advancement of science and technology, new composite materials are constantly being developed to replace traditional materials, including polymer-based, cement-based, metal-based and other bio-based composite materials. The freeze-thaw resistance of these new materials needs to be verified and optimized through rigorous tests. Freeze-thaw tests are an important means to objectively evaluate the ability of composite materials to resist internal damage and reduce mechanical performance degradation under the action of freeze-thaw cycles, which is related to whether the material can maintain its function for a long time in cold areas. Through freeze-thaw tests, we can deeply study the microstructural evolution of composite materials during freeze-thaw processes, interface interactions, volume changes caused by pore water freezing and the resulting stress, so as to reveal the freeze-thaw damage mechanism of materials.

[0003] In order to detect the antifreeze performance of composite material specimens, it is necessary to simulate the temperature changes in the natural environment and test the composite material specimens, which is called freeze-thaw test. At present, the shape of the specimens selected for freeze-thaw tests of composite materials is mostly in the form of sheets. During the freeze-thaw test, a freeze-thaw test machine is often used to simulate the natural environment of the outside world. The composite material specimens are measured under the conditions of water freezing and water thawing. The number of rapid freeze-thaw cycles experienced is used to represent the antifreeze performance of the composite material. Since there is no clear method and test device for freeze-thaw test of composite sheet materials, the freeze-thaw test method and test device for composite sheet materials basically adopt the freeze-thaw test method of concrete. The existing freeze-thaw test of concrete is to place the concrete specimen in a specimen placement container, and then put the specimen placement container containing the specimen into the freeze-thaw box to start the freeze-thaw cycle. For details, please refer to the national standard: GB / T50082-2009 "Concrete Freeze-Thaw Test Method". However, during the composite material experiment, the specimen is very likely to move and tilt; the test surface of the specimen cannot be completely in contact with the liquid medium, affecting the accuracy of the test; and the uneven freezing and melting affect the accuracy of the freeze-thaw test results of the sheet specimen. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiencies in the above-mentioned prior art and provide a device for testing freeze-thaw tests of composite material sheets, which can limit the position of the composite material sheet to prevent the specimen from moving or tilting, enable water to be evenly attached to and dispersed on the surface of the specimen and in the specimen, and prevent the specimen from being incompletely frozen or incompletely melted during the freezing and melting stages, thereby simulating the test results of the composite material under freeze-thaw conditions to the greatest extent.

[0005] In order to solve the above problems, the utility model provides a device for testing freeze-thaw test of composite material sheets, which is characterized by comprising:

[0006] A test box, wherein the test box is a hollow shell structure, and an upper opening is formed at the upper end of the shell, and the upper opening communicates the inside and the outside of the shell;

[0007] A container for placing a specimen, wherein the structure of the specimen box is adapted to the container for placing the specimen;

[0008] and a specimen fixing connection part, wherein the specimen fixing connection part is sleeved on the outside of the specimen box, and the specimen fixing connection part is provided with a slot for fixing the composite material sheet in the middle between the outside of the side wall of the specimen box and the inside of the side wall of the specimen placement container, so that the slot is clamped with the composite material sheet.

[0009] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that the specimen fixing connection part is fixedly connected to the specimen box by welding or gluing.

[0010] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that the device for testing freeze-thaw test of composite material sheets also includes a sealing strip, which is arranged on the upper and lower sides of the connection between the specimen fixing connection part and the specimen box, and the sealing strip is bonded to the specimen fixing connection part and the specimen box by epoxy resin glue.

[0011] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that the specimen fixing connection part includes an upper specimen fixing connection part and a lower specimen fixing connection part, and the upper specimen fixing connection part and the lower specimen fixing connection part have the same structure and are arranged at intervals on the specimen box.

[0012] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that the upper specimen fixing connection part and the lower specimen fixing connection part are both provided with a plurality of slots for installing a plurality of composite material sheet specimens.

[0013] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that the upper specimen fixing connection part and the lower specimen fixing connection part are both made by cutting plate materials.

[0014] The above-mentioned device for testing freeze-thaw test of composite material sheets is characterized in that a handle is provided on the specimen box.

[0015] The above-mentioned device for testing freeze-thaw test of composite material sheet is characterized in that the specimen box is a square shell, and the length dimension of the specimen box is given by the formula: w=nb+2nx+(n+1)y

[0016] And formula: t = (Lw-2d) / 4

[0017] The number of specimens, the length of the specimen, the thickness of the specimen, the distance between the specimen and the slot, the thickness of the slot, the distance between the specimen and the inner wall of the specimen placement container, the distance between the specimen and the outer wall of the specimen box, and the length of the specimen placement container are calculated;

[0018] In the formula, w is the length of the specimen box, n is the number of specimens placed on each side of the specimen box, b is the length of the specimen, x is the distance between the specimen and the slot, y is the thickness of the slot, t is the distance between the specimen and the inner wall of the specimen placement container and the distance between the specimen and the outer wall of the specimen box, L is the length of the specimen placement container, and d is the thickness of the specimen.

[0019] Compared with the prior art, the utility model has the following advantages:

[0020] 1. The utility model fixes the composite material specimen on the side wall of the specimen box during operation by setting the card slot, the specimen can be effectively close to the outer wall of the specimen box, and the composite material sheet cannot be moved or tilted at will, which will not affect the normal operation of the test.

[0021] 2. The utility model places the composite sheet specimen into the slot. Due to the limitation of the limit slots on both sides of the composite sheet specimen, the distance from the composite sheet to the specimen box body is the same as the distance from the composite sheet specimen to the rubber cover, so that the water volume on both sides of the composite sheet is consistent, which will make the freezing and melting conditions consistent, so that the temperature of the specimen is balanced, and the additional pressure caused by the freezing of water around the specimen is eliminated, thereby ensuring the accuracy of the test.

[0022] The utility model is further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the three-dimensional structure of the test piece box and the test piece fixing connection part in the embodiment of the utility model.

[0024] Figure 2 for Figure 1 Enlarged view of point A.

[0025] Figure 3 It is a top view of the specimen box placed in the specimen placement container when no composite material sheet specimen is installed in the embodiment of the utility model.

[0026] Figure 4 It is a top view of a test piece box placed in a test piece placement container when installing a composite material sheet test piece in an embodiment of the utility model.

[0027] Description of reference numerals:

[0028] 1—test piece box; 11—upper opening; 12—handle;

[0029] 2—test piece fixing connection part; 21—card slot;

[0030] 22—fixed connection portion of the upper specimen; 23—fixed connection portion of the lower specimen;

[0031] 3—Sealing strip; 4—Test piece placement container. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0033] The utility model discloses a device for testing freeze-thaw test of composite material sheet, which comprises a specimen box 1, a placement container 4 and a specimen fixing connection part 2; the specimen box 1 is a hollow shell structure, and an upper opening 11 is provided at the upper end of the shell, and the upper opening 11 communicates the inside and the outside of the shell; the structure of the specimen box 1 is adapted to the specimen placement container 4; the specimen fixing connection part 2 is sleeved on the outside of the specimen box 1, and a clamping groove 21 for fixing the composite material sheet in the middle between the outer side wall of the specimen box 1 and the inner side wall of the specimen placement container 4 is provided on the specimen fixing connection part 2, so that the clamping groove 21 is clamped with the composite material sheet.

[0034] The device for testing the freeze-thaw test of composite sheet in this embodiment fixes the composite sheet specimen through the specimen fixing connection part 2, and can fix the specimen outside the specimen box 1, which can prevent the specimen from moving and tilting, and improve the accuracy of the test results. However, in the existing freeze-thaw test, there is no limit device after the specimen is placed. First, the specimen is placed in the specimen box in a movable state, so it is very easy for the specimen to move and tilt during the actual test; second, the specimen is directly placed in the specimen placement container 4, and the sheet specimen is very easy to contact and get close to the specimen placement container 4, so that the test surface of the specimen cannot be completely in contact with the liquid medium, affecting the accuracy of the test; the current specimen placement container 4 often uses a rubber leather cover, that is, the specimen is directly placed in the rubber leather cover, and the sheet specimen is very easy to contact and get close to the rubber leather cover, so that the test surface of the specimen cannot be completely in contact with the liquid medium, affecting the accuracy of the test; third, the specimen is placed in the rubber leather cover without a limiting device, resulting in uneven water distribution on both sides of the sheet specimen, and there may be more water on one side and less water on the other side. The specimen can freeze faster under the action of low temperature. Due to the uneven freezing of the specimen, uneven ablation will occur in the melting stage. At the same time, it is not completely ablated and a new freezing is performed, and the effect of freeze-thaw on the composite material specimen cannot be accurately evaluated, affecting the accuracy of the freeze-thaw test results of the sheet specimen.

[0035] like Figures 1 to 4 As shown, the specimen fixing connection part 2 is fixedly connected to the specimen box 1 by welding or gluing. The apparatus for testing the freeze-thaw test of composite material sheets also includes a sealing strip 3, which is arranged on the upper and lower sides of the connection between the specimen fixing connection part 2 and the specimen box 1, and the sealing strip 3 is bonded to the specimen fixing connection part 2 and the specimen box 1 by epoxy resin glue.

[0036] In this embodiment, the specimen fixing connection part 2 is fixedly connected to the specimen box 1 by welding or gluing. Since the specimen box 1 has a thin-walled shell structure, the welding connection is likely to cause damage to the thin-walled shell. Therefore, sealing strips 3 are provided on the upper and lower sides of the connection between the specimen fixing connection part 2 and the specimen box 1. The sealing strips 3 can play a sealing role to prevent water between the outer wall of the specimen box 1 and the rubber leather cover from penetrating into the interior of the specimen box 1.

[0037] In this embodiment, the composite sheet specimen is placed in the slot 21, which is a U-shaped slot. The notches of two adjacent and spaced U-shaped slots are arranged relative to each other to facilitate placing the composite sheet specimen in the slot. Due to the restrictions of the slots 21 on both sides of the composite sheet specimen, the distance from the composite sheet to the specimen box body is the same as the distance from the composite sheet specimen to the rubber sleeve, so that the water volume on both sides of the composite sheet is consistent, which will make the freezing and melting conditions consistent, so that the specimen is subjected to balanced temperature and the additional pressure caused by the freezing of water around the specimen is eliminated, thereby ensuring the accuracy of the test.

[0038] like Figure 1 As shown, the specimen fixing connection part 2 includes an upper specimen fixing connection part 22 and a lower specimen fixing connection part 23 . The upper specimen fixing connection part 22 and the lower specimen fixing connection part 23 have the same structure and are arranged on the specimen box 1 at intervals.

[0039] like Figure 1 , Figure 3 and Figure 4 As shown, the upper specimen fixing connection portion 22 and the lower specimen fixing connection portion 23 are both provided with a plurality of slots 21 for mounting a plurality of composite material sheet specimens.

[0040] In this embodiment, there are multiple card slots 21, and each side wall of the specimen box 1 can hold a number of specimens. The arrangement of the card slots 21 allows the composite material specimen to be fixed to the side wall of the specimen box 1 during operation, and the specimen can be effectively close to the outer wall of the specimen box 1. The composite material sheet cannot be moved or tilted at will, and will not affect the normal operation of the test. The operation during the test is simpler, more convenient and effective, which helps to save time and improve efficiency.

[0041] The upper specimen fixing connection portion 22 and the lower specimen fixing connection portion 23 are both made by cutting plate materials.

[0042] like Figure 1 As shown, the sample box 1 is provided with a handle 12 .

[0043] In this embodiment, a handle 12 is provided on the outer side of the top of the test box 1, and the test box 1 is conveniently placed in the rubber leather case through the handle 12, and then placed in the freeze-thaw test box for testing. The provision of the handle also facilitates the test box 1 to be taken out of the test box, reducing the possibility of scratches on the operator.

[0044] In this embodiment, the specimen box 1 is a square shell. The size of the specimen box 1 has a calculated relationship between the specimen volume, the required freeze-thaw water volume and the size of the rubber holster. The length L of the rubber holster is known. n specimens are placed on each side. The distance from the card slot along the specimen width direction can be ignored according to the specimen width. The distance from the specimen to the rubber holster should be consistent with the distance from the specimen to the specimen box. Then the length w of the specimen box can be expressed by calculation formula (1-1), and the distance from the specimen to the rubber holster and the distance t from the specimen to the specimen box can be expressed by calculation formula (1-2).

[0045] w=nb+2nx+(n+1)y (1-1)

[0046]

[0047] Among them, w is the length of the specimen box 1, n is the number of specimens placed on each side of the specimen box 1, b is the length of the specimen, x is the distance between the specimen and the slot 21, y is the thickness of the slot 21, t is the distance between the specimen and the inner wall of the specimen placement container 4 and the distance between the specimen and the outer wall of the specimen box 1, L is the length of the specimen placement container 4, and d is the thickness of the specimen.

[0048] According to the above calculation formula, the size of the specimen box is not limited to a fixed length. The size of the specimen box can be adjusted according to variables such as the specimen size, the number of specimens, the width of the limit groove, the size of the rubber cover, etc., so that the size of the test box can be adjusted according to the actual test conditions.

[0049] The freeze-thaw test method for composite sheet materials refers to the freeze-thaw test method for concrete, and the freeze-thaw cycle test is carried out in accordance with the national standard: GB / T50082-2009 "Concrete Freeze-thaw Test Method". The operation process of the composite sheet rapid freeze-thaw test in this embodiment is as follows:

[0050] 1. Four days before the freeze-thaw test, the specimens should be taken out for appearance inspection and then immersed in water at a temperature of 15-20°C (including the temperature measurement specimens). The water surface should be at least 20 mm higher than the top surface of the specimens during immersion. After the specimens are immersed for 4 days, freeze-thaw cycles should be carried out.

[0051] 2. After soaking, take out the test piece, wipe off the surface moisture with a wet cloth, and weigh it to determine its basic initial value.

[0052] 3. Before the test, place the specimen in the specimen box. In order to make the specimen be evenly heated and eliminate the additional pressure caused by the freezing of water around the specimen, the sheet specimen should be placed in the slot.

[0053] 4. Place the specimen box into the rubber cover and then place the rubber cover into the freeze-thaw box to start the freeze-thaw cycle.

[0054] 5. The freeze-thaw cycle process shall meet the following requirements: A. Each freeze-thaw cycle shall be completed within 2 to 4 hours, and the time used for thawing shall not be less than 1 / 4 of the entire freeze-thaw time; B. At the end of freezing and thawing, the center temperature of the specimen shall be controlled at -17±2℃ and 8±2℃ respectively; C. The time used for each specimen to drop from 6℃ to -15℃ shall not be less than 1 / 2 of the freezing time, and the time used for each specimen to rise from -15℃ to 6℃ shall not be less than 1 / 2 of the entire thawing time. The temperature difference between the inside and outside of the specimen should not exceed 28℃; D. The conversion time between freezing and thawing should not exceed 10 minutes.

[0055] 6. The specimen should generally be measured every 25 cycles. Before measurement, the surface of the specimen should be cleaned, surface water should be wiped off, and its external damage and weight loss should be checked.

[0056] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. A device for testing freeze-thaw test of composite material sheets, characterized in that: include: A test box (1), the test box (1) being a hollow shell structure, and an upper opening (11) is provided at the upper end of the shell, the upper opening (11) communicating the inside and the outside of the shell; A test piece placement container (4), wherein the structure of the test piece box (1) is adapted to the test piece placement container (4); and a specimen fixing connection portion (2), the specimen fixing connection portion (2) being sleeved on the outside of the specimen box (1), the specimen fixing connection portion (2) being provided with a clamping groove (21) for fixing the composite material sheet in the middle between the outside of the side wall of the specimen box (1) and the inside of the side wall of the specimen placement container (4), so that the clamping groove (21) is clamped with the composite material sheet.

2. The device for testing freeze-thaw test of composite material sheets according to claim 1, characterized in that: The specimen fixing connection portion (2) is fixedly connected to the specimen box (1) by welding or gluing.

3. The device for testing freeze-thaw test of composite material sheet according to claim 2, characterized in that: The device for testing the freeze-thaw test of composite material sheets also includes a sealing strip (3), which is arranged on the upper side and the lower side of the connection between the specimen fixing connection part (2) and the specimen box (1), and the sealing strip (3) is bonded to the specimen fixing connection part (2) and the specimen box (1) by epoxy resin glue.

4. The device for testing freeze-thaw test of composite material sheets according to claim 1, characterized in that: The specimen fixing connection part (2) comprises an upper specimen fixing connection part (22) and a lower specimen fixing connection part (23); the upper specimen fixing connection part (22) and the lower specimen fixing connection part (23) have the same structure and are arranged at intervals on the specimen box (1).

5. The device for testing freeze-thaw test of composite material sheets according to claim 4, characterized in that: The upper specimen fixing connection portion (22) and the lower specimen fixing connection portion (23) are both provided with a plurality of slots (21) for mounting a plurality of composite material sheet specimens.

6. The device for testing freeze-thaw test of composite material sheets according to claim 5, characterized in that: The upper test piece fixing connection portion (22) and the lower test piece fixing connection portion (23) are both manufactured by cutting a plate.

7. The device for testing freeze-thaw test of composite material sheet according to claim 1, characterized in that: The test piece box (1) is provided with a handle (12).

8. The device for testing freeze-thaw test of composite material sheets according to claim 1, characterized in that: The test piece box (1) is a square shell, and the length dimension of the test piece box (1) is given by the formula: w=nb+2nx+(n+1)y And formula: t = (Lw-2d) / 4 The number of test pieces, the length of the test pieces, the thickness of the test pieces, the distance between the test piece and the slot (21), the thickness of the slot (21), the distance between the test piece and the inner wall of the test piece placement container (4), the distance between the test piece and the outer wall of the test piece box (1), and the length parameters of the test piece placement container (4) are calculated; In the formula, w is the length of the specimen box (1), n ​​is the number of specimens placed on each side of the specimen box (1), b is the length of the specimen, x is the distance between the specimen and the slot (21), y is the thickness of the slot (21), t is the distance between the specimen and the inner wall of the specimen placement container (4) and the distance between the specimen and the outer wall of the specimen box (1), L is the length of the specimen placement container (4), and d is the thickness of the specimen.

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