A test specimen fastening device for structural sealant fatigue cycle testing and method of use

Abstract

The application provides a structure sealant fatigue cycle test specimen fastening device and a use method. The fastening device is composed of upper clamping strips and lower clamping strips. The upper clamping strips and the lower clamping strips are in strip shapes, the middle parts are clamping parts, and the two ends are connecting parts. During the test, two pairs of upper clamping strips and lower clamping strips are used to fix the two ends of the two specimen adhering surfaces respectively, a first fastening part is formed, then a specimen is placed above or below the first fastening part for fixation, and the finally formed fastening part is placed on a test fixture for fixation. When a group of specimens are repeatedly stretched back and forth, stress concentration of the specimens is avoided.

Description

Technical Field

[0001] This invention belongs to the technical field of material testing devices, and in particular relates to a testing device and its usage method. Background Technology

[0002] Structural sealants are high-performance engineering materials widely used in prefabricated buildings, building curtain walls, and other fields. They are primarily used for bonding and sealing critical joints and minute gaps in building structures. In application, this material plays a role in transferring loads and sealing. Because buildings are subjected to long-term loads such as their own weight and wind, structural sealants must be able to withstand certain pressure and deformation to ensure the integrity and airtightness of the structure. Therefore, the fatigue cycle resistance of this material is crucial and has significant practical implications for guiding manufacturers' research and development, actual engineering construction, and engineering maintenance.

[0003] Currently, the method for testing the fatigue cycle performance of structural sealants mainly follows JG / T 475-2015 "Silicone Structural Sealants for Building Curtain Walls": a set of specimens is subjected to repeated tensile stresses, with each cycle lasting 8 seconds, to perform fatigue cycle testing. A key element in fatigue cycle performance testing is ensuring reliable and secure fastening of the specimens to prevent stress concentration during repeated tensile testing. Our findings indicate a lack of structurally sound and reliable specimen fastening devices, making it difficult to achieve high-quality and efficient fatigue cycle performance testing of a set of specimens. Furthermore, the existing test fixtures in GB / T 13477.8-2017, used for testing the tensile adhesion of "H"-shaped specimens, can only withstand single tensile stresses and do not meet the technical requirements for repeated tensile stresses on a set of specimens during fatigue cycle testing. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a specimen fastening device and its usage method for fatigue cycle testing of structural sealant, so as to avoid stress concentration in the specimen when a group of specimens are subjected to repeated back-and-forth stretching in fatigue cycle testing.

[0005] In a first aspect, the present invention discloses a specimen fastening device for fatigue cycle testing of structural sealant. One side of the sealant specimen to be tested is a glass substrate, the other side is an aluminum / glass substrate, and the middle is sealant. The device consists of an upper clamping strip and a lower clamping strip. Both the upper clamping strip and the lower clamping strip are strip-shaped, with a clamping part in the middle for clamping the specimen, and connecting parts at both ends for connecting the upper clamping strip and the lower clamping strip.

[0006] Furthermore, the clamping part is positioned lower than the connecting part, forming a groove shape, and the depth of the groove is less than half the sum of the thicknesses of the glass substrate and the aluminum / glass substrate; the connecting part has a threaded hole, and the threaded hole of the upper clamping bar is a countersunk threaded hole.

[0007] Furthermore, both the upper clamping bar and the lower clamping bar are made of aluminum.

[0008] Secondly, the present invention also discloses a method of using the aforementioned device, comprising:

[0009] Step 1: The glass substrates of both the first and second sealant test specimens are placed horizontally upwards. The aluminum / glass substrate of the second sealant test specimen is aligned and bonded to the glass substrate of the first sealant test specimen. Two pairs of upper and lower clamping strips are used to fix the two ends of the bonding surfaces of the first and second sealant test specimens to form the first fastener.

[0010] Step 2: Place the third sealant test specimen aligned with the upper or lower end of the first fastener, with the glass substrate of the third sealant test specimen facing upwards. Use the upper and lower clamping strips to fix the third sealant test specimen to the first fastener in the same manner as in Step 2 to form the second fastener.

[0011] Step 3: Repeat step 2 to fix N+1 sealant test specimens together to form the Nth fastener, where N is not less than 1;

[0012] Step four: Place the Nth fastener onto the test fixture and secure the Nth fastener onto the test fixture using bolts.

[0013] Furthermore, before fixing the upper clamping strip and the lower clamping strip, the upper clamping strip and the lower clamping strip are pre-installed using bolts, and after the pre-installation, there is a gap between the connecting parts of the upper clamping strip and the lower clamping strip.

[0014] Furthermore, in step four, a hard rubber plate and a metal plate are placed on both the upper and lower surfaces of the Nth fastener, with the metal plate on the upper surface located above the hard rubber plate and the metal plate on the lower surface located below the hard rubber plate.

[0015] Furthermore, N is 4.

[0016] Beneficial effects:

[0017] The fastening device provided by this invention includes an upper clamping bar and a lower clamping bar, which can connect a group of fatigue test specimens in series. In the series system, each specimen bears the same force, so that the high stress originally concentrated in a certain part is distributed to each specimen in series, thereby effectively dispersing the stress borne by the specimen during the test, avoiding stress concentration, improving the accuracy and reliability of the test results, and providing a new and effective solution for the field of fatigue testing of structural sealants.

[0018] The fastening device of the present invention has wide applicability. It can be used not only for fatigue cycle testing of structural sealants, but also for tensile-compression cycle testing of a group of structural sealants in accordance with the test procedures and parameters of standard GB / T 13477.12-2018, saving time and costs.

[0019] On the other hand, the fastening device method provided by the present invention only uses upper and lower clamping strips for connection. The method of use is simple and does not require complicated installation and debugging processes. Operators can quickly get started and perform test operations. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0021] Figure 1 This is a physical image of a fixture slot used for testing a group of specimens in parallel.

[0022] Figure 2 These are the front view and top view of the upper and lower clamping strips in Embodiment 1 of the present invention;

[0023] (a) Upper clamping strip (b) Lower clamping strip

[0024] Figure 3 This is a front view of the pre-installed upper and lower clamping strips according to Embodiment 2 of the present invention;

[0025] Figure 4 This is a three-dimensional view of the two specimens before they were fixed in Embodiment 2 of the present invention;

[0026] Figure 5 This is a front view of the two specimens after they have been fixed in Embodiment 2 of the present invention;

[0027] Figure 6 This is a front view of the first fastener in Embodiment 2 of the present invention;

[0028] Figure 7 This is a front view of the second fastener in Embodiment 2 of the present invention;

[0029] Figure 8 This is a front view of the third fastener in Embodiment 2 of the present invention;

[0030] Figure 9 This is a front view of the fastener according to Embodiment 2 of the present invention;

[0031] Figure 10 This is a front view of the fastener of Embodiment 2 of the present invention installed on the test fixture. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. The principles and features of the present invention are described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0033] JG / T 475-2015, "Silicone Structural Sealants for Building Curtain Walls," specifies the shape, dimensions, and substrate of the sealant test specimens. The substrate can be of type AL, G, or M. Type AL conforms to GB / T13477.1, with an anodized aluminum thickness of not less than 3 mm; type G conforms to GB / T13477.1, consisting of clean, uncoated float glass with a thickness of not less than 5 mm; type M is other metal substrates as required by the supplier. In this embodiment of the invention, the sealant test specimen has one side as a glass substrate, the other side as an aluminum / glass substrate, and the sealant in the middle.

[0034] Example 1

[0035] When conducting fatigue cycle performance tests according to JG / T 475-2015 "Silicone Structural Sealants for Building Curtain Walls," it is required to repeatedly tensile a set of specimens. However, the standard does not explicitly specify the testing procedure. In practice, because multiple specimens are of the same shape, to simultaneously tensile multiple specimens, those skilled in the art have long used the method of connecting multiple specimens in parallel and then placing them in a fixture slot for testing. (See...) Figure 1 .

[0036] In theory, this method of testing is highly efficient. However, technicians in the same field have not realized that the dimensions of multiple specimens cannot be guaranteed to be completely consistent, the dimensions of the fixture slots for installing each specimen may also have errors, or improper use of the fixtures may cause stress to concentrate on the specimen with the smallest dimension in the tensile direction during the test.

[0037] After discovering the technical problems that need to be solved in fatigue cycle performance testing, this invention attempts to overcome the shortcomings of the prior art by drawing inspiration from the test method GB / T 13477.8-2017 for testing the tensile adhesion of "H"-shaped specimens. However, this method is a single specimen test, and the specimen can only be subjected to a single tensile stress during the test, which is not applicable to the scenario of the above-mentioned problem.

[0038] This invention proposes a technical solution of "connecting" a group of specimens in series. In the series system, each specimen bears the same force, which disperses the high stress that may have been concentrated in a certain part to each specimen connected in series.

[0039] It should be noted that the terms "parallel" and "series" are used to more vividly describe the technical solution of this invention. In reality, those skilled in the art, when testing a group of specimens placed in a fixture slot, would not be familiar with these terms. They would naturally assume that multiple specimens should be placed side-by-side in the fixture slot to simultaneously apply tension to them. Therefore, the technical solution of this invention cannot be simply derived from a parallel-to-series connection as in other fields.

[0040] Moreover, even if we consider using a series connection method, the first problem to solve is how to connect and tighten multiple specimens in series without causing uneven stress on each specimen due to the tightening connection method.

[0041] Here, the present invention first proposes a specimen fastening device for fatigue cycle testing of structural sealant, such as... Figure 2 As shown, the device consists of an upper clamping bar and a lower clamping bar; both the upper and lower clamping bars are strip-shaped, with a clamping part in the middle for clamping the specimen and connecting parts at both ends for connecting the upper and lower clamping bars.

[0042] The clamping part is positioned lower than the connecting part, forming a groove shape. The sum of the groove depths of the upper and lower clamping bars should be less than the sum of the thicknesses of the glass substrate and the aluminum / glass substrate to achieve a fastening effect during installation. The connecting part has a threaded hole, and the threaded hole of the upper clamping bar is a countersunk threaded hole.

[0043] Preferably, both the upper clamping strip and the lower clamping strip are made of aluminum.

[0044] The specimen fastening device in this embodiment of the invention uses an upper clamping bar and a lower clamping bar, which has a simple structure and can firmly fix the specimens connected in series, so that the specimens are subjected to uniform force and avoid the generation of new stress concentration.

[0045] Example 2

[0046] This embodiment describes the method of using the fastening device of Embodiment 1, which includes the following steps:

[0047] Step 1: First, arrange the two aluminum clips neatly in top-to-bottom order, and slightly secure both ends with the matching bolts. See... Figure 3 ;

[0048] Step 2, as follows Figure 4 , Figure 5 As shown, take two sealant test specimens, with the glass substrate facing upwards and vertically aligned. Place the pre-fixed fastening device at one end of the contact surface between the first and second sealant test specimens, adjust the position of the bolts at both ends, and then rotate the screw to tighten.

[0049] Step 3, similarly, place the slightly fixed other fastening device at the other end of the contact surface between the first and second sealant test specimens, adjust the positions of the bolts at both ends, and tighten by rotating the screw to form the first fastener. See Figure 6 .

[0050] Step 4: Take the third sealant test specimen, with the glass substrate facing upwards and vertically aligned, and place it on top of the first fastener. Place the pre-slightly fixed fastening device at one end of the contact surface between the second and third sealant test specimens, and adjust the positions of the bolts at both ends until one end of the specimen is tightened and constrained. Similarly, place the slightly fixed fastening device at the other end of the contact surface between the second and third sealant test specimens, and adjust the positions of the bolts at both ends until the other end of the specimen is tightened and constrained, forming the second fastener. See [link to previous steps]. Figure 7 .

[0051] Step 5: Take the fourth sealant sample to be tested, and fix it to the upper part of the second fastener using the fastening device according to the procedure in Step 4, forming the third fastener. See [link to Step 5]. Figure 8 .

[0052] Step 6: Take the fifth sealant specimen to be tested, and fix it to the upper part of the third fastener using the fastening device, following the same procedure as in Step 4, to form the final fastener 4. (See...) Figure 9 .

[0053] Step 7: Place the assembled fourth fastener onto test fixture 1, which is used for fatigue testing. Place a layer of hard rubber sheet 3 and a layer of metal sheet 2 on both the upper and lower surfaces of the specimen. Finally, use bolts to fix the entire fastener 4 onto test fixture 1. See... Figure 1 .

[0054] The metal plate 2 on the upper surface of the fastener 4 is located above the rigid rubber plate 3, and the metal plate 2 on the lower surface is located below the rigid rubber plate 3.

[0055] Of course, the upper and lower clamping strips can also be installed directly at the contact surface of the two specimens without prior micro-fixation. Although this can also achieve fixation, it is not convenient to operate.

[0056] The method of this embodiment is easy to operate. During fatigue cycle testing, a group of specimens can be subjected to repeated tensile testing, which avoids stress concentration in the specimens during repeated tensile testing.

[0057] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0058] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0059] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for using a specimen fastening device for fatigue cycle testing of structural sealant, characterized in that, The device includes a sealant specimen with one side being a glass substrate and the other side being an aluminum / glass substrate, with sealant in the middle. The device consists of an upper clamping strip and a lower clamping strip. Both the upper clamping strip and the lower clamping strip are strip-shaped, with a clamping part in the middle for clamping the specimen and connecting parts at both ends for connecting the upper clamping strip and the lower clamping strip. The clamping part is positioned lower than the connecting part, forming a groove shape, and the depth of the groove is less than half the sum of the thickness of the glass substrate and the aluminum / glass substrate; The connecting part has a threaded hole, and the threaded hole of the upper clamping bar is a countersunk threaded hole; The method of use includes: Step 1: The glass substrates of the first and second sealant test specimens are placed horizontally upwards. The aluminum / glass substrate of the second sealant test specimen is aligned and bonded to the glass substrate of the first sealant test specimen. Two pairs of upper and lower clamping strips are used to fix the two ends of the bonding surfaces of the first and second sealant test specimens to form the first fastener. Step 2: Place the third sealant test specimen aligned with the upper or lower end of the first fastener, with the glass substrate of the third sealant test specimen facing upwards. Use the upper and lower clamping strips to fix the third sealant test specimen to the first fastener in the same manner as in Step 2 to form the second fastener. Step 3: Repeat step 2 to fix N+1 sealant test specimens together to form the Nth fastener, where N is not less than 1; Step four: Place the Nth fastener onto the test fixture and secure the Nth fastener onto the test fixture using bolts.

2. The method of use according to claim 1, characterized in that, Before fixing the upper clamping strip and the lower clamping strip, the upper clamping strip and the lower clamping strip are pre-installed using bolts, and after the pre-installation, there is a gap between the connecting parts of the upper clamping strip and the lower clamping strip.

3. The method of use according to claim 1, characterized in that, In step four, a hard rubber plate and a metal plate are placed on both the upper and lower surfaces of the Nth fastener, with the metal plate on the upper surface above the hard rubber plate and the metal plate on the lower surface below the hard rubber plate.

4. The method of use according to claim 1, characterized in that, N is 4.

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