Test piece fastening device for fatigue cycle test of structural sealant and use method

Abstract

The invention provides a test piece fastening device for a fatigue cycle test of a structural sealant and a use method, the fastening device is composed of an upper clamping strip and a lower clamping strip, the upper clamping strip and the lower clamping strip are strip-shaped, the middle is a clamping part, and the two ends are connecting parts. During testing, the two ends of the binding faces of the two test pieces are fixed through the two pairs of upper clamping strips and the two pairs of lower clamping strips respectively to form a first fastening piece, then the test pieces are placed above or below the first fastening piece to be fixed, and the finally-formed fastening piece is placed on a testing clamp to be fixed. When a group of test pieces are repeatedly stretched back and forth, stress concentration of the test pieces is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of material testing devices, and in particular relates to a testing device and a use method thereof. Background Art

[0002] Structural sealant is a high-performance engineering material widely used in the fields of prefabricated buildings, building curtain walls, etc. It is mainly used for bonding and sealing key nodes and tiny gaps in building structures. This material plays the role of transferring loads and sealing in applications. Since buildings are subjected to self-weight, wind and other loads for a long time, structural sealants must be able to withstand certain pressures and deformations to ensure the integrity and sealing of the structure. Therefore, the fatigue cycle resistance of this material is crucial, and it has important practical significance for guiding the research and development of production enterprises, actual engineering construction, and engineering maintenance.

[0003] At present, the fatigue cycle performance test of structural sealants is mainly based on JG / T 475-2015 "Silicone Structural Sealant for Building Curtain Walls": Take a group of test pieces, subject them to repeated stretching, and perform fatigue cycle treatment with a cycle of 8s. The key element of the fatigue cycle performance test is to tighten and reliably constrain the test pieces to avoid stress concentration during repeated tensile testing. We concluded that there is a lack of test piece tightening and restraint devices with reasonable structure and reliable performance, making it difficult to achieve high-efficiency fatigue cycle performance testing of a group of test pieces with high quality. In addition, the test fixture used to test the tensile adhesion of "H" type test pieces in the existing building sealing material test method GB / T 13477.8-2017 can only achieve single tensile stress, and cannot meet the technical requirements of repeated back and forth stretching of a group of test pieces during fatigue cycle testing. Summary of the invention

[0004] To this end, the technical problem to be solved by the present invention is to provide a specimen fastening device for structural sealant fatigue cycle testing and a method of using the same, so as to avoid stress concentration in the specimens when a group of specimens are repeatedly stretched back and forth in the fatigue cycle test.

[0005] In the first aspect, the present invention discloses a specimen fastening device for fatigue cycle testing of structural sealants, wherein one side of the sealant specimen to be tested is a glass substrate, the other side is an aluminum / glass substrate, and there is sealant in the middle, and the device is composed of an upper clamping bar and a lower clamping bar; the upper clamping bar and the lower clamping bar are both in the shape of a bar, with a clamping part in the middle for clamping the specimen, and connecting parts at both ends for connecting the upper clamping bar and the lower clamping bar.

[0006] Furthermore, the clamping portion is located lower than the connecting portion to form a groove shape, and the depth of the groove is less than half of the sum of the thicknesses of the glass substrate and the aluminum / glass substrate; the connecting portion has a threaded hole, and the threaded hole of the upper clamping strip is a countersunk threaded hole.

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

[0008] In a second aspect, the present invention further discloses a method for using the aforementioned device, comprising:

[0009] Step 1: The glass substrates of the first sealant specimen to be tested and the second sealant specimen to be tested are both placed horizontally upward, the aluminum / glass substrate of the second sealant specimen to be tested is aligned and bonded with the glass substrate of the first sealant specimen to be tested, and two pairs of the upper clamping strips and the lower clamping strips are used to respectively fix the two ends of the bonding surface of the first sealant specimen to be tested and the second sealant specimen to be tested to form a first fastener.

[0010] Step 2: align and place a third sealant sample to be tested on the upper end or the lower end of the first fastener, with the glass substrate of the third sealant sample to be tested facing upward, and use the upper clamping strip and the lower clamping strip to fix the third sealant sample to be tested to the first fastener in the same manner as in step 2 to form a second fastener;

[0011] Step 3, repeating step 2, fixing N+1 sealant specimens to be tested together to form an Nth fastener, where N is not less than 1;

[0012] Step 4: placing the Nth fastener on a test fixture, and fixing the Nth fastener on the test fixture using bolts.

[0013] Furthermore, before fixing the upper clamp bar and the lower clamp bar, the upper clamp bar and the lower clamp bar are pre-installed using bolts, and after the pre-installation, a gap is provided between the connecting portions of the upper clamp bar and the lower clamp bar.

[0014] Furthermore, in the step 4, a hard rubber plate and a metal plate are placed on the upper and lower surfaces of the Nth fastener, the metal plate on the upper surface is located above the hard rubber plate, and the metal plate on the lower surface is located below the hard rubber plate.

[0015] Furthermore, N is 4.

[0016] Beneficial effects:

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

[0018] The fastening device of the present invention has wide applicability. The device can not only be used for fatigue cycle testing of structural sealants, but also can perform tension-compression cycle testing on a group of structural sealants at the same time according to the test process and parameters of standard GB / T 13477.12-2018, thereby saving time and cost.

[0019] On the other hand, the method for using the fastening device provided by the present invention only uses upper and lower clamping strips for connection, and the method for using is simple, and does not require complicated installation and debugging processes, so the operator can quickly get started and perform testing operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0021] Figure 1 A physical picture of the fixture slots for testing a group of specimens in parallel;

[0022] Figure 2 The front view and top view of the upper and lower clamping strips of Example 1 of the present invention;

[0023] (a) Upper clamp (b) Lower clamp

[0024] Figure 3 This is a front view of the pre-installed upper clamping strip and lower clamping strip of embodiment 2 of the present invention;

[0025] Figure 4 This is a three-dimensional view of two test pieces before being fixed in Example 2 of the present invention;

[0026] Figure 5 This is a front view of two test pieces after being fixed in Example 2 of the present invention;

[0027] Figure 6 It is a front view of a first fastener of Example 2 of the present invention;

[0028] Figure 7 It is a front view of the second fastener of Example 2 of the present invention;

[0029] Figure 8 It is a front view of the third fastener of Example 2 of the present invention;

[0030] Fig. 9 It is a front view of a fastener according to Embodiment 2 of the present invention;

[0031] Fig.10 This is a front view of the fastener of Example 2 of the present invention installed on a test fixture. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. The principles and features of the present invention are described below in combination with the accompanying drawings. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other without conflict. The embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.

[0033] JG / T 475-2015 "Silicone Structural Sealant for Building Curtain Walls" specifies the shape, size and substrate of the sealant specimen to be tested. The substrate can be AL, G and M. AL meets the requirements of GB / T13477.1, and the thickness of anodized aluminum is not less than 3mm; G meets the requirements of GB / T13477.1, and is clean, uncoated float glass with a thickness of not less than 5mm; M is other metal substrates required by the supplier. The sealant specimen to be tested in the embodiment of the present invention has a glass substrate on one side and an aluminum / glass substrate on the other side, with sealant in the middle.

[0034] Example 1

[0035] When conducting fatigue cycle performance test according to JG / T 475-2015 "Silicone Structural Sealant for Building Curtain Walls", it is required to repeatedly stretch a group of test pieces. "Silicone Structural Sealant for Building Curtain Walls" does not clearly specify the test process. In specific tests, because multiple test pieces have the same shape, in order to stretch multiple test pieces at the same time, technicians in this field have long used "parallel connection" of multiple test pieces and then put them into the fixture slot for testing. Figure 1 .

[0036] Theoretically, this testing method is more efficient, but technicians in the same field do not realize that the shapes and sizes of multiple specimens cannot be guaranteed to be completely consistent, and there are errors in the size of the fixture slots for installing each specimen, or improper use of the fixture, which will cause stress to be concentrated on the specimen with the smallest size in the tensile direction during the test.

[0037] After discovering the technical problems that need to be solved in the fatigue resistance cycle performance test, in order to overcome the defects of the prior art, the present invention attempts to get inspiration from the tensile adhesion of "H" type specimens tested in the building sealing material test method GB / T 13477.8-2017. 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 problem.

[0038] The present invention proposes a technical solution of "connecting a group of test pieces in series". In the series system, the force borne by each test piece is the same, so that the high stress that may originally be concentrated in a certain part is dispersed to each test piece in series.

[0039] It should be pointed out that in order to more vividly describe the technical solution of the present invention, the words parallel and series are used. In fact, those skilled in the art do not know this word when they use a group of test pieces to be placed in the fixture slot for testing. They naturally think that the placement of multiple test pieces should obviously be placed in the fixture slot side by side so that multiple test pieces can be stretched at the same time. Therefore, the technical solution of the present invention is not a simple association and conversion from parallel to series like other fields.

[0040] Moreover, even if the series connection method is considered, the first thing that needs to be solved is how to fasten multiple test pieces in series without causing uneven force on each test piece due to the fastening connection method.

[0041] Here, the embodiment of the present invention first proposes a specimen fastening device for fatigue cycle testing of structural sealants, such as Figure 2 As shown, the device consists of an upper clamping bar and a lower clamping bar; the upper clamping bar and the lower clamping bar are both in a bar shape, with a clamping portion in the middle for clamping the test piece, and connecting portions at both ends for connecting the upper clamping bar and the lower clamping bar.

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

[0043] Preferably, the upper clamping bar and the lower clamping bar are both aluminum clamping bars.

[0044] The specimen fastening device of the embodiment of the present invention adopts an upper clamping bar and a lower clamping bar, has a simple structure, and can firmly fix each specimen connected in series, so that the specimen is evenly stressed and new stress concentration is avoided.

[0045] Example 2

[0046] This embodiment is a method for using the fastening device of embodiment 1, and the method comprises the following steps:

[0047] Step 1: Place the two aluminum clips neatly in the upper and lower order, and slightly fix them with matching bolts at both ends. Figure 3 ;

[0048] Step 2, such as Figure 4 , Figure 5 As shown, take two sealant specimens to be tested, put the glass substrates horizontally upwards, and align them vertically up and down; put the pre-fixed fastening device on one end of the contact surface of the first sealant specimen to be tested and the second sealant specimen to be tested, adjust the positions of the bolts at both ends, and then rotate the screws to tighten.

[0049] Step 3, similarly, place another slightly fixed fastening device on the other end of the contact surface between the first sealant specimen to be tested and the second sealant specimen to be tested, adjust the positions of the bolts at both ends, and tighten them by rotating the screws to form a first fastener, see Figure 6 .

[0050] Step 4, take the third sealant specimen to be tested, with the glass substrate facing upward horizontally, and place it vertically aligned up and down on the upper end of the first fastener, and place the pre-slightly fixed fastening device on one end of the contact surface between the second sealant specimen to be tested and the third sealant specimen to be tested, and adjust the positions of the bolts at both ends to tighten one end of the constrained specimen. Similarly, place the slightly fixed fastening device on the other end of the contact surface between the second sealant specimen to be tested and the third sealant specimen to be tested, and adjust the positions of the bolts at both ends to tighten the other end of the constrained specimen to form a second fastener, see Figure 7 .

[0051] Step 5, take the fourth sealant specimen to be tested, and fix the fourth sealant specimen to be tested to the upper part of the second fastener with a fastening device according to the process of step 4 to form a third fastener. Figure 8 .

[0052] Step 6, take the fifth sealant specimen to be tested, and fix the fifth sealant specimen to be tested to the upper part of the third fastener using a fastening device in the same manner as in step 4, to form a final fastener 4, see Fig. 9 .

[0053] Step 7, place the assembled fourth fastener on the test fixture 1, which can be used for fatigue testing. Place a layer of hard rubber plate 3 and a layer of metal plate 2 on the upper and lower surfaces of the test piece, and finally use bolts to fix the entire fastener 4 on the test fixture 1. Figure 1 .

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

[0055] Of course, the upper clamping strip and the lower clamping strip can also be installed directly at the contact surface of the two test pieces without being pre-fixed. Although fixation can be achieved, the operation is inconvenient.

[0056] The method of using this embodiment is easy to operate. During fatigue cycle testing, a group of test pieces can be repeatedly stretched back and forth, thereby avoiding stress concentration on the test pieces during repeated stretching tests.

[0057] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0061] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A specimen fastening device for fatigue cycle testing of structural sealants, wherein 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 a sealant, characterized in that: The device is composed of an upper clamping bar and a lower clamping bar; the upper clamping bar and the lower clamping bar are both in a bar shape, with a clamping portion in the middle for clamping the test piece, and connecting portions at both ends for connecting the upper clamping bar and the lower clamping bar.

2. The device according to claim 1, characterized in that The clamping portion is located lower than the connecting portion to form a groove shape, and the depth of the groove is less than half of the sum of the thickness of the glass substrate and the aluminum / glass substrate; the connecting portion has a threaded hole, and the threaded hole of the upper clamping strip is a countersunk threaded hole.

3. The device according to claim 2, characterized in that The upper clamping strip and the lower clamping strip are both made of aluminum.

4. A method for using the device according to any one of claims 1 to 3, characterized in that: include: Step 1: The glass substrates of the first sealant specimen to be tested and the second sealant specimen to be tested are both placed horizontally upward, the aluminum / glass substrate of the second sealant specimen to be tested is aligned and bonded with the glass substrate of the first sealant specimen to be tested, and two pairs of the upper clamping strips and the lower clamping strips are used to respectively fix the two ends of the bonding surface of the first sealant specimen to be tested and the second sealant specimen to be tested to form a first fastener. Step 2: align and place a third sealant sample to be tested on the upper end or the lower end of the first fastener, with the glass substrate of the third sealant sample to be tested facing upward, and use the upper clamping strip and the lower clamping strip to fix the third sealant sample to be tested to the first fastener in the same manner as in step 2 to form a second fastener; Step 3, repeating step 2, fixing N+1 sealant specimens to be tested together to form an Nth fastener, where N is not less than 1; Step 4: placing the Nth fastener on a test fixture, and fixing the Nth fastener on the test fixture using bolts.

5. The method of use according to claim 4, characterized in that: Before fixing the upper clamp bar and the lower clamp bar, the upper clamp bar and the lower clamp bar are pre-installed using bolts, and after the pre-installation, a gap is provided between the connecting parts of the upper clamp bar and the lower clamp bar.

6. The method of use according to claim 4, characterized in that: In the step 4, a hard rubber plate and a metal plate are placed on the upper and lower surfaces of the Nth fastener, the metal plate on the upper surface is located above the hard rubber plate, and the metal plate on the lower surface is located below the hard rubber plate.

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

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