Method for measuring equivalent thickness of composite glass

Abstract

The invention discloses a method for measuring the equivalent thickness of composite glass, and belongs to the technical field of equivalent thickness measurement of composite glass. Under the same condition, the maximum deflection 1max of a single piece of glass and the maximum deflection 2max of the to-be-measured composite glass are measured, and the equivalent thickness of the to-be-measured composite glass can be obtained by substituting the maximum deflection 1max and the maximum deflection 2max into an equivalent thickness calculation formula. The method does not need to consider how to change a material, a lamination mode, a thickness direction material and a structure of the to-be-tested composite glass, the change is finally represented in the maximum deflection, the actual deformation bearing capacity of the structure can be reflected most truly only by testing the change, the obtained equivalent thickness has a good application prospect in promoting the application of the glass material in the field of engineering structures, and the application range is wide. And the method has important practical significance in guaranteeing the safety application of glass structure engineering.

Description

Technical Field

[0001] This invention relates to the field of equivalent thickness measurement technology for composite glass, and in particular to a method for measuring the equivalent thickness of composite glass. Background Technology

[0002] Glass materials are widely used in construction, aerospace, transportation, and other fields. To meet the functions of light transmission, structural load-bearing, energy saving, and thermal insulation, glass materials have gradually evolved from single-pane glass to various composite glass structures, such as commonly used laminated glass, vacuum glass, insulated glass, and composite structures composed of them. Currently, the application of single-pane glass in engineering is very rare; instead, various multi-layer composite glass is used to make various load-bearing structures such as beams and slabs.

[0003] Glass thickness is one of the important design parameters. For single-pane glass, the nominal thickness is generally sufficient to meet engineering accuracy requirements. However, for composite glass structures, due to the discontinuity and uniformity of the thickness direction, directly using the nominal thickness in the calculation will inevitably lead to large calculation errors or even incorrect results, seriously affecting the safety, stability, and service life of the glass structure in subsequent service.

[0004] Using equivalent thickness can greatly simplify the calculation of the load-bearing deformation performance of composite glass and obtain calculation results that meet engineering accuracy. However, due to the exceptionally complex or special structure of some composite glasses, it is even impossible to establish a theoretical model for equivalent thickness calculation, which poses certain challenges for structural designers in engineering applications. For beam specimens, under bending loads, the maximum stress and displacement are distributed in the center of the beam, with the maximum tensile stress at the center of the outer surface of the tension surface and the maximum compressive stress at the center of the outer surface of the compression surface, while the stress at the neutral axis of the beam is zero. Under laboratory conditions, four-point bending tests using beam specimens are a common method. Under these conditions, the beam segment between the loading heads only bears bending moment and is not affected by shear force, belonging to a pure bending state, thus effectively simulating the bending stress of laminated glass in actual use. Calculating the mechanical parameters under four-point bending using the determined equivalent thickness can provide a valid reference for the performance evaluation of this type of bending member. In addition, composite glass is often used as a plate-like member in practical engineering, often bearing uniformly distributed loads such as wind loads and snow loads. The equivalent thickness is significantly affected by the loading method and the geometry of the component. Therefore, when calculating the mechanical parameters of composite glass panels under uniformly distributed loads based on the equivalent thickness, accurate and reliable calculation values ​​must be provided to ensure the safety of the engineering structure. For this reason, it is necessary to develop a method for detecting and evaluating the equivalent thickness of plate-shaped specimens. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for determining the equivalent thickness of composite glass. This invention, through experimental methods and comparative experiments under identical conditions, can obtain a relatively accurate equivalent thickness value for the composite glass under test. It features convenient operation and accurate data, making it particularly suitable for determining the equivalent thickness of various composite glass structures. This has significant practical implications for promoting the application of glass materials in engineering structures and ensuring the safe application of glass structure engineering.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] The composite glass defined in this invention refers to a component consisting of two or more single pieces of glass that are laminated and fixed together with other materials and possess load-bearing capacity, wherein the thickness direction exhibits material heterogeneity or continuity. Examples include vacuum glass, laminated glass, and vacuum-laminated composite glass.

[0008] In this invention, "effective thickness" refers to the deflection equivalent thickness. The deflection equivalent thickness is defined as follows: when the load conditions, support boundary conditions, glass shape, and dimensions other than thickness are identical, the deflection of the composite glass under test at the same location is equal to the deflection of a single piece of glass of a certain thickness. In this case, the nominal thickness of the single piece of glass can be used as the deflection equivalent thickness of the composite glass under test.

[0009] The inventors discovered that by selecting flat monolithic glass and composite glass of the same length and width dimensions, under the same load conditions and support, the maximum deflection produced can be ƒ respectively. 1max and ƒ 2max The calculation formulas are as follows:

[0010] (1)

[0011] (2)

[0012] In the formula:

[0013] t1 — The thickness of a single pane of glass, in millimeters (mm).

[0014] t equ —Equivalent thickness of the composite glass to be tested, in millimeters (mm);

[0015] k — a variable related to the length and width dimensions of the glass, the support method, and the stress state.

[0016] In actual testing, under the same conditions, the maximum deflection ƒ of a single pane of glass is measured. 1max and the maximum deflection ƒ of the composite glass to be tested 2maxThe equivalent thickness of the composite glass under test can be obtained from the calculation results. There is no need to consider changes in the materials, lamination method, thickness direction, or structure of the composite glass under test; its final manifestation is the change in maximum deflection. Only this change needs to be tested, providing the most accurate reflection of the structure's actual load-bearing deformation capacity.

[0017] The formula for calculating the equivalent thickness only requires equation (1) / (2), that is:

[0018] (3);

[0019] The formula for calculating the equivalent thickness is as follows:

[0020] (4).

[0021] Based on the above, the present invention provides a method for determining the equivalent thickness of composite glass, including:

[0022] Step 1: Prepare the sample. The sample consists of a single piece of glass and the composite glass to be tested, both with the same length and width dimensions.

[0023] When the glass type of the composite glass sample to be tested is a single type, the glass composition and processing technology of the single glass and the composite glass to be tested must be the same. When the composite glass sample to be tested uses two or more types of glass, the single glass should be the same type as the tensioned glass of the composite glass to be tested. Specifically, the thickness of the single glass should be similar, but the thickness test of the composite glass to be tested is non-destructive. The comparison sample can be reused, but a visual inspection should be performed before the test, and there should be no visible scratches, cracks, chipping, or other defects. Preferably, the composite glass sample to be tested is a plate sample, the length of which is 1020 mm ± 1 mm, and the width of which is 1020 mm ± 1 mm.

[0024] Step 2: The negative pressure application device applies loads to the single glass and the composite glass to be tested under the same conditions, and plots the load-maximum deflection curves of the single glass and the composite glass to be tested.

[0025] Step 3: Determine the linear segment of the load-maximum deflection curve. Within this linear segment, arbitrarily select a load P. Based on the load-maximum deflection curve, obtain the maximum deflection ƒ of a single pane of glass under the specific load P condition. 1max The maximum deflection of the composite glass under test ƒ 2max ;

[0026] The equivalent thickness of the deflection is calculated using the following formula:

[0027] ;

[0028] Among them, t equ The equivalent thickness for deflection is expressed in millimeters (mm).

[0029] ƒ 1max The maximum deflection of a single pane of glass under load P is expressed in millimeters (mm).

[0030] ƒ 2max The value is the maximum deflection of the composite glass under load P, expressed in millimeters (mm).

[0031] t1 is the thickness of a single pane of glass, in millimeters (mm).

[0032] Furthermore, the negative pressure application device includes a stainless steel metal cavity and a vacuum pump communicating with the stainless steel metal cavity. A pressure gauge is also provided on the side of the stainless steel metal cavity. The top of the stainless steel metal cavity is open and extends outward to form an overlapping platform. A vertical metal short plate is fixed to the outer extension of the overlapping platform. The sample is placed on the overlapping platform, and the space between the sample and the metal short plate is filled with sealant. The vacuum pump is used to draw a vacuum to achieve negative pressure loading.

[0033] Preferably, the top opening of the stainless steel metal cavity is 1000mm±2mm, the width of the overlapping platform is 20mm±2mm, forming an opening with a size of 1040mm±2mm; the thickness of the stainless steel metal cavity is 5mm.

[0034] Preferably, a rubber gasket is provided between the sample and the overlapping platform. The rubber gasket has a width of 10.0±1.0 mm, a thickness of 5.0±0.1 mm, and a Shore hardness of 85±5. The sealant filling width is 10.0±1.0 mm.

[0035] For deflection equivalent thickness testing: place the deflection measuring device on the specimen, align it with the center position of the upper surface of the specimen (the intersection of the midlines of the two adjacent sides of the upper surface during the test), and then load the specimen at a loading rate of 50 Pa ± 1 Pa / min. When the load reaches an integer multiple of 50 Pa, stop and maintain the load for 1 min, record the maximum deflection value, and plot the load-maximum deflection curve.

[0036] Preferably, the deflection measuring device is a dial indicator or a non-contact displacement sensor; preferably, the deflection measuring device is a linear variable differential transformer (LVDT), which is aligned with the center of the upper surface of the sample to ensure that it is in contact with the sample throughout the entire process.

[0037] Preferably, the composite glass to be tested is one of vacuum glass, laminated glass, or vacuum laminated glass.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] This invention compares and tests on composite glass and monolithic glass under the same conditions to obtain a more accurate equivalent thickness value of the composite glass. It features convenient operation and accurate data, and is particularly suitable for determining the equivalent thickness of composite glass structures of various plate samples. It has important practical significance for promoting the application of glass materials in the field of engineering structures and ensuring the safe application of glass structure engineering. Attached Figure Description

[0040] Figure 1 Schematic diagram of the negative pressure application device for plate sample;

[0041] Figure 2 This is a load-maximum deflection curve of a single pane of glass in Example 1;

[0042] Figure 3 This is a load-maximum deflection curve of the PVB laminated glass in Example 1;

[0043] Figure 4 This is a load-maximum deflection curve of the SGP laminated glass in Example 2;

[0044] Figure 5 This is a load-maximum deflection curve of the vacuum glass in Example 3;

[0045] Figure 6 This is the load-maximum deflection curve of the composite glass in Example 4. Detailed Implementation

[0046] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with specific drawings and embodiments.

[0047] Unless otherwise specified, all materials and devices used in this invention can be purchased commercially. The length of the plate sample is 1020 mm ± 1 mm, and the width of the sample is 1020 mm ± 1 mm.

[0048] The laser displacement gauge is accurate to 1μm, and the relative error of the deflection reading is less than ±1%.

[0049] During the application of load, the sample needs to be fixed on the negative pressure application device, such as... Figure 1 As shown, it includes a stainless steel metal cavity 7 and a vacuum pump 6 connected to the stainless steel metal cavity 7. A pressure gauge 5 is also provided on the side of the stainless steel metal cavity 7. The top of the stainless steel metal cavity 7 is open and extends to the surrounding area to form an overlapping platform 8. A vertical metal short plate 9 is fixed to the outer extension of the overlapping platform 8. The sample 2 is placed on the overlapping platform 8. The space between the sample 2 and the metal short plate 9 is filled with sealant 4. The vacuum pump 6 is used to draw a vacuum, forming a negative pressure chamber 1 below the sample 2 to achieve negative pressure loading.

[0050] Preferably, the top opening size a of the stainless steel metal cavity 7 is 1000mm±2mm, and the width b of the overlapping platform 8 is 20mm±2mm; the thickness of the stainless steel plate constituting the stainless steel metal cavity 7 is 5mm; a neoprene rubber gasket 3 is provided between the sample 2 and the overlapping platform 8, the neoprene rubber gasket 3 being 10.0±1.0mm wide, 5.0±0.1mm thick, and having a Shore hardness of 85±5; the sealant 4 having a filling width of 10.0±1.0mm, and the sample is fixed to the negative pressure application device by the sealant.

[0051] After the glass is installed, a deflection detection device mounted on a bracket is placed above the stainless steel metal cavity 7. This deflection measuring device (linear variable differential transformer, LVDT) is used to measure the deflection change of the tensile surface of the specimen. It is aligned with the center of the upper surface of the specimen, ensuring full contact throughout the test. Once the deflection detection device is fixed, it is connected to the power supply and computer. The specimen should be placed 24 hours before the start of the test and stored in the test environment (23°C ± 1°C, relative humidity 40%-80%) for at least 4 hours before the test. During the test, a vacuum pump is used to extract air from the cavity, and the pressure gauge reading is used to determine the current load level.

[0052] This invention provides a method for determining the equivalent thickness of composite glass, and specific embodiments are as follows.

[0053] Example 1

[0054] A method for determining the equivalent thickness of composite glass, comprising:

[0055] Step 1: Prepare a single pane of glass (tempered glass with a length of 1020 mm, a width of 1020 mm, and a thickness of 8 mm) and a PVB laminated glass (with a length of 1020 mm, a width of 1020 mm, consisting of 8 mm glass + 0.38 mm PVB + 8 mm glass). The composition and processing technology of the glass in the laminated glass are exactly the same as those of the single pane of glass.

[0056] Step 2: Fix the single piece of glass onto the negative pressure application device, and fix the laser displacement gauge at the center of the upper surface of the specimen. The specimen should be placed 24 hours before the start of the test and stored for 6 hours in the test environment (23°C±1°C, relative humidity 40%-80%) before the test; loading rate (50Pa±1.0Pa) / min. Stop and maintain the load for 1 minute every time the load reaches an integer multiple of 50Pa, and record the deflection value; until the maximum load value is 4000Pa, and the specimen should not break during the entire loading process.

[0057] The loads and their corresponding maximum deflections are shown in Table 1.

[0058] Then, the PVB laminated glass was fixed on the negative pressure application device, and the same testing conditions as the monolithic glass were used to obtain the load and the corresponding maximum deflection, as shown in Table 1.

[0059] Table 1

[0060]

[0061] Based on the above data, the load-maximum deflection curves for monolithic glass and PVB laminated glass were obtained, as follows: Figure 2-3 ;

[0062] Step 3: From Figure 2 It can be seen that for monolithic glass, the load is linear below 4000 Pa; for laminated glass, the load is linear. Figure 3 It can be seen that the load is below 4000 Pa and is also a linear segment. Here, loads of 1000 Pa, 2000 Pa, 3000 Pa and 4000 Pa are selected respectively. The corresponding equivalent thickness is calculated according to the following formula based on the corresponding maximum deflection. The results are shown in Table 2.

[0063]

[0064] Among them, t equ The equivalent thickness for deflection is expressed in millimeters (mm).

[0065] ƒ 1max The maximum deflection of a single pane of glass under load P is expressed in millimeters (mm).

[0066] ƒ 2max The value is the maximum deflection of the composite glass under load P, expressed in millimeters (mm).

[0067] t1 is the thickness of a single pane of glass, in millimeters (mm).

[0068] Table 2

[0069]

[0070] As shown in Table 2, the equivalent thickness calculation method of the present invention yields small differences in the calculated deflection equivalent thickness under different load and wind pressure levels, indicating that the method has good repeatability.

[0071] Example 2

[0072] In this embodiment, the composite glass is 8mm glass + 0.38mm SGP + 8mm glass, and the other conditions are the same as in Embodiment 1. The corresponding deflections are shown in Table 3.

[0073] Table 3

[0074]

[0075] From the data in Table 3, the load-maximum deflection curve of the SGP laminated glass is obtained as follows: Figure 4 .

[0076] With loads of 1000 Pa, 2000 Pa, 3000 Pa, and 4000 Pa selected, the corresponding equivalent thickness was calculated based on the maximum deflection. The results are shown in Table 4.

[0077] Table 4

[0078]

[0079] As shown in Table 4, the equivalent thickness calculation method of the present invention yields small differences in the calculated deflection equivalent thickness under different load and wind pressure levels, indicating that the method has good repeatability.

[0080] Example 3

[0081] In this embodiment, the composite glass is 8mm glass + vacuum (support height 0.1 mm) + 8mm glass, and the other conditions are the same as in Embodiment 1. The corresponding deflections are shown in Table 5.

[0082] Table 5

[0083]

[0084] From the data in Table 5, the load-maximum deflection curve of the vacuum glass is obtained as follows: Figure 5 .

[0085] With loads of 1000 Pa, 2000 Pa, 3000 Pa, and 4000 Pa selected, the corresponding equivalent thickness was calculated based on the maximum deflection. The results are shown in Table 6.

[0086] Table 6

[0087]

[0088] As shown in Table 6, the equivalent thickness calculation method of the present invention yields small differences in the calculated deflection equivalent thickness under different load and wind pressure levels, indicating that the method has good repeatability.

[0089] Example 4

[0090] In this embodiment, the composite glass consists of 6mm glass + vacuum (support height 0.1 mm) + 6mm glass + EVA (0.38mm) + 6mm glass, with other conditions the same as in Embodiment 1. The corresponding deflections are shown in Table 7.

[0091] Table 7

[0092]

[0093] From the data in Table 7, the load-maximum deflection curve of the vacuum laminated glass is obtained as follows: Figure 6 .

[0094] With loads of 1000 Pa, 2000 Pa, 3000 Pa, and 4000 Pa selected, the corresponding equivalent thickness was calculated based on the maximum deflection. The results are shown in Table 8.

[0095] Table 8

[0096]

[0097] As shown in Table 8, the equivalent thickness calculation method of the present invention yields small differences in the calculated deflection equivalent thickness under different load and wind pressure levels, indicating that the method has good repeatability.

[0098] In summary, this invention allows for comparative testing of composite glass and monolithic glass under the same conditions, yielding a more accurate equivalent thickness value for the composite glass under test. It features convenient operation and accurate data, making it particularly suitable for determining the equivalent thickness of various composite glass structures.

[0099] The above description is a preferred embodiment of the present invention. For those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for determining the equivalent thickness of composite glass, characterized in that, include: Step 1: Prepare the composite glass sample to be tested, and prepare a single piece of glass with the same length and width as the composite glass sample to be tested as a comparison glass. Step 2: Apply loads to the single glass and the composite glass under test under the same conditions using a negative pressure application device, and plot the load-maximum deflection curves of the single glass and the composite glass under test. Step 3: Determine the linear segment of the load-maximum deflection curve. Within this linear segment, arbitrarily select a load P. Based on the load-maximum deflection curve, obtain the maximum deflection ƒ of a single pane of glass under the specific load P condition. 1max The maximum deflection of the composite glass under test ƒ 2max Three composite glass samples were selected for each group for testing, and the average value was taken as the final result. The equivalent thickness of the deflection is calculated using the following formula (I): （I）； Among them, t equ The equivalent thickness for deflection is expressed in millimeters. ƒ 1max The maximum deflection of a single pane of glass under load P is expressed in millimeters. ƒ 2max The maximum deflection of the composite glass under test is expressed in millimeters under load P. t1 is the thickness of a single pane of glass, in millimeters.

2. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, In step 1, the sample is a plate sample with a length of 1020 mm ± 1 mm and a width of 1020 mm ± 1 mm.

3. The method for determining the equivalent thickness of composite glass according to claim 2, characterized in that, The negative pressure application device includes a stainless steel metal cavity and a vacuum pump connected to the stainless steel metal cavity. A pressure gauge is also provided on the side of the stainless steel metal cavity. The top of the stainless steel metal cavity is open and extends outward to form an overlapping platform. A vertical metal short plate is fixed to the outer extension of the overlapping platform. The sample is placed on the overlapping platform, and the space between the sample and the metal short plate is filled with sealant. The vacuum pump is used to draw a vacuum to achieve negative pressure loading.

4. The method for determining the equivalent thickness of composite glass according to claim 3, characterized in that, The top opening of the stainless steel metal cavity is 1000mm ± 2mm, the width of the overlapping platform is 20mm ± 2mm, and the thickness of the stainless steel metal cavity is 5mm.

5. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, A rubber gasket is provided between the sample and the overlapping platform. The rubber gasket is 10.0±1.0mm wide, 5.0±0.1mm thick, and has a Shore hardness of 85±5. The sealant filling width is 10.0±1.0mm.

6. The method for determining the equivalent thickness of composite glass according to claim 5, characterized in that, In step 2, before applying the load, align the deflection measuring device with the center of the upper surface of the specimen to ensure that the deflection measuring device and the specimen are in contact throughout the process. Then, load the specimen at a rate of 50 Pa ± 1.0 Pa / min. Stop and maintain the load for 1 minute every time the load reaches an integer multiple of 50 Pa, and record the deflection value. The maximum load value shall not exceed 3000 Pa, and the specimen shall not break during the entire loading process. Plot the load-maximum deflection curve.

7. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, The glass type of the composite glass sample to be tested is one, and the glass composition and processing technology of the single glass and the composite glass to be tested are the same.

8. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, The composite glass sample to be tested uses two or more types of glass, and the single glass piece is selected from the same type of glass as the tensile glass of the composite glass to be tested.

9. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, The thickness of the single glass pane is 85%-99% of the thickness of the composite glass to be tested.

10. The method for determining the equivalent thickness of composite glass according to claim 1, characterized in that, The composite glass to be tested is one of vacuum glass, double-layer laminated glass, multi-layer laminated glass, or vacuum laminated composite glass.

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