High temperature axial compression test specimen end displacement measuring device

Abstract

The application provides a high-temperature axial compression test specimen end displacement measuring device, which comprises an end plate, a heat-resistant rigid rod, a fixing clamp, a connecting sheet, a heat insulation sheet and a linear displacement meter; the end plate is used for being placed at the upper and lower ends of a to-be-tested specimen in a high-temperature furnace to transfer the relative displacement of the two ends of the specimen; the heat-resistant rigid rod is connected with the end plate through the fixing clamp and is used for transferring the relative displacement of the end plate to outside of the high-temperature furnace; the connecting sheet is connected with one end of the heat-resistant rigid rod outside of the high-temperature furnace; the linear displacement meter is connected with the connecting sheet through the heat insulation sheet, the heat insulation sheet is used for blocking heat propagation and preventing the linear displacement meter from being damaged by high temperature, and the linear displacement meter is used for measuring the displacement of the heat-resistant rigid rod. The rigid rod made of heat-resistant low-expansion material is used to indirectly obtain the deformation displacement of the end of the axial compression test specimen under high temperature, so that the measurement of the end displacement of the specimen is more convenient, and the mechanical connection between the components improves the stability and accuracy of the displacement measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to experimental mechanics high temperature measurement technology, and in particular, to a kind of high temperature axial compression test specimen end displacement measuring device. BACKGROUND

[0002] In actual engineering, axial compression members are widely used in buildings. In addition, building fires occur frequently, and the mechanical properties of axial compression members at high temperatures are of great concern. Therefore, the study of the ultimate bearing capacity of axial compression test specimens at high temperatures is of great significance, and the end displacement of the test specimen needs to be measured in this study. Common deformation displacement measurement methods include contact and non-contact methods. Contact mainly uses displacement meters for direct measurement, and non-contact uses digital image correlation measurement technology.

[0003] Compared with normal temperature, high temperature axial compression test has certain particularity: first, the test is carried out in a closed high temperature furnace, and the deformation displacement measuring device in the high temperature furnace must be resistant to high temperature, so the ordinary contact displacement meter measurement method is not available. Second, the existence of hot air disturbance in the high temperature environment will affect the measurement accuracy of the non-contact digital image correlation measurement technology, so this method is also not available.

[0004] In the current high temperature axial compression test, the deformation displacement is usually measured by pulling the line, and the molybdenum wire is used to connect the end plate of the axial compression test specimen in the high temperature furnace with the linear displacement meter outside the high temperature furnace to obtain the deformation displacement of the test specimen. In this method:

[0005] Firstly, the connection between the molybdenum wire and the end plate and the displacement meter is troublesome and unstable;

[0006] Secondly, since the molybdenum wire needs to be straightened as much as possible, the linear displacement meter will lose part of the range due to the tension of the molybdenum wire;

[0007] In addition, the molybdenum wire is not easy to be completely straightened, and it cannot be guaranteed that the displacement measured by the displacement meter is completely the displacement of the end of the test specimen, and part of the displacement may come from the deformation displacement of the molybdenum wire itself, and the accuracy is low. SUMMARY

[0008] In view of the defects in the prior art, the purpose of the present application is to provide a high temperature axial compression test specimen end displacement measuring device, which indirectly obtains the deformation displacement of the end of the axial compression test specimen at high temperature by using a rigid rod of heat-resistant low-expansion material, so that the measurement of the end displacement of the test specimen is more convenient, and the mechanical connection between the components improves the stability and accuracy of the displacement measurement.

[0009] The high temperature axial compression test specimen end displacement measuring device provided by the present application comprises an end plate, a heat-resistant rigid rod, a fixing clamp, a connecting sheet, a heat insulation sheet and a linear displacement meter.

[0010] The end plate is used to be placed at the upper and lower ends of the test piece in the high-temperature furnace to transfer the relative displacement of the two ends of the test piece.

[0011] The heat-resistant rigid rod is connected to the end plate through the fixing clamp and is used to transfer the relative displacement of the end plate to the outside of the high-temperature furnace.

[0012] The connecting piece is connected to one end of the heat-resistant rigid rod outside the high-temperature furnace.

[0013] The linear displacement meter is connected to the connecting piece through the heat insulation piece, the heat insulation piece is used to block the heat propagation and prevent the linear displacement meter from being damaged by high temperature, and the linear displacement meter is used to measure the displacement of the heat-resistant rigid rod.

[0014] Preferably, the end plate comprises an upper end plate and a lower end plate.

[0015] The upper end plate is used to be placed at the upper end of the test piece in the high-temperature furnace.

[0016] The lower end plate is used to be placed at the lower end of the test piece in the high-temperature furnace.

[0017] Preferably, the end plate is square.

[0018] A first threaded blind hole is formed in the center of the four sides of the end plate, and the first threaded blind hole is used to connect the fixing clamp.

[0019] Preferably, one end of the heat-resistant rigid rod is provided with an external thread.

[0020] The heat-resistant rigid rod is connected to the connecting piece through the external thread.

[0021] Preferably, one end of the fixing clamp is provided with an external thread, and the external thread is connected to the end plate.

[0022] The other end of the fixing clamp is provided with a vertical through-hole with a mouth, and the through-hole with a mouth is used to clamp the heat-resistant rigid rod.

[0023] Preferably, threaded through-holes are formed in two fixing plates extending from the through-hole with a mouth, and the threaded through-holes are used to install bolts and nuts to adjust the tightness of the clamping of the fixing plates.

[0024] Preferably, a second threaded blind hole is formed in the center of the connecting piece, and the second threaded blind hole is used to connect the heat-resistant rigid rod.

[0025] Four corners of the connecting piece are provided with through-holes, and the through-holes are used to install bolts to connect the heat insulation piece.

[0026] Preferably, the linear displacement meter is supported on the heat insulation piece through a support.

[0027] Preferably, the number of the heat-resistant rigid rods is four, and each of the heat-resistant rigid rods is connected to the first threaded blind hole of the side surface of the end plate through the fixing clamp.

[0028] Preferably, the heat insulation sheet is heat insulation glass, and the heat-resistant rigid rod is a ceramic rod.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] 1. The whole displacement measuring device is connected and assembled through screw connection, clamping and the like, simple and convenient to operate, and high in stability.

[0031] 2. The heat-resistant rigid rod in the present application is made of low-expansion material, and the length of the heat-resistant rigid rod is hardly affected by high temperature. The relative displacement of the heat-resistant rigid rods connected to the upper and lower end plates is the relative displacement of the two ends of the test piece, and the measuring precision is high.

[0032] 3. The position of the heat-resistant rigid rod clamped by the steel clamp can be adjusted, and the length of the heat-resistant rigid rod vertically downward relative to the end plate can be adjusted, so that the present application is suitable for measuring the end deformation displacement of test pieces of different lengths.

[0033] 4. The experimental device is easy to obtain and simple to manufacture. BRIEF DESCRIPTION OF DRAWINGS

[0034] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0035] Figure 1 It is a schematic diagram of the principle of converting the end displacement of the test piece in the high-temperature furnace to the measurement in the normal-temperature environment in the embodiment of the present application.

[0036] Figure 2 It is a structural schematic diagram of the end displacement measuring device of the test piece in the high-temperature axial compression test in the embodiment of the present application.

[0037] Figure 3 It is an elevation view of the end displacement measuring device of the test piece in the high-temperature axial compression test in the embodiment of the present application.

[0038] Figure 4 It is a plan view of the end plate in the embodiment of the present application.

[0039] Figure 5 It is a front view of the end plate in the embodiment of the present application.

[0040] Figure 6 It is a plan view of the component for clamping the heat-resistant rigid rod in the embodiment of the present application.

[0041] Figure 7 It is a front view of the component for clamping the heat-resistant rigid rod in the embodiment of the present application.

[0042] Figure 8 This is a plan view of the connecting piece and the glass sheet after connection in an embodiment of the present invention;

[0043] Figure 9 This is a front view of the connecting piece and the glass sheet after they are connected in an embodiment of the present invention;

[0044] In the figure: 1 is the axial compression test piece; 2 is the end plate; 3 is the heat-resistant rigid rod; 4 is the fixing clamp; 5 is the connecting piece; 6 is the heat insulation piece; 7 is the fixing clamp locking bolt; 8 is the fixing clamp locking nut; 9 is the locking bolt; 10 is the locking nut; 11 is the linear displacement gauge; 12 is the threaded blind hole of the end plate; 13 is the through hole with an opening; 14 is the threaded blind hole of the connecting piece; 15 is the fixing rod. Detailed Implementation

[0045] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0046] like Figure 1 As shown, the present invention can convert the end displacement of the specimen in the axial compression test into the relative displacement between the end plates placed at both ends of the specimen. The end displacement of the specimen at high temperature is led out of the high temperature furnace by the heat-resistant rigid rod connected to the end plate. The displacement of the ceramic rod is measured by a linear displacement meter at room temperature, thereby indirectly obtaining the end displacement of the specimen in the axial compression test.

[0047] like Figure 2 As shown, the high-temperature axial compression test specimen end displacement measuring device provided by the present invention includes an end plate 2, a heat-resistant rigid rod 3, a fixing clamp 4, a connecting piece 5, a heat insulation piece 6, a locking bolt 7 for adjusting the tightness of the fixing clamp 4 and a matching locking nut 8, a locking bolt 9 for fixing the connecting piece 5 and the heat insulation piece 6 and a matching locking nut 10, and a linear displacement meter 11.

[0048] In this embodiment of the invention, the fixing clip 4 is a rigid clip, the connecting piece 5 is a rigid sheet, the heat insulation piece 6 is heat-insulating glass, and the heat-resistant rigid rod 3 is a ceramic rod.

[0049] The end plate 2 is divided into upper and lower parts, which are placed on the upper and lower ends of the axial compression specimen 1, respectively; one end of the heat-resistant rigid rod 3 is connected to the threaded blind hole of the connecting piece 5 through the external thread, and the whole is held by the fixing clamp 4. The clamping tightness of the fixing clamp 4 is determined by the locking bolt 7 and the locking nut 8; the connecting piece 5 and the heat insulation piece 6 are connected by the locking bolt 9 and the locking nut 10; the pull rod of the linear displacement meter 11 will be vertically pushed against the lower end of the heat insulation piece 6.

[0050] In this embodiment, as shown in Figure 2 , 3 , the upper and lower end plates are connected with other components in the same way, except that the position of the heat-resistant rigid rod 3 clamped by the fixed clamp 4 is adjusted according to the length of the shaft test piece 1 in the test, so only the upper end plate is described in the following embodiments (the end plate 2 described below refers to the upper end plate).

[0051] In this embodiment, as shown in Figure 4 , Figure 5 , the end plate 2 is a square steel plate, which must be relatively thick to prevent deformation under pressure in the shaft test. Threaded blind holes 12 of appropriate depth are provided on the four sides of the end plate 2 (in actual connection, only two holes on opposite sides are usually needed, but to use more flexibly, threaded blind holes are provided on all four sides), to ensure that the fixed clamp 4 can be stably connected with the end plate 2.

[0052] In this embodiment, as shown in Figure 6 , Figure 7 , one end of the fixed clamp 4 is provided with external threads, which is connected with the end plate 2 through the threaded blind hole 12; the other end of the fixed clamp 4 is provided with a circular through-hole 13 with a mouth, which is used to clamp the heat-resistant rigid rod 3; the clamping tightness of the fixed clamp 4 is controlled by the locking bolt 7 and the locking nut 8.

[0053] In this embodiment, the heat-resistant rigid rod 3 is in the shape of an elongated cylinder, and the material used must have low linear expansion to prevent the displacement measured by the device from being affected by the expansion of the heat-resistant rigid rod at high temperature, ensuring the accuracy of the device measurement. Low-expansion ceramics can be used; the lower end of the heat-resistant rigid rod 3 is provided with external threads for connecting the connecting plate 5.

[0054] In this embodiment, as shown in Figure 8 , Figure 9 , the connecting plate 5 and the heat insulation plate 6 are rectangular plates of the same size, with the connecting plate 5 on top and the heat insulation plate 6 on bottom; circular through-holes are provided at the four corners of the connecting plate 5 and the heat insulation plate 6, which are used to pass through the four locking bolts 9, and the two are tightly connected by the four locking nuts 10; a threaded blind hole is provided on the upper surface of the connecting plate 5, which is connected with the heat-resistant rigid rod 3 through the external threads at the lower end of the heat-resistant rigid rod 3.

[0055] In this embodiment, the pull rod of the linear displacement meter 11 is vertically placed on the lower surface of the heat insulation plate 6 and connected with the shaft test system to obtain the relative displacement of the end of the test piece 1.

[0056] In this embodiment, all components of the device are made by precision machining, and the assembly is connected by threads and threaded holes, bolts and nuts, without any welding process, ensuring the dimensional accuracy and surface flatness of the device. In addition, this stable mechanical connection also improves the accuracy of displacement measurement, and the installation is time-saving and labor-saving, and the operation is simple.

[0057] When using the high-temperature axial compression test specimen end displacement measuring device provided in the embodiment of the application, the following steps are taken:

[0058] Step 1: Measure the geometric dimensions of the axial compression test specimen 1.

[0059] Step 2: According to the data obtained from the geometric dimensions, select the appropriate size of the end plate 2, the heat-resistant rigid rod 3, the fixing clamp 4, the locking bolt 7, and the locking nut 8, and prepare the corresponding number, as shown in the reference Figure 2 ;

[0060] Step 3: Threaded blind holes 12 are respectively formed in the two end plates 2, as shown in the reference Figure 4 , and are placed at the upper and lower ends of the axial compression test specimen 1, and the geometric centers of the upper and lower ends of the axial compression test specimen 1 are aligned with the geometric centers of the upper and lower end plates, and the side directions of the upper and lower end plates are consistent.

[0061] Step 4: One end of the heat-resistant rigid rod 3 is provided with external threads.

[0062] Step 5: The fixing clamp 4 is provided with external threads, a port circular hole 13, and a threaded hole, as shown in the reference Figure 6 .

[0063] Step 6: Threaded blind holes 14 and circular holes are formed in the connecting piece 5, and circular holes are formed in the heat insulation piece 6, and the connecting piece 5 and the heat insulation piece 6 are connected and fixed by the locking bolt 9 and the locking nut 10.

[0064] Step 7: Two fixing clamps 4 are respectively screwed into the left and right sides of the upper end plate, as shown in the reference Figure 2 , and the two fixing clamps 4 are respectively screwed into the front and rear sides of the upper and lower end plates, as shown in the reference Figure 2 , and the front and rear directions of the front view are used as the reference, and the upper surface of the fixing clamp 4 is used as the reference, and the upper surface of the end plate 2 is used as the reference, and the corresponding surface in the reference Figure 6 is used as the reference, and the corresponding surface in the reference Figure 4 is used as the reference, and the corresponding surface in the reference is used as the reference, to ensure that the heat-resistant rigid rod 3 and the end plate 2 are in a vertical relationship.

[0065] Step 8: pass the heat-resistant rigid rod 3 through the circular through-hole with an opening in the fixing clamp 4, and adjust the clamping position to make the lower end of the heat-resistant rigid rod 3 extend out of the high-temperature furnace, and clamp the heat-resistant rigid rod 3 with the fixing clamp 4 by using the locking bolt 7 and the locking nut 8 so that the heat-resistant rigid rod 3 cannot move up and down; clamp the heat-resistant rigid rod with four fixing clamps, and the operation is the same;

[0066] Step 9: screw the lower end of the four heat-resistant rigid rods 3 extending out of the high-temperature furnace into the threaded blind holes 14 in the four connecting plates 5 respectively, and install the displacement meters 11 at the lower end of each heat insulation plate 6, and make sure that the displacement meters are installed vertically; Figure 6 ) in the four connecting plates 5 respectively, and install the displacement meters 11 at the lower end of each heat insulation plate 6, and make sure that the displacement meters are installed vertically;

[0067] Step 10: start the test loading under high temperature, and finally obtain the relative displacement of the end of the axial compression test piece by subtracting the average value of the front and rear displacement meters from the average value of the left and right displacement meters, as shown in the following formula: Figure 2 .

[0068] In the embodiment of the present application, the end displacement of the axial compression test piece in the axial compression test is equivalent to the relative displacement between the end plates placed at the two ends of the test piece, the end displacement of the test piece under high temperature is led out of the high-temperature furnace through the heat-resistant rigid rods connected to the end plates, the displacement of the ceramic rod is measured by using the linear displacement meter at normal temperature, and thus the end displacement of the axial compression test piece is indirectly obtained. The whole device has clear principle, simple manufacturing, convenient use, and high measurement accuracy.

[0069] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the above specific embodiments, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A device for measuring the end displacement of a high-temperature axial compression test specimen, characterized in that, The utility model relates to a high temperature furnace test device, including: end plate, heat-resistant rigid rod, fixed clamp, connecting sheet, heat insulation sheet and linear displacement meter; the end plate is used for placing at the upper and lower ends of the test piece in the high temperature furnace to transfer the relative displacement of the two ends of the test piece; the heat-resistant rigid rod is connected with the end plate through the fixed clamp and is used for transferring the relative displacement of the end plate outside the high temperature furnace; the connecting sheet is connected with one end of the heat-resistant rigid rod outside the high temperature furnace; the linear displacement meter is connected with the connecting sheet through the heat insulation sheet, the heat insulation sheet is used for blocking heat propagation and preventing the linear displacement meter from being damaged by high temperature, and the linear displacement meter is used for measuring the displacement of the heat-resistant rigid rod; the number of the heat-resistant rigid rod is four, and each heat-resistant rigid rod is connected with the first threaded blind hole in the side surface of the end plate through the fixed clamp.

2. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, the end plate includes an upper end plate and a lower end plate; the upper end plate is used for placing at the upper end of the test piece in the high temperature furnace; the lower end plate is used for placing at the lower end of the test piece in the high temperature furnace.

3. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, the end plate is square; first threaded blind holes are formed in the center of the four side surfaces of the end plate, and the first threaded blind holes are used for connecting the fixed clamp.

4. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, one end of the heat-resistant rigid rod is provided with external threads; the heat-resistant rigid rod is connected with the connecting sheet through the external threads.

5. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, one end of the fixed clamp is provided with external threads, and the fixed clamp is connected to the end plate through the external threads; the other end of the fixed clamp is provided with a vertical through hole with a mouth, and the through hole with a mouth is used for clamping the heat-resistant rigid rod.

6. The high temperature axial compression test specimen end displacement measuring apparatus of claim 5 wherein, threaded through holes are formed in two fixed plates extending from the through hole with a mouth, and the threaded through holes are used for mounting bolts and nuts to adjust the tightness of the fixed plates.

7. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, a second threaded blind hole is formed in the center of the connecting sheet, and the second threaded blind hole is used for connecting the heat-resistant rigid rod; through holes are formed in the four corners of the connecting sheet, and the through holes are used for mounting bolts to connect the heat insulation sheet.

8. The high temperature axial compression test specimen end displacement measuring apparatus of claim 1 wherein, the linear displacement meter is placed on the heat insulation sheet through a support.

9. The high temperature axial compression test specimen end displacement measuring device of claim 1, wherein, the heat insulation sheet is made of heat insulation glass, and the heat-resistant rigid rod is made of ceramic rod.

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