Double-breakpoint bending experiment device

Abstract

The invention discloses a double-breakpoint bending experiment device in the technical field of anti-bending detection, which comprises pressing plate devices and a force application device, the pressing plate devices are used for clamping and protecting a flat plate test piece and ensuring the stability of the flat plate test piece, the force application device is a hydraulic machine and is used for hydraulically applying force to the test piece, and the device is provided with an upper pressing plate device and a lower pressing plate device. The pressing plate devices are fixedly installed on the force application device, the upper pressing plate device and the lower pressing plate device are each provided with two stress rods, the stress rods form four point positions, pressing force application can be conducted on a flat plate test piece in a staggered mode, and double-point-position reverse breaking is directly conducted on the flat plate test piece. The device is simple and convenient and convenient to operate, two results are obtained through one-time pressing, the cracking rate can be slowed down, a stable test curve is obtained, consumed time in the detection process is reduced by half, a buffering spring and an elastic cushion are additionally arranged, and the testing efficiency is improved. And two breaking points of the flat plate test piece can be ensured not to influence secondary stress mutually.

Description

Technical Field

[0001] The present invention relates to the technical field of anti-bending detection, in particular to a double-breakpoint bending test device. Background Art

[0002] The new fiber-reinforced cement-based composite material has the advantages of high ductility, high strength and good durability. It is currently a commonly used material in reinforcement projects and is widely used in bridge projects, earthquake-resistant projects and building repair projects. It combines materials with different properties together, and the adhesion of concrete and different fibers will form a common whole, which will improve the strength and toughness of the composite material and avoid eccentric stress in traditional reinforced concrete structures due to changes in the stress state.

[0003] The use of these new composite materials requires prior testing of their properties. Compressive strength is a key parameter of concrete performance. For example, eccentric compression and eccentric tension can be converted into flexural or flexural strength through force analysis. Testing these performance parameters can significantly improve the stability and safety of the structure. Therefore, ductility and high flexural strength are also primary parameters to be tested for concrete materials.

[0004] The current test method for the mechanical properties of high-ductility fiber-reinforced cement-based composite materials requires the production of flat test pieces before testing. The testing methods mainly include three-point flexure and four-point flexure.

[0005] Regardless of the testing method, a hydraulic press is used to break the flat test piece. Two points at the bottom support the test plate, while the hydraulic tester applies pressure from above to test the force required to break the plate. A single pressure point at the top is considered three-point flexure, while two pressure points are considered four-point flexure. Regardless of whether the test is three-point or four-point flexure, the pressure point at the top is always between the two bottom load points.

[0006] The disadvantages of the two detection methods are:

[0007] 1. Ordinary concrete flexural devices can only measure the flexural value once in one test. Moreover, the two halves of the specimen formed after flexure are small and difficult to clamp, so they can only be discarded. This results in a low utilization rate of the sample blocks, increases the test operation steps, and is time-consuming and labor-intensive.

[0008] 2. The existing testing method can only test a small number of flexural tests. If the number of tests is increased, the testing cost will increase, especially for high-ductility and ultra-high-performance concrete. This type of concrete tends to have a high consistency. When making test pieces, the amount of concrete used is small, resulting in uneven molding structure, causing deviations in test results and inaccurate test data.

[0009] 3. Although the anti-bending operation of the existing device is simple, it requires many tests, a lot of labor, high costs, backward equipment, and low work efficiency. This results in the entire test process being time-consuming, cumbersome test work, repeated use of equipment, large workload, and a long cycle.

[0010] Based on this, the present invention designs a double-breakpoint bending experimental device to solve the above problems. Summary of the Invention

[0011] The purpose of the present invention is to provide a double-breakpoint bending test device, which is provided with an upper and lower pressure plate device, which is fixedly mounted on a force-applying device, and each of the upper and lower pressure plate devices has two force-bearing rods, which form four points, and can be staggered to press and apply force to a flat test piece, and directly break the flat test piece in double-point reverse positions, thereby efficiently performing a flexural strength test on fiber-reinforced cement-based composite materials. The device is simple and easy to operate, and can obtain two results with one press. It can also slow down the cracking rate and obtain a stable test curve, and the detection process time is reduced by half. Although the results obtained are bidirectional, the upper and lower sides are both force-bearing sides, and buffer springs and elastic pads are added to ensure that the two breaking points of the flat test piece do not affect each other's secondary force.

[0012] The present invention is implemented as follows: a double-breakpoint bending experimental device comprising:

[0013] A pressure plate device and a force applying device;

[0014] The pressure plate device includes a base plate, a spring and a stress-bearing rod;

[0015] Each of the pressure plate devices is provided with two stress rods and two sets of guard plates;

[0016] The bottom plate is a solid flat plate erected horizontally, with a side guard protruding vertically upward on the left edge of the bottom plate, a splash guard protruding vertically on the front edge of the bottom plate, and multiple guard plates vertically protruding upward on the front and rear edges of the top of the bottom plate;

[0017] Every two guard plates form a group, and the guard plates of the same group are symmetrically arranged on the front and rear sides of the base plate, and the axes of the guard plates of the same group coincide along the front-to-back direction;

[0018] The stress-bearing rod is a straight rod, which is mounted on the top of the bottom plate, and a stress-bearing rod is sandwiched between the guard plates of the same group. The stress-bearing rod is arranged horizontally along the front-back direction, and one stress-bearing rod is arranged on the top of the right edge of the bottom plate;

[0019] An elastic pad is clamped at the bottom of the stress-bearing rod, and the elastic pad is a U-shaped groove structure with an open top, and the stress-bearing rod is locked in the groove of the elastic pad;

[0020] The spring is fixed on the top of the bottom plate, and the upper end of the spring is locked with the elastic pad and the stress rod;

[0021] The force-applying device includes a support seat and a hydraulic rod; the support seat is a fixed base, the hydraulic rod is the force-applying end of the hydraulic testing machine, the hydraulic rod is vertically arranged, and the support seat is directly below the hydraulic rod;

[0022] A pressure plate device is installed on each of the support seat and the hydraulic rod. The two pressure plate devices have the same structure, and the front and rear and left and right directions of the upper and lower pressure plate devices are set in opposite directions. The force rods of the two pressure plate devices are parallel to each other, and the force rods of the upper and lower pressure plate devices are staggered with each other, and the horizontal spacing s between the axes of each two staggered force rods is the same.

[0023] Furthermore, the stress-bearing rod is a solid circular steel rod, and each stress-bearing rod on the clamping device is horizontally arranged along the front-to-back direction.

[0024] Furthermore, the elastic pad is a semicircular long rubber pad, and the thickness of the elastic pad is between 5-15 mm;

[0025] The U-shaped groove of the elastic pad and the stress-bearing rod are in interference fit, and the diameter of the stress-bearing rod is between 10-30 mm.

[0026] Furthermore, an annular washer is fixed on the top of the spring; a locking rod is provided inside the spring, the locking rod is a screw, and the nut end of the locking rod is clamped on the bottom of the washer;

[0027] A screw hole is provided on the outer wall of the stress-bearing rod, and the threaded end of the locking rod passes through a washer and an elastic pad and is locked inside the screw hole of the stress-bearing rod.

[0028] Furthermore, 1-2 springs are arranged between the stress-bearing rod and the bottom plate, and the axes of the springs arranged on each stress-bearing rod are on the same straight line.

[0029] Furthermore, the distance between the two stress-bearing rods on the same pressure plate device is 2s, the diameter of each stress-bearing rod is smaller than s, and the distance s ranges from 3 to 5 cm;

[0030] There is a clearance fit between the guard plate and the stress-bearing rod, and the clearance range is 0.5-1mm.

[0031] Furthermore, it also includes an energy-absorbing pad, which is a sponge pad. The energy-absorbing pad is spread all over the force-applying pressure surface of the bottom plate, and the energy-absorbing pad does not block the force-bearing rod.

[0032] Furthermore, the bottom plate is made of high-strength steel plate, and the side guards and guard plates are also made of steel plates;

[0033] The splash plate is a transparent PVC partition.

[0034] The beneficial effects of the present invention are as follows: 1. A pressing plate device is provided on the upper and lower sides of the force-applying device, and the flat test piece is placed and clamped by the pressing plate device to form a stable force-bearing state. At the same time, each pressing plate device has two force-bearing rods, and the four upper and lower force-bearing rods are pressed together to form four staggered reverse force-bearing positions in both directions, forming a double breaking position, so that the flat test piece can be pressed once to obtain two breaking forces, and two test results can be obtained by applying force once, which can also slow down the cracking rate, obtain a stable test curve, and effectively improve the detection efficiency;

[0035] 2. By breaking at two points and in opposite directions, we can obtain bidirectional fracture force data. Bidirectional fracture simulates more complex engineering usage conditions, supplements missing data, provides richer mechanical performance data for material testing, and enables a more comprehensive understanding of material performance.

[0036] 3. This device also adds springs, energy-absorbing pads and elastic pads, which can buffer the impact of breakage, especially the first breakage of the flat test piece, effectively avoiding the mutual influence of the two different break data, and preventing the flat test piece from falling or bouncing off when it breaks, ensuring that the second test can be carried out normally. At the same time, the addition of side guards and front splash guards can also effectively prevent concrete debris from flying out when the flat test piece breaks, providing a certain degree of protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0039] Figure 2 This is a schematic diagram of the top view of the stress-bearing rod on the top of the bottom plate of the present invention;

[0040] Figure 3 This is a schematic diagram of the internal front structure of two butted pressing plate devices of the present invention;

[0041] Figure 4 This is a schematic diagram of the external front structure of two butted pressing plate devices of the present invention;

[0042] Figure 5 This is a structural schematic diagram of the spring of the present invention in the assembled state at the bottom of the elastic pad.

[0043] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0044] 1-base plate, 11-side baffle, 12-splash guard, 13-guard plate, 2-spring, 21-washer, 22-energy absorbing pad, 23-locking rod, 3-force rod, 31-elastic pad, 4-support seat, 41-hydraulic rod. DETAILED DESCRIPTION

[0045] See also Figures 1 to 5 As shown, the present invention provides a double-breakpoint bending test device. In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0046] In a specific embodiment of the technical solution of the present invention:

[0047] It includes a pressing plate device and a force applying device;

[0048] The pressure plate device includes a base plate 1, a spring 2 and a force-bearing rod 3;

[0049] Each pressure plate device is provided with two force-bearing rods 3 and two sets of guard plates 13;

[0050] The base plate 1 is a solid flat plate mounted horizontally. A side guard 11 is provided on the left edge of the base plate 1 protruding vertically upward, a splash guard 12 is provided on the front edge of the base plate 1 vertically, and a plurality of guard plates 13 are provided vertically upward on the front and rear edges of the top of the base plate 1; the height of the side guard 11 can be lower than the height of the guard plate 13, and the height difference does not exceed 5 mm, and the height of the side guard 11 can also be the same as the height of the guard plate 13, which mainly plays a protective effect on the side of the flat test piece.

[0051] The bottom plate 1 is made of high-strength steel plate, and the side guards 11 and guard plates 13 are also made of steel plates;

[0052] The splash guard 12 is a transparent PVC partition. The splash guard 12 has toughness and elasticity when needed, and plays a role in bearing impact and absorbing energy, thereby reducing the kinetic energy of the flying concrete debris and effectively reducing the harm. The splash guard 12 can also be made of rubber and silicone materials to avoid the use of brittle materials.

[0053] Every two guard plates 13 form a group, and the guard plates 13 of the same group are symmetrically arranged on the front and rear sides of the base plate 1, and the axes of the guard plates 13 of the same group coincide along the front and rear directions;

[0054] The force rod 3 is a solid, round, straight steel rod. Each force rod 3 on the clamping device is horizontally arranged in the front-to-back direction. The force rod 3 is mounted on top of the base plate 1, and a force rod 3 is sandwiched between each set of guard plates 13. The force rods 3 are horizontally arranged in the front-to-back direction, and one force rod 3 is located at the top of the right edge of the base plate 1.

[0055] An elastic pad 31 is clamped at the bottom of the stress-bearing rod 3. The elastic pad 31 is a U-shaped groove structure with an open top. The stress-bearing rod 3 is locked in the groove of the elastic pad 31.

[0056] The elastic pad 31 is a semicircular long rubber pad, and the thickness of the elastic pad 31 is between 5-15 mm;

[0057] The U-shaped groove of the elastic pad 31 and the stressed rod 3 are interference fit, and the diameter of the stressed rod 3 is between 10-30 mm, so that the stressed rod 3 and the elastic pad 31 are stably and firmly clamped.

[0058] An annular washer 21 is fixed to the top of the spring 2; a locking rod 23 is provided inside the spring 2, and the locking rod 23 is a screw, and the nut end of the locking rod 23 is clamped on the bottom of the washer 21;

[0059] The outer wall of the stress-bearing rod 3 is provided with a screw hole, and the threaded end of the locking rod 23 passes through the washer 21 and the elastic pad 31 and is locked inside the screw hole of the stress-bearing rod 3. Therefore, the stress-bearing rod 3 and the elastic pad 31 are both locked by the locking rod 23, and the nut end at the lower end of the locking rod 23 is clamped with the washer 21. In this way, the upper end of the spring 2 is locked to the stress-bearing rod 3 and the elastic pad 31, while the lower end of the spring 2 can form an elastic connection to play a buffering role. In this way, the elastic pad 31 that is easily fatigued by stress can be replaced. The locking rod 23 can be easily disassembled to replace the elastic pad 31, and a damaged stress-bearing rod 3 can also be replaced.

[0060] The spring 2 is fixed on the top of the base plate 1, and the upper end of the spring 2 is locked with the elastic pad 31 and the force-bearing rod 3; 1-2 springs 2 are arranged between the force-bearing rod 3 and the base plate 1, and the axes of the springs 2 arranged on each force-bearing rod 3 are in the same straight line, so that the force-bearing rod 3 forms a buffering force and elastic support on the base plate 1 through the spring 2. The spring needs to use a spring with higher hardness and sufficient supporting force to ensure the stability of the force-bearing rod 3. The role it plays is the same as the buffer spring on the automobile chassis, which can provide both stable support and buffering and shock absorption. Therefore, the spring 2 needs to meet the detection force strength of the flat test piece.

[0061] The top of the base plate 1 also needs to be covered with an energy-absorbing pad 22, which is a sponge pad. The energy-absorbing pad 22 is spread over the force-applying pressure surface of the base plate 1, that is, the energy-absorbing pad 22 of the pressure plate device on the top of the support seat 4 below is laid on the top of the base plate 1, and the pressure plate device at the bottom of the upper hydraulic rod 41, the energy-absorbing pad 22 is laid on the bottom of the base plate 1, the energy-absorbing pad 22 does not block the force-bearing rod 3, the energy-absorbing pad 22 plays a role in supplementing the gap between the force-bearing rods 3, and the flat test piece is placed on the top of the energy-absorbing pad 22.

[0062] The force-applying device includes a support base 4 and a hydraulic rod 41; the support base 4 is a fixed base, the hydraulic rod 41 is the force-applying end of the hydraulic testing machine, the hydraulic rod 41 is vertically arranged, and the support base 4 is directly below the hydraulic rod 41;

[0063] A pressure plate device is installed on each of the support seat 4 and the hydraulic rod 41. The two pressure plate devices have the same structure, and the front and rear and left and right directions of the upper and lower pressure plate devices are set in opposite directions. The force rods 3 of the two pressure plate devices are parallel to each other, and the force rods 3 of the upper and lower pressure plate devices are staggered with each other, and the horizontal spacing s between the axes of each two staggered force rods 3 is the same.

[0064] The spacing between the two stress rods 3 on the same pressure plate device is 2s, and the diameter of each stress rod 3 is smaller than s. The purpose of this design is to ensure that a certain distance is maintained between the stress rods 3 when pressing down, so that the test plate can be pressed and broken. If the stress rods 3 are too close to each other, the pressing force on the plate will be affected by the stress rods 3 on the upper and lower sides. The spacing s between the stress rods 3 of this device needs to be kept within a range that does not affect the test accuracy. The spacing s range is 3-5cm;

[0065] There is a clearance fit between the guard plate 13 and the stress-bearing rod 3, and the clearance range is 0.5-1 mm.

[0066] It should be noted that:

[0067] This kind of concrete strip or flat plate test piece, the existing way, whether it is three-point or four-point anti-bending, is only bent once, the bottom is supported on the left and right sides, and the hydraulic rod 41 pressing down on the top is pressing in the middle position, thereby pressing and breaking the flat plate test piece, and only the middle is broken downward, such as Figure 3 As shown, the device applies double-point reverse force at the two middle stress rods 3 of the staggered jacking, thereby breaking the test piece in two directions. A single press of force can obtain double and reverse fracture data, which is not available in the prior art. The current force application is unidirectional. The bidirectional fracture method of the device greatly increases the detection efficiency of the test piece, thereby obtaining more fracture results and more comprehensive test curve data, and simulates the flexural strength of concrete under extreme conditions. The conventional data is obtained by the first fracture, and the high-strength data that is more difficult to break is obtained by the second fracture. Not only is the test efficiency high, but the data obtained are richer, providing support for the research on the flexural strength of concrete.

[0068] When the present invention is in use, the upper and lower pressure plate devices are installed stably, and then the flat test piece is placed flat on the top of the two force-bearing rods 3 below. Afterwards, ensure that the flat test piece is within the range of the side guards 11, splash guards 12 and guard plates 13 on the upper and lower sides, and then start the hydraulic rod 41 and start pressing. At this time, the flat test piece will be supported and bent by one of the force-bearing rods 3, but the bending will not completely break. At this time, the broken part of the flat test piece has lost its supporting force. If pressure is continued, the other force point of the flat test piece will also bend, forming two bending effects and two data, and completing the bending test.

[0069] The four upper and lower force-bearing rods 3 have the same length and the same direction, and need to be set horizontally and parallel to each other.

[0070] The four load-bearing rods are alternately distributed up and down, the center distance between the upper rod or the lower rod is 100mm, and the center distance s between the upper and lower rods is 50mm.

[0071] Finally, a symmetrical force structure diagram with the test specimen as the center is formed. The two pressure plate devices are just at the upper and lower ends of the test specimen, wrapping the concrete test specimen in the front, back, left and right directions, and the side guards 11 and guard plates 13 are clamped on the periphery of the test specimen to ensure that the test specimen does not slip out, and each force rod 3 must fit with the force surface of the test specimen to ensure uniform force during the test.

[0072] The U-shaped elastic pad 31 can ensure that the load-bearing rod 3 is wrapped and does not directly contact the flexural test piece during the test, ensuring that the test piece is in hard contact with the load-bearing rod 3, avoiding energy transfer or loss during the test piece's stress process; the outer side of the load-bearing rod 3 and the spring 2 are tightly wrapped into a whole, absorbing the energy of vibration during the test and maintaining overall stability.

[0073] Thus, through various buffer components, the second breaking anti-bending test is ensured to be unaffected by the first breaking damage; the energy-absorbing pad 22 sponge is evenly distributed on the inner side of the side guard 11, avoiding the fragments after the first breaking damage to directly contact the pressure plate device and generate vibration that is unfavorable to the second breaking anti-bending test.

[0074] In addition, in the description of the present invention, it should be noted that when terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "front", "back", "top", "bottom", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0075] Although the specific embodiments of the present invention are described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A double-breakpoint bending test device, characterized in that: include: A pressure plate device and a force applying device; The pressure plate device comprises a base plate (1), a spring (2) and a force-bearing rod (3); Each of the pressure plate devices is provided with two force-bearing rods (3) and two sets of guard plates (13); The bottom plate (1) is a solid flat plate erected horizontally, a side guard (11) is provided on the left edge of the bottom plate (1) and vertically protrudes upward, a splash plate (12) is provided on the front edge of the bottom plate (1) and a plurality of guard plates (13) are also provided vertically upward on the front and rear edges of the top of the bottom plate (1); Every two guard plates (13) form a group, and the guard plates (13) of the same group are symmetrically arranged on the front and rear sides of the bottom plate (1), and the axes of the guard plates (13) of the same group coincide along the front and rear directions; The stress rod (3) is a solid circular straight rod. Each stress rod (3) on the clamping device is horizontally arranged along the front-back direction. The stress rod (3) is mounted on the top of the bottom plate (1). A stress rod (3) is clamped between the same group of guard plates (13). The stress rod (3) is horizontally arranged along the front-back direction, and one stress rod (3) is arranged on the top of the right edge of the bottom plate (1). An elastic pad (31) is clamped at the bottom of the stress-bearing rod (3), and the top of the elastic pad (31) is an open long U-shaped groove, and the stress-bearing rod (3) is locked in the groove of the elastic pad (31); The spring (2) is fixed on the top of the base plate (1), and an annular washer (21) is fixed on the top of the spring (2); a locking rod (23) is provided inside the spring (2), and the threaded end of the locking rod (23) passes through the washer (21) and the elastic pad (31) and is locked on the force-bearing rod (3), and the elastic pad (31) is locked by the spring (2) and the force-bearing rod (3); The force-applying device comprises a support seat (4) and a hydraulic rod (41); the support seat (4) is a fixed base, the hydraulic rod (41) is a force-applying end of the hydraulic testing machine, the hydraulic rod (41) is vertically arranged, and the support seat (4) is located directly below the hydraulic rod (41); A pressure plate device is installed on each of the support seat (4) and the hydraulic rod (41), the two pressure plate devices have the same structure, and the front and rear directions and left and right directions of the upper and lower pressure plate devices are opposite, the force rods (3) of the two pressure plate devices are parallel to each other, and the force rods (3) of the upper and lower pressure plate devices are staggered, and the horizontal spacing s between the axes of each two staggered force rods (3) is the same; The base plate (1) is also covered with an energy absorbing pad (22), which is spread over the contact surface between the base plate (1) and the test piece, and does not block the force-bearing rod (3).

2. The double-breakpoint bending test device according to claim 1, characterized in that: The elastic pad (31) is a long rubber pad with a semicircular cross section, and the thickness of the elastic pad (31) is between 5 and 15 mm; The U-shaped groove of the elastic pad (31) and the stress-bearing rod (3) are in interference fit, and the diameter of the stress-bearing rod (3) is between 10 and 30 mm.

3. The double-breakpoint bending test device according to claim 1, characterized in that: The locking rod (23) is a screw rod, and the nut end of the locking rod (23) is clamped on the bottom of the washer (21); A screw hole is provided on the outer wall of the stress-bearing rod (3), and the locking rod (23) is locked in the screw hole of the stress-bearing rod (3).

4. The double-breakpoint bending test device according to claim 1, characterized in that: One to two springs (2) are provided between the stress-bearing rod (3) and the bottom plate (1), and the axes of the springs (2) provided on each stress-bearing rod (3) are on the same straight line.

5. The double-breakpoint bending test device according to claim 1, characterized in that: The distance between the two stress-bearing rods (3) on the same pressure plate device is 2s, the diameter of each stress-bearing rod (3) is smaller than s, and the distance s ranges from 3 to 5 cm; There is a clearance fit between the guard plate (13) and the stressed rod (3), and the clearance range is 0.5-1 mm.

6. The double-breakpoint bending test device according to claim 1, characterized in that: The energy absorbing pad (22) is a sponge pad.

7. The double-breakpoint bending test device according to claim 1, characterized in that: The bottom plate (1) is a high-strength steel plate, and the side guards (11) and guard plates (13) are also steel plates.

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