High-precision dog-bone specimen uniaxial tensile testing device and testing method

Abstract

The application relates to a high-precision dog-bone test piece uniaxial tensile test device and a test method, wherein the high-precision dog-bone test piece uniaxial tensile test device comprises a dog-bone test piece clamp, a displacement meter clamp and a displacement meter arranged in the displacement meter clamp; the dog-bone test piece clamp comprises an upper clamp and a lower clamp; the displacement meter clamp comprises an upper clamping plate mechanism and a lower clamping plate mechanism; the upper clamping plate mechanism comprises an upper clamping plate and a movable upper clamping plate arranged on one side of the upper clamping plate; the two longitudinal ends of the upper clamping plate are provided with vertical insertion holes for inserting the displacement meter; the lower clamping plate mechanism comprises a lower clamping plate and a movable lower clamping plate; and the application also discloses a test method. The high-precision dog-bone test piece uniaxial tensile test device can accurately define the measurement position of the dog-bone test piece through displacement meter measurement; in the tensile test, the displacement meter clamp will not slide, and the measurement precision is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the civil engineering field, and particularly relates to a high-precision dog bone specimen uniaxial tensile test device and test method. BACKGROUND

[0002] Concrete material is the most widely used material in the current construction engineering, and the tensile performance is an important mechanical property of the concrete material. At present, the dog bone specimen uniaxial tensile test is the most commonly used test and can best reflect the tensile strength and strain change of the concrete, and the test can conveniently obtain the stress-strain relationship of the concrete. In the existing dog bone specimen uniaxial tensile test, the contact between the displacement meter clamp and the dog bone specimen is surface-to-surface, and the length boundary of the displacement meter collection section is relatively ambiguous. Moreover, after the test starts, the existing displacement meter clamp is prone to sliding due to the development of the specimen crack, which leads to inaccurate strain calculation distance. Meanwhile, the existing displacement meter clamp cannot guarantee that the upper and lower two parts are kept horizontal and parallel during the installation process of each test, which also leads to inaccurate strain calculation. Therefore, it is particularly important to determine a high-precision dog bone specimen uniaxial tensile test device. However, there is a lack of high-precision dog bone specimen uniaxial tensile test device in the prior art.

[0003] INVENTION CONTENT

[0004] The present application provides a high-precision dog bone specimen uniaxial tensile test device and test method to solve the above technical problems.

[0005] The utility model provides a kind of high-precision dog bone test piece uniaxial tensile test device, including dog bone test piece clamp, displacement meter clamp and the displacement meter in displacement meter clamp, dog bone test piece clamp includes upper clamp and lower clamp, the bottom of upper clamp has V-shaped socket and the top of lower clamp has inverted V-shaped socket, the displacement meter clamp includes upper clamping plate mechanism and lower clamping plate mechanism, the upper clamping plate mechanism includes upper clamping plate and detachably arranged in upper clamping plate one side movable upper clamping plate, the middle part of upper clamping plate has first convex letter shape slot, first convex letter shape slot includes first narrow slot and the first wide slot communicated with first narrow slot, the slot bottom of movable upper clamping plate and first narrow slot is rotatably equipped with at least two first taper set screw, movable upper clamping plate is clamped in first wide slot and is rotatably equipped with fixed by two first fastening bolts passing through movable upper clamping plate and upper clamping plate, two longitudinal ends of upper clamping plate are all provided with the insertion hole of vertically inserting displacement meter, and the longitudinal outer side of each insertion hole is provided with clamping seam, and second fastening bolt is rotatably equipped with on the upper clamping plate at clamping seam, the lower clamping plate mechanism includes lower clamping plate and movable lower clamping plate, and the middle part of lower clamping plate has second convex letter shape slot, second convex letter shape slot includes second narrow slot and the second wide slot communicated with second narrow slot, movable lower clamping plate and the slot bottom of second narrow slot are rotatably equipped with at least two second taper set screw, movable lower clamping plate is clamped in second wide slot and is rotatably equipped with fixed by two third fastening bolts passing through movable lower clamping plate and lower clamping plate.

[0006] Preferably, the upper clamping plate and the lower clamping plate are both fixedly provided with a level.

[0007] Preferably, the two sides of the V-shaped socket and the two sides of the inverted V-shaped socket are both provided with a fixed steel sheet, and the fixed steel sheet is fixed on the corresponding upper clamp or lower clamp by a fourth fastening bolt.

[0008] Preferably, the top of the upper clamp is provided with a lifting chain for connecting the tensile part of a universal testing machine, and the bottom of the lower clamp is provided with a double-hinged mechanism for connecting the universal testing machine.

[0009] Preferably, the movable upper clamping plate and the slot bottom of the first narrow slot are rotatably equipped with two first taper set screws, and each pair of adjacent first taper set screws is provided with a first observation hole; the movable lower clamping plate and the slot bottom of the second narrow slot are rotatably equipped with two second taper set screws, and each pair of adjacent second taper set screws is provided with a second observation hole.

[0010] The test method using the dog bone test piece uniaxial tensile test device for testing includes the following steps:

[0011] Step 1, mark the upper and lower variable cross-sections of the dog bone test piece with horizontal lines, then clamp the dog bone test piece into the dog bone test piece clamp, and position the dog bone test piece through the fixing sheet and the fourth fastening bolt, then adjust the universal testing machine to rise or fall so that the dog bone test piece is clamped by the dog bone test piece clamp;

[0012] Step 2, according to the actual thickness of the dog bone test piece, screw the first tapered set screw on the bottom of the first narrow groove of the movable upper clamping plate, so that each first tapered set screw extends into the first narrow groove with equal length, then insert two displacement meters into the corresponding insertion holes, and then clamp and fix the displacement meters in the corresponding insertion holes by screwing the second fastening bolt; screw the second tapered set screw on the bottom of the second narrow groove of the movable lower clamping plate, so that each second tapered set screw extends into the second narrow groove with equal length;

[0013] Step 3, clamp the variable cross-section at the lower part of the dog bone test piece into the second narrow groove in the middle of the lower clamping plate mechanism, observe and adjust the position of the lower clamping plate through the second observation hole to ensure that the tips of the second tapered set screws are accurately aligned with the horizontal line at the variable cross-section at the lower part of the dog bone test piece, then fix the movable lower clamping plate clamped in the second wide groove on the lower clamping plate through the third fastening bolt, at this time each second tapered set screw is in contact with the lower part of the dog bone test piece;

[0014] Step 4, contact the displacement meter needle with the lower clamping plate, and press down the upper clamping plate mechanism so that the middle part of the upper clamping plate is clamped at the variable cross-section at the upper part of the dog bone test piece, observe and adjust the position of the upper clamping plate through the first observation hole to ensure that the tips of the first tapered set screws are accurately aligned with the horizontal line at the variable cross-section at the upper part of the dog bone test piece, then fix the movable upper clamping plate clamped in the first wide groove on the upper clamping plate through the first fastening bolt, at this time each first tapered set screw is in contact with the upper part of the dog bone test piece;

[0015] Step 5, check whether each component is firmly assembled in turn, and start the uniaxial tensile test through the computer-controlled universal testing machine after the check is correct, and record the data measured by the displacement meter.

[0016] The high-precision dog bone test piece uniaxial tensile test device of the application is provided with first tapered set screws on the bottom of the first narrow groove of the movable upper clamping plate and second tapered set screws on the bottom of the second narrow groove of the movable lower clamping plate, so that the first tapered set screws and the second tapered set screws are in point contact with the variable cross-section of the dog bone test piece, compared with the surface contact mode, the displacement meter measures the specific section of the dog bone test piece, and the displacement meter clamp does not slide during the tensile test, thereby greatly improving the measurement accuracy.

[0017] Furthermore, the level is fixed on the upper clamping plate and the lower clamping plate, which can prompt and correct whether the upper and lower clamping plates are horizontal.

[0018] Further, the two sides of the V-shaped notch and the two sides of the inverted V-shaped notch are provided with fixed steel sheets, and the fixed steel sheets are fixed on the corresponding upper and lower clamps through fourth fastening bolts to prevent the dog bone test piece from slipping out of the upper and lower clamps due to deformation during stretching.

[0019] Further, a first observation hole is arranged between each pair of adjacent first conical set screws, and a second observation hole is arranged between each pair of adjacent second conical set screws, so that the fixed positions of the first conical set screws and the second conical set screws on the dog bone test piece can be observed and adjusted when the upper and lower clamping plates are fixed on the dog bone test piece.

[0020] The test method for testing by using the dog bone test piece uniaxial tensile test device greatly improves the measurement accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a structural schematic view of a dog bone test piece clamp in the embodiment of the present application.

[0022] Figure 2 is a top view structural schematic view of an upper clamping plate mechanism in the embodiment of the present application.

[0023] Figure 3 is a front view structural schematic view of an upper clamping plate mechanism in the embodiment of the present application.

[0024] Figure 4 is a front view structural schematic view of a lower clamping plate mechanism in the embodiment of the present application.

[0025] Figure 5 is a front view structural schematic view of a lower clamping plate mechanism in the embodiment of the present application.

[0026] Figure 6 is a structural schematic view of a dog bone test piece in the embodiment of the present application.

[0027] Figure 7 is a structural schematic view of a dog bone test piece uniaxial tensile test device in the embodiment of the present application. DETAILED DESCRIPTION

[0028] Embodiment 1

[0029] A high-precision dog bone test piece uniaxial tensile test device, like Figures 1-7As shown, the device includes a dog bone specimen clamp, a displacement gauge clamp, and a displacement gauge 14 disposed in the displacement gauge clamp. The dog bone specimen clamp includes an upper clamp 1 and a lower clamp 1'. The bottom of the upper clamp has a V-shaped latch, and the top of the lower clamp has an inverted V-shaped latch. Fixing steel plates 2 are provided on both sides of the V-shaped latch and both sides of the inverted V-shaped latch. The fixing steel plates are fixed to the corresponding upper and lower clamps by a fourth fastening bolt 3. The top of the upper clamp has a lifting chain 15 for connecting to the tensile part of the universal testing machine, and the bottom of the lower clamp has a double hinge mechanism 4 for connecting to the universal testing machine. The double hinge mechanism 4 includes a connecting plate 401, a first rotating shaft 402, a connecting piece 403, and a second rotating shaft 404.

[0030] The displacement gauge clamp includes an upper clamping plate mechanism and a lower clamping plate mechanism. The upper clamping plate mechanism includes an upper clamping plate 7 and a movable upper clamping plate 8 detachably disposed on one side of the upper clamping plate. The middle part of the upper clamping plate has a first U-shaped groove, which includes a first narrow groove and a first wide groove communicating with the first narrow groove. At least two first conical set screws 6 are screwed into the bottom of the movable upper clamping plate 8 and the first narrow groove. The movable upper clamping plate is engaged in the first wide groove and fixed by two first fastening bolts 16 that penetrate the movable upper clamping plate and the upper clamping plate. Both longitudinal ends of the upper clamping plate have vertical insertion positions. The insertion holes 12 of the measuring instrument have a locking seam 15 on the longitudinal outer side of each insertion hole. A second fastening bolt 14 is horizontally screwed onto the upper clamping plate at the locking seam. The lower clamping plate mechanism includes a lower clamping plate 10 and a movable lower clamping plate 20. The middle part of the lower clamping plate has a second U-shaped locking groove, which includes a second narrow groove and a second wide groove communicating with the second narrow groove. At least two second conical set screws 19 are screwed onto the bottom of the movable lower clamping plate and the second narrow groove. The movable lower clamping plate is engaged in the second wide groove and fixed by two third fastening bolts 21 that penetrate the movable lower clamping plate and the lower clamping plate. Levels 5 and 18 are fixed onto both the upper and lower clamping plates.

[0031] In this embodiment, two first conical set screws are screwed onto the bottom of the movable upper plate and the first narrow groove, and a first observation hole 9 is provided between each pair of adjacent first conical set screws; two second conical set screws are screwed onto the bottom of the movable lower plate and the second narrow groove, and a second observation hole 22 is provided between each pair of adjacent second conical set screws.

[0032] Example 2

[0033] The test method for conducting the test using the aforementioned uniaxial tensile testing apparatus for dog bone specimens, such as... Figures 1-7 As shown, it includes the following steps:

[0034] Step 1: Mark the upper and lower cross sections of the dog bone specimen 11 with horizontal lines 13. Then, insert the dog bone specimen into the dog bone specimen clamp and limit the dog bone specimen by fixing the steel plate and the fourth fastening bolt. Then, adjust the universal testing machine to raise or lower so that the dog bone specimen is completely clamped by the dog bone specimen clamp.

[0035] Step 2: Based on the actual thickness of the dog bone specimen, tighten the first conical set screws screwed into the bottom of the movable upper clamping plate and the first narrow groove, so that each of the first conical set screws extends into the first narrow groove by an equal length. Then, insert the two displacement gauges into their corresponding holes, and then tighten the second fastening bolts to clamp and fix the displacement gauges in their corresponding holes. Tighten the second conical set screws screwed into the bottom of the movable lower clamping plate and the second narrow groove, so that each of the second conical set screws extends into the second narrow groove by an equal length.

[0036] Step 3: Insert the variable cross-section of the lower part of the dog bone specimen into the second narrow groove in the middle of the lower clamping plate mechanism. Observe and adjust the position of the lower clamping plate through the second observation hole to ensure that the tip of the second tapered set screw is accurately aligned with the horizontal line of the variable cross-section of the lower part of the dog bone specimen. Then, fix the movable lower clamping plate, which is inserted into the second wide groove, onto the lower clamping plate through the third fastening bolt. At this time, each of the second tapered set screws presses against the lower part of the dog bone specimen.

[0037] Step 4: Contact the displacement gauge pin with the lower clamping plate and press down the upper clamping plate mechanism so that the middle part of the upper clamping plate is locked at the variable cross section of the upper part of the dog bone specimen. Observe and adjust the position of the upper clamping plate through the first observation hole to ensure that the tip of the first tapered set screw is accurately aligned with the horizontal line of the variable cross section of the upper part of the dog bone specimen. Then, fix the movable upper clamping plate locked in the first wide groove on the upper clamping plate through the first fastening bolt. At this time, each of the first tapered set screws is pressed against the upper part of the dog bone specimen.

[0038] Step 5: Check the assembly of each component in turn to ensure it is secure. After confirming that there are no errors, start the uniaxial tensile test using the computer-controlled universal testing machine and record the data measured by the displacement gauge.

Claims

1. A test method using a uniaxial tensile testing apparatus for dog bone specimens, wherein, The uniaxial tensile testing apparatus for dog bone specimens includes a dog bone specimen clamp, a displacement gauge clamp, and a displacement gauge disposed within the displacement gauge clamp. The dog bone specimen clamp includes an upper clamp and a lower clamp. The bottom of the upper clamp has a V-shaped notch, and the top of the lower clamp has an inverted V-shaped notch. The displacement gauge clamp includes an upper clamping plate mechanism and a lower clamping plate mechanism. The upper clamping plate mechanism includes an upper clamping plate and a movable upper clamping plate detachably disposed on one side of the upper clamping plate. The middle of the upper clamping plate has a first U-shaped groove, which includes a first narrow groove and a groove communicating with the first narrow groove. The first wide slot, the movable upper clamping plate, and the bottom of the first narrow slot are all screwed with at least two first conical set screws. The movable upper clamping plate is engaged in the first wide slot and fixed by two first fastening bolts that pass through the movable upper clamping plate and the upper clamping plate. The two longitudinal ends of the upper clamping plate have insertion holes for vertically inserting displacement gauges. Each insertion hole has a locking seam on its longitudinal outer side. A second fastening bolt is screwed laterally on the upper clamping plate at the locking seam. The lower clamping plate mechanism includes a lower clamping plate and a movable lower clamping plate. The middle of the lower clamping plate has a second convex U-shaped locking groove. The two-convex U-shaped slot includes a second narrow slot and a second wide slot communicating with the second narrow slot. At least two second conical set screws are screwed onto the bottom of both the movable lower clamping plate and the second narrow slot. The movable lower clamping plate is engaged in the second wide slot and fixed by two third fastening bolts passing through the movable lower clamping plate and the lower clamping plate. A level is fixed onto both the upper clamping plate and the lower clamping plate. Fixing steel plates are provided on both sides of the V-shaped opening and both sides of the inverted V-shaped opening. The fixing steel plates are fixed to the corresponding upper and lower clamps by fourth fastening bolts. The upper clamping plate... The top of the fixture has a lifting chain for connecting to the tensile section of the universal testing machine, and the bottom of the lower fixture has a double hinge mechanism for connecting to the universal testing machine; two first conical set screws are screwed onto the movable upper clamping plate and the bottom of the first narrow slot, and a first observation hole is provided between each pair of adjacent first conical set screws; two second conical set screws are screwed onto the movable lower clamping plate and the bottom of the second narrow slot, and a second observation hole is provided between each pair of adjacent second conical set screws; the feature is that it includes the following steps: Step 1: Mark the upper and lower cross sections of the dog bone specimen with horizontal lines. Then, insert the dog bone specimen into the dog bone specimen clamp and limit the dog bone specimen by fixing the steel plate and the fourth fastening bolt. Then, adjust the universal testing machine to raise or lower so that the dog bone specimen is completely clamped by the dog bone specimen clamp. Step 2: Based on the actual thickness of the dog bone specimen, tighten the first conical set screws screwed into the bottom of the movable upper clamping plate and the first narrow groove, so that each of the first conical set screws extends into the first narrow groove by an equal length. Then, insert the two displacement gauges into their corresponding holes, and then tighten the second fastening bolts to clamp and fix the displacement gauges in their corresponding holes. Tighten the second conical set screws screwed into the bottom of the movable lower clamping plate and the second narrow groove, so that each of the second conical set screws extends into the second narrow groove by an equal length. Step 3: Insert the variable cross-section of the lower part of the dog bone specimen into the second narrow groove in the middle of the lower clamping plate mechanism. Observe and adjust the position of the lower clamping plate through the second observation hole to ensure that the tip of the second tapered set screw is accurately aligned with the horizontal line of the variable cross-section of the lower part of the dog bone specimen. Then, fix the movable lower clamping plate, which is inserted into the second wide groove, onto the lower clamping plate through the third fastening bolt. At this time, each of the second tapered set screws presses against the lower part of the dog bone specimen. Step 4: Contact the displacement gauge pin with the lower clamping plate and press down the upper clamping plate mechanism so that the middle part of the upper clamping plate is locked at the variable cross section of the upper part of the dog bone specimen. Observe and adjust the position of the upper clamping plate through the first observation hole to ensure that the tip of the first tapered set screw is accurately aligned with the horizontal line of the variable cross section of the upper part of the dog bone specimen. Then, fix the movable upper clamping plate locked in the first wide groove on the upper clamping plate through the first fastening bolt. At this time, each of the first tapered set screws is pressed against the upper part of the dog bone specimen. Step 5: Check the assembly of each component in turn to ensure it is secure. After confirming that there are no errors, start the uniaxial tensile test using the computer-controlled universal testing machine and record the data measured by the displacement gauge.

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