Adjustable concrete uniaxial stretching arc-shaped dog bone test clamp
By designing an adjustable concrete uniaxial tensile curved dog bone test fixture, the problem of the fixture and the test piece not being tightly fitted, the test success rate is improved, stress concentration is reduced, and the economy and ease of operation are realized in replacing the fixture.
Patent Information
- Application Number
- CN202422221619.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-11
- Publication Date
- 2025-08-08
- Estimated Expiration
- 2034-09-11
AI Technical Summary
The existing dog bone fixtures are difficult to fit closely with concrete specimens, resulting in stress concentration and non-axial tension, reducing the success rate of uniaxial tensile tests.
An adjustable concrete uniaxial tensile curved dog bone test fixture is designed. Through the combined structure of the outer fixture frame and the inner fixture frame, the adjustable baffle and screw hole connection are used to achieve a close fit between the fixture and the test piece, increase the contact area and reduce stress concentration.
It improves the success rate of the test, reduces the stress concentration phenomenon, increases the contact area between the fixture and the test piece, has a simple structure and is convenient to operate, and saves the steel for replacing the fixture.
Smart Images
Figure CN223205251U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of concrete uniaxial tension test, in particular to a concrete uniaxial tension arc-shaped dog-bone test fixture. Background Art
[0002] The uniaxial tensile test is the most basic test method for measuring the tensile properties of concrete. It can measure both the direct tensile strength and the stress-strain relationship. The dogbone specimen is a commonly used specimen shape for concrete tensile testing.
[0003] Research has shown that dogbone fixtures significantly impact test success rates. Existing dogbone fixtures are often integrally formed, but concrete dogbone specimens often cannot conform to the specified dimensions due to factors such as casting, curing, and the material's own shrinkage. This makes it difficult for existing fixtures to securely fit the concrete dogbone specimens, resulting in insufficient contact. Due to the reduced contact area, the concrete dogbone specimens experience significant stress concentration when subjected to tension, causing failure at the ends. Cracks initiating outside the uniform cross-sectional inspection area result in a reduced success rate for tensile tests.
[0004] Therefore, how to make the fixture fit more tightly with the dog-bone specimen, avoid stress concentration and non-axial tension of the specimen during tension, and improve the success rate of the test has become an urgent problem that technicians in this field need to solve. Utility Model Content
[0005] The purpose of the utility model is to provide an adjustable concrete uniaxial tensile arc dog bone test fixture. The adjustable characteristics of the fixture structure make the fixture and the specimen fit more closely, increase the contact area between the fixture and the specimen, reduce stress concentration and non-axial tension phenomena, and improve the success rate of the test.
[0006] The technical solution of the utility model is: a concrete uniaxial tensile arc-shaped dog bone test fixture, which is composed of two parts: an outer fixture frame and an inner fixture frame, the upper end of the outer fixture frame is fixedly connected to a fixture head, the outer fixture frame body is composed of front and rear claw arms and left and right claw arms, and is in the shape of an octagon, and the inner fixture frame is composed of front and rear baffles and left and right baffles, and the inner sides of the left and right baffles are provided with arc-shaped baffles for fitting the transition zone of the dog bone specimen.
[0007] Furthermore, a clamp head for clamping by a testing machine is provided at the upper end of the outer clamp frame, and the clamp head is fixedly connected to the outer clamp frame.
[0008] Furthermore, the front and rear claw arms are in an inverted L shape, and the left and right claw arms are in a [ shape. Each claw arm is provided with a circular screw hole for fastening the outer clamp frame and the inner clamp frame.
[0009] Furthermore, the left and right claw arms are longer than the front and rear claw arms, and the ends of the left and right claw arms extend inward to serve as a bracket.
[0010] Furthermore, the front and rear baffles are completely identical in structure, and the left and right baffles are completely identical in structure;
[0011] Furthermore, a clamp head for clamping by a testing machine is provided at the upper end of the outer clamp frame, and the clamp head is fixedly connected to the outer clamp frame.
[0012] Furthermore, the outer clamp frame is an octagonal clamp frame, and each clamp arm of the outer clamp frame is provided with a circular threaded connection port for fastening the outer clamp frame and the inner clamp frame.
[0013] Furthermore, the claw arm consists of front and rear claw arms and left and right claw arms. The left and right claw arms are longer than the front and rear claw arms, and the ends extend inward to serve as a bracket to facilitate left and right adjustment of the inner clamp and prevent the inner clamp from falling during installation.
[0014] Furthermore, the inner fixture frame adjustment baffle composition includes a front baffle, a rear baffle, a left baffle and a right baffle.
[0015] Furthermore, the front baffle and the rear baffle are rectangular in shape, and the front and rear baffles are arranged opposite to each other in the horizontal direction. The left and right baffles are provided with through grooves that can slide freely along the length direction of the front and rear baffles, that is, the left and right directions, thereby achieving a tight fit on the left and right directions of the end of the dog bone specimen.
[0016] Furthermore, the front and rear baffles are provided with long grooves, and the connecting rods fix the inner clamp to the outer clamp through the screw holes of the outer clamp and the grooves on the baffles.
[0017] Furthermore, the left and right baffles are composed of a rectangular baffle and an arc-shaped baffle. A long groove is provided in the middle of the rectangular baffle, and the long groove is used to connect the outer fixture frame. Through grooves are provided at the left and right ends of the rectangular baffle, and the through grooves form a track that allows forward and backward movement. The front and rear baffles move forward and backward along the through groove track and are limited to the two sides of the through groove, thereby adjusting the relative positions of the front and rear baffles on the left and right baffles to achieve forward and backward adjustment of the end of the dog bone specimen.
[0018] Furthermore, the arc-shaped baffles of the left baffle and the right baffle are fixedly connected to a screw rod, and the screw rod is rotatably connected to the rectangular baffle portion, and the angle of the arc-shaped baffle is adjusted by rotating the screw rod.
[0019] Furthermore, the claw arms of the outer fixture frame, the front and rear baffles of the inner fixture frame, and the rectangular baffles of the left and right baffles are all made of stainless steel.
[0020] Furthermore, the clamp head and the connecting rod are both made of stainless steel.
[0021] Furthermore, the arc-shaped baffle is made of stainless steel.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] This fixture can be adjusted according to the actual size of the specimen, reducing the chances of the specimen not fitting properly due to deformation. It also increases the contact area between the specimen and the fixture, improving stress concentration and increasing the success rate of the test. Replacing the fixture only requires replacing the curved baffle, saving steel. Furthermore, this technical solution offers a simple structure and easy operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0025] Figure 1 It is a structural diagram of the utility model;
[0026] Figure 2 This is a structural diagram of the outer clamp frame of the utility model;
[0027] Figure 3 This is a structural diagram of the inner fixture frame of the present utility model;
[0028] Figure 4 This is a schematic structural diagram of the front and rear baffles of the present invention;
[0029] Figure 5 This is a schematic structural diagram of the left and right baffles of the present invention;
[0030] Figure 6 This is a schematic diagram of the split structure of the left and right baffles of the present invention;
[0031] Among them, 1. Clamp head; 2. Outer clamp frame; 3. Inner clamp frame; 4. Connecting rod; 5. Screw hole; 6. Front and rear claw arms; 7. Left and right claw arms; 8. Front and rear baffles; 9. Left and right baffles; 10. Long groove; 11. Arc baffle; 12. Nut; 13. Arc baffle screw; 14. Through slot; 15. Rectangular baffle; 16. Rectangular baffle connecting hole. DETAILED DESCRIPTION
[0032] To make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description, but the present invention is not limited thereto.
[0033] refer to Figures 1 to 6
[0034] An adjustable concrete uniaxial tensile curved dogbone test fixture comprises an outer fixture frame 2 and an inner fixture frame 3. The upper end of the outer fixture frame is rotatably connected to a fixture head 1. The outer fixture frame comprises front and rear claw arms 6 and left and right claw arms 7, each with a circular screw hole 5. The inner fixture frame comprises front and rear baffles 8 and left and right baffles 9, ensuring a tight fit between the specimen and the fixture. Connecting rods 4 pass through the screw holes in the claw arms and contact the longitudinal grooves 10 in the front and rear baffles and left and right baffles. Nuts then lock the connecting rods, forming a locking mechanism that secures the specimen to the fixture.
[0035] In this embodiment, in order to facilitate the connection between the outer clamp frame and the inner clamp frame, the other end of the connecting rod 4 is provided with a thread. After the connecting rod passes through the screw hole 5 on the claw arm of the outer clamp frame, it is locked in the long groove 10 on the adjustment baffle and fixed with a nut.
[0036] In this embodiment, in order to facilitate the adjustment of the baffle, a through groove 14 is provided on the left and right baffles 9 of the adjustment baffle, and the through groove forms a track that allows forward and backward movement. The front and rear baffles 8 move forward and backward along the through groove track and are limited to the two sides of the through groove, thereby adjusting the relative positions of the front and rear baffles on the left and right baffles to achieve the adjustment of the front and rear directions of the end of the dog bone specimen.
[0037] In this embodiment, in order to facilitate the adjustment of the arc baffle 11, the arc baffle is fixed to the arc baffle screw 13, and both ends of the arc baffle screw are rotatably connected to the rectangular baffle 15. The angle of the arc baffle can be adjusted by rotating the arc baffle screw.
[0038] In this embodiment, the claw arms of the outer clamp frame, the rectangular baffle parts of the front and rear baffles and the left and right baffles of the inner clamp frame, the clamp head, and the connecting rod are all made of stainless steel.
[0039] In this embodiment, the arc-shaped baffle is made of stainless steel.
[0040] The steps for using the fixture are as follows:
[0041] Step 1: Fix the fixture head to the testing machine first;
[0042] Step 2: First, place the left and right baffles of the inner fixture onto the brackets of the left and right claw arms of the outer fixture. Secure the outer fixture, left and right baffles, and dogbone specimen using connecting rods and long grooves. Adjust the angles of the curved baffles on the left and right baffles to ensure they align with the curved portion of the dogbone specimen. Insert the front and rear baffles into the through slots on the left and right baffles and secure them to the outer fixture using connecting rods.
[0043] Step 3: Fine-tune the front, rear, left, and right baffles to ensure they fit snugly against the ends of the dog-bone specimen.
Claims
1. An adjustable concrete uniaxial tensile curved dog bone test fixture consisting of two parts: The outer clamp frame (2) and the inner clamp frame (3) are characterized in that: the upper end of the outer clamp frame (2) is fixedly connected to the clamp head (1); the main body of the outer clamp frame (2) is composed of front and rear claw arms (6) and left and right claw arms (7), and is in the shape of an octagon; the inner clamp frame (3) is composed of front and rear baffles (8) and left and right baffles (9); the inner sides of the left and right baffles (9) are provided with arc-shaped baffles (11) for fitting the transition zone of the dog bone specimen.
2. The adjustable concrete uniaxial tensile arc-shaped dog-bone test fixture according to claim 1, characterized in that: A clamp head (1) for clamping the testing machine is provided at the upper end of the outer clamp frame (2), and the clamp head (1) is fixedly connected to the outer clamp frame (2).
3. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 1, characterized in that: The front and rear claw arms (6) are in an inverted L-shape, and the left and right claw arms (7) are in a [-shape. A circular screw hole (5) is provided on each claw arm for fastening the outer clamp frame (2) and the inner clamp frame (3).
4. The adjustable concrete uniaxial tensile arc-shaped dog-bone test fixture according to claim 3, characterized in that: The left and right claw arms (7) are longer than the front and rear claw arms (6), and the ends of the left and right claw arms (7) extend inwards for a section to serve as a bracket.
5. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 1, characterized in that: The front and rear baffles (8) are completely identical in structure, and the left and right baffles (9) are completely identical in structure.
6. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 3, characterized in that: The front and rear baffles (8) are rectangular in shape and are provided with long grooves (10). The connecting rod (4) fixes the inner clamp frame (3) and the outer clamp frame (2) through the screw holes (5) and the long grooves (10).
7. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 5, characterized in that: The left and right baffles (9) are composed of a rectangular baffle (15) and an arc-shaped baffle (11). The rectangular baffle (15) is used to fit the left and right ends of the dog-bone specimen, and the arc-shaped baffle (11) is used to fit the arc-shaped transition area of the dog-bone specimen.
8. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 7, characterized in that: A long groove is provided in the middle of the rectangular baffle (15), and through grooves (14) are provided at the left and right ends of the rectangular baffle (15).
9. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 7, characterized in that: The arc baffle (11) is fixedly connected to the arc baffle screw (13), and the arc baffle screw (13) is rotationally connected to the arc baffle (15). The angle of the arc baffle (11) is changed by rotating the arc baffle screw (13).
10. The adjustable concrete uniaxial tension arc-shaped dog-bone test fixture according to claim 1, characterized in that: The clamp head (1), front and rear claw arms (6), left and right claw arms (7), front and rear baffles (8), and rectangular baffle (15) are all made of stainless steel, and the arc baffle (11) is also made of stainless steel.