Composite material DCB test clamp capable of measuring crack length

Abstract

The invention relates to the technical field of test equipment, in particular to a composite material DCB test clamp capable of measuring crack length, which comprises a lower T-shaped base and an upper T-shaped base, the upper T-shaped base is arranged at the upper end of the lower T-shaped base, a clamping mechanism is arranged on the lower T-shaped base, a lower supporting plate is arranged in the clamping mechanism, a fixing plate is arranged on the lower supporting plate, and a clamping mechanism is arranged on the fixing plate. A first fixing bolt is arranged on the fixing plate, a lower T-shaped connecting piece is arranged on the fixing plate, a lower T-shaped fixing piece is arranged on the lower T-shaped connecting piece, second fixing bolts are arranged on the two sides of the lower T-shaped fixing piece, a test clamping block is arranged at the upper end of the lower T-shaped fixing piece, a pin shaft is arranged on the test clamping block, a test mechanism is arranged on the upper T-shaped base, and an upper supporting plate is arranged in the test mechanism. A grating ruler connecting base is arranged on one side of the upper supporting plate, a third fixing bolt is arranged on the grating ruler connecting base, a grating ruler cross beam is arranged on the grating ruler connecting base, and the double-cantilever beam test piece can be clamped and limited according to needs by adopting the clamping mechanism.

Description

Technical Field

[0001] The invention relates to the technical field of test equipment, in particular to a composite material DCB test fixture capable of measuring crack length. Background Art

[0002] The dual-cantilever beam test for composite materials uses tensile testing to determine the critical energy release rate at the composite interface. According to ASTM D5528, the ends of the dual-cantilever beam specimen must be fixed to the tensile testing machine fixture via a hinged connection to achieve load application without generating additional bending moments. Currently, dual-cantilever beam tests are performed by gluing a loading block or hinge to the end of the specimen.

[0003] In this regard, China has applied for patent number: CN104237007A, which discloses a device for testing the growth rate of composite fatigue cracks. The device includes a plate-shaped specimen, and also includes a first clamping mechanism for applying tension, shearing, and torsion to the specimen through a second clamping mechanism; the second clamping mechanism is used to clamp the specimen and cooperate with the first clamping mechanism to generate composite fatigue cracks in the specimen; the device also includes a fatigue crack measuring instrument for measuring and recording the length of the composite fatigue crack generated on the specimen. The device drives the first clamping mechanism and the second clamping mechanism to apply tension, shearing, and torsion to the specimen through an ordinary tension-compression or tension-compression + torsion fatigue testing machine, thereby fully meeting the requirements of type I, type II, type III, and composite fatigue crack growth rate tests, laying the foundation for achieving accurate prediction of fatigue life of key mechanical parts and engineering components under complex service conditions.

[0004] However, when using the composite DCB test fixture that can measure crack length, there are two problems due to the existing technology of gluing. First, the strength of the glue is relatively low, which causes the hinge to detach from the test piece during loading, making it impossible to complete the test smoothly. Second, the residual glue is difficult to clean, which is not conducive to recycling. Since the double cantilever beam test piece will deform during the test, for asymmetric test pieces, deflection will also occur, making it difficult to measure the crack propagation length.

[0005] Therefore, in order to solve the above problems, a composite DCB test fixture that can measure crack length is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a composite material DCB test fixture that can measure the crack length, so as to solve the problem that the composite material DCB test fixture that can measure the crack length proposed in the above background technology has two problems when in use due to the prior art through gluing: one is that the strength of the glue is relatively low, resulting in the hinge and the test piece being detached during the loading process, and the test cannot be completed smoothly; the other is that the residual glue is difficult to clean, which is not conducive to recycling. Since the double cantilever beam test piece will deform during the test, for asymmetric test pieces, deflection will also occur, making it difficult to measure the length of the crack extension.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a composite material DCB test fixture capable of measuring crack length, comprising: a lower T-shaped base and an upper T-shaped base, wherein the upper end of the lower T-shaped base is provided with an upper T-shaped base, the lower T-shaped base is provided with a clamping mechanism, a lower support plate is provided in the clamping mechanism, a fixing plate is provided on the lower support plate, a first fixing bolt is provided on the fixing plate, and a lower T-shaped connecting piece is provided on the fixing plate, a lower T-shaped fixing piece is provided on the lower T-shaped connecting piece, second fixing bolts are provided on both sides of the lower T-shaped fixing piece, and a test clamp is provided at the upper end of the lower T-shaped fixing piece, a pin is provided on the test clamp, a test mechanism is provided on the upper T-shaped base, an upper support plate is provided in the test mechanism, a grating scale connection base is provided on one side of the upper support plate, and the A third fixing bolt is provided on the grating scale connection base, and a grating scale crossbeam is provided on the grating scale connection base. The clamping mechanism can be used to clamp and limit the double cantilever beam test piece as needed. This process can be achieved by supporting the fixing plate through the first fixing bolt through the lower support plate, and then supporting the lower T-shaped connecting piece through the fixing plate. The lower T-shaped fixing piece can be supported by the second fixing bolt through the lower T-shaped connecting piece, and then one end of the double cantilever beam test piece can be clamped and fixed through the test clamp through the pin shaft. As needed, the threaded rod can be driven to rotate in the limit sleeve through the rotating block in the test mechanism, and the threaded sleeve can be driven to move through the threaded rod, and then the grating scale cursor in the test assembly can be driven to move through the threaded sleeve and the connecting rod, and then the L-shaped scale can be driven to move to perform the test work.

[0008] Preferably, a limiting sleeve is fixedly installed on the upper support plate, a threaded rod is provided on the limiting sleeve, a rotating block is fixedly installed on one end of the threaded rod, and one end of the threaded rod is rotatably installed on the limiting sleeve. The upper support plate can be used to support and fix the limiting sleeve, and the threaded rod is driven to rotate by the rotating block.

[0009] Preferably, a threaded sleeve is threadedly installed on the threaded rod, a connecting rod is fixedly installed on one side of the threaded sleeve, and a test assembly is provided at one end of the connecting rod. The threaded sleeve can be driven to move by the threaded rod, and the test assembly can be driven to work by the connecting rod through the thread.

[0010] Preferably, a grating scale vernier is provided in the test assembly, a limit slot is provided on one side of the grating scale vernier, and a grating scale fixed cover is movably installed on one side of the grating scale vernier, and a fourth fixing bolt is provided on the grating scale fixed cover. The grating scale vernier can be limited by the limit slot on one side in combination with the grating scale fixed cover through the fourth fixing bolt.

[0011] Preferably, the grating scale vernier is slidably mounted on the grating scale beam through a limiting groove and a grating scale fixed cover plate, and the grating scale fixed cover plate can be used to support and limit the grating scale vernier.

[0012] Preferably, an L-shaped slide is fixedly installed at the bottom end of the grating scale cursor, the L-shaped slide is provided with an L-shaped ruler, a limit cap is movably installed on the upper end of the L-shaped ruler, and the L-shaped ruler is slidably installed on the L-shaped slide through the limit cap. The L-shaped slide can be used to drive the L-shaped ruler to move through the limit cap as needed.

[0013] Preferably, the lower support plate is fixedly mounted on the lower T-shaped base, and the fixing plate is fixedly mounted on the lower support plate by a first fixing bolt. The fixing plate can be mounted on the lower support plate by using the first fixing bolt on the lower support plate.

[0014] Preferably, the lower T-shaped connector is fixedly mounted on the fixing plate, the lower T-shaped fixing piece is arranged on the lower T-shaped connector, and the lower T-shaped fixing piece is fixedly mounted on the lower T-shaped connector by a second fixing bolt, and the lower T-shaped connector can be used to support the lower T-shaped fixing piece.

[0015] Preferably, the test clamp is fixedly mounted on the lower T-shaped fixing piece, and a double cantilever beam test piece is provided in the test clamp, and one end of the double cantilever beam test piece is fixed by a pin shaft on the test clamp. The test clamp can be used to clamp and limit one end of the double cantilever beam test piece.

[0016] Preferably, the upper support plate is fixedly mounted on the upper T-shaped base, the grating scale connecting base is fixedly mounted on the upper support plate by a third fixing bolt, and the grating scale crossbeam is fixedly mounted on the grating scale connecting base. The upper support plate can be used to fix the grating scale connecting base on the upper support plate by the third fixing bolt.

[0017] Compared with the prior art, the beneficial effects of the present invention are: the present invention can drive the threaded rod to rotate through the rotating block, which is different from the existing structure that requires manual pushing of the grating scale cursor to move. The present invention can drive the test assembly to move through the rotating block and the threaded rod through the threaded sleeve and the connecting rod, which is smoother than the existing structure, thereby improving the stability of the device during operation.

[0018] A clamping mechanism is provided, through which one end of the double cantilever beam test piece can be clamped and fixed. Compared with the existing structure, the present invention adopts a structure in the clamping mechanism, and the test clamp can be adjusted according to the size of one end of the double cantilever beam test piece through the test clamp and the pin shaft, thereby clamping and limiting the double cantilever beam test piece. The present invention has a simple structure and is easy to disassemble and assemble, and the test piece will not be misplaced, thereby improving the practicality of the device.

[0019] A testing mechanism is provided through which the double cantilever beam test piece can be tested. Compared with the existing structure, the present invention adopts the structure within the testing mechanism. Through the L-shaped slide groove, the L-shaped scale can be driven to fit with one side of the double cantilever beam test piece through the limit cap as needed, and the L-shaped scale can be driven by the grating scale cursor to perform mobile testing. Compared with the existing structure, the present invention can accurately measure the crack extension length, thereby improving the working accuracy of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic front view of the structure of the test body of the present invention; Figure 2 It is a schematic front cross-sectional view of the structure of the test body of the present invention; Figure 3 This is a schematic front view of the main structure of the test mechanism of the present invention; Figure 4 It is a side cross-sectional schematic diagram of the main structure of the test mechanism of the present invention; Figure 5 It is a schematic front cross-sectional view of the structure of the test assembly of the present invention; Figure 6 Schematic diagram of a top cross-section of the structure of the clamping mechanism of the present invention; Figure 7 It is an enlarged schematic diagram of the structure of the test mechanism of the present invention.

[0021] In the figure: 1. Lower T-shaped base; 2. Upper T-shaped base; 3. Clamping mechanism; 31. Lower support plate; 32. Fixing plate; 33. First fixing bolt; 34. Lower T-shaped connecting piece; 35. Lower T-shaped fixing piece; 36. Second fixing bolt; 37. Test clamp; 38. Pin; 4. Test mechanism; 41. Upper support plate; 42. Grating scale connecting base; 43. Third fixing bolt; 44. Grating scale beam; 45. Limit sleeve; 46. Threaded rod; 47. Rotating block; 48. Threaded sleeve; 49. Test assembly; 491. Grating scale vernier; 492. Limit groove; 493. Grating scale fixing cover; 494. Fourth fixing bolt; 495. L-shaped slide; 496. Limit cap; 497. L-shaped scale; 410. Connecting rod; 5. Double cantilever beam test piece. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] See also Figure 1-Figure 7 , an embodiment provided by the present invention: The double cantilever beam test piece 5 used in this application is a product that can be directly purchased on the market. Its principle and connection method are existing technologies well known to those skilled in the art, so they will not be described here in detail.

[0024] A composite material DCB test fixture capable of measuring crack length comprises: a lower T-shaped base 1 and an upper T-shaped base 2, wherein the upper end of the lower T-shaped base 1 is provided with the upper T-shaped base 2, the lower T-shaped base 1 is provided with a clamping mechanism 3, a lower support plate 31 is provided in the clamping mechanism 3, a fixing plate 32 is provided on the lower support plate 31, a first fixing bolt 33 is provided on the fixing plate 32, and a lower T-shaped connector 34 is provided on the fixing plate 32, and a lower T-shaped fixing bolt 33 is provided on the fixing plate 32. The fixing member 35 is provided with a second fixing bolt 36 on both sides of the lower T-shaped fixing member 35, and a test clamp 37 is provided on the upper end of the lower T-shaped fixing member 35, and a pin 38 is provided on the test clamp 37. The upper T-shaped base 2 is provided with a test mechanism 4, and an upper support plate 41 is provided in the test mechanism 4. A grating scale connecting base 42 is provided on one side of the upper support plate 41, and a third fixing bolt 43 is provided on the grating scale connecting base 42, and a grating scale cross bar is provided on the grating scale connecting base 42. The beam 44 is provided with this component, and the double cantilever beam test piece 5 can be clamped and limited by the clamping mechanism 3 as needed. The fixing plate 32 can be supported and fixed by the lower support plate 31 in the mechanism through the first fixing bolt 33. The lower T-shaped connecting piece 34 is supported by the fixing plate 32, and the lower T-shaped fixing piece 35 can be supported and fixed by the lower T-shaped connecting piece 34 through the second fixing bolt 36. The double cantilever beam test piece 5 can be clamped and limited by the test clamp 37 through the pin 38. The threaded rod 46 is driven to rotate by the rotating block 47 in the test mechanism 4, and the threaded sleeve 48 is driven to move by the threaded rod 46. The test assembly 49 can be driven to work by the threaded sleeve 48 through the connecting rod 410. In this process, the L-shaped scale 497 can be moved on the L-shaped slide groove 495 by the limiting cap 496 as needed, and the L-shaped scale can be driven to move by the grating scale cursor 491, thereby completing the test work.

[0025] As a further feature of the present invention, a limiting sleeve 45 is fixedly mounted on the upper support plate 41, and a threaded rod 46 is provided on the limiting sleeve 45. A rotating block 47 is fixedly mounted on one end of the threaded rod 46, and one end of the threaded rod 46 is rotatably mounted on the limiting sleeve 45. By providing this component, the limiting sleeve 45 can be supported by the upper support plate 41, and the Luo Wenbin rod 46 can be supported by the limiting sleeve 45.

[0026] As a further feature of the present invention, a threaded sleeve 48 is threadedly installed on the threaded rod 46, a connecting rod 410 is fixedly installed on one side of the threaded sleeve 48, and a test assembly 49 is provided at one end of the connecting rod 410. By setting this component, the threaded sleeve 48 can be driven by the threaded rod 46 to move, and the test assembly 49 can be driven by the threaded sleeve 48 through the connecting rod 410 to work.

[0027] As a further feature of the present invention, a grating scale vernier 491 is provided in the test assembly 49, and a limiting slot 492 is provided on one side of the grating scale vernier 491, and a grating scale fixing cover 493 is movably installed on one side of the grating scale vernier 491, and a fourth fixing bolt 494 is provided on the grating scale fixing cover 493. By setting this component, the L-shaped scale 497 can be driven to work by the grating scale vernier 491, and the position of the L-shaped scale 497 can be adjusted as needed through the limiting cap 496 on the L-shaped slide 495.

[0028] As a further feature of the present invention, the grating scale cursor 491 is slidably mounted on the grating scale beam 44 through the limiting groove 492 and the grating scale fixed cover 493. By setting this component, the grating scale cursor 491 can be limited by the grating fixed cover 493.

[0029] As a further feature of the present invention, an L-shaped slide groove 495 is fixedly installed at the bottom end of the grating scale cursor 491, and the L-shaped slide groove 495 is provided with an L-shaped scale 497. A limiting cap 496 is movably installed on the upper end of the L-shaped scale 497, and the L-shaped scale 497 is slidably installed on the L-shaped slide groove 495 through the limiting cap 496. By setting this component, the position of the L-shaped scale 497 can be adjusted and limited through the limiting cap 496 through the L-shaped slide groove 495.

[0030] As a further feature of the present invention, the lower support plate 31 is fixedly mounted on the lower T-shaped base 1 , and the fixing plate 32 is fixedly mounted on the lower support plate 31 by a first fixing bolt 33 , and the lower support plate 31 is used to support the fixing plate 32 .

[0031] As a further feature of the present invention, the lower T-shaped connecting member 34 is fixedly mounted on the fixing plate 32, the lower T-shaped fixing member 35 is arranged on the lower T-shaped connecting member 34, and the lower T-shaped fixing member 35 is fixedly mounted on the lower T-shaped connecting member 34 by a second fixing bolt 36. By setting this component, the lower T-shaped fixing member 35 can be supported by the lower T-shaped connecting member 34.

[0032] As a further feature of the present invention, a test clamp 37 is fixedly mounted on the lower T-shaped fixing member 35, and a double cantilever beam test piece 5 is provided in the test clamp 37, and one end of the double cantilever beam test piece 5 is fixed by a pin 38 on the test clamp 37. By providing this component, the double cantilever beam test piece 5 can be clamped and fixed by the pin 38 on the test clamp 37.

[0033] As a further feature of the present invention, the upper support plate 41 is fixedly mounted on the upper T-shaped base 2, the grating scale connecting base 42 is fixedly mounted on the upper support plate 41 by a third fixing bolt 43, and the grating scale crossbeam 44 is fixedly mounted on the grating scale connecting base 42. By setting this component, the grating crossbeam 44 can be supported and fixed by the grating scale connecting base 42.

[0034] Working principle: A composite material double cantilever beam test fixture of the present invention is used to perform a double cantilever beam test on a test piece. The lower T-shaped base 1 and the upper T-shaped base 2 are respectively fixed to the upper and lower clamps of the load test piece, and can move as the load test machine is loaded. The lower T-shaped connecting member 34 is connected and fixed to the lower T-shaped base 1 by a first bolt 33, and is hingedly connected to the lower T-shaped fixing member 35 by a second fixing bolt 36. The test clamp 37 is fixed to the lower T-shaped fixing member 35 by bolts, and the double cantilever beam 5 is fixedly clamped. The grating scale connecting base 42 is fixed to the upper support plate 41 by a third fixing bolt 43, and the grating scale cursor 491 is fixed to the grating scale beam 44 by a grating scale fixing cover 493 and a fourth fixing bolt 494. The grating ruler 491 has a limit slot 492 inside, which can slide freely left and right. The L-shaped slide 495 is fixed on the cursor by screws and can slide with the cursor. The L-shaped ruler 497 is fixed to the L-shaped slide 495 by a limit cap 496. When testing, first, the fixture and the double cantilever beam test piece 5 are aligned according to the Figure 1-7Perform the installation and connection as shown, loosen the pin 38, adjust the position of the L-shaped scale 497 along the L-shaped slot 495 according to the width of the double cantilever beam test piece 5, so that the L-shaped scale 497 is attached to the double cantilever beam test piece 5, and after the test loading, stop loading after the crack expands a certain distance, and drive the threaded sleeve 48 to work through the threaded rod 46. The threaded sleeve 48 can then drive the test assembly 49 grating scale cursor 491 through the connecting rod 410, align the L-shaped scale 497 with the crack tip, read the current grating scale cursor 491 reading and the L-shaped scale 497 reading, and the current total crack length can be obtained.

[0035] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any ordinary technician in this industry can smoothly implement the present invention as shown in the drawings and described above. However, any equivalent changes, modifications and evolutions made by technicians familiar with this profession without departing from the scope of the technical solution of the present invention using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A composite material DCB test fixture capable of measuring crack length, comprising: A lower T-shaped base (1) and an upper T-shaped base (2), wherein the upper end of the lower T-shaped base (1) is provided with the upper T-shaped base (2); The invention is characterized in that: a clamping mechanism (3) is provided on the lower T-shaped base (1), a lower support plate (31) is provided in the clamping mechanism (3), a fixing plate (32) is provided on the lower support plate (31), a first fixing bolt (33) is provided on the fixing plate (32), a lower T-shaped connecting piece (34) is provided on the fixing plate (32), a lower T-shaped fixing piece (35) is provided on the lower T-shaped connecting piece (34), and second fixing bolts (36) are provided on both sides of the lower T-shaped fixing piece (35). A test clamp (37) is provided at the upper end of the lower T-shaped fixing member (35), a pin shaft (38) is provided on the test clamp (37), a test mechanism (4) is provided on the upper T-shaped base (2), an upper support plate (41) is provided in the test mechanism (4), a grating scale connecting base (42) is provided on one side of the upper support plate (41), a third fixing bolt (43) is provided on the grating scale connecting base (42), and a grating scale crossbeam (44) is provided on the grating scale connecting base (42).

2. A composite material DCB test fixture capable of measuring crack length according to claim 1, characterized in that: A limiting sleeve (45) is fixedly mounted on the upper support plate (41), a threaded rod (46) is provided on the limiting sleeve (45), a rotating block (47) is fixedly mounted on one end of the threaded rod (46), and one end of the threaded rod (46) is rotatably mounted on the limiting sleeve (45).

3. A composite material DCB test fixture capable of measuring crack length according to claim 2, characterized in that: A threaded sleeve (48) is threadedly mounted on the threaded rod (46), a connecting rod (410) is fixedly mounted on one side of the threaded sleeve (48), and a test assembly (49) is provided at one end of the connecting rod (410).

4. A composite material DCB test fixture capable of measuring crack length according to claim 3, characterized in that: A grating scale vernier (491) is provided in the test assembly (49), a limiting slot (492) is provided on one side of the grating scale vernier (491), and a grating scale fixed cover (493) is movably installed on one side of the grating scale vernier (491), and a fourth fixing bolt (494) is provided on the grating scale fixed cover (493).

5. A composite material DCB test fixture capable of measuring crack length according to claim 4, characterized in that: The grating scale cursor (491) is slidably mounted on the grating scale beam (44) via the limiting groove (492) and the grating scale fixed cover (493).

6. A composite material DCB test fixture capable of measuring crack length according to claim 5, characterized in that: The bottom end of the grating ruler cursor (491) is fixedly mounted with an L-shaped chute (495), the L-shaped chute (495) is provided with an L-shaped scale (497), the upper end of the L-shaped scale (497) is movably mounted with a limiting cap (496), and the L-shaped scale (497) is slidably mounted on the L-shaped chute (495) through the limiting cap (496).

7. A composite material DCB test fixture capable of measuring crack length according to claim 1, characterized in that: The lower support plate (31) is fixedly mounted on the lower T-shaped base (1), and the fixing plate (32) is fixedly mounted on the lower support plate (31) via a first fixing bolt (33).

8. The composite material DCB test fixture capable of measuring crack length according to claim 1, characterized in that: The lower T-shaped connecting piece (34) is fixedly mounted on the fixing plate (32), the lower T-shaped fixing piece (35) is arranged on the lower T-shaped connecting piece (34), and the lower T-shaped fixing piece (35) is fixedly mounted on the lower T-shaped connecting piece (34) via a second fixing bolt (36).

9. A composite material DCB test fixture capable of measuring crack length according to claim 1, characterized in that: The test clamp (37) is fixedly mounted on the lower T-shaped fixing piece (35), and a double cantilever beam test piece (5) is provided in the test clamp (37), and one end of the double cantilever beam test piece (5) is fixed by a pin (38) on the test clamp (37).

10. A composite material DCB test fixture capable of measuring crack length according to claim 1, characterized in that: The upper support plate (41) is fixedly mounted on the upper T-shaped base (2), the grating scale connecting base (42) is fixedly mounted on the upper support plate (41) via a third fixing bolt (43), and the grating scale crossbeam (44) is fixedly mounted on the grating scale connecting base (42).

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