Preparation and monitoring device suitable for precracks of multi-size fracture toughness samples

Abstract

The utility model provides a preparation and monitoring device suitable for precracks of multi-size fracture toughness samples. The preparation and monitoring device suitable for the precracks of the multi-size fracture toughness samples comprises two clamps which are symmetrically arranged, two supporting rollers are symmetrically installed on the clamps, a same loading pin is arranged between the same supporting roller, the two ends of the loading pin extend into the supporting rollers correspondingly, and the two ends of the loading pin extend into the supporting rollers correspondingly. The same to-be-tested sample is mounted on the two loading pins, and a stress sheet is mounted on one side of the to-be-tested sample. The preparation and monitoring device suitable for the multi-size fracture toughness sample precracks has the advantages that the preparation and monitoring device is suitable for fracture toughness test tools of various sizes, the crack length is monitored by a strain monitoring method, and the high-frequency use of a COD (Chemical Oxygen Demand) gauge is reduced.

Description

Technical Field

[0001] This utility model relates to the field of fracture toughness monitoring technology, and in particular to a device for preparing and monitoring pre-cracked fracture toughness specimens of various sizes. Background Technology

[0002] Fracture toughness is one of the important mechanical properties of metals, reflecting the resistance of a metallic material to crack propagation. Pre-inducing fatigue cracks is a crucial step in fracture toughness testing; however, in practice, the length of the pre-induced fatigue crack is difficult to observe. ASTM E399 specifies a method for calculating fatigue crack length using the opening size of a COD gauge; however, COD gauges are easily damaged under prolonged high-frequency fatigue loading, and in some small-sized specimen tests, it is difficult to match the COD gauge to the specimen. Therefore, a more suitable method is needed to monitor crack initiation and propagation. Furthermore, fracture toughness specimen sizes vary across different product standards, requiring various tooling options, which occupies test space and reduces testing efficiency.

[0003] Therefore, it is necessary to provide a new device for the preparation and monitoring of pre-cracks in multi-size fracture toughness specimens to solve the above-mentioned technical problems. Utility Model Content

[0004] The technical problem solved by this utility model is to provide a fracture toughness testing fixture suitable for multiple sizes, and to monitor crack length by monitoring strain, thereby reducing the high-frequency use of COD gauges. This is a device for preparing and monitoring pre-cracks in fracture toughness specimens of multiple sizes.

[0005] To solve the above-mentioned technical problems, the present invention provides a device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens, comprising: two symmetrically arranged clamps 1, two support rollers 2 symmetrically mounted on the clamps 1, a common loading pin 3 located between the same support rollers 2, the two ends of the loading pin 3 extending into the support rollers 2 respectively, a common test specimen 6 mounted on the two loading pins 3, and a stress plate 5 mounted on one side of the test specimen 6.

[0006] Preferably, it also includes a dynamic strain gauge 7, which is connected to the stress plate 5.

[0007] Preferably, positioning pads 4 are provided on both sides of the clamp 1, and the positioning pads 4 are in contact with the support roller 2.

[0008] Preferably, screws are provided on both sides of the clamp 1, and the screws pass through the corresponding positioning washers 4.

[0009] Preferably, the support roller 2 has multiple mounting grooves on one side, and the diameters of the multiple mounting grooves are different.

[0010] Compared with related technologies, the device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens provided by this utility model has the following advantages:

[0011] This invention provides a device for preparing and monitoring pre-cracks in multi-sized fracture toughness specimens. The support roller 2 can be equipped with loading pins 3 of different diameters according to different test specimens 6, thereby improving the applicability of the entire device. The positioning shim 4 can limit the support roller 2, thereby ensuring that the support roller 2 will not slip during the test. The strain gauge 5 and dynamic strain meter 7 can monitor the strain curve at the bottom center of the specimen. Attached Figure Description

[0012] Figure 1 A cross-sectional view of a preferred embodiment of the device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens provided by this utility model.

[0013] Figure 2 for Figure 1 The diagram shows a side view of the structure.

[0014] Figure 3 for Figure 1 The diagram shows a side view of the support roller structure.

[0015] The following are the labels in the diagram: 1. Fixture, 2. Support roller, 3. Loading pin, 4. Positioning pad, 5. Strain gauge, 6. Test sample, 7. Dynamic strain gauge. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Please refer to the following: Figure 1 , Figure 2 and Figure 3 ,in, Figure 1 A cross-sectional view of a preferred embodiment of the device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens provided by this utility model. Figure 2 for Figure 1 The diagram shows a side view of the structure. Figure 3 for Figure 1 The diagram shows a side view of the support roller structure. The device for preparing and monitoring pre-cracked specimens of multi-size fracture toughness includes: two symmetrically arranged clamps 1, on which two support rollers 2 are symmetrically mounted; a common loading pin 3 is located between the support rollers 2, with both ends of the loading pin 3 extending into the support rollers 2; a common test specimen 6 is mounted on the two loading pins 3; and a stress plate 5 is mounted on one side of the test specimen 6.

[0018] It also includes a dynamic strain gauge 7, which is connected to the stress plate 5.

[0019] The clamp 1 is provided with positioning pads 4 on both sides, and the positioning pads 4 are in contact with the support roller 2.

[0020] Screws are provided on both sides of the clamp 1, and the screws pass through the corresponding positioning washers 4.

[0021] The support roller 2 has multiple mounting grooves on one side, and the diameters of the multiple mounting grooves are all different.

[0022] The working principle of the device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens provided by this utility model is as follows:

[0023] Clamp and fix the fixture 1 on the testing machine, remove the positioning shim 4, place the two support rollers 2 on one side into the two holes of the upper and lower fixtures 1 respectively, and machine mounting grooves of different sizes on the support rollers 2. Rotate the support rollers 2 according to the sample size so that the appropriate mounting groove is in the center position. Then install the loading pin 3 of appropriate size, the sample to be tested 6, and the support roller 2 on the other side into the corresponding positions respectively. Finally, rotate the positioning shim 4 to the vertical position and tighten the screw to ensure that the support rollers 2 will not slip during the test.

[0024] After fatigue crack preparation begins, the strain curve at the center of the bottom of the specimen is monitored by the dynamic strain gauge 7. The tensile-tensile load generated by the testing machine will produce a compressive-compressive fatigue load at the bottom of the specimen. As the crack propagates, the compressive load generated at the bottom will gradually increase under the same load of the testing machine. Therefore, the fatigue crack of the specimen can be monitored by the strain curve at the bottom of the specimen.

[0025] Compared with related technologies, the device for preparing and monitoring pre-cracks in multi-size fracture toughness specimens provided by this utility model has the following advantages:

[0026] This invention provides a device for preparing and monitoring pre-cracks in multi-sized fracture toughness specimens. The support roller 2 can be equipped with loading pins 3 of different diameters according to different test specimens 6, thereby improving the applicability of the entire device. The positioning shim 4 can limit the support roller 2, thereby ensuring that the support roller 2 will not slip during the test. The strain gauge 5 and dynamic strain meter 7 can monitor the strain curve at the bottom center of the specimen.

[0027] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A device for preparing and monitoring pre-existing cracks in multi-size fracture toughness specimens, characterized in that, include: Two symmetrically arranged clamps are provided, with two support rollers symmetrically mounted on each clamp. A loading pin is provided between the support rollers, with both ends of the loading pin extending into the support rollers. The same test sample is mounted on the two loading pins, and a stress plate is mounted on one side of the test sample.

2. The device for preparing and monitoring pre-cracked specimens of multi-size fracture toughness according to claim 1, characterized in that, It also includes a dynamic strain gauge, which is connected to the stress gauge.

3. The device for preparing and monitoring pre-cracked specimens of multi-size fracture toughness according to claim 1, characterized in that, Positioning pads are provided on both sides of the clamp, and the positioning pads are in contact with the support roller.

4. The device for preparing and monitoring pre-cracked specimens of multi-size fracture toughness according to claim 3, characterized in that, Screws are provided on both sides of the clamp, and the screws pass through the corresponding positioning washers.

5. The device for preparing and monitoring pre-cracked specimens of multi-size fracture toughness according to claim 1, characterized in that, The support roller has multiple mounting grooves on one side, and the diameters of the multiple mounting grooves are all different.

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