Quick-calibration fracture mechanics extensometer

Abstract

The utility model discloses a fast calibration fracture mechanics extensometer, which comprises a shell, an adjustable calibration block and a fixed calibration block, a mechanics extensometer structure is arranged in the shell, the mechanics extensometer structure comprises a pressing block, an upper measuring arm is arranged below the pressing block, a lower measuring arm is arranged below the upper measuring arm, an upper measuring arm is arranged below the upper measuring arm, and a lower measuring arm is arranged below the lower measuring arm. A support is arranged under the pressing block. The upper measuring arm and the lower measuring arm deform along with the displacement of a sample notch, the resistance value of a bridge circuit changes, the deformation of the sample is measured through bridge circuit imbalance output, the initial deformation of the measuring arms provides clamping force for the extensometer, the extensometer is matched with the sample notch or a knife edge, other mounting structures are not needed, and when the sample is broken, the extensometer can be automatically separated from the sample; and when the scale distance is increased, the support with an angle is designed, so that the approximate height size of the extensometer is ensured, the size of the extensometer is reduced, the space is saved, and the problem of uncoordinated proportion is avoided.

Description

Technical Field

[0001] This utility model relates to the field of extensometer technology, specifically a fracture mechanics extensometer that can be calibrated quickly. Background Technology

[0002] Fracture testing has developed alongside the study of engineering fracture problems and the advancement of fracture mechanics. Currently, common testing methods include the three-point bending test and the compact tensile test to measure critical parameters such as K1c, δ, and J integral. The compact tensile test and three-point bending test are used to determine parameters such as the stress intensity factor K1c, crack opening displacement δ, and J integral. During the test, the measured load-displacement (crack opening displacement or force application point displacement) curves allow for the calculation of parameter values ​​corresponding to the critical conditions. The compact tensile test has been widely used in fracture toughness and crack propagation rate testing, particularly in the evaluation and research of nuclear pressure vessel materials. During the test, a tensile load is applied to the specimen through a loading hole.

[0003] Currently, fracture mechanics extensometers mainly rely on imports, and calibration requires the use of calibration instruments and accessories, making calibration inconvenient. Utility Model Content

[0004] The purpose of this invention is to provide a fracture mechanics extensometer that can be calibrated quickly, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a rapid-calibration fracture mechanics extensometer, comprising a housing, an adjustable calibration block, and a fixed calibration block. The housing contains a mechanics extensometer structure, which includes a pressure block. Below the pressure block is an upper measuring arm. Below the upper measuring arm, directly below the pressure block, is a support. Below the support is a lower measuring arm. Below the lower measuring arm, below the support, is a lower pressure block.

[0006] Strain gauges are attached to the upper and lower measuring arms, which together form a full-bridge circuit.

[0007] Preferably, the adjustable calibration block includes a column with a through hole, and a plurality of trapezoidal blocks are slidably connected to the through hole, forming a connecting space between the trapezoidal blocks. The upper measuring arm and the lower measuring arm are connected to the trapezoidal blocks at the connecting space.

[0008] Preferably, the fixed calibration block includes a column with several trapezoidal slots, and the upper measuring arm and the lower measuring arm are connected to the column within the trapezoidal slots.

[0009] Preferably, the upper and lower measuring arms are made of materials with a flexible segment length.

[0010] Compared with the prior art, the beneficial effects of this utility model are as follows: the upper and lower measuring arms deform as they follow the displacement of the sample notch, and the bridge circuit resistance changes. The sample deformation is measured by the unbalanced output of the bridge circuit. The initial deformation of the measuring arms provides the clamping force of the extensometer. With the sample notch or knife edge, no other installation structure is required. When the sample breaks, the extensometer will automatically detach from the sample and will not be damaged due to exceeding the range. When the gauge length increases, the height dimension of the extensometer is kept approximately the same by designing an angled support, which reduces the volume of the extensometer, saves space, and avoids the problem of disproportionate ratio. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0012] Figure 2 This is a schematic diagram of the adjustable calibration block structure of this utility model;

[0013] Figure 3 This is a schematic diagram of the fixed calibration block structure of this utility model;

[0014] Figure 4 This is a schematic diagram of the mechanical extensometer structure of this utility model.

[0015] In the diagram: 1. Outer shell; 2. Adjustable calibration block; 21. Column; 22. Through hole; 23. Trapezoidal block; 3. Fixed calibration block; 31. Trapezoidal groove; 4. Mechanical extensometer structure; 41. Pressure block; 42. Upper measuring arm; 43. Support; 44. Lower measuring arm; 45. Lower pressure block. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0017] Please refer to 1-4. One embodiment of this utility model is provided: a fracture extensometer for rapid calibration, including a housing 1, an adjustable calibration block 2 and a fixed calibration block 3. The housing 1 is provided with a mechanical extensometer structure 4. The mechanical extensometer structure 4 includes a pressure block 41. An upper measuring arm 42 is provided below the pressure block 41. A support 43 is provided directly below the pressure block 41 below the upper measuring arm 42. A lower measuring arm 44 is provided below the support 43. A lower pressure block 45 is provided below the lower measuring arm 44 and below the support 43.

[0018] Strain gauges are attached to the upper measuring arm 42 and the lower measuring arm 44, forming a full-bridge circuit. The upper measuring arm 42 and the lower measuring arm 44 are used as elastic elements of the deformation sensor. The upper measuring arm 42 and the lower measuring arm 44 deform as they follow the displacement of the notch in the sample, and the bridge resistance changes. The deformation of the sample is measured by the bridge imbalance output.

[0019] The adjustable calibration block 2 includes a column 21 with a through hole 22. Several trapezoidal blocks 23 are slidably connected to the through hole 22, forming a connecting space between the trapezoidal blocks 23. The upper measuring arm 42 and the lower measuring arm 44 are connected to the trapezoidal blocks 23 at the connecting space. The distance between the movable blade and the blade is adjusted to the gauge length, that is, the closest end between the trapezoidal blocks 23 is the gauge length. The mechanical extensometer structure 4 is installed, and the upper measuring arm 42 and the lower measuring arm 44 are respectively engaged with the two ends of the gauge length. At this time, the extensometer deformation reading is zeroed, and then adjusted until the distance between the blades is the gauge length + calibration value. The mechanical extensometer structure 4 is installed. At this time, the extensometer deformation reading should be the calibration value. If the error exceeds the requirement, it is adjusted according to the reading.

[0020] The fixed calibration block 3 includes a column with several trapezoidal slots 31. The upper measuring arm 42 and the lower measuring arm 44 are connected to the column within the trapezoidal slots 31. The extensometer is installed in the gauge length section, and the extensometer deformation reading is zeroed. Then, the mechanical extensometer structure 4 is installed in the gauge length + calibration value section. At this time, the deformation reading of the mechanical extensometer structure 4 should be the calibration value. If the error exceeds the requirement, adjustments are made according to the reading.

[0021] Electrical calibration:

[0022] Clear the deformation reading to zero, connect a resistor with a fixed value in parallel with the excitation and signal of the bridge circuit, and the bridge circuit will have an output. Use electrical shunt to calibrate the output.

[0023] The upper measuring arm 42 and the lower measuring arm 44 are made of materials with elastic segments, which can undergo elastic deformation, making it easy to connect with the adjustable calibration block 2 and the fixed calibration block 3.

Claims

1. A fast-calibrated fracture mechanics extensometer comprising a housing (1), an adjustable calibration block (2) and a fixed calibration block (3), characterized in that: The outer casing (1) is provided with a mechanical extensometer structure (4). The mechanical extensometer structure (4) includes a pressure block (41). An upper measuring arm (42) is provided below the pressure block (41). A support (43) is provided below the upper measuring arm (42) and directly below the pressure block (41). A lower measuring arm (44) is provided below the support (43). A lower pressure block (45) is provided below the lower measuring arm (44) and below the support (43). Strain gauges are attached to the upper measuring arm (42) and the lower measuring arm (44), and the upper measuring arm (42) and the lower measuring arm (44) form a full-bridge circuit.

2. The fracture mechanics extensometer for rapid calibration according to claim 1, characterized in that: The adjustable calibration block (2) includes a column (21) with a through hole (22) on the column (21). Several trapezoidal blocks (23) are slidably connected to the through hole (22), and a connecting space is formed between the trapezoidal blocks (23). The upper measuring arm (42) and the lower measuring arm (44) are connected to the trapezoidal blocks (23) at the connecting space.

3. The fracture mechanics extensometer with rapid calibration according to claim 1, characterized in that: The fixed calibration block (3) includes a column with several trapezoidal grooves (31) on it. The upper measuring arm (42) and the lower measuring arm (44) are connected to the column in the trapezoidal grooves (31).

4. The fracture mechanics extensometer for rapid calibration according to claim 1, characterized in that: The upper measuring arm (42) and the lower measuring arm (44) are made of a material with an elastic segment length.

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