A test apparatus for visual crack propagation

Abstract

This utility model discloses a test device for visual crack propagation, including a locking ring. The top of the locking ring is provided with an aluminum alloy connecting rod, each end having a connecting rod. One connecting rod is rotatably connected to the top of the locking ring via a shaft, and the top of the other connecting rod is rotatably connected to a connecting rod via a shaft. The front of the connecting rod is inserted into the aluminum alloy connecting rod. A lens mounting bracket is fixedly connected to the end of the aluminum alloy connecting rod, and a zoomable measuring lens with a supplementary light source is installed inside the lens mounting bracket. A real-time display screen for image storage is connected to the front of the measuring lens. This utility model provides a test device for visual crack propagation, enabling high-precision and high-reliability dynamic crack monitoring, solving the industry pain points of crack propagation monitoring under high temperature, enclosed spaces, and complex loads.

Description

Technical Field

[0001] This utility model relates to the field of fatigue crack propagation detection of metallic materials, and in particular to a test device for visual crack propagation. Background Technology

[0002] In aerospace, nuclear energy, and transportation, high-temperature components need to operate under high temperature and high stress conditions for extended periods. For example, high-temperature alloys are widely used in engine blades and fuselage frames, but they are prone to crack initiation and propagation under high-stress cyclic loading, affecting the safety and reliability of the equipment. High-temperature crack propagation tests can assess the crack propagation rate and fracture toughness of these materials in high-temperature environments, providing crucial data support for material reliability assessment, structural safety design, and life prediction. This ensures that cracked components do not fail during their service life, optimizes maintenance strategies, and avoids catastrophic consequences.

[0003] Currently, the main techniques for measuring fatigue crack propagation under high-temperature conditions are the compliance method and the potential drop method, but both face technical bottlenecks in practical applications. The compliance method calculates crack length based on the linear relationship between crack opening displacement (COD) and load, and its measurement accuracy is highly dependent on the sensitivity and response speed of the COD gauge (crack opening displacement sensor). In high-temperature environments, the thermal expansion effect of materials causes dynamic changes in the geometry of components, resulting in phase lag in the displacement signal output by the COD gauge. Simultaneously, the accumulation of a high-temperature oxide layer on the crack surface alters crack closure behavior, making it difficult for the sensor to accurately distinguish between true crack propagation and pseudo-displacement caused by thermal expansion. Furthermore, when the temperature exceeds 400℃, the creep effect of metallic materials exacerbates the nonlinear deformation of the plastic zone at the crack tip. Traditional COD gauges, limited by measurement resolution and sampling frequency, often fail to capture the transient propagation characteristics of micron-level cracks, leading to significant errors in crack morphology reconstruction.

[0004] The potentiometric method inverses the crack length by monitoring changes in the potential difference across a crack, based on Ohm's law and the characteristics of current path distribution. However, this method has stringent requirements for the homogeneity of material conductivity, and strong electromagnetic interference from electromagnetic induction heating devices or arc discharges can completely drown out the microvolt-level voltage signal. More importantly, the plastic zone at the crack tip continues to expand under high-temperature cyclic loading, and its strain hardening effect changes the material resistivity, causing the potentiometric calibration curve to deviate from the preset model.

[0005] While traditional visual methods can directly obtain crack morphology, they face limitations in high-temperature testing: testers must conduct intermittent manual observation through a high-temperature observation window. However, limitations in human visual resolution, poor light transmission in the window glass due to high temperatures, and surface oxidation and reflection from the component make it difficult to accurately quantify crack propagation. Furthermore, manual observation and recording of crack length at standard intervals is required, consuming significant manpower.

[0006] To overcome the aforementioned technical bottlenecks, a test device for visual crack propagation was designed. Utility Model Content

[0007] The main objective of this invention is to provide a test device for crack propagation by visual inspection, which can effectively solve the problems pointed out in the background art.

[0008] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0009] A test device for visual crack propagation includes a locking ring. The top of the locking ring has an aluminum alloy connecting rod with connecting rods at both ends. One connecting rod is rotatably connected to the top of the locking ring via a shaft. The top of the other connecting rod is rotatably connected to a connecting rod via a shaft. The front of the connecting rod is inserted into the aluminum alloy connecting rod. A lens mounting bracket is fixedly connected to the end of the aluminum alloy connecting rod. A zoomable measuring lens with supplementary lighting is housed within the lens mounting bracket. A real-time display screen for image capture and storage is connected to the front of the measuring lens.

[0010] As a further embodiment of this utility model, the locking ring is composed of two locking blocks, each with a semi-circular groove on its opposite surface and a fixed threaded groove on its rear.

[0011] As a further embodiment of this utility model, the lens fixing bracket is composed of a connecting block and a fixing plate. A circular groove is provided through the inner side of the fixing plate, and a limiting threaded groove communicating with the circular groove is provided on the outer periphery of the fixing plate.

[0012] As a further embodiment of this utility model, the front part of the connecting rod 2 has two positioning threaded grooves.

[0013] As a further embodiment of this utility model, angle fixing grooves are respectively provided on the opposite sides of the two connecting rods for limiting the first and second shafts.

[0014] As a further embodiment of this utility model, the second aluminum alloy connecting rod is cylindrical in shape.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This utility model's locking ring, in conjunction with aluminum alloy connecting rod one and aluminum alloy connecting rod two, along with shaft one and shaft two, allows for convenient connection and fixation to the column of the testing machine frame. It also possesses good adjustability, effectively addressing the technical challenges of crack propagation monitoring under high-temperature environments. This non-contact testing device, based on a visual method, integrates optical sensing and control measures to achieve high-precision, high-reliability dynamic crack monitoring. Furthermore, its non-contact design avoids additional interference and structural damage, offering high environmental adaptability and supporting real-time monitoring under extreme conditions. It solves the industry pain points of crack propagation monitoring under high temperatures, enclosed spaces, and complex loads, providing a new tool for the safe service and lifespan management of high-temperature components. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a test device for visual crack propagation according to the present invention;

[0018] Figure 2 This is a rear view of the assembly structure of aluminum alloy connecting rod one and aluminum alloy connecting rod two of a test device for visual crack propagation according to the present invention.

[0019] Figure 3 This is a top view of the assembly of aluminum alloy connecting rod one and aluminum alloy connecting rod two in a test device for visual crack propagation according to this utility model.

[0020] Figure 4 This is an exploded view of alloy connecting rod one and aluminum alloy connecting rod two of a test device for visual crack propagation according to the present invention.

[0021] In the diagram: 1. Locking ring; 2. Aluminum alloy connecting rod one; 3. Connecting rod one; 4. Shaft one; 5. Shaft two; 6. Aluminum alloy connecting rod two; 7. Connecting rod two; 8. Lens mounting bracket; 9. Measuring lens; 10. Real-time display screen. Detailed Implementation

[0022] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0023] like Figure 1-4As shown, a test device for visual crack propagation includes a locking ring 1. The top of the locking ring 1 is provided with an aluminum alloy connecting rod 2, which has connecting rods 3 at both ends. One of the connecting rods 3 is rotatably connected to the top of the locking ring 1 via a shaft 4. The top of the other connecting rod 3 is rotatably connected to a connecting rod 7 via a shaft 5. An aluminum alloy connecting rod 6 is inserted into the front of the connecting rod 7. A lens fixing bracket 8 is fixedly connected to the end of the aluminum alloy connecting rod 6. A focusing and zoom measuring lens 9 with a supplementary light source is provided in the lens fixing bracket 8. A real-time display screen 10 for taking pictures and storing images is connected to the front of the measuring lens 9.

[0024] The locking ring 1 consists of two locking blocks. The opposite surfaces of the two locking blocks are provided with semi-circular grooves, and the rear of the two locking blocks are provided with fixed thread grooves.

[0025] Specifically, by setting a fixed threaded groove, two locking blocks can be connected and fixed with screws, which makes it easy to install on the column of the testing machine frame.

[0026] The lens mounting bracket 8 consists of a connecting block and a fixing plate. A circular groove is provided through the inner side of the fixing plate, and a limiting threaded groove communicating with the circular groove is provided on the outer periphery of the fixing plate.

[0027] Specifically, by setting a limiting threaded groove, the measuring lens 9, which is installed in the lens mounting bracket 8, can be fixed by screws.

[0028] Two positioning threaded grooves are provided at the front of the connecting rod 27.

[0029] Specifically, by setting a positioning threaded groove, the position of the aluminum alloy connecting rod 26 can be fixed by screws after it has been moved and adjusted.

[0030] Both connecting rods 3 have angular fixing grooves on their opposite sides for limiting the movement of shaft 4 and shaft 5, respectively.

[0031] Specifically, by setting an angle fixing groove, screws can be used to fix the adjustment angle of connecting rod 1 3 and connecting rod 2 7, thereby fixing the adjustment angle.

[0032] The aluminum alloy connecting rod 26 is cylindrical, which facilitates its lateral movement and adjustment and reduces friction.

[0033] It should be noted that this utility model is a test device for visual crack propagation. In use, the locking ring 1 is locked and fixed to the column of the test machine frame by fixing screws. Then, the measuring lens 9 is fixed to the lens fixing bracket 8 and fixed with screws. The horizontal position of the measuring lens 9 is adjusted by moving the aluminum alloy connecting rod 2 6. At the same time, the orientation of the measuring lens 9 is adjusted by rotating the connecting rod 1 3 through the shaft 1 4 and by rotating the connecting rod 2 7 through the shaft 2 5, thereby realizing the installation of the measuring lens 9.

[0034] During testing, the crack propagation at the tip of the notch in the sample is monitored in real time by the measuring lens 9 and displayed on the real-time display screen 10. The crack length is also measured. Before measurement, the measurement scale on the display screen needs to be calibrated with a ruler at the current magnification.

[0035] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A test device for visual crack propagation comprising a locking ring (1), characterized in that, The top of the locking ring (1) is provided with an aluminum alloy connecting rod (2) with connecting rods (3) at both ends. One of the connecting rods (3) is rotatably connected to the top of the locking ring (1) via a shaft (4). The top of the other connecting rod (3) is rotatably connected to a connecting rod (7) via a shaft (5). The front part of the connecting rod (7) is inserted into an aluminum alloy connecting rod (6). The end of the aluminum alloy connecting rod (6) is fixedly connected to a lens fixing bracket (8). The lens fixing bracket (8) is provided with a focusing and zoom measuring lens (9) with a supplementary light source. The front part of the measuring lens (9) is connected to a real-time display screen (10) for taking pictures and storing images.

2. The testing apparatus for visual crack propagation according to claim 1, characterized in that: The locking ring (1) consists of two locking blocks. The two locking blocks have semi-circular grooves on their opposite surfaces, and the two locking blocks have fixed thread grooves on their rear parts.

3. The testing apparatus for visual crack propagation according to claim 1, characterized in that: The lens fixing bracket (8) consists of a connecting block and a fixing plate. A circular groove is provided through the inner side of the fixing plate, and a limiting threaded groove communicating with the circular groove is provided on the outer periphery of the fixing plate.

4. The testing apparatus for visual crack propagation according to claim 1, characterized in that: The front part of the connecting rod 2 (7) has two positioning threaded grooves.

5. The testing apparatus for visual crack propagation according to claim 1, characterized in that: Both connecting rods (3) have angular fixing grooves on their opposite sides for limiting the movement of shafts (4) and (5).

6. The testing apparatus for visual crack propagation according to claim 1, characterized in that: The aluminum alloy connecting rod 2 (6) is cylindrical.

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