A collaborative characterization detection system and method for material surface deformation and internal defects

Abstract

The present invention discloses a collaborative characterization detection system and method for material surface deformation and internal defects. The detection method is to heat a test piece with a high-temperature speckle pattern on the surface to a set temperature, fatigue load the test piece, and use a 3D DIC system to collect the test piece surface image at a set frequency. After loading to the set fatigue cycle, the fatigue loading and image acquisition are suspended, and then the X-ray CT device is used to perform CT scanning on the test piece that rotates 360° until the test piece is fatigue fractured; the computer performs DIC analysis on the image data collected during the fatigue loading process to obtain the surface deformation result of the test piece, and at the same time, the internal full-field defect map of the test piece is obtained according to the CT scanning data. The present invention can realize the in-situ measurement and collaborative characterization detection of the 3D deformation field of the material surface and the shape, size, and distribution of internal defects within 1000°C.

Description

Technical Field

[0001] The invention belongs to the field of experimental solid mechanics, and in particular relates to a collaborative characterization detection system and method for material surface deformation and internal defects. Background Art

[0002] Aircraft engines are known as the jewel in the crown of modern industry. Their core hot-end components have been in service for a long time in extreme environments such as high temperature, thermal shock, fatigue overload, etc., and are mostly made of high-performance alloys that are resistant to high temperature, corrosion, and oxidation. With the continuous improvement of aircraft performance requirements, the requirements for aircraft engine structure and process are becoming increasingly stringent, and there is an urgent need to develop stronger, lighter, and more durable parts. Laser additive manufacturing technology is a new manufacturing technology that integrates laser, digitalization, materials and other disciplines. It is not limited to the shape and internal structure of parts, can process parts with complex shapes and structures, and has the advantages of high material utilization, multiple types, and rapid response manufacturing, which provides unlimited possibilities for the design and manufacture of aircraft engine parts. However, the internal defects of additively manufactured parts cannot be completely eliminated, and they have the characteristics of global distribution, diverse shapes, and large size spans. Defects, as typical stress / strain concentration sources, can induce the initiation and expansion of fatigue cracks, and even cause structural fracture failure. They are important factors affecting the service performance and reliability of laser additively manufactured parts. In order to ensure the safety and reliability of laser additive manufacturing parts in aeroengines, it is an important way to study the high-temperature fatigue mechanical behavior based on advanced experimental test methods and technologies and understand its high-temperature fatigue fracture mechanical behavior and mechanism. However, traditional contact and non-full-field measurement methods such as displacement extensometers and strain gauges have great limitations in fatigue testing, especially fatigue testing under extreme environments: on the one hand, the failure of the surface of the specimen is likely to lead to the rapid failure of the surface strain gauge, making it difficult to collect more strain data, and the extensometer is at risk of damage. At the same time, the impact of clamping on the specimen itself also needs to be considered; on the other hand, high-temperature extensometers / strain gauges are expensive, prone to data drift and damage under long-term high-temperature fatigue, and difficult to characterize the non-uniform deformation behavior of the material. Therefore, it is urgent to develop effective experimental measurement systems and measurement methods. Digital Image Correlation (DIC) has the advantages of full-field, non-contact, and applicable to high-temperature and multi-scale testing, and has shown great advantages and application potential in studying the high-temperature fatigue behavior of materials. In addition, the emerging advanced X-ray computed tomography (CT) technology can achieve in-situ characterization of the evolution of internal defects in materials, thereby revealing the service damage mechanism. Combining these two technologies can achieve visual collaborative measurement and quantitative characterization of material surface deformation and internal defects during high-temperature fatigue, providing new means and experimental support for damage tolerance design and fatigue life prediction. However, the related integrated design also faces many difficulties and challenges, such as the dual-camera 3D DIC system is difficult to match with the narrow observation window of the high-temperature furnace, multiple cameras require complex synchronous triggering devices, the X-ray transmission window blocks the optical path of the DIC subsystem, and the heating subsystem affects the transmission of X-rays. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a collaborative characterization and detection system and method for material surface deformation and internal defects under high-temperature fatigue environment based on commercial X-ray CT equipment and existing single-lens 3D DIC system, which can realize in-situ measurement and collaborative characterization detection of material surface 3D deformation field and internal defect shape, size and distribution within 1000°C.

[0004] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0005] The collaborative characterization detection system for material surface deformation and internal defects proposed by the present invention comprises an X-ray CT device provided with a detection platform, a synchronous rotation device provided on the detection platform of the X-ray CT device and capable of allowing a high-temperature fatigue test device to perform 360° rotational motion, a high-temperature fatigue test device installed on the synchronous rotation device for performing fatigue loading test on a specimen and provided with a radiation heating device for heating the specimen, a 3D DIC system fixed on the high-temperature fatigue test device for photographing the specimen, and a computer electrically connected to the high-temperature fatigue test device, the 3D DIC system and the X-ray CT device, wherein the X-ray CT device is used to perform CT scanning on the specimen in the high-temperature fatigue test device, and the computer is used to process and analyze fatigue loading data, image data and CT scanning data of the specimen collected by the high-temperature fatigue test device, the 3D DIC system and the X-ray CT device.

[0006] The high temperature fatigue testing device includes a base, a driving part arranged on the base, a supporting shell arranged on the driving part, a top cover arranged on the top of the supporting shell, upper and lower clamps and a radiation heating device arranged on the driving part and the top cover inside the supporting shell, and the supporting shell is provided with a DIC observation window corresponding to the 3D DIC system and a circle of X-ray transmission windows corresponding to the X-ray emitter of the X-ray CT equipment.

[0007] The driving part and the top cover are provided with a plane reflector for reflecting the image of the test piece to the 3D DIC system for observation.

[0008] The radiation heating device is a radiation heating array composed of a plurality of heating units arranged around the test piece.

[0009] The synchronous rotation device includes a shell, in which a motor is arranged, a planetary reducer driven by the motor through a transmission mechanism, a packaging cover arranged on the shell to seal the planetary reducer, and a three-jaw self-centering chuck arranged on the packaging cover and driven by the planetary reducer, and a thrust bearing is arranged between the three-jaw self-centering chuck and the planetary reducer.

[0010] The collaborative characterization detection method for material surface deformation and internal defects proposed in the present invention is to heat a specimen with a high-temperature speckle pattern on its surface to a set temperature, perform fatigue loading on the specimen using a high-temperature fatigue test device, and use a 3D DIC system to collect specimen surface images at a set frequency. After loading to a set fatigue cycle, fatigue loading and image acquisition are suspended, and then an X-ray CT device is used to perform a CT scan on the specimen that is rotated 360°. After the scan is completed, the X-ray CT device is suspended, and the above steps are repeated until the specimen is fatigue fractured; a computer performs DIC analysis on the image data collected during the fatigue loading process to obtain a surface deformation result of the specimen, and at the same time, an internal full-field defect map of the specimen is obtained based on the CT scanning data.

[0011] The test piece is heated to a high temperature of 1000° C. by a radiation heating array composed of a plurality of heating units arranged around the test piece in a high temperature fatigue test device.

[0012] The specimen image collected by the 3D DIC system is obtained by reflection from a plane reflector disposed in a high temperature fatigue test device.

[0013] The 3D DIC system is a single-lens 3D DIC system.

[0014] The test piece that performs 360° rotation is driven by a synchronous rotation device arranged on the detection platform of the X-ray CT equipment to perform 360° rotation on the test piece of the high temperature fatigue test device.

[0015] The method of the present invention is further described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the detection system adopted by the present invention.

[0017] Figure 2 It is a schematic diagram of the structure of the high temperature fatigue test device in the detection system.

[0018] Figure 3 It is a schematic diagram of the structure of the synchronous rotation device in the detection system.

[0019] In the figure, 1-3D DIC system, 2-high temperature fatigue test device, 201-DIC observation window, 202-X-ray transmission window, 203-radiation heating device, 204-fixture, 205-base, 206-driving part, 207-plane reflector, 208-support shell, 209-test piece, 210-plane reflector mounting bracket, 211-top cover, 3-synchronous rotation device, 301-motor, 302-transmission mechanism, 303-shell, 304-planetary reducer, 305-packaging cover, 306-thrust bearing, 307-three-jaw self-centering chuck, 4-X-ray CT equipment, 5-computer. DETAILED DESCRIPTION

[0020] Figure 1 The figure shows the collaborative characterization detection system for material surface deformation and internal defects proposed by the present invention, which includes an X-ray CT device 4 provided with a detection platform, a synchronous rotation device 3 provided on the detection platform of the X-ray CT device 4 and capable of allowing a high-temperature fatigue test device 2 to perform 360° rotation, a high-temperature fatigue test device 2 mounted on the synchronous rotation device 3 for performing fatigue loading test on a specimen and provided with a radiation heating device for heating the specimen, a 3D DIC system 1 fixed on the high-temperature fatigue test device 2 for taking pictures of the specimen, and a computer 5 electrically connected to the high-temperature fatigue test device 2, the 3D DIC system 1 and the X-ray CT device 4, wherein the X-ray CT device 4 is used to perform CT scanning on the specimen in the high-temperature fatigue test device 2, and the computer 5 is used to process and analyze the specimen fatigue loading data, image data and CT scanning data collected by the high-temperature fatigue test device 2, the 3D DIC system 1 and the X-ray CT device 4.

[0021] The high temperature fatigue testing device 2 includes a base 205, a driving part 206 arranged on the base 205, a circular supporting shell 208 arranged on the driving part 206, a top cover 211 arranged on the top of the supporting shell 208, upper and lower clamps 204 and a radiation heating device 203 arranged on the driving part 206 and the top cover 211 in the supporting shell 208, and a DIC observation window 201 and a circle of X-ray transmission windows 202 corresponding to the X-ray CT device 4 are provided on the supporting shell 208.

[0022] The driving part 206 and the top cover 211 are provided with a plane mirror 207 for reflecting the sample image to the 3D DIC system 1 for observation. The plane mirror 207 is installed on the top cover 211 and the driving part 206 through a bracket 210 .

[0023] The radiation heating device 203 is a radiation heating array composed of a plurality of heating units arranged around the specimen.

[0024] The computer 5 can be electrically connected to the high temperature fatigue test device 2, the 3D DIC system 1 and the X-ray CT device 4 in a wireless or wired manner. When a wired manner is adopted, the wires of the computer 5 are connected to the wires of the high temperature fatigue test device 2 and the 3D DIC system 1 through a conductive rotary joint.

[0025] The synchronous rotation device 3 includes a shell 303, in which a motor 301 is arranged, a planetary reducer 304 driven by the motor 301 through a transmission mechanism 302, a packaging cover 305 arranged on the shell 303 to seal the planetary reducer 304, and a three-jaw self-centering chuck 307 arranged on the packaging cover 305 and driven by the planetary reducer 304, and a thrust bearing 306 is arranged between the three-jaw self-centering chuck 307 and the planetary reducer 304.

[0026] The synchronous rotating device 3 is placed on the detection platform of the X-ray CT device 4, so that the rotation axis of the synchronous rotating device 3 is aligned with the path of the X-ray, and the high-temperature fatigue test device 2 is placed on the three-jaw self-centering chuck 307 of the synchronous rotating device 3 and locked; the 3D DIC system 1 and the top cover 211 of the high-temperature fatigue test device 2 are connected together with rigid fasteners, so that the 3DDIC system 1 is always aligned with the DIC observation window 201 of the high-temperature fatigue test device 2, and the input ends of the X-ray CT device 4 and the 3DDIC system 1 are connected to the computer 5 through cables.

[0027] In the detection system adopted by the present invention, the upper and lower clamps 204 of the high-temperature fatigue test device 2 perform fatigue loading on the specimen 209; the radiation heating device 203 applies a controllable high-temperature environment to heat the specimen stably and evenly; the plane reflector 207 reflects the image of the surface of the specimen 209 through the DIC observation window 201 and is received by the 3D DIC system 1; the X-ray transmission window 202 allows the X-rays to penetrate the window and act on the specimen and be received by the detector of the X-ray CT device, thereby three-dimensionally reconstructing the internal defects of the specimen 209; the synchronous rotation device 3 allows the high-temperature fatigue device 2 and the 3D DIC system 1 to rotate 360° synchronously on the X-ray CT device, avoiding the reset error caused by multiple rotations of the high-temperature fatigue device 2 during asynchronous rotation, thereby ensuring the matching of the 3D DIC system 1 with the DIC observation window 201 and its in-situ observation of the sample.

[0028] The 3D DIC system 1 is an existing technology and is a 3D DIC system based on a single lens (see Applied Optics, 2015, 54, 7842-7850). Compared with the traditional dual-camera 3D DIC system, it does not need to consider the camera synchronization problem and has better compatibility with the narrow high-temperature observation window.

[0029] The X-ray transmission window 202 is made of a material with sufficient strength and low X-ray absorption rate, such as pure aluminum and carbon fiber, so as to avoid the shielding effect of X-rays.

[0030] The radiation heating device 203 uses a halogen lamp or laser heating method and is evenly arranged around the specimen 209 on the top cover 211 and the driving part 206. It can stably, evenly and controllably heat the central area of ​​the specimen 209 to a high temperature of 1000°C without blocking X-rays.

[0031] The plane reflector 207 has two pieces, an upper piece and a lower piece, which are arranged between the radiation heating device 203 , and can reflect the surface of the specimen 209 to the 3D DIC system 1 and prevent other components from interfering with the observation optical path of the 3D DIC system 1 .

[0032] The deformation calculation method is a single-lens 3D DIC method (see Applied Optics, 2015, 54, 7842-7850), and the internal defect characterization method is a built-in software in a commercial X-ray CT device.

[0033] The collaborative characterization detection method for material surface deformation and internal defects provided by the present invention adopts the detection system and comprises the following steps:

[0034] 1. Prepare high temperature resistant clear speckles on the surface of the test piece 209, and then install the test piece 209 on the fixture 204 in the high temperature fatigue test device 2;

[0035] 2. Move the X-ray emitter of the X-ray CT device 4 to the height of the X-ray transmission window 202 to ensure that the gauge section of the specimen 209 can be fully irradiated by X-rays, so that the defects inside the specimen 209 can be clearly observed;

[0036] 3. Adjust the position of the 3D DIC system 1 until a clear and unobstructed image of the specimen 209 can be observed from the computer 5 through the DIC observation window 201; then collect several images of the specimen 209 and store them in the computer 5 for future use;

[0037] 4. Turn on the radiation heating device 203 to heat the specimen 209 evenly and stably, and wait for the specimen 209 to be heated to the set temperature and remain stable;

[0038] 5. Setting the process parameters of the fatigue test and performing fatigue loading through the high temperature fatigue test device 2. When the fatigue loading reaches the set stage, using the 3D DIC system 1 to collect the surface image of the test piece 209 at the set frequency and store it in the computer 5;

[0039] 6. After loading to the set fatigue cycle, the fatigue loading and image acquisition are suspended, and the synchronous rotation device 3 is turned on, so that the entire high temperature fatigue test device 2 can rotate slowly and evenly inside the X-ray CT device 4. The X-ray CT device 4 is turned on, and its X-ray emitter will continuously emit X-rays to start scanning the test piece 209 that is rotating 360°;

[0040] 7. After the CT scan is completed, the X-ray CT device 4 is paused, the synchronous rotation device 3 is turned off, and steps 5 and 6 are repeated until the specimen 209 is fatigue-fractured, and the fatigue test is terminated;

[0041] 8. The computer 5 performs DIC analysis on the image data collected by the 3D DIC system 1 during the fatigue loading of the specimen 209 to obtain the surface deformation result of the specimen. At the same time, the internal full-field defect map of the specimen is obtained based on the CT scanning data of the specimen 209 collected by the X-ray CT device 4. The reconstruction results of the two are compared in a coordinated manner to lay the foundation for in-depth analysis of the fatigue mechanical behavior of the material.

[0042] The working principle of the high temperature fatigue test device 2 is as follows: the radiation heating device 203 is evenly distributed in space, and the driving part 206 applies cyclic stress to the test piece 209 through the clamp 204 in the form of stretching. The X-ray transmission window 202 is made of a material with low X-ray absorption rate, such as pure aluminum / carbon fiber, and still has a high strength after being irradiated by X-rays, and basically does not affect the scanning of the test piece 209. Since the radiation heating device 203, the plane reflector 207 and the plane reflector mounting bracket 210 are all flat designs, they are not within the range of the X-ray transmission window 202, so they will not block the X-rays and will not cause scanning defects. The observation window 201 is set between the top cover 211 and the X-ray transmission window 202, and the 3D DIC system 1 is not on the X-ray scanning path, which also avoids the damage of the X-ray to the 3D DIC system 1. The light emitted by the specimen 209 is reflected twice by the plane reflector 207, then emitted from the observation window 201 through the space between the radiation heating devices 203, and collected by the 3D DIC system 1, thereby obtaining an image of the specimen 209 at the center of the high temperature fatigue test device 2. Through such a design and layout, the DIC optical path and the X-ray scanning line do not conflict, thereby achieving the purpose of coordinated characterization.

[0043] The working principle of the synchronous rotation device 3 is as follows: the motor 301 provides power for the entire device, and the transmission mechanism 302 transmits the motor power to the planetary reducer 304. The planetary reducer 304 can convert high-speed, low-torque power into low-speed, high-torque stable power. Considering that the device has to bear a large force, a thrust bearing 306 is used. The three-jaw self-centering chuck 307 can ensure that the high-temperature fatigue test device 2 has high coaxiality with the rotating shaft through the simultaneous radial contraction of the three jaws, thereby avoiding radial runout of the specimen 209. The 3D DIC system 1 and the top cover 211 are connected together by rigid fasteners. The 3D DIC system 1 will always keep in sync with the observation window 201, ensuring that the 3D DIC system 1 always observes the same position of the specimen 209, without disassembling the specimen 209 to cause reset errors.

[0044] The present invention can not only perform non-contact, full-field accurate deformation calculation of the specimen in a high temperature environment, but also simultaneously observe the defects inside the specimen by combining X-ray CT scanning technology, and synergistically correlate the evolution of cyclic stress and internal defects.

[0045] The method of the present invention combines DIC and X-ray CT technology to collaboratively characterize the deformation field and internal defects of the material surface under thermal-mechanical coupling conditions, achieve accurate measurement of the three-dimensional deformation field at multiple scales, and perform high-precision characterization of the fatigue properties of materials within 1000°C. The method of the present invention can be used for fatigue performance characterization of laser additive manufacturing, laser repair materials and structures, and high-temperature alloys in high-temperature environments, and is widely used in material fracture and fatigue performance evaluation in various fields such as aerospace and special equipment manufacturing. In addition, it has the following advantages:

[0046] 1. The single-lens 3D DIC system can realize 3D full-field deformation measurement without considering the camera synchronization triggering problem. It has a simple structure, low cost, and can fit a narrow observation window.

[0047] 2. Through novel design and ingenious layout, X-ray CT and DIC technologies are combined without affecting each other, and the fatigue behavior of materials at high temperatures is synergistically characterized. The external cyclic stress and the internal defects of the material itself are comprehensively considered, which is closer to the actual situation;

[0048] 3. After the test piece is installed, 3D DIC measurement and X-ray CT scanning can be completed without removing the test piece. The operation is simple and does not introduce errors, which improves the measurement accuracy;

[0049] 4. Use a synchronous rotation device to allow the 3D DIC system to rotate synchronously with the high-temperature fatigue test device, avoiding the impact of reset errors caused by multiple rotations of the specimen, thereby improving measurement accuracy.

Claims

1. A collaborative characterization and detection system for material surface deformation and internal defects, characterized by It includes an X-ray CT device with a detection platform, a synchronous rotating device installed on the detection platform of the X-ray CT device and capable of allowing a high-temperature fatigue test device to perform 360° rotation, a high-temperature fatigue test device installed on the synchronous rotating device for performing fatigue loading test on a test piece and provided with a radiation heating device for heating the test piece, a 3D DIC system fixed on the high-temperature fatigue test device for taking photos of the test piece, and a computer electrically connected to the high-temperature fatigue test device, the 3D DIC system and the X-ray CT device, wherein the X-ray CT device is used to perform CT scanning on the test piece in the high-temperature fatigue test device, and the computer is used to process and analyze fatigue loading data, image data and CT scanning data of the test piece collected by the high-temperature fatigue test device, the 3D DIC system and the X-ray CT device; The high temperature fatigue testing device comprises a base, a driving part arranged on the base, a supporting shell arranged on the driving part, a top cover arranged on the top of the supporting shell, upper and lower clamps and a radiation heating device arranged on the driving part and the top cover in the supporting shell, the supporting shell is provided with a DIC observation window corresponding to the 3D DIC system and a circle of X-ray transmission windows corresponding to the X-ray emitter of the X-ray CT device; the driving part and the top cover are provided with a plane reflector for reflecting the image of the specimen to the 3D DIC system for observation.

2. The collaborative characterization and detection system for material surface deformation and internal defects according to claim 1 is characterized by: The radiation heating device is a radiation heating array composed of a plurality of heating units arranged around the test piece.

3. The collaborative characterization and detection system for material surface deformation and internal defects according to claim 1 is characterized by: The synchronous rotation device includes a shell, in which a motor is arranged, a planetary reducer driven by the motor through a transmission mechanism, a packaging cover arranged on the shell to seal the planetary reducer, and a three-jaw self-centering chuck arranged on the packaging cover and driven by the planetary reducer, and a thrust bearing is arranged between the three-jaw self-centering chuck and the planetary reducer.

4. A method for collaboratively characterizing and detecting surface deformation and internal defects of a material using the system of claim 1, characterized in that After heating the specimen with high-temperature speckle pattern on the surface to the set temperature, the specimen is fatigue loaded by the high-temperature fatigue test device, and the surface image of the specimen is collected by the 3D DIC system at the set frequency. After loading to the set fatigue cycle, the fatigue loading and image collection are suspended, and the specimen is rotated 360° and CT scanned by the X-ray CT device. After the scanning is completed, the X-ray CT device is suspended, and the above steps are repeated until the specimen is fatigue fractured; The surface deformation results of the specimen are obtained by computer DIC analysis of the image data collected during fatigue loading, and the internal full-field defect map of the specimen is obtained based on the CT scanning data.

5. The collaborative characterization detection method for material surface deformation and internal defects according to claim 4 is characterized by: The test piece is heated to a high temperature of 1000° C. by a radiation heating array composed of a plurality of heating units arranged around the test piece in a high temperature fatigue test device.

6. The collaborative characterization detection method for material surface deformation and internal defects according to claim 4 is characterized by: The specimen image collected by the 3D DIC system is obtained by reflection from a plane reflector disposed in a high temperature fatigue test device.

7. The collaborative characterization detection method for material surface deformation and internal defects according to claim 4 is characterized by: The 3D DIC system is a single-lens 3D DIC system.

8. The collaborative characterization detection method for material surface deformation and internal defects according to claim 4 is characterized by: The test piece that performs 360° rotation is driven by a synchronous rotation device arranged on the detection platform of the X-ray CT equipment to perform 360° rotation on the test piece of the high temperature fatigue test device.

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