Testing method for multi-directional residual stress on complex surfaces and normal adjustment device

Abstract

The present invention belongs to the technical field of complex surface detection, and particularly relates to a multi-directional residual stress testing method and a normal line adjustment device applicable to complex surfaces. Among them, the multi-directional residual stress testing method applicable to complex surfaces includes the following steps: First step, establish a three-dimensional model and an absolute coordinate system of the specimen, and determine the absolute coordinates of the measured point; Second step, determine the normal line of the measured point so that the direction of the normal line of the measured point is collinear with the probe direction of the X-ray stress detector; Third step, detect the residual stress of the measured point. It also includes a normal line declination adjustment device for surface test points. By making the normal line direction of the measured point collinear with the probe direction of the X-ray stress detector, the accuracy of the residual stress detection data is improved in the present invention.

Description

Technical Field

[0001] The present invention belongs to the technical field of complex surface detection, and particularly relates to a method for testing multi-directional residual stress on a complex surface and a normal line adjustment device. Background Art

[0002] In the vast field of mechanical engineering, there are a large number of complex surface structural parts such as compressor blades. The working environment they are in is often extremely harsh, facing extreme conditions such as high rotational speed, high load, and high stress. The structure of these structural parts is extremely complex, and the load-bearing situation is extremely difficult. In addition to bearing huge pressures such as centrifugal load and bending and torsion load, they may also be subject to many severe challenges at any time, such as violent impacts from external objects, continuous vibrations, erosion by various corrosive substances, strong impacts from strong airflows, and long-term fatigue effects. From the extensive actual situation and detailed data statistics, the failures of such complex surface structural parts account for a relatively large proportion in the failures of the entire huge mechanical system. The common problems are diverse, covering a series of defects such as cracks at the root, cracks in the tenon teeth, fractures in the blade body, and wear at the blade crown. These thorny problems undoubtedly become the most prominent and key problems seriously affecting the quality of related technologies, posing a great threat and challenge to the use safety of the entire mechanical system.

[0003] In the non-destructive testing of residual stress, common methods include X-ray diffraction method, neutron diffraction method, and hard X-ray diffraction such as high-energy synchrotron radiation method. However, these methods have disadvantages such as high cost, small detection thickness, and difficulty in commercial use. The short-wavelength characteristic X-ray diffraction technology has the characteristics of low cost, high detection accuracy, and large detection thickness. However, in the actual measurement process, the detector probe cannot be perpendicular to the detection point of the detected surface, resulting in low accuracy of the residual stress detection data. Therefore, there is an urgent need for a method for testing multi-directional residual stress on a complex surface and a normal line adjustment device to solve this problem. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for testing multi-directional residual stress on a complex surface and a normal line adjustment device to solve the above problems.

[0005] To achieve the above purpose, the present invention provides the following solution:

[0006] A method for testing multi-directional residual stress on a complex surface includes the following steps:

[0007] First step, establish a three-dimensional model and an absolute coordinate system of the specimen, and determine the absolute coordinates of the measured point;

[0008] Second step, determine the normal line of the measured point, and make the direction of the normal line of the measured point collinear with the probe direction of the X-ray stress detector;

[0009] Step 3: Detect the residual stress at the measured point.

[0010] Preferably, install the specimen on the normal angle adjustment device for the curved surface test point, zero the X-axis rotation angle, Y-axis rotation angle, and Z-axis rotation angle of the normal angle adjustment device for the curved surface test point, and use a coordinate measuring machine to model the specimen and the normal angle adjustment device for the curved surface test point to form the three-dimensional model and the absolute coordinate system.

[0011] Preferably, find the absolute coordinate position of the measured point in the three-dimensional model, generate the normal line of the measured point, calculate the deflection angles of the normal line with the X-axis, Y-axis, and Z-axis of the absolute coordinate system, and adjust the angle of the specimen so that the normal line of the measured point is collinear with the probe direction of the X-ray stress detector.

[0012] Preferably, the deflection angle of the normal line with the X-axis of the absolute coordinate system is denoted as the X-direction deflection angle, the deflection angle of the normal line with the Y-axis of the absolute coordinate system is denoted as the Y-direction deflection angle, and the deflection angle of the normal line with the Z-axis of the absolute coordinate system is denoted as the Z-direction deflection angle. Adjust the normal angle adjustment device for the curved surface test point according to the X-direction deflection angle, Y-direction deflection angle, and Z-direction deflection angle so that the X-axis rotation angle of the specimen is the same as the X-direction deflection angle, the Y-axis rotation angle is the same as the Y-direction deflection angle, and the Z-axis rotation angle is the same as the Z-direction deflection angle, making the normal line collinear with the probe direction of the X-ray stress detector.

[0013] Preferably, after moving the probe of the X-ray stress detector to the measured point, detect the residual stress at the measured point.

[0014] Preferably, during the process of determining the normal line, find four adjacent nodes on the same tangent plane as the measured point in the three-dimensional model, record the absolute coordinates of the measured point and the four nodes, fit the plane where the measured point is located, and take the normal line of the plane as the normal line direction of the measured point.

[0015] Preferably, the three-dimensional model and the absolute coordinates are generated by ABAQUS software. Mesh the three-dimensional model using the mesh type of C3D8R, and find the relative coordinate position of the measured point in ABAQUS.

[0016] Preferably, use Matlab to fit the plane where the measured point is located, and use Matlab to calculate the X-direction deflection angle, Y-direction deflection angle, and Z-direction deflection angle.

[0017] A normal angle adjustment device for a curved surface test point, using the above-mentioned method for testing multi-directional residual stress on a complex curved surface, includes:

[0018] Z-axis rotation adjustment device, used to adjust the Z-axis direction rotation angle of the specimen;

[0019] X-axis rotation adjustment device, installed at the movable end of the Z-axis rotation adjustment device, used to adjust the X-axis direction tilt angle of the specimen;

[0020] Y-axis rotation adjustment device, installed at the movable end of the X-axis rotation adjustment device through a 90° inclined block, used to adjust the Y-axis direction rotation angle of the specimen.

[0021] Preferably, a 30° inclined block for increasing the adjustment range of the X-axis direction tilt angle is provided between the X-axis rotation adjustment device and the 90° inclined block.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] Through three-dimensional modeling and establishing an absolute coordinate system where the model is the same as the physical object, and combining the point position coordination of simulation and physical object, the present invention realizes the precise positioning of the measured point and the determination of the normal direction. Compared with the traditional method of detecting residual stress by X-ray on the curved surface, by making the normal direction of the measured point collinear with the probe direction of the X-ray stress detector, the present invention improves the accuracy of the residual stress detection data. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings:

[0025] Figure 1 It is a schematic structural diagram of the normal deviation angle adjustment device for the curved surface test point of the present invention;

[0026] Figure 2 It is a schematic structural diagram of the normal deviation angle adjustment device for the curved surface test point of the present invention from another angle;

[0027] Figure 3 It is an exploded view of the structure of the normal deviation angle adjustment device for the curved surface test point of the present invention;

[0028] Figure 4 It is a schematic structural diagram of the 90° inclined block of the present invention;

[0029] Figure 5 It is a schematic structural diagram of the 30° inclined block of the present invention;

[0030] Figure 6 It is a schematic diagram of establishing a grid for the measured curved surface of the present invention;

[0031] Figure 7 is the position of the measured point of the present invention in the grid;

[0032] Figure 8 is the coordinate data diagram of four nodes near the measured point of the present invention;

[0033] Figure 9 is the plane normal direction after fitting of the present invention;

[0034] Figure 10 is the structural schematic diagram of the Y-axis rotation adjustment device of the present invention;

[0035] Figure 11 is the internal structure diagram of the Y-axis rotation adjustment device of the present invention;

[0036] Figure 12 is the structural schematic diagram of the X-axis rotation adjustment device of the present invention;

[0037] Figure 13 is the internal schematic diagram of the X-axis rotation adjustment device of the present invention;

[0038] Figure 14 is the structural schematic diagram of the Z-axis rotation adjustment device of the present invention;

[0039] Among them, 1. Y-axis rotation adjustment device; 2. 90° inclined block; 3. 30° inclined block; 4. X-axis rotation adjustment device; 5. Z-axis rotation adjustment device; 101. First base; 102. Locking device; 103. First micrometer adjustment component; 104. First support component; 401. Second base; 402. Rotating part; 403. Second micrometer adjustment component; 501. Third base; 502. Third locking device; 503. Third micrometer adjustment component; 504. Third support component. Specific embodiments

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0042] Referring to Figures 1 to 4 , the present invention discloses a method for testing multi-directional residual stress applicable to complex curved surfaces, including the following steps:

[0043] A method for testing multi-directional residual stress applicable to complex curved surfaces, including the following steps:

[0044] First step, establish the three-dimensional model of the test piece and the absolute coordinate system, and determine the absolute coordinates of the measured point;

[0045] Second step, determine the normal line of the measured point so that the direction of the normal line of the measured point is collinear with the probe direction of the X-ray stress detector;

[0046] Third step, detect the residual stress of the measured point.

[0047] Through three-dimensional modeling and establishing an absolute coordinate system identical to the physical object, and combining the point position coordination between the simulation and the physical object, the present invention realizes the precise positioning of the measured point and the determination of the normal line direction. Compared with the traditional method of detecting residual stress by X-ray on a curved surface, by making the normal line direction of the measured point collinear with the probe direction of the X-ray stress detector, the present invention improves the accuracy of the residual stress detection data.

[0048] For a further optimized solution, install the test piece on the normal line declination adjustment device for the curved surface test point, and zero the X-axis rotation angle, Y-axis rotation angle, and Z-axis rotation angle of the normal line declination adjustment device for the curved surface test point. Use a coordinate measuring machine to model the test piece and the normal line declination adjustment device for the curved surface test point to form a three-dimensional model and an absolute coordinate system.

[0049] After installing the test piece on the normal line declination adjustment device for the curved surface test point, zero the declination angles in the X, Y, and Z directions of the normal line declination adjustment device for the curved surface test point. Subsequently, place the normal line declination adjustment device for the curved surface test point and the test piece under the coordinate measuring machine. A coordinate measuring machine (CMM) is a device used for precisely measuring the geometric shape of an object, mainly composed of a measuring head, X, Y, and Z-axis guide rails, drive motors, and a base. Among them, the measuring head is the core component of the coordinate measuring machine, responsible for measuring the surface of the workpiece in contact or non-contact manner. It can be equipped with different types of probes (such as styli, lasers, etc.) to adapt to different measurement requirements. The X, Y, and Z-axis guide rails allow the measuring head to move in three dimensions, ensuring that every measurement point on the workpiece can be accurately positioned. The drive motors control the movement of the measuring head on each axis, ensuring that it can quickly and accurately reach the specified position. And the base provides stable support, ensuring the rigidity and stability of the entire measurement system and reducing measurement errors.

[0050] For a further optimized solution, find the absolute coordinate position of the measured point in the three-dimensional model, generate the normal line of the measured point, calculate the declination angles between the normal line and the X-axis, Y-axis, and Z-axis of the absolute coordinate system, and adjust the angle of the test piece so that the normal line of the measured point is collinear with the probe direction of the X-ray stress detector.

[0051] For a further optimized solution, the deviation angle of the normal line from the X-axis of the absolute coordinate system is denoted as the X-direction deviation angle, the deviation angle of the normal line from the Y-axis of the absolute coordinate system is denoted as the Y-direction deviation angle, and the deviation angle of the normal line from the Z-axis of the absolute coordinate system is denoted as the Z-direction deviation angle. Adjust the normal line deviation angle adjusting device of the surface test point according to the X-direction deviation angle, Y-direction deviation angle, and Z-direction deviation angle so that the X-axis rotation angle of the test piece is the same as the X-direction deviation angle, the Y-axis rotation angle is the same as the Y-direction deviation angle, and the Z-axis rotation angle is the same as the Z-direction deviation angle, making the normal line collinear with the probe direction of the X-ray stress detector.

[0052] For a further optimized solution, after moving the probe of the X-ray stress detector to the measured point, detect the residual stress at the measured point.

[0053] For a further optimized solution, during the process of determining the normal line, find four adjacent nodes in the three-dimensional model that are on the same tangent plane as the measured point, record the absolute coordinates of the measured point and the four nodes, fit the plane where the measured point is located, and take the normal line of the plane as the normal line direction of the measured point.

[0054] For a further optimized solution, the three-dimensional model and the absolute coordinates are generated by the ABAQUS software. Use the mesh type of C3D8R to divide the mesh of the three-dimensional model, and find the relative coordinate position of the measured point in ABAQUS.

[0055] For a further optimized solution, use Matlab to fit the plane where the measured point is located, and use Matlab to calculate the X-direction deviation angle, Y-direction deviation angle, and Z-direction deviation angle.

[0056] Taking the impeller as an example, apply this method to measure the residual stress at the measured position on the impeller.

[0057] The test process and the test results of the case are as follows:

[0058] 1. Install the impeller to be measured on the normal line deviation angle adjusting device of the surface test point. And place it under the three-coordinate measuring instrument. After determining the measured point, establish an absolute coordinate system for the blade where the measured point is located separately.

[0059] 2. Based on the three-coordinate measuring instrument, perform three-dimensional modeling and establish an absolute coordinate system for the blade and the normal line deviation angle adjusting device of the surface test point in ABAQUS. Use the mesh type of C3D8R to divide the mesh, and find the relative coordinate position of the measured point in ABAQUS to achieve the goal of coordinating the simulation and the physical position points, facilitating subsequent measurements.

[0060] 3. Find four adjacent nodes on the same tangent plane as the measured point, record the absolute coordinates of the target point and these four points. Then, in Matlab, the plane where the measured point is located can be fitted through the absolute coordinates of the four nodes, and further the normal line direction of this plane can be obtained. It can be approximately considered that the normal line direction of this plane is the normal line direction of the measured point.

[0061] 4. Calculate the angles between the normal direction and the three absolute coordinate axes in Matlab, and adjust the deflection angles of the X, Y, and Z directions of the normal deflection angle adjustment device for the surface test points according to the deviation angles, so that the normal direction of the measured points on the blade is collinear with the probe direction of the X-ray stress detector, in order to achieve the function of detecting the residual stress along the surface normal direction, thereby improving the accuracy.

[0062] 5. Use the X-ray stress detector to measure the residual stress of the measured points.

[0063] 6. Based on the above detection process, select five target points on the aluminum alloy impeller, and the detection results are shown in the following table:

[0064] Table 1 Measured values of residual stress in the X and Y directions

[0065]

[0066] Based on the above table, the measured values of the residual stress are:

[0067] In the X direction (processing direction): 190 MPa; 185 MPa; 178 MPa; 192 MPa; 188 MPa;

[0068] In the Y direction (perpendicular to the processing direction): 135 MPa; 142 MPa; 130 MPa; 128 MPa; 139 MPa;

[0069] Since the processing process parameters of the five test points are the same and the residual stress detection is carried out immediately after processing, the residual stress values between the five points should not differ much. From the results, this law is also verified, thus indirectly ensuring the reliability of this method.

[0070] It can be seen that this method has the following advantages compared with the traditional method:

[0071] 1) Point position coordination combining simulation and physical object: Using a coordinate measuring machine and professional software for point position coordination of physical object and simulation, realizing accurate positioning of the measured points and determination of the normal direction. This way of combining multiple technical means improves the accuracy and reliability of detection.

[0072] 2) Intelligent angle deviation display: In Matlab, the angles by which the normal direction deviates from the absolute coordinates can be displayed, enabling the user to intuitively understand and make precise adjustments, improving the convenience and visualization of operation.

[0073] A normal deflection angle adjustment device for surface test points, using the above-mentioned method for multi-directional residual stress testing applicable to complex surfaces, includes:

[0074] The Z-axis rotation adjustment device 5 is used to adjust the rotation angle of the specimen in the Z-axis direction;

[0075] The X-axis rotation adjustment device 4 is installed at the movable end of the Z-axis rotation adjustment device 5 and is used to adjust the inclination angle of the specimen in the X-axis direction;

[0076] The Y-axis rotation adjustment device 1 is installed at the movable end of the X-axis rotation adjustment device 4 through a 90° inclined block 2 and is used to adjust the rotation angle of the specimen in the Y-axis direction.

[0077] In a further optimized solution, a 30° inclined block 3 for increasing the adjustment range of the inclination angle in the X-axis direction is provided between the X-axis rotation adjustment device 4 and the 90° inclined block 2.

[0078] A normal deviation angle adjustment device for curved surface test points includes three rotation adjustment devices, an impeller connecting plate and two inclined blocks. Connected by bolts and cooperating with interlocking spiral chutes, it can achieve the free rotation of the impeller in the X, Y, and Z directions, thereby ensuring that the probe of the X-ray stress detector can always be along the normal direction of the curved surface to more accurately detect the residual stress of the curved surface.

[0079] The workpiece to be measured is connected to the supporting component below through M5 hexagon socket head cap screws to ensure its stable fixation. The Y-axis rotation adjustment device 1 can make the blade rotate with the Y-axis direction as the rotation axis through the adjustment knob above, and is connected to the lower inclined block through M2.5 hexagon socket head cap screws; the inclined blocks can be selected as the 90° inclined block 2 and the 30° inclined block 3, which can increase the angle adjustment range. Usually, the Y-axis rotation adjustment device 1 is connected to the X-axis rotation adjustment device 4 through the 90° inclined block 2. When an increased angle adjustment range is required, the 90° inclined block 2 and the 30° inclined block 3 can be used together to increase the angle adjustment range. The X-axis rotation adjustment device 4 and the Z-axis rotation adjustment device 5 make the blade rotate through the adjustment knob above. Among them, the X-axis rotation adjustment device 4 is connected to the bottom of the 90° inclined block 2 through M4 hexagon socket head cap screws, and the X-axis rotation adjustment device 4 and the Z-axis rotation adjustment device 5 are connected through M14 hexagon socket head cap screws, allowing the platform to perform rotation operations. Finally, the function of determining the normal direction of any point on the blade in space is realized. These connection methods ensure the overall stability and functionality of the device, enabling it to perform rotation and adjustment operations smoothly.

[0080] The Y-axis rotation adjustment device 1, the X-axis rotation adjustment device 4, and the Z-axis rotation adjustment device 5 are all provided with micrometer scales for displaying and adjusting the rotation angle, which can precisely control the rotation angle of the workpiece. The user can align the rotation axis with the micrometer by adjusting the knob on the platform, thereby ensuring that each rotation reaches an accurate angle. In addition, the user only needs to rotate the knob on the rotation axis to precisely control the rotation angle of the workpiece, which can be easily achieved whether it is clockwise or counterclockwise, and the operation is simple and convenient.

[0081] The 90° inclined block and the 30° inclined block, as the core intermediate force transmission components, are designed and selected to ensure the highest stability and load-bearing capacity. The 90° inclined block and the 30° inclined block are made of high-strength alloy steel and achieve the optimal balance of mechanical strength and corrosion resistance through precision machining processes, thus ensuring precise shape and long-term durability when bearing complex curved surface components.

[0082] The adjustable inclination angle of the inclined block enables this device to adapt to complex workpieces with different curvatures and shapes. By simply adjusting the angle of the inclined block, users can quickly respond to various detection requirements. Whether it is for high-precision components in the aerospace field or complex-structured components in the automotive industry, precise positioning and efficient detection can be achieved. The interchangeable design further reduces the manufacturing cost and simplifies the maintenance process. Users do not need to configure dedicated equipment for different workpieces, significantly improving the resource utilization rate and economic benefits.

[0083] Among them, the Y-axis rotation adjustment device 1 includes a first base 101, a first locking screw 102, a first micrometer 103, a first turntable 104, a first elastic rod 105, a translation thread block 106, and a pressing block 107.

[0084] The first turntable 104 is rotatably arranged in the first base 101. The translation threaded block 106 and the extrusion block 107 are movably arranged in the first base 101. An activity groove for the horizontal movement of the translation threaded block 106 and the extrusion block 107 is provided in the first base 101. The cross-section of the activity groove is in a runway shape. The first locking screw 102 is threadedly connected to the translation threaded block 106. One end of the first locking screw 102 is located outside the first base 101, and the other end of the first locking screw 102 is rotatably connected to the extrusion block 107. The end of the extrusion block 107 away from the first locking screw 102 contacts the side wall of the first turntable 104 and is used to rub and drive the first turntable 104 to rotate. Under the threaded action with the translation threaded block 106, the first locking screw 102 can drive the extrusion block 107 to contact or separate from the side wall of the first turntable 104. The movable end of the first elastic rod 105 contacts one side of the translation threaded block 106, and the fixed end of the first elastic rod 105 is fixedly connected to the first base 101. The movable end of the first micrometer 103 contacts the other side of the translation threaded block 106, and the fixed end of the first micrometer 103 is fixedly connected to the first base 101. By adjusting the extension amount of the movable end of the first micrometer 103, the translation threaded block 106 can be pushed to move horizontally in the chute provided in the first base 101, and its moving direction is parallel to the tangent direction of the side wall of the first turntable 104. Then, the extrusion block 107 is driven to move by the first locking screw 102. The end face of the extrusion block 107 contacts the side wall of the first turntable 104, and the end face of the extrusion block 107 is collinear with the tangent direction of the side wall of the first turntable 104. Therefore, the first turntable 104 can be rubbed and driven to rotate by the extrusion block 107 to achieve precise angle adjustment. In addition, when the extrusion block 107 is separated from the first turntable 104 under the threaded action between the first locking screw 102 and the translation threaded block 106, the first turntable 104 can rotate freely, and the rotation angle can be quickly and roughly adjusted.

[0085] Among them, the X-axis rotation adjustment device 4 includes a second base 401, a sliding block 402, a worm 403, a worm gear block 404, and a second locking screw 405. The worm 403 is rotatably arranged in the second base 401. The worm 403 meshes with the worm gear block 404. The worm gear block 404 is movably arranged on the second base 401. The sliding block 402 is fixed to the worm gear block 404. The second locking screw 405 is threadedly connected to one side of the sliding block 402, and the second locking screw 405 is used to lock the sliding block 402 to the second base 401. By driving the worm gear block 404 to slide relative to the second base 401 through the rotation of the worm 403, the inclination angle of the sliding block 402 can be changed.

[0086] Among them, the Z-axis rotation adjustment device 5 includes a third base 501, a push rod 502, a third elastic rod 503, a third turntable 504, a third micrometer 505, a rotating seat 506 and a third locking screw 507. The rotating seat 506 is rotatably arranged on the third base 501. A push rod 502 is fixedly connected to the side wall of the rotating seat 506. The push rod 502 is located between the movable end of the third elastic rod 503 and the movable end of the third micrometer 505. Both sides of the push rod 502 are in contact with the movable end of the third elastic rod 503 and the movable end of the third micrometer 505 respectively. The fixed end of the third elastic rod 503 and the fixed end of the third micrometer 505 are fixedly connected to the third base 501. A third turntable 504 is rotatably connected to the rotating seat 506. The third turntable 504 is locked with the rotating seat 506 through the third locking screw 507. The third locking screw 507 is threadedly connected to the third turntable 504. By loosening the third locking screw 507, the third turntable 504 is rotated to a approximate angle, and then the third turntable 504 and the rotating seat 506 are locked. The third micrometer 505 is used to push the push rod 502 to make the rotating seat 506 rotate to achieve fine adjustment. The rotating seat 506 can be fixed to the third base 501 through another locking screw.

[0087] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0088] The above-described embodiments are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for testing multi-directional residual stress on complex curved surfaces, characterized in that, It includes the following steps: In the first step, establish a three-dimensional model of the test piece and an absolute coordinate system, and determine the absolute coordinates of the measured point; In the second step, determine the normal line of the measured point so that the direction of the normal line of the measured point is collinear with the probe direction of the X-ray stress detector; In the third step, detect the residual stress of the measured point; Install the test piece on the normal line deflection angle adjustment device of the curved surface test point, and zero the X-axis rotation angle, Y-axis rotation angle and Z-axis rotation angle of the normal line deflection angle adjustment device of the curved surface test point. Use a three-coordinate measuring instrument to model the test piece and the normal line deflection angle adjustment device of the curved surface test point to form the three-dimensional model and the absolute coordinate system; The normal line deflection angle adjustment device of the curved surface test point is used to make the direction of the normal line of the measured point collinear with the probe direction of the X-ray stress detector; The normal line deflection angle adjustment device of the curved surface test point includes: A Z-axis rotation adjustment device (5) for adjusting the Z-axis direction rotation angle of the test piece; The Z-axis rotation adjustment device (5) includes a third base (501), a push rod (502), a third elastic rod (503), a third turntable (504), a third micrometer (505), a rotating seat (506) and a third locking screw (507); An X-axis rotation adjustment device (4) is installed at the movable end of the Z-axis rotation adjustment device (5) for adjusting the inclination angle of the test piece in the X-axis direction. The X-axis rotation adjustment device (4) includes a second base (401), a sliding block (402), a worm (403), a worm wheel block (404) and a second locking screw (405); A Y-axis rotation adjustment device (1) is installed at the movable end of the X-axis rotation adjustment device (4) through a 90° inclined block (2) for adjusting the Y-axis direction rotation angle of the test piece. The Y-axis rotation adjustment device (1) includes a first base (101), a first locking screw (102), a first micrometer (103), a first turntable (104), a first elastic rod (105), a translation thread block (106) and an extrusion block (107).

2. The method for testing multi-directional residual stress on a complex curved surface according to claim 1, characterized in that: Find the absolute coordinate position of the measured point in the three-dimensional model, generate the normal line of the measured point, calculate the deflection angles of the normal line with the X-axis, Y-axis and Z-axis of the absolute coordinate system, and adjust the angle of the test piece so that the normal line of the measured point is collinear with the probe direction of the X-ray stress detector.

3. The method for testing multi-directional residual stress on a complex curved surface according to claim 2, characterized in that: The declination angle between the normal line and the X-axis of the absolute coordinate system is denoted as the X-direction declination angle, the declination angle between the normal line and the Y-axis of the absolute coordinate system is denoted as the Y-direction declination angle, and the declination angle between the normal line and the Z-axis of the absolute coordinate system is denoted as the Z-direction declination angle. According to the X-direction declination angle, Y-direction declination angle, and Z-direction declination angle, adjust the normal line declination angle adjusting device of the surface test point so that the X-axis rotation angle of the specimen is the same as the X-direction declination angle, the Y-axis rotation angle is the same as the Y-direction declination angle, and the Z-axis rotation angle is the same as the Z-direction declination angle, so that the normal line is collinear with the probe direction of the X-ray stress detector.

4. The method for multi-directional residual stress testing applicable to complex surfaces according to claim 3, characterized in that: After moving the probe of the X-ray stress detector to the measured point, detect the residual stress at the measured point.

5. The multi-directional residual stress testing method for complex curved surfaces according to claim 4, characterized in that: During the process of determining the normal line, find four adjacent nodes on the same section as the measured point in the three-dimensional model, record the absolute coordinates of the measured point and the four nodes, fit the plane where the measured point is located, and take the normal line of the plane as the normal line direction of the measured point.

6. The multi-directional residual stress testing method for complex curved surfaces according to claim 5, characterized in that: The three-dimensional model and the absolute coordinates are generated by ABAQUS software. The three-dimensional model is meshed using the mesh type of C3D8R, and the relative coordinate position of the measured point is found in ABAQUS.

7. The multi-directional residual stress testing method for complex curved surfaces according to claim 6, characterized in that: Use Matlab to fit the plane where the measured point is located, and use Matlab to calculate the X-direction declination angle, Y-direction declination angle, and Z-direction declination angle.

8. The multi-directional residual stress testing method for complex curved surfaces according to claim 1, characterized in that: A 30° inclined block (3) for increasing the adjustment range of the inclination angle in the X-axis direction is provided between the X-axis rotation adjustment device (4) and the 90° inclined block (2).

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