Device and method for nondestructively acquiring incident angle in stress detection direction of composite material

Abstract

The invention discloses a device and a method for non-destructively acquiring an incident angle in a stress detection direction of a composite material, and belongs to the field of ultrasonic stress detection of composite materials. A slewing bearing inner ring is coaxially and rotatably mounted on a slewing bearing outer ring of the device, a wedge block is mounted on the slewing bearing inner ring, and a first piezoelectric wafer gear, a second piezoelectric wafer gear, a driven wheel, a driving wheel and an ultrasonic signal module are mounted on the wedge block; piezoelectric wafers are mounted at the bottom ends of the first piezoelectric wafer gear and the second piezoelectric wafer gear, and echo signals can be obtained in the rotating process; ultrasonic signal modules are symmetrically installed on the two sides of the top of the wedge block and used for being connected with an upper computer, and the upper computer is connected with the driving wheel through a servo control module. Through the technical means of dynamically adjusting the incidence angle, the incidence angle of the unknown composite material in the 0-degree fiber direction can be rapidly and nondestructively obtained, and a brand new solution is provided for efficient and accurate stress detection of the composite material.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic stress detection of composite materials, and particularly relates to a device and method for non-destructively obtaining the incident angle of a composite material stress detection direction. Background Art

[0002] In ultrasonic testing, LCR waves (critically refracted waves) are an important propagation mode, capable of penetrating thick composite layers and providing crucial stress and crack information. LCR wave generation is closely related to the angle of incidence, particularly in composite materials, where changes in the angle of incidence directly affect LCR wave formation and propagation. However, due to the anisotropy of composite materials, the angle of incidence and frequency for each test direction must be determined before testing.

[0003] Currently, determining the angle of incidence requires using Snell's theorem. By cutting and measuring the sound velocity of composite materials, the angle of incidence in each direction is calculated. Ultrasonic LCR stress detection is then performed by machining fixed wedges. This method requires cutting composite specimens to measure the longitudinal and shear wave velocities, thereby calculating the critical refraction angles in different directions. This prerequisite places stringent demands on the test piece during actual testing and is not suitable for situations where only the test piece is available but no specimen is available. Furthermore, the series of steps—cutting specimens, measuring sound velocity, calculating the angle of incidence, and machining fixed wedges—is time-consuming and unsuitable for rapid or real-time testing of composite materials. This cumbersome process not only reduces testing efficiency but also increases testing costs, making it particularly inconvenient when frequent adjustments to the testing plan are required. Furthermore, the incident angle of the machined fixed wedge is preset. If the material structure (such as ply orientation or thickness) changes, the wedge may need to be redesigned and remachined, making it very inflexible when dealing with different materials or complex structures. Especially in actual engineering applications, composite materials may exhibit complex conditions such as non-uniformity, unknown layup orientation, or multi-directional stacking. Fixed wedges are unable to meet the testing requirements in these complex scenarios. Furthermore, the sound velocity measurement of composite materials is highly sensitive to experimental conditions (such as coupling state and temperature). Even small errors in the sound velocity can directly affect the calculated incident angle, leading to inaccurate LCR wave detection. Once errors occur in the sound velocity measurement, the machined fixed wedge may fail to generate LCR waves, necessitating re-measurement and re-machining, further increasing uncertainty and cost. Finally, once the fixed wedge's incident angle is determined, it cannot be dynamically adjusted to meet on-site testing requirements. This static characteristic makes it impossible to adapt to material changes or optimize testing results during the testing process. In certain dynamic monitoring scenarios (such as real-time stress measurement when the material's stress state changes), fixed-angle wedges cannot meet real-time testing requirements. In practical applications, their lack of flexibility, low efficiency, and excessive reliance on specimen and material properties limit their applicability in complex composite material testing. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a device and method for non-destructively obtaining the incident angle of the composite material stress detection direction. The present invention solves a number of problems existing in the existing methods, including: relying on cutting samples to measure the sound velocity, and being unable to directly perform detection on composite materials with unknown layers; the detection preparation process is complicated, time-consuming, and difficult to meet the needs of rapid detection; the fixed wedge incident angle lacks flexibility and is difficult to adapt to complex material structures and dynamic detection scenarios; the sound velocity measurement is sensitive to experimental conditions, resulting in error accumulation that affects detection accuracy; and the traditional method cannot adjust the incident angle in real time and cannot adapt to the changing working conditions on site. The present invention uses the technical means of dynamically adjusting the incident angle to achieve rapid and non-destructive acquisition of the incident angle of the 0° fiber direction of the unknown composite material, providing a new solution for efficient and accurate stress detection of composite materials.

[0005] The specific technical solutions adopted in the present invention are as follows:

[0006] In a first aspect, the present invention provides a device for non-destructively obtaining the incident angle in the stress detection direction of a composite material, comprising a slewing bearing inner ring, a slewing bearing outer ring, and a wedge;

[0007] A slewing bearing inner ring is coaxially mounted on the slewing bearing outer ring, and a scale is provided on the circumference of the slewing bearing outer ring; a wedge is mounted on the slewing bearing inner ring, and the bottom of the wedge is in contact with the surface of the workpiece to be measured, and a first piezoelectric chip gear, a second piezoelectric chip gear, a driven wheel, a driving wheel and an ultrasonic signal module are mounted on the wedge; the first piezoelectric chip gear and the second piezoelectric chip gear are symmetrically mounted at both ends of the front side of the wedge, and the first piezoelectric chip gear is meshed and connected to the second piezoelectric chip gear through the driven wheel and the driving wheel in turn; piezoelectric chips are mounted on the bottom ends of the first piezoelectric chip gear and the second piezoelectric chip gear, and echo signals can be obtained during rotation; ultrasonic signal modules are symmetrically mounted on both sides of the top of the wedge, and the ultrasonic signal modules are used to be connected to the host computer, and the host computer is connected to the driving wheel through the servo control module.

[0008] Preferably, a circular stepped groove is coaxially opened inside the outer ring of the slewing bearing, and a scale is provided on the outer circumference of the stepped groove. The stepped groove is used to place the inner ring of the slewing bearing; the tops of the inner ring of the slewing bearing and the outer ring of the slewing bearing are flush, and the inner ring of the slewing bearing realizes relative rotation with the outer ring of the slewing bearing through rolling elements.

[0009] Preferably, two groups of opposite square grooves are provided on the upper, lower, left and right sides of the inner ring of the slewing bearing, and each group of square grooves is used to place installation wedges; threaded holes are provided on the outer sides of the square grooves on the inner ring of the slewing bearing, and scale indicators are provided next to each threaded hole, and the scale indicators are used to match the scales on the outer ring of the slewing bearing; rockers are used to install rockers, which can drive the inner ring of the slewing bearing to rotate around the outer ring of the slewing bearing.

[0010] Preferably, square holes are provided on both sides of the upper surface of the wedge block, which are used to install the ultrasonic signal module; four holes are provided on the front surface of the wedge block, which are used to place gear shafts, and the four gear shafts are coaxially connected to the first piezoelectric chip gear, the second piezoelectric chip gear, the driven wheel and the driving wheel respectively.

[0011] Preferably, the wedge is made of organic glass, and the scale spacing on the outer ring of the slewing bearing is 5°.

[0012] Preferably, the ultrasonic signal module is used to realize functions including signal transmission, reception, and amplification, and the servo control module includes a servo motor and an encoder.

[0013] In a second aspect, the present invention provides a method for using the device for non-destructively obtaining the incident angle in the stress detection direction of a composite material according to any one of the first aspects, as follows:

[0014] S1: Rotate the piezoelectric wafers on the first piezoelectric wafer gear and the second piezoelectric wafer gear to their initial horizontal positions, fix the bottom of the outer ring of the slewing bearing to the surface of the workpiece to be measured via rubber, and fit the bottom of the wedge to the surface of the workpiece to be measured via coupling fluid; connect the ultrasonic signal module to the host computer, and connect the host computer to the driving wheel via the servo control module;

[0015] S2: At the initial position of the wedge block, the host computer controls the servo control module to drive the driving wheel to rotate, so that the first piezoelectric chip gear and the second piezoelectric chip gear start to rotate synchronously from the initial position;

[0016] S3: During the rotation of the first piezoelectric wafer gear and the second piezoelectric wafer gear, the host computer obtains a series of echo signals. After processing the series of echo signals, it determines when the optimal LCR wave signal is generated and obtains the corresponding rotation angle of the piezoelectric wafer, which is the ultrasonic LCR wave stress detection incident angle and acoustic time difference in that direction of the wedge block;

[0017] S4: Control the inner ring of the slewing bearing to rotate along the outer ring of the slewing bearing by a specified angle. At this time, the wedge rotates to the specified position along with the inner ring of the slewing bearing.

[0018] S5: Repeat steps S2 to S4 in a loop to obtain the critical refraction angle at which the wedge can excite the LCR wave in the 360° direction during the rotation process;

[0019] S6: Based on the principle that the speed of sound propagates fastest along the fiber direction, the 0° fiber direction of the composite material is determined through data from various directions, and the incident angle of the ultrasonic LCR wave stress detection in this direction is obtained.

[0020] Preferably, in S3, the method for determining the optimal LCR wave signal is as follows:

[0021] By dynamically adjusting the wedge angle θ, the echo received at each angle is collected and its signal characteristics are analyzed; when the angle reaches the critical condition θ c When the received LCR wave signal amplitude reaches the maximum and the characteristics are most significant; the threshold is set according to the signal amplitude and arrival time, and the angle is automatically identified and recorded through signal analysis.

[0022] Preferably, each time after the S4 operation is completed, a coupling agent needs to be added to the bottom of the wedge to ensure that the wedge is well coupled with the surface of the workpiece to be measured.

[0023] Preferably, the method for determining the 0° fiber direction of the composite material in S6 is as follows:

[0024] Since the longitudinal wave speed of composite materials is anisotropic due to the directionality of the fiber layer,

[0025] Fiber direction, i.e. 0° direction: the sound velocity is the largest;

[0026] Perpendicular to the fiber direction, i.e. 90° direction: the sound velocity is the smallest;

[0027] Other directions: The sound velocity is between 0° and 90°, which is related to the laying and arrangement of the fibers;

[0028] The wedge is rotated 360° along the surface of the composite material, and the incident angle of the wedge is dynamically adjusted in each direction to find the critical refraction angle that can excite the LCR wave; the critical angle θ in each direction is recorded. c , calculate the longitudinal wave speed of the composite material in all directions:

[0029]

[0030] Among them, V L is the longitudinal wave velocity of the composite material, V w is the longitudinal wave speed of the wedge material;

[0031] The longitudinal wave sound velocity V of the composite material in different directions L Plotted in the polar coordinate system, the sound velocity distribution diagram of the composite material is obtained;

[0032] The directions corresponding to the maximum and minimum values of the speed of sound in the polar coordinate diagram are 0° and 90° respectively.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. No sample required for sound velocity measurement: The present invention can achieve LCR wave detection by dynamically adjusting the incident angle, without cutting the composite material sample for sound velocity measurement, thus avoiding the traditional method's dependence on the sample. It is particularly suitable for actual detection scenarios with only the test piece.

[0035] 2. Simple and efficient test preparation: It eliminates the tedious steps of measuring the speed of sound, calculating the incident angle, and processing the fixed wedges, which greatly shortens the test preparation time and significantly improves the test efficiency, making it suitable for rapid testing needs.

[0036] 3. Adaptability to complex material structures: The present invention can dynamically adjust the incident angle to adapt to complex composite material structures (such as unknown ply orientation, thickness variations, or non-uniform materials), breaking through the limitations of the fixed wedge method and improving the adaptability to various detection environments.

[0037] 4. Reduced sensitivity to sound velocity errors: No need to rely on precise sound velocity measurements, the LCR wave is searched directly at an adjustable angle, avoiding the incident angle deviation caused by sound velocity measurement errors and improving detection accuracy and reliability.

[0038] 5. Real-time adjustment and optimization: The present invention has the ability to adjust the incident angle in real time, and can dynamically optimize the detection effect according to the needs of the detection site, especially showing obvious advantages in the monitoring of dynamic stress of materials.

[0039] 6. Non-destructive and economical: Non-destructive testing is achieved through the technical means of variable incident angle, avoiding the material waste and high cost caused by cutting samples and processing fixed wedges, with good economy and universality.

[0040] The present invention breaks through the multiple limitations of traditional technologies in ultrasonic LCR wave stress detection of composite materials, and provides an innovative solution for efficient, accurate and flexible non-destructive testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a front view structural schematic diagram of the device of the present invention;

[0042] Figure 2 This is a schematic diagram of the 45° structure of the device of the present invention;

[0043] Figure 3 Schematic diagram of the top view of the device of the present invention;

[0044] Figure 4 This is a schematic diagram of the working connection state of the device of the present invention;

[0045] The reference numerals in the figure are: first piezoelectric chip gear 21, second piezoelectric chip gear 22, driven wheel 3, driving wheel 4, slewing support inner ring 5, slewing support outer ring 6, wedge block 7, rocker 8. DETAILED DESCRIPTION

[0046] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention may be combined accordingly, provided that there is no conflict between them.

[0047] like Figures 1 to 3 As shown in FIG, a device for non-destructively obtaining the incident angle in the stress detection direction of a composite material provided by the present invention is provided. The device mainly includes a slewing bearing inner ring 5, a slewing bearing outer ring 6 and a wedge 7.

[0048] The structure and connection method of each component will be described in detail below.

[0049] In the device of the present invention, Figure 2 and 3 As shown, the slewing bearing inner ring 5 is coaxially rotatably mounted on the slewing bearing outer ring 6, and the slewing bearing outer ring 6 is provided with scales in the circumferential direction.

[0050] In a preferred embodiment of the present invention, a circular stepped groove is coaxially defined within the slewing bearing outer ring 6. A continuous graduated scale is positioned on the outer circumference of the stepped groove, with graduations spaced 5° apart. The stepped groove accommodates the slewing bearing inner ring 5. When the slewing bearing inner ring 5 is placed on the circular stepped groove of the slewing bearing outer ring 6, its upper surface is flush with that of the slewing bearing outer ring 6. The slewing bearing inner ring 5 and the slewing bearing outer ring 6 are connected by rolling elements, enabling relative rotation.

[0051] In the device of the present invention, Figure 1 and 2 As shown, a wedge block 7 is installed on the inner ring 5 of the slewing bearing, and the bottom of the wedge block 7 is in contact with the surface of the workpiece to be measured. The first piezoelectric chip gear 21, the second piezoelectric chip gear 22, the driven wheel 3, the driving wheel 4 and the ultrasonic signal module are installed on the wedge block 7.

[0052] In a preferred embodiment of the present invention, square grooves are defined on the top, bottom, left, and right sides of the slewing bearing inner ring 5. Two opposing square grooves constitute a group (i.e., there are two sets of opposing square grooves), each of which is used to accommodate a wedge 7. Threaded holes are defined outside the square grooves on the slewing bearing inner ring 5. Each threaded hole is accompanied by a scale indicator that aligns with the scale on the slewing bearing outer ring 6. Rockers 8 are mounted within the threaded holes, which drive the slewing bearing inner ring 5 to rotate about the slewing bearing outer ring 6. The wedges 7 are preferably made of plexiglass.

[0053] In actual use, the lower surface of the slewing bearing outer ring 6 is fixed to the workpiece to be inspected; the wedge block 7 is fixedly matched with the slewing bearing inner ring 5 through the square groove; and the rocker 8 is fixedly matched with the slewing bearing inner ring 5 through the threaded hole.

[0054] In the device of the present invention, Figure 2 As shown, a first piezoelectric wafer gear 21 and a second piezoelectric wafer gear 22 are symmetrically mounted at the front ends of the wedge 7. The first piezoelectric wafer gear 21 is meshed with the second piezoelectric wafer gear 22 via the driven wheel 3 and the driving wheel 4. Piezoelectric wafers are mounted at the bottom ends of each of the first and second piezoelectric wafer gears 21 and 22, enabling echo signals to be generated during their rotation.

[0055] As a preferred embodiment of the present invention, Figure 3 As shown, the wedge block 7 has square holes on either side of its upper surface for mounting the ultrasonic signal module. The wedge block 7 also has four holes on its front surface for receiving gear shafts, which are coaxially connected to the first piezoelectric wafer gear 21, the second piezoelectric wafer gear 22, the driven wheel 3, and the driving wheel 4. In actual use, the driving wheel 4 directly drives the second piezoelectric wafer gear 22 while meshing with the driven wheel 3, indirectly driving the first piezoelectric wafer gear 21.

[0056] In the device of the present invention, Figure 4 As shown, ultrasonic signal modules are symmetrically installed on both sides of the top of the wedge block 7. The ultrasonic signal modules are used to connect to the host computer, and the host computer is connected to the driving wheel 4 through the servo control module.

[0057] As a preferred embodiment of the present invention, an ultrasonic signal module is used to implement functions including signal transmission, reception, and amplification. The ultrasonic signal module is connected to a host computer, which can acquire ultrasonic signals in real time. A servo control module includes a servo motor and an encoder. Connecting the servo control module to the host computer allows the host computer to control the servo motor's rotation angle and obtain the corresponding gear rotation angle.

[0058] The present invention also provides a method for using the above-mentioned device for non-destructively obtaining the incident angle in the stress detection direction of a composite material. The specific method is as follows:

[0059] S1: If Figure 4As shown, before use, the ultrasonic signal module needs to be installed and fixed in the square hole on the upper surface of the wedge block 7; the first piezoelectric wafer gear 21 and the second piezoelectric wafer gear 22 are respectively placed in the two outer holes of the wedge block 7 and placed in the initial position (i.e., the piezoelectric wafers are rotated to the horizontal direction); the driving wheel 4 and the driven wheel 3 are placed in the two inner holes of the wedge block 7, and the driving wheel 4 and the driven wheel 3 are meshed with each other and with the first piezoelectric wafer gear 21 and the second piezoelectric wafer gear 22 respectively; the bottom of the slewing bearing outer ring 6 is fixed to the surface of the workpiece to be measured with a rubber cover, and the slewing bearing inner ring 6 is placed on the circular stepped groove in the slewing bearing outer ring 5. The wedge block 7 is fixed to a set of square grooves in the slewing bearing inner ring 6, and the bottom of the wedge block 7 is bonded to the surface of the workpiece to be measured using coupling fluid.

[0060] The ultrasonic signal module is connected to a host computer, where ultrasonic signals can be acquired in real time. The host computer is connected to the driving wheel 4 via a servo control module. This module is connected to the host computer, where the servo motor rotation angle can be controlled and the corresponding gear rotation angle can be obtained. During testing, the composite material sample remains stationary, and the servo motor, connected to the driving wheel 4 via a shaft, drives it to rotate, thereby driving the piezoelectric chip gear.

[0061] S2: With wedge 7 at its initial position, the host computer controls the servo control module to drive the driving wheel 4, causing the first piezoelectric wafer gear 21 and the second piezoelectric wafer gear 22 to rotate synchronously from their initial positions. The host computer processes the ultrasonic signal to generate an echo signal, and simultaneously determines the piezoelectric wafer rotation angle in real time.

[0062] S3: During the rotation of the first piezoelectric chip gear 21 and the second piezoelectric chip gear 22, the upper computer obtains a series of echo signals. After processing the series of echo signals, it determines when the optimal LCR wave signal is generated and obtains the corresponding rotation angle of the piezoelectric chip, which is the ultrasonic LCR wave stress detection incident angle and sound time difference in this direction of the wedge block 7.

[0063] That is to say, after the host computer receives the ultrasonic echo signal, it processes the ultrasonic signal in the host computer to determine when the optimal LCR wave signal is generated, thereby obtaining the ultrasonic sound velocity in that direction and the ultrasonic critical refracted longitudinal wave excitation angle when the wedge is in that position.

[0064] S4: The rocker 8 is used to control the slewing bearing inner ring 5 to rotate along the slewing bearing outer ring 6 to a specified angle. At this time, the wedge 7 rotates to a specified position along with the slewing bearing inner ring 5.

[0065] S5: According to the experimental requirements, steps S2 to S4 are repeated cyclically to obtain the critical refraction angle at which the wedge 7 can excite the LCR wave in the 360° direction during the rotation process.

[0066] S6: Based on the principle that the speed of sound propagates fastest along the fiber direction, the 0° fiber direction of the composite material can be determined through data from various directions, and the incident angle of the ultrasonic LCR wave stress detection in this direction can be obtained.

[0067] As a preferred embodiment of the present invention, the wedge block 7 can be fixed with any pair of square grooves in the slewing bearing inner ring 5, and the rocker 8 can be connected with any threaded hole on the slewing bearing inner ring 5. The specific connection method can be determined according to the actual detection environment.

[0068] As a preferred embodiment of the present invention, in step S3, the method for determining the optimal LCR wave signal is as follows:

[0069] By dynamically adjusting the wedge angle θ, the echo received at each angle is collected and its signal characteristics are analyzed. c When the received LCR wave signal reaches its maximum amplitude and has the most significant characteristics, the threshold is set based on the signal amplitude and arrival time, and the angle is automatically identified and recorded through signal analysis.

[0070] As a preferred embodiment of the present invention, in step S4, the rocker 8 is used to control the rotation of the slewing bearing inner ring 5, and the rotation angle is determined by comparing the scale line next to the threaded hole with the scale line on the slewing bearing outer ring 6.

[0071] As a preferred embodiment of the present invention, each time after completing step S4, a coupling agent needs to be added to the bottom of the wedge block 7 to ensure that the wedge block 7 is well coupled with the surface of the workpiece to be measured.

[0072] As a preferred embodiment of the present invention, the method for determining the 0° fiber direction of the composite material in step S6 is as follows:

[0073] Since the longitudinal wave speed of composite materials is anisotropic due to the directionality of the fiber layer,

[0074] Fiber direction (0° direction): The sound speed is usually the largest because the energy transfer efficiency is highest when longitudinal waves propagate along the fiber.

[0075] Perpendicular to the fiber direction (90° direction): The sound speed is usually the smallest because the wave propagates along the matrix and the energy transfer efficiency is low.

[0076] Other directions (such as 45° direction): The sound velocity is between 0° and 90°, which is usually related to the layup and arrangement of the fibers.

[0077] Rotate the wedge 7 360° along the composite surface and dynamically adjust the incident angle of the wedge 7 in each direction to find the critical refraction angle that can excite the LCR wave. Record the critical angle θ in each direction. c, calculate the longitudinal wave speed of the composite material in all directions:

[0078]

[0079] Among them, V L is the longitudinal wave velocity of the composite material, V w is the longitudinal wave speed of the wedge 7 material.

[0080] The longitudinal wave sound velocity V of the composite material in different directions L Plotted in the polar coordinate system, the sound velocity distribution diagram of the composite material is obtained.

[0081] The directions corresponding to the maximum and minimum sound velocity in the polar coordinate diagram are 0° (fiber direction) and 90° (perpendicular to the fiber direction), respectively. If the composite material is laid in multiple layers, the sound velocity distribution may be more complex, but the main fiber direction usually corresponds to the direction of the maximum sound velocity.

[0082] The embodiment described above is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Persons skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent substitution or equivalent transformation falls within the scope of protection of the present invention.

Claims

1. A device for non-destructively obtaining the incident angle of a composite material stress detection direction, characterized in that: It includes a slewing bearing inner ring (5), a slewing bearing outer ring (6) and a wedge (7); The slewing bearing inner ring (5) is coaxially mounted on the slewing bearing outer ring (6), and the slewing bearing outer ring (6) is provided with a scale in the circumferential direction; a wedge block (7) is mounted on the slewing bearing inner ring (5), and the bottom of the wedge block (7) is in contact with the surface of the workpiece to be measured; a first piezoelectric chip gear (21), a second piezoelectric chip gear (22), a driven wheel (3), a driving wheel (4) and an ultrasonic signal module are mounted on the wedge block (7); the first piezoelectric chip gear (21) and the second piezoelectric chip gear (22) are symmetrically mounted. At both ends of the front side of the wedge block (7), a first piezoelectric chip gear (21) is meshed and connected to a second piezoelectric chip gear (22) through a driven wheel (3) and a driving wheel (4) in sequence; the bottom ends of the first piezoelectric chip gear (21) and the second piezoelectric chip gear (22) are both installed with piezoelectric chips, and echo signals can be obtained during the rotation process; ultrasonic signal modules are symmetrically installed on both sides of the top of the wedge block (7), and the ultrasonic signal modules are used to be connected to a host computer, and the host computer is connected to the driving wheel (4) through a servo control module.

2. The device for non-destructively obtaining the incident angle of a composite material stress detection direction according to claim 1, characterized in that: A circular stepped groove is coaxially provided inside the slewing bearing outer ring (6), and a scale is provided on the outer circumference of the stepped groove. The stepped groove is used to place the slewing bearing inner ring (5); the tops of the slewing bearing inner ring (5) and the slewing bearing outer ring (6) are flush, and the slewing bearing inner ring (5) and the slewing bearing outer ring (6) are relatively rotated through rolling bodies.

3. The device for non-destructively obtaining the incident angle of a composite material stress detection direction according to claim 1, characterized in that: The inner ring (5) of the slewing bearing is provided with two groups of opposite square grooves on the upper, lower, left and right sides, and each group of square grooves is used to place a mounting wedge (7); threaded holes are provided on the outer side of the square grooves on the inner ring (5) of the slewing bearing, and a scale indicator line is provided next to each threaded hole, and the scale indicator line is used to match the scale on the outer ring (6) of the slewing bearing; and a rocker (8) is used to install in the threaded holes, and the rocker (8) can drive the inner ring (5) of the slewing bearing to rotate around the outer ring (6) of the slewing bearing.

4. The device for non-destructively obtaining the incident angle of composite material stress detection direction according to claim 1, characterized in that: Square holes are respectively provided on both sides of the upper surface of the wedge block (7), and the square holes are used to install the ultrasonic signal module; four holes are provided on the front surface of the wedge block (7), and are used to place gear shafts, and the four gear shafts are respectively coaxially connected to the first piezoelectric chip gear (21), the second piezoelectric chip gear (22), the driven wheel (3) and the driving wheel (4).

5. The device for non-destructively obtaining the incident angle of composite material stress detection direction according to claim 1, characterized in that: The wedge (7) is made of organic glass material, and the scale spacing on the slewing bearing outer ring (6) is 5°.

6. The device for non-destructively obtaining the incident angle of composite material stress detection direction according to claim 1, characterized in that: The ultrasonic signal module is used to realize functions including signal transmission, reception, and amplification, and the servo control module includes a servo motor and an encoder.

7. A method for using the device for non-destructively obtaining the incident angle of a composite material stress detection direction according to any one of claims 1 to 6, characterized in that: The details are as follows: S1: The piezoelectric chips on the first piezoelectric chip gear (21) and the second piezoelectric chip gear (22) are respectively rotated to their initial positions in the horizontal direction, the bottom of the slewing bearing outer ring (6) is fixed to the surface of the workpiece to be measured through a rubber skin, and the bottom of the wedge block (7) is attached to the surface of the workpiece to be measured through a coupling liquid; the ultrasonic signal module is connected to the host computer, and the host computer is connected to the driving wheel (4) through the servo control module; S2: At the initial position of the wedge block (7), the host computer controls the servo control module to drive the driving wheel (4) to rotate, so that the first piezoelectric chip gear (21) and the second piezoelectric chip gear (22) start to rotate synchronously from the initial position; S3: During the rotation of the first piezoelectric chip gear (21) and the second piezoelectric chip gear (22), the host computer obtains a series of echo signals, processes the series of echo signals, determines when the best LCR wave signal is generated, and obtains the corresponding rotation angle of the piezoelectric chip, which is the ultrasonic LCR wave stress detection incident angle and acoustic time difference of the wedge block (7) in this direction; S4: Control the slewing bearing inner ring (5) to rotate along the slewing bearing outer ring (6) to a specified angle, and at this time the wedge (7) rotates to a specified position along with the slewing bearing inner ring (5); S5: Repeat steps S2 to S4 in a loop to obtain the critical refraction angle at which the wedge (7) can excite the LCR wave in the 360° direction during the rotation process; S6: Based on the principle that the speed of sound propagates fastest along the fiber direction, the 0° fiber direction of the composite material is determined through data from various directions, and the incident angle of the ultrasonic LCR wave stress detection in this direction is obtained.

8. The method of use according to claim 7, characterized in that: In S3, the method for determining the optimal LCR wave signal is as follows: By dynamically adjusting the wedge angle θ, the echo received at each angle is collected and its signal characteristics are analyzed; when the angle reaches the critical condition θ c When the received LCR wave signal amplitude reaches the maximum and the characteristics are most significant; the threshold is set according to the signal amplitude and arrival time, and the angle is automatically identified and recorded through signal analysis.

9. The method of use according to claim 7, characterized in that: After each completion of the S4 operation, a coupling agent needs to be added to the bottom of the wedge block (7) to ensure that the wedge block (7) is in a good coupling state with the surface of the workpiece to be measured.

10. The method of use according to claim 7, characterized in that: The method for determining the 0° fiber direction of the composite material in S6 is specifically as follows: Since the longitudinal wave speed of composite materials is anisotropic due to the directionality of the fiber layer, Fiber direction, i.e. 0° direction: the sound velocity is the largest; Perpendicular to the fiber direction, i.e. 90° direction: the sound velocity is the smallest; Other directions: The sound velocity is between 0° and 90°, which is related to the laying and arrangement of the fibers; The wedge (7) is rotated 360° along the surface of the composite material, and the incident angle of the wedge (7) is dynamically adjusted in each direction to find the critical refraction angle that can excite the LCR wave; the critical angle θ in each direction is recorded. c , calculate the longitudinal wave speed of the composite material in all directions: Among them, V L is the longitudinal wave velocity of the composite material, V w is the longitudinal wave sound velocity of the wedge (7) material; The longitudinal wave sound velocity V of the composite material in different directions L Plotted in the polar coordinate system, the sound velocity distribution diagram of the composite material is obtained; The directions corresponding to the maximum and minimum values of the speed of sound in the polar coordinate diagram are 0° and 90° respectively.

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