阅读说明：本技术 一种弹性常数测量及分布的测试系统及方法 (System and method for measuring and distributing elastic constants ) 是由 袁懋诞 戴安帮 吴俊伟 纪轩荣 陈燕 曾吕明 于 2021-08-30 设计创作，主要内容包括：本申请公开了一种弹性常数测量及分布的测试系统及方法,包括：多自由度工业机器人、机器人控制器、终端计算机、示波器、超声脉冲发射接收器和三模式超声换能器；终端计算机与超声脉冲发射接收器连接；超声脉冲发射接收器与三模式超声换能器连接；三模式超声换能器与测试样品接触；示波器与超声脉冲发射接收器连接；终端计算机与示波器连接；机器人控制器与多自由度工业机器人连接；终端计算机与机器人控制器连接。本发明能够对测试样品任意区域不同方向的弹性常数进行测量及分布状态表征,适用于各向同性或各向异性平板类或复杂曲面类样品不同方向的弹性常数测量及分布状态表征,以及适用于测量样品的动态弹性模量和泊松比。(The application discloses a system and a method for measuring and distributing elastic constants, which comprises the following steps: the system comprises a multi-degree-of-freedom industrial robot, a robot controller, a terminal computer, an oscilloscope, an ultrasonic pulse transmitting receiver and a three-mode ultrasonic transducer; the terminal computer is connected with the ultrasonic pulse transmitting and receiving device; the ultrasonic pulse transmitting and receiving device is connected with the three-mode ultrasonic transducer; the three-mode ultrasonic transducer is contacted with a test sample; the oscilloscope is connected with the ultrasonic pulse transmitting and receiving device; the terminal computer is connected with the oscilloscope; the robot controller is connected with the multi-degree-of-freedom industrial robot; and the terminal computer is connected with the robot controller. The invention can measure the elastic constants of any region of the test sample in different directions and characterize the distribution state, is suitable for measuring the elastic constants of isotropic or anisotropic flat plate samples or complex curved surface samples in different directions and characterizing the distribution state, and is suitable for measuring the dynamic elastic modulus and Poisson ratio of the samples.)

1. A system for measuring and distributing elastic constants, comprising: the ultrasonic wave generator comprises a multi-degree-of-freedom industrial robot, a robot controller, a terminal computer, an oscilloscope, an ultrasonic pulse transmitting and receiving device and a three-mode ultrasonic transducer, wherein the three-mode ultrasonic transducer is used for generating a longitudinal wave and two transverse waves with mutually orthogonal polarization directions simultaneously or in a time-sharing manner after a piezoelectric wafer is polarized;

the three-mode ultrasonic transducer is arranged on the multi-degree-of-freedom industrial robot;

the terminal computer is connected with the ultrasonic pulse transmitting and receiving device and is used for controlling the response and parameter adjustment of the ultrasonic pulse transmitting and receiving device;

the ultrasonic pulse transmitting and receiving device is connected with the three-mode ultrasonic transducer and is used for transmitting and receiving pulse signals;

the three-mode ultrasonic transducer is in contact with a test sample and is used for converting the pulse signal into an ultrasonic signal, transmitting the ultrasonic signal to the test sample and receiving the ultrasonic signal by the three-mode ultrasonic transducer;

the oscilloscope is connected with the ultrasonic pulse transmitting and receiving device and is used for visualizing data waveform signals, converting acquired analog signals into digital signals and transmitting the digital signals to the terminal computer for analysis;

the terminal computer is connected with the oscilloscope and is used for exporting and processing image data in the visual image to obtain the elastic constant and the distribution state of the test sample;

the robot controller is connected with the multi-degree-of-freedom industrial robot and used for guiding and controlling the motion track of the multi-degree-of-freedom industrial robot and feeding back the three-dimensional point coordinate information of the contact position of the three-mode ultrasonic transducer and the test sample in the motion process to the robot controller;

and the terminal computer is connected with the robot controller and used for planning the motion trail of the multi-degree-of-freedom industrial robot, transmitting the motion trail into the robot controller and transmitting the three-dimensional point coordinate information fed back in the robot controller into the terminal computer.

2. The system for elastic constant measurement and distribution testing of claim 1, wherein said three-mode ultrasonic transducer is comprised of a longitudinal wave straight probe and a transverse wave straight probe.

3. The system for elastic constant measurement and distribution testing of claim 1, wherein said three-mode ultrasonic transducer comprises an open-bottomed housing, a piezoelectric wafer, a damping mass, and a matching layer;

the matching layer is positioned at the opening of the shell;

the piezoelectric wafer is horizontally disposed between the damping mass and the matching layer.

4. The system for measuring and distributing elastic constants according to claim 3, wherein the piezoelectric wafers comprise a longitudinal wave piezoelectric wafer, a first transverse wave piezoelectric wafer and a second transverse wave piezoelectric wafer;

the polarization directions of transverse waves generated after the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer are polarized are mutually orthogonal and the propagation directions are the same.

5. The system as claimed in claim 4, wherein the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer are transmitting and receiving piezoelectric wafers.

6. The system for measuring and distributing elastic constants according to claim 4, wherein the combination of the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer is of an embedded inclusion type;

the middle part of the piezoelectric wafer is provided with the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer, and the outer ring of the piezoelectric wafer is provided with the longitudinal wave piezoelectric wafer;

sound insulation materials are arranged between the longitudinal wave piezoelectric wafer and the first transverse wave piezoelectric wafer, between the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer, and between the second transverse wave piezoelectric wafer and the longitudinal wave piezoelectric wafer.

7. The system as claimed in claim 4, wherein the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer are respectively led out from the top opening of the housing through electrode leads.

8. A method of testing a test system based on the elastic constant measurement and distribution according to any one of claims 1 to 7, the method comprising the steps of:

step 1: placing a test sample in a working area of a multi-degree-of-freedom industrial robot carrying a three-mode ultrasonic transducer; the multi-degree-of-freedom industrial robot carries out path planning, carries out contact scanning on the surface of the test sample according to the planned path, and feeds back the three-dimensional point coordinate information of the motion track of the three-mode ultrasonic transducer in real time;

step 2: the three-mode ultrasonic transducer measures the ultrasonic sound velocity through a contact pulse echo method, and simultaneously obtains the longitudinal wave sound velocity of a longitudinal wave piezoelectric wafer incident to a test sample detection point and two orthogonal polarized transverse wave sound velocities of a first transverse wave piezoelectric wafer and a second transverse wave piezoelectric wafer incident to the test sample detection point through measurement;

and step 3: calculating according to the longitudinal wave sound velocity, the transverse wave sound velocity and the density of the test sample to obtain elastic constants of the test sample, wherein the elastic constants comprise Poisson's ratio, Young modulus and shear modulus; distributing gray shade or color to an elastic constant value, and matching and constructing a gray or color image in a terminal computer by using the three-dimensional point coordinate information and the elastic constant value with the gray shade or color; and measuring the elastic constants of the test sample in different directions, representing the distribution state of the elastic constants, and evaluating the mechanical property of the test sample.

9. The method for measuring and distributing elastic constants according to claim 8, wherein in step 1, the surface of the test sample is a plane or a curved surface;

the material of the test sample is isotropic material or anisotropic material.

10. The method for measuring and distributing elastic constants according to claim 8, wherein in step 1, the working parameters of the multi-degree-of-freedom industrial robot are regulated and controlled before the surface of the test sample is subjected to contact scanning according to a planned path;

the operating parameters include at least scan speed and scan step.

Technical Field

The application relates to the technical field of elastic constant ultrasonic nondestructive testing, in particular to a system and a method for testing elastic constant measurement and distribution.

Background

The elastic constant is used as a mechanical property index for representing the elastic deformation property of the solid material, the elastic constant of the sample is accurately measured, the performance of the material can be effectively evaluated, the optimal design of the sample is facilitated, and an important basis is provided for safe and reliable operation and failure analysis of parts.

In the related art, a static tensile method, i.e., a stress-strain method, is mostly used for mechanical property testing of a processed material. The test method is destructive, the load size, acceleration and the like can influence the test result, the change of the internal structure of the material cannot be truly reflected due to the influence of the relaxation process and the like, and the performance of specially prepared irregular materials and brittle materials is difficult to measure. Other novel detection technologies, such as nanoindentation technology and digital image technology. The nano indentation technology is characterized in that a nano indenter is used for calculating the elastic constant of a material through a curve of force and indentation depth of an indenter, and the nano indentation method needs to be measured in a nano scale, so that the requirement on the size of a workpiece is high, nano indentation equipment and use cost are high, and the measurement error is large; in the digital image technology, in the process of testing the surface deformation of a sample, the motion of scattered spots is tracked by matching speckle image sub-areas before and after the sample is deformed, and finally the surface deformation information of the sample is measured, so that the elastic constant of the sample is obtained.

In order to test the elastic constant of the anisotropic material, the conventional method adopts an ultrasonic sound velocity method for measurement, has the advantages of wide adaptability, rapidness, convenience, reliable result and the like, and is widely concerned in the elastic constant test of the material. However, most of the existing ultrasonic sound velocity measurement and test systems are single-value measurement and flat plate type material measurement with constant thickness, the measurement of elastic constants in different directions of the whole plane or complex curved surface type material and the visualization of distribution cannot be directly realized, and the problems of weak signal energy, more noise waves and the like exist. Therefore, the invention provides a system and a method for measuring and distributing elastic constants.

Disclosure of Invention

The embodiment of the application provides a system and a method for measuring and distributing elastic constants, which can measure and characterize the distribution state of the elastic constants in different directions in any region of a test sample, are suitable for measuring the elastic constants in different directions of isotropic or anisotropic flat plate samples or complex curved surface samples and characterizing the distribution state, and are suitable for measuring the dynamic elastic modulus and Poisson's ratio of the samples.

The first aspect of the present application provides a system for measuring and distributing elastic constants, comprising: the ultrasonic wave generator comprises a multi-degree-of-freedom industrial robot, a robot controller, a terminal computer, an oscilloscope, an ultrasonic pulse transmitting and receiving device and a three-mode ultrasonic transducer, wherein the three-mode ultrasonic transducer is used for generating a longitudinal wave and two transverse waves with mutually orthogonal polarization directions simultaneously or in a time-sharing manner after a piezoelectric wafer is polarized;

the three-mode ultrasonic transducer is arranged on the multi-degree-of-freedom industrial robot;

the terminal computer is connected with the ultrasonic pulse transmitting and receiving device and is used for controlling the response and parameter adjustment of the ultrasonic pulse transmitting and receiving device;

the ultrasonic pulse transmitting and receiving device is connected with the three-mode ultrasonic transducer and is used for transmitting and receiving pulse signals;

the three-mode ultrasonic transducer is in contact with a test sample and is used for converting the pulse signal into an ultrasonic signal, transmitting the ultrasonic signal to the test sample and receiving the ultrasonic signal by the three-mode ultrasonic transducer;

the oscilloscope is connected with the ultrasonic pulse transmitting and receiving device and is used for visualizing data waveform signals, converting acquired analog signals into digital signals and transmitting the digital signals to the terminal computer for analysis;

the terminal computer is connected with the oscilloscope and is used for exporting and processing image data in the visual image to obtain the elastic constant and the distribution state of the test sample;

the robot controller is connected with the multi-degree-of-freedom industrial robot and used for guiding and controlling the motion track of the multi-degree-of-freedom industrial robot and feeding back the three-dimensional point coordinate information of the contact position of the three-mode ultrasonic transducer and the test sample in the motion process to the robot controller;

and the terminal computer is connected with the robot controller and used for planning the motion trail of the multi-degree-of-freedom industrial robot, transmitting the motion trail into the robot controller and transmitting the three-dimensional point coordinate information fed back in the robot controller into the terminal computer.

Optionally, the three-mode ultrasound transducer is comprised of a longitudinal wave straight probe and a transverse wave straight probe.

Optionally, the three-mode ultrasonic transducer comprises a housing with an open bottom, a piezoelectric wafer, a damping mass and a matching layer;

the matching layer is positioned at the opening of the shell;

the piezoelectric wafer is horizontally disposed between the damping mass and the matching layer.

Optionally, the piezoelectric wafers include a longitudinal wave piezoelectric wafer, a first transverse wave piezoelectric wafer and a second transverse wave piezoelectric wafer;

the polarization directions of transverse waves generated after the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer are polarized are mutually orthogonal and the propagation directions are the same.

Optionally, the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer, and the second transverse wave piezoelectric wafer are all transmit-receive piezoelectric wafers.

Optionally, the combination form of the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer is an embedded inclusion type;

the middle part of the piezoelectric wafer is provided with the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer, and the outer ring of the piezoelectric wafer is provided with the longitudinal wave piezoelectric wafer;

sound insulation materials are arranged between the longitudinal wave piezoelectric wafer and the first transverse wave piezoelectric wafer, between the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer, and between the second transverse wave piezoelectric wafer and the longitudinal wave piezoelectric wafer.

Optionally, the longitudinal wave piezoelectric wafer, the first transverse wave piezoelectric wafer and the second transverse wave piezoelectric wafer are respectively led out from the top opening of the housing through electrode leads.

In a second aspect, the present application provides a method for testing a system based on the above elastic constant measurement and distribution, the method specifically includes the following steps:

step 1: placing a test sample in a working area of a multi-degree-of-freedom industrial robot carrying a three-mode ultrasonic transducer; the multi-degree-of-freedom industrial robot carries out path planning, carries out contact scanning on the surface of the test sample according to the planned path, and feeds back the three-dimensional point coordinate information of the motion track of the three-mode ultrasonic transducer in real time;

step 2: the three-mode ultrasonic transducer measures the ultrasonic sound velocity through a contact pulse echo method, and simultaneously obtains the longitudinal wave sound velocity of a longitudinal wave piezoelectric wafer incident to a test sample detection point and two orthogonal polarized transverse wave sound velocities of a first transverse wave piezoelectric wafer and a second transverse wave piezoelectric wafer incident to the test sample detection point through measurement;

and step 3: calculating according to the longitudinal wave sound velocity, the transverse wave sound velocity and the density of the test sample to obtain elastic constants of the test sample, wherein the elastic constants comprise Poisson's ratio, Young modulus and shear modulus; distributing gray shade or color to an elastic constant value, and matching and constructing a gray or color image in a terminal computer by using the three-dimensional point coordinate information and the elastic constant value with the gray shade or color; and measuring the elastic constants of the test sample in different directions, representing the distribution state of the elastic constants, and evaluating the mechanical property of the test sample.

Optionally, in step 1, the surface of the test sample is a plane or a curved surface;

the material of the test sample is isotropic material or anisotropic material.

Optionally, in step 1, before the surface of the test sample is subjected to contact scanning according to a planned path, regulating and controlling working parameters of the multi-degree-of-freedom industrial robot;

the operating parameters include at least scan speed and scan step.

According to the technical scheme, the embodiment of the application has the following advantages: the elastic constant measuring and distributing test system comprises a multi-degree-of-freedom industrial robot, a robot controller, a terminal computer, an oscilloscope, an ultrasonic pulse transmitting receiver and a tri-mode ultrasonic transducer, elastic constants in two orthogonal directions of a detection position are obtained by recording three-dimensional point coordinate information of a motion track of a contact part of the tri-mode ultrasonic transducer and a test sample, and longitudinal wave and two orthogonal transverse wave sound velocities corresponding to the detection point, the elastic constant distribution of a detection surface of the test sample is obtained by a multi-degree-of-freedom industrial robot scanning system, gray shade or color is distributed to the elastic constant value, and the elastic constants and the distribution states of the test sample in different directions of isotropic or anisotropic flat plate type or complex curved surface type are represented by gray or color images. The method can measure the elastic constants of any region of the test sample in different directions and characterize the distribution state, is suitable for measuring the elastic constants of isotropic or anisotropic flat plate samples or complex curved surface samples in different directions and characterizing the distribution state, and is suitable for measuring the dynamic elastic modulus and Poisson's ratio of the samples.

Drawings

FIG. 1 is a schematic diagram of a system for measuring and distributing elastic constants in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a three-mode ultrasonic transducer in an embodiment of the present application;

FIG. 3 is a view showing an assembly form of a piezoelectric wafer in an embodiment of the present application;

FIG. 4 is a flowchart illustrating a method for measuring and distributing elastic constants according to an embodiment of the present invention;

wherein the reference numerals are:

the method comprises the following steps of 1-a shell, 2-a longitudinal wave piezoelectric wafer, 3-a sound insulation material, 4-an electrode lead, 5-a damping block, 6-a first transverse wave piezoelectric wafer, 7-a second transverse wave piezoelectric wafer, 8-a matching layer, 9-a multi-degree-of-freedom industrial robot, 10-a robot controller, 11-a terminal computer, 12-an oscilloscope, 13-an ultrasonic pulse transmitting and receiving device, 14-a three-mode ultrasonic transducer and 15-a test sample.

Detailed Description

In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

One embodiment of a system for measuring and distributing elastic constants is provided, and particularly please refer to fig. 1.

The system for measuring and distributing elastic constants in the embodiment includes: the ultrasonic wave generating device comprises a multi-degree-of-freedom industrial robot 9, a robot controller 10, a terminal computer 11, an oscilloscope 12, an ultrasonic pulse transmitting and receiving device 13 and a three-mode ultrasonic transducer 14, wherein the three-mode ultrasonic transducer is used for generating a longitudinal wave and two transverse waves with mutually orthogonal polarization directions simultaneously or in a time-sharing mode after a piezoelectric wafer is polarized; the three-mode ultrasonic transducer 14 is arranged on the multi-degree-of-freedom industrial robot 9; the terminal computer 11 is connected with the ultrasonic pulse transmitting and receiving device 13 and is used for controlling the response and parameter adjustment of the ultrasonic pulse transmitting and receiving device 13; the ultrasonic pulse transmitter-receiver 13 is connected with the three-mode ultrasonic transducer 14 and is used for transmitting and receiving pulse signals; the three-mode ultrasonic transducer 14 is in contact with the test sample 15, and is used for converting the pulse signal into an ultrasonic signal, transmitting the ultrasonic signal to the test sample 15, and receiving the ultrasonic signal by the three-mode ultrasonic transducer 14; the oscilloscope 12 is connected with the ultrasonic pulse transmitting and receiving device 13 and is used for visualizing the data waveform signal, converting the acquired analog signal into a digital signal and transmitting the digital signal to the terminal computer 11 for analysis; the terminal computer 11 is connected with the oscilloscope 12 and is used for exporting and processing image data in the visual image to obtain an elastic constant and a distribution state of the test sample 15; the robot controller 10 is connected with the multi-degree-of-freedom industrial robot 9 and is used for guiding and controlling the motion track of the multi-degree-of-freedom industrial robot 9 and feeding back the three-dimensional point coordinate information of the contact position of the three-mode ultrasonic transducer 14 and the test sample 15 in the motion process to the robot controller 10; the terminal computer 11 is connected with the robot controller 10, and is used for planning the motion trail of the multi-degree-of-freedom industrial robot 9, transmitting the motion trail into the robot controller 10, and transmitting the three-dimensional point coordinate information fed back into the robot controller 10 into the terminal computer 11.

It should be noted that: the elastic constant measuring and distributing test system comprises a multi-degree-of-freedom industrial robot 9, a robot controller 10, a terminal computer 11, an oscilloscope 12, an ultrasonic pulse transmitting and receiving device 13 and a tri-mode ultrasonic transducer 14, wherein the elastic constants in two orthogonal directions of a detection position are obtained by recording the three-dimensional point coordinate information of a motion track of a contact part of the tri-mode ultrasonic transducer 14 and a test sample 15, and the sound velocities of a longitudinal wave and two orthogonal transverse waves corresponding to the detection point, the elastic constants are distributed in the detection plane of the test sample 15 through a multi-degree-of-freedom industrial robot 9 scanning system, gray shades or colors are distributed to the elastic constant values, and the elastic constants and the distribution states of the test sample 15 in different directions of an isotropic or anisotropic flat plate type or a complex curved surface type are represented by gray scales or color images. The method can measure the elastic constants of any region of the test sample 15 in different directions and characterize the distribution state, and is suitable for measuring the elastic constants of isotropic or anisotropic flat plate samples or complex curved surface samples in different directions and characterizing the distribution state, and measuring the dynamic elastic modulus and Poisson's ratio of the samples.

The above is a first embodiment of a system for measuring and distributing elastic constants according to the present application, and the following is a second embodiment of a system for measuring and distributing elastic constants according to the present application, specifically referring to fig. 1 to 3.

The system for measuring and distributing elastic constants in the embodiment includes: the ultrasonic wave generating device comprises a multi-degree-of-freedom industrial robot 9, a robot controller 10, a terminal computer 11, an oscilloscope 12, an ultrasonic pulse transmitting and receiving device 13 and a three-mode ultrasonic transducer 14, wherein the three-mode ultrasonic transducer is used for generating a longitudinal wave and two transverse waves with mutually orthogonal polarization directions simultaneously or in a time-sharing mode after a piezoelectric wafer is polarized; the three-mode ultrasonic transducer 14 is arranged on the multi-degree-of-freedom industrial robot 9; the terminal computer 11 is connected with the ultrasonic pulse transmitting and receiving device 13 and is used for controlling the response and parameter adjustment of the ultrasonic pulse transmitting and receiving device 13; the ultrasonic pulse transmitter-receiver 13 is connected with the three-mode ultrasonic transducer 14 and is used for transmitting and receiving pulse signals; the three-mode ultrasonic transducer 14 is in contact with the test sample 15, and is used for converting the pulse signal into an ultrasonic signal, transmitting the ultrasonic signal to the test sample 15, and receiving the ultrasonic signal by the three-mode ultrasonic transducer 14; the oscilloscope 12 is connected with the ultrasonic pulse transmitting and receiving device 13, and is used for visualizing data waveform signals, converting acquired analog signals into digital signals, and transmitting the digital signals to the terminal computer 11 for analysis; the terminal computer 11 is connected with the oscilloscope 12 and is used for exporting and processing image data in the visual image to obtain an elastic constant and a distribution state of the test sample 15; the robot controller 10 is connected with the multi-degree-of-freedom industrial robot 9 and is used for guiding and controlling the motion track of the multi-degree-of-freedom industrial robot 9 and feeding back the three-dimensional point coordinate information of the contact position of the three-mode ultrasonic transducer 14 and the test sample 15 in the motion process to the robot controller 10; the terminal computer 11 is connected with the robot controller 10, and is used for planning the motion trail of the multi-degree-of-freedom industrial robot 9, transmitting the motion trail into the robot controller 10, and transmitting the three-dimensional point coordinate information fed back into the robot controller 10 into the terminal computer 11.

The three-mode ultrasonic transducer 14 consists of a longitudinal wave straight probe and a transverse wave straight probe, so that the ultrasonic waves emitted by the three-mode ultrasonic transducer 14 can vertically enter the surface of the test sample 15, and the problems of weak energy, multiple clutter and the like caused by waveform conversion are solved.

Specifically, as shown in fig. 2, the three-mode ultrasonic transducer 14 includes a housing 1 with an opening at the bottom, a piezoelectric wafer, a damping block 5, and a matching layer 8, wherein the matching layer 8 is located at the opening of the housing 1, and the piezoelectric wafer is horizontally disposed between the damping block 5 and the matching layer 8. Wherein the shell 1 is used for protecting the internal elements of the three-mode ultrasonic transducer 14 and encapsulating the core part; the piezoelectric wafer is used for mutual conversion between electric sound and electricity, when the piezoelectric wafer transmits ultrasonic waves, the piezoelectric wafer vibrates under the excitation of electric pulses to generate ultrasonic waves, and when the piezoelectric wafer receives the ultrasonic waves, the ultrasonic waves act on the piezoelectric wafer to cause the piezoelectric wafer to generate deformation under the forced vibration to be converted into corresponding electric signals; the damping block 5 is used for absorbing ultrasonic waves emitted by the piezoelectric wafer so as to prevent excessive clutter from interfering with signal acquisition of the transducer and generate a damping effect, so that the three-mode ultrasonic transducer 14 stops vibrating as soon as possible after emitting ultrasonic pulses, in addition, the damping block 5 does not transmit sound waves and only plays a role in absorbing back stray sound waves, noise is reduced, and the signal-to-noise ratio of the probe is improved; the matching layer 8 is used for realizing acoustic impedance matching between the three-mode ultrasonic transducer 14 and the test sample 15, improving the utilization rate of the sound wave energy radiated by the probe, protecting the piezoelectric wafer and avoiding pollution or damage in the working environment; the sound insulation material 3 is used for vibration isolation to reduce mutual vibration crosstalk so as to improve the overall signal-to-noise ratio.

The piezoelectric wafers comprise a longitudinal wave piezoelectric wafer 2, a first transverse wave piezoelectric wafer 6 and a second transverse wave piezoelectric wafer 7, and transverse wave polarization directions generated after the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7 are polarized are mutually orthogonal and have the same propagation direction.

As shown in fig. 2 and 3, the combination of the longitudinal wave piezoelectric wafer 2, the first transverse wave piezoelectric wafer 6, and the second transverse wave piezoelectric wafer 7 may be an embedded inclusion type, in which the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7 are in the middle of the piezoelectric wafers, and the longitudinal wave piezoelectric wafer 2 is in the outer ring of the piezoelectric wafers; sound insulation materials 3 are arranged between the longitudinal wave piezoelectric wafer 2 and the first transverse wave piezoelectric wafer 6, between the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7, and between the second transverse wave piezoelectric wafer 7 and the longitudinal wave piezoelectric wafer 2.

The longitudinal wave piezoelectric wafer 2, the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7 are transmitting and receiving piezoelectric wafers, ultrasonic longitudinal waves and ultrasonic transverse waves can be directly transmitted and received, the three can transmit and receive the ultrasonic longitudinal waves and the ultrasonic transverse waves simultaneously or in a time-sharing manner, and the three can have the same or different frequencies.

The longitudinal wave piezoelectric wafer 2, the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7 are respectively led out from the top opening of the housing 1 through the electrode leads 4.

It can be understood that the multi-degree-of-freedom industrial robot 9 is required to be capable of performing free motion in a three-dimensional space, such as a conventional stanotbier six-axis manipulator.

As shown in fig. 4, the present application further provides a testing method of the testing system based on the above elastic constant measurement and distribution, the method specifically includes the following steps:

step 1: placing a test sample 15 in a working area of a multi-degree-of-freedom industrial robot 9 carrying a three-mode ultrasonic transducer 14; the multi-degree-of-freedom industrial robot 9 performs path planning, performs contact scanning on the surface of the test sample 15 according to the planned path, and feeds back the three-dimensional point coordinate information of the motion track of the three-mode ultrasonic transducer 14 in real time.

It should be noted that: the multi-degree-of-freedom industrial robot 9 can feed back coordinates of each joint or three-dimensional space rectangular coordinates to the robot controller 10, and then the three-dimensional space rectangular coordinates of the end effector of the multi-degree-of-freedom industrial robot 9 are read from the robot controller 10 through the terminal computer 11, so that three-dimensional point coordinate information feedback of a motion track of a contact part of the three-mode ultrasonic transducer 14 and the test sample 15 can be obtained.

Step 2: the three-mode ultrasonic transducer 14 measures the ultrasonic sound velocity by a contact pulse echo method, and simultaneously obtains the longitudinal wave sound velocity of the longitudinal wave piezoelectric wafer 2 incident to a detection point of the test sample 15 and two orthogonal polarized transverse wave sound velocities of the first transverse wave piezoelectric wafer 6 and the second transverse wave piezoelectric wafer 7 incident to the detection point of the test sample 15 by measurement.

It should be noted that: the speed of sound can be determined from the ultrasonic propagation time and the thickness of the test specimen 15 at the inspection point. Specifically, the speed of the longitudinal and transverse sound waves is measured by the time difference between the corresponding peaks of the waveforms of the first bottom surface reflection echo B1 and the second bottom surface reflection echo B2 and the thickness of the test sample 15, and the speed of the three modes of ultrasonic waves propagating in the test sample 15 can be determined.

Sound velocity:

wherein h is the thickness of a detection point of the test sample 15, (t)_B2-t_B1) The time difference between the second bottom surface reflection echo and the first bottom surface reflection echo is obtained.

And step 3: the terminal computer 11 calculates the longitudinal wave sound velocity, the transverse wave sound velocity and the density of the test sample 15 (wherein the density of the test sample 15 can be measured before scanning detection and is directly input into the terminal computer 11), and obtains the elastic constants of the test sample 15, wherein the elastic constants comprise Poisson's ratio, Young's modulus and shear modulus; assigning the gray shade or color to the elastic constant value, and matching in the terminal computer 11 using the three-dimensional point coordinate information and the elastic constant value having the gray shade or color to construct a gray or color image; and measuring the elastic constants of the test sample 15 in different directions and representing the distribution state of the elastic constants, and evaluating the mechanical property of the test sample 15.

In the step 1, the surface of a test sample 15 is a plane or a curved surface; the material of the test sample 15 is an isotropic material or an anisotropic material.

In the step 1, before the surface of the test sample 15 is scanned in a contact manner according to a planned path, the working parameters of the multi-degree-of-freedom industrial robot 9 can be regulated and controlled, the working parameters at least comprise scanning speed and scanning stepping, and when scanning according to the planned path, the longitudinal and transverse wave waveforms are ensured to be simultaneously acquired and constantly kept perpendicular to the contact surface to enter the test sample 15.

In step 3, elastic constants such as poisson's ratio, young's modulus, shear modulus and the like of the test sample 15 are calculated according to the longitudinal wave sound velocity, the transverse wave sound velocity and the density of the test sample 15. In the anisotropy test specimen 15, the sound velocities and elastic constants in different directions are different from each other, and V is given as V for the anisotropy_ijAnd represents the sound velocity, wherein i is the wave propagation direction, j is the wave vibration direction, and i, j are x, y and z. When i is j, the wave is a longitudinal wave; otherwise, it is a transverse wave. The elastic constant of the test sample 15 was calculated as follows:

poisson ratio:

young's modulus:

shear modulus:

wherein: v_iiIs the longitudinal wave sound velocity; v_ijIs the transverse wave sound velocity; rho is density; sigma_ijIs the poisson ratio; e_ijIs Young's modulus; g_ijIs the shear modulus.

In specific implementation, as shown in fig. 1, first, a semicircular ring test sample 15 is placed in a working area of the multi-degree-of-freedom industrial robot 9 on which the three-mode ultrasonic transducer 14 is mounted, and a three-dimensional model of the test sample 15 is introduced into robot path planning software of the terminal computer 11. The multi-degree-of-freedom industrial robot 9 is controlled by the robot controller 10 to carry out workpiece coordinate system calibration on the test sample 15, so that the position coordinates of the test specimen 15 in the robot path planning software are consistent with the position coordinates of the actual detection area of the test specimen 15, then scanning path planning is carried out on the area needing to be detected of the test sample 15 in the robot path planning software of the terminal computer 11, a scanning path file generated by the robot path planning software is imported into the robot controller 10, the multi-degree-of-freedom industrial robot 9 is controlled to perform contact scanning on the surface of a test sample 15 according to a planned path, a terminal computer 11 can read the three-dimensional space rectangular coordinate of an end effector of the multi-degree-of-freedom industrial robot 9 from a robot controller 10 through a program, three-dimensional point coordinate information feedback of the motion trail of the contact part of the three-mode ultrasonic transducer 14 and the test sample 15 can be obtained;

then, the three-mode ultrasonic transducer 14 measures the ultrasonic sound velocity by using a contact pulse echo method, the terminal computer 11 controls the response of the ultrasonic pulse transmitting and receiving device 13, the three-mode ultrasonic transducer 14 is excited to generate an ultrasonic signal, the ultrasonic signal is transmitted to the bottom surface of the test sample 15 to be reflected, then is received by the three-mode ultrasonic transducer 14 and transmitted into the ultrasonic pulse transmitting and receiving device 13, then the signal is transmitted into the oscilloscope 12 to visualize a data waveform signal, and the acquired analog signal is converted into a digital signal and transmitted into the terminal computer 11 to be analyzed, so that longitudinal wave and two orthogonal transverse wave sound velocities are obtained;

finally, the poisson's ratio, young's modulus and shear modulus of the test sample 15 are obtained through the calculation of the ultrasonic longitudinal wave and transverse wave sound velocities and the mass density of the test sample 15. The gray shade or color is assigned to the poisson ratio, young's modulus and shear modulus values, the gray shade or color is matched and constructed in the terminal computer 11 by using the fed back three-dimensional point coordinate information and the elastic constant value with the gray shade or color to construct a gray or color image, the elastic constants of the test sample 15 in different directions are measured and the distribution state of the elastic constants is represented, and the mechanical property of the test sample 15 is evaluated.

The invention tests the elastic constants and distribution states of isotropic or anisotropic flat plate type or complex curved surface type test samples 15 in different directions, and monitors the change of the elastic constants of the samples on line, such as the on-line monitoring of the elastic constants of the samples in the additive manufacturing process. The complexity and limitation of the all-round detection of the large-area plane or complex curved surface sample by manual work at present are effectively solved, elastic constants and distribution such as Poisson's ratio, Young modulus and shear modulus in different directions are rapidly and effectively obtained at the same time, the detection efficiency is high, the automation degree is high, and the visualization degree is high.

The above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.