Micro-crack positioning system and method based on nonlinear ultrasonic different-side time-delay mixing signal
阅读说明：本技术 基于非线性超声异侧延时混频信号的微裂缝定位系统及方法 (Micro-crack positioning system and method based on nonlinear ultrasonic different-side time-delay mixing signal ) 是由 李一博 王晢 芮小博 綦磊 刘嘉玮 于 2019-08-26 设计创作，主要内容包括：本发明涉及一种基于非线性超声异侧延时混频信号的微裂缝定位系统,其特征在于：包括计算机、非线性超声仪、衰减器、低通滤波器、信号激励传感器、待测样件、双工器、高通滤波器及示波器。本发明还涉及一种基于非线性超声异侧延时混频信号的微裂缝定位方法,其步骤为：1)系统搭建；2)异侧延时信号激励；3)激励信号调节；4)信号处理；5)疲劳裂纹定位。本发明设计科学合理,能够快速精确的发现并确定结构中微裂纹的位置,降低因过早对不含损伤结构的材料进行替换而造成的浪费,提高材料的利用率,同时也避免因未能及时发现损伤结构的存在而引发的安全事故,对预测金属材料剩余寿命的研究具有很好的借鉴意义。(The invention relates to a microcrack positioning system based on nonlinear ultrasonic different-side delay mixing signals, which is characterized in that: the device comprises a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, a signal excitation sensor, a sample to be tested, a duplexer, a high-pass filter and an oscilloscope. The invention also relates to a microcrack positioning method based on the nonlinear ultrasonic different-side time-delay mixing signal, which comprises the following steps: 1) building a system; 2) exciting an opposite-side delay signal; 3) excitation signal conditioning; 4) signal processing; 5) and (5) positioning fatigue cracks. The method has scientific and reasonable design, can quickly and accurately discover and determine the position of the microcrack in the structure, reduces waste caused by replacing materials without damaged structures too early, improves the utilization rate of the materials, avoids safety accidents caused by failing to discover the existence of the damaged structures in time, and has good reference significance for the research of predicting the residual life of the metal materials.)
1. The utility model provides a microcrack positioning system based on non-linear supersound opposite side time delay mixing signal which characterized in that: comprises a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, a signal excitation sensor, a sample piece to be tested, a duplexer, a high-pass filter and an oscilloscope, the computer is connected with the nonlinear ultrasonic instrument which is provided with two paths of radio frequency output ends and one path of radio frequency input end, the two paths of radio frequency output ends are respectively connected with attenuators which are respectively connected with a low pass filter and a duplexer, the two sides of the sample piece to be measured are symmetrically provided with signal excitation sensors, the low-pass filter is connected to the signal excitation sensor on the left side of the sample piece to be measured, the duplexer is connected to the signal excitation sensor on the right side of the sample piece to be tested, the other end of the duplexer is connected to the high-pass filter, the high-pass filter is connected to the radio frequency input end of the nonlinear ultrasonic instrument, and the nonlinear ultrasonic instrument is connected to the oscilloscope.
2. The system of claim 1, wherein the system comprises: and signal excitation sensors symmetrically arranged on two sides of the sample piece to be detected are modulated by adopting a Hanning window.
3. The method for positioning the microcracks based on the nonlinear ultrasonic different-side time-delay mixing signals according to claim 1, wherein the method comprises the following steps: the positioning method comprises the following steps:
1) system construction: adhering a signal excitation sensor to two sides of a sample piece to be detected through a high vacuum silicone grease coupling agent, and connecting a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, the signal excitation sensor, the sample piece to be detected, a duplexer, a high-pass filter and an oscilloscope;
2) excitation of different-side delay signals: the computer generates excitation signals and transmits the excitation signals to the nonlinear ultrasonic instrument, the excitation signals are respectively acted on a sample to be tested through two paths of radio frequency output ends, 20 periodic 800kHz signals are applied to a signal excitation sensor on the left side of the sample to be tested in an initial state, and 15 periodic 600kHz signals are applied to a signal excitation sensor on the right side of the sample to be tested;
3) excitation signal conditioning: changing the signal application time of the left signal excitation sensor and the right signal excitation sensor so that the excitation signals meet at different positions, wherein the difference between the excitation application time of the left signal excitation sensor and the excitation application time of the right signal excitation sensor is changed from-50 microseconds to 50 microseconds at an interval of 1 microsecond;
4) signal processing: using MATLAB software to carry out fast Fourier transform on the acquired signals, and recording the time difference of applying left and right excitation signals when the sum frequency signal amplitude is maximum;
5) fatigue crack positioning: the fatigue crack position calculation formula is as follows:
wherein:
b is the distance from the fatigue crack to the left signal excitation sensor;
a is the distance between the left and right signal excitation sensors;
delta t is the application time difference of the left and right excitation signals when the sum frequency signal amplitude is maximum;
cgis the group velocity of the excitation signal.
Technical Field
The invention belongs to the field of metal nondestructive testing, and relates to a microcrack positioning system and a microcrack positioning method based on nonlinear ultrasonic different-side time-delay mixing signals.
Background
The metal plate is widely applied to the fields of military affairs, industry, medical treatment, aerospace and the like, the material is inevitably influenced by external factors such as repeatedly applied load, temperature change, corrosion and the like in the using process, fatigue is further generated, and when the fatigue is accumulated to a certain degree, a macrocrack is developed, so that safety accidents and great economic loss are caused.
There are four major categories of currently mature methods for nondestructive testing of metals: ultrasonic flaw detection, which mainly detects metallurgical defects such as slag inclusion, holes, cracks and the like; x-ray flaw detection, detecting high-density inclusions in parts, such as defects of tungsten inclusion and the like; a fluorescent penetrant inspection method for detecting surface opening defects; eddy current inspection, the detection of surface and near-surface defects. These conventional non-destructive inspection methods are feasible and effective for conventional open cracks, but do nothing to the microcracks caused by fatigue damage. With the development of lamb wave theory and nonlinear ultrasonic frequency mixing theory, a new idea is provided for the nondestructive testing of the microcracks of the sheet metal structure.
According to a Dun clear team, the generation condition of secondary lamb waves in a plate structure is researched by a waveguide excitation mode analysis method on the basis of a second order perturbation theory, the result shows that the generation efficiency of the secondary harmonic waves is related to the constant of an interface, and the result lays a foundation for the application of the secondary harmonic waves of the lamb waves in the aspect of nondestructive testing of a thin plate structure. ChristohpPruell experimentally demonstrated that lamb wave nonlinearity has similar results in interaction with plastic materials as longitudinal and transverse waves, thus indicating that lamb wave higher harmonics can be used to evaluate plastic-driven material damage. Thereafter, Christoph Pruell continues to excite and receive lamb waves and second harmonics by using a pair of wedge-shaped sensors, and the results show that the acoustic nonlinearity measured based on the lamb waves is directly related to fatigue damage, so that an experimental program for representing the fatigue damage of the metal sheet by using the nonlinearity of the lamb waves is developed. H Xu et al studied the evaluation of lamb nonlinear effect characterization structural damage, and proposed a time-frequency analysis algorithm to process the acquired nonlinear lamb signals. When the XWan is simulated by using a finite element analysis method, the fact that the lamb wave generates second harmonic when acting with the micro-size cracks in the thin plate is found, and further, a structural damage detection method of applying the nonlinear lamb wave to the thin plate is provided. In the same year, Z Su extracts linear and nonlinear signals by extracting almost invisible fatigue cracks of the metal plate, and proves the feasibility, accuracy and practicability of the nonlinear lamb wave for detecting the micro-damage structure. In 2017, the team of the worship article completes the frequency mixing ultrasonic detection of the closed cracks by utilizing body waves, and makes a positive search for the evaluation of the microcracks in the structure.
Through a search for a patent publication, no patent publication that is the same as the present patent application is found.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a microcrack positioning system and a microcrack positioning method based on nonlinear ultrasonic different-side delay mixing signals for solving the problem that fatigue damage in a metal plate is difficult to identify and position. The position of the microcrack in the structure is discovered and determined as soon as possible, so that the waste caused by replacing the material without the damaged structure too early is reduced, the utilization rate of the material is improved, meanwhile, the safety accident caused by failing to discover the existence of the damaged structure in time is avoided, and the method has good reference significance for the research on predicting the residual life of the metal material.
The technical problem to be solved by the invention is realized by the following technical scheme:
the utility model provides a microcrack positioning system based on non-linear supersound opposite side time delay mixing signal which characterized in that: comprises a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, a signal excitation sensor, a sample piece to be tested, a duplexer, a high-pass filter and an oscilloscope, the computer is connected with the nonlinear ultrasonic instrument which is provided with two paths of radio frequency output ends and one path of radio frequency input end, the two paths of radio frequency output ends are respectively connected with attenuators which are respectively connected with a low pass filter and a duplexer, the two sides of the sample piece to be measured are symmetrically provided with signal excitation sensors, the low-pass filter is connected to the signal excitation sensor on the left side of the sample piece to be measured, the duplexer is connected to the signal excitation sensor on the right side of the sample piece to be tested, the other end of the duplexer is connected to the high-pass filter, the high-pass filter is connected to the radio frequency input end of the nonlinear ultrasonic instrument, and the nonlinear ultrasonic instrument is connected to the oscilloscope.
And the signal excitation sensors symmetrically arranged on two sides of the sample piece to be detected are modulated by using a Hanning window.
A micro-crack positioning method based on nonlinear ultrasonic different-side delay mixing signals is characterized in that: the positioning method comprises the following steps:
1) system construction: adhering a signal excitation sensor to two sides of a sample piece to be detected through a high vacuum silicone grease coupling agent, and connecting a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, the signal excitation sensor, the sample piece to be detected, a duplexer, a high-pass filter and an oscilloscope;
2) excitation of different-side delay signals: the computer generates excitation signals and transmits the excitation signals to the nonlinear ultrasonic instrument, the excitation signals are respectively acted on a sample to be tested through two paths of radio frequency output ends, 20 periodic 800kHz signals are applied to a signal excitation sensor on the left side of the sample to be tested in an initial state, and 15 periodic 600kHz signals are applied to a signal excitation sensor on the right side of the sample to be tested;
3) excitation signal conditioning: changing the signal application time of the left signal excitation sensor and the right signal excitation sensor so that the excitation signals meet at different positions, wherein the difference between the excitation application time of the left signal excitation sensor and the excitation application time of the right signal excitation sensor is changed from-50 microseconds to 50 microseconds at an interval of 1 microsecond;
4) signal processing: using MATLAB software to carry out fast Fourier transform on the acquired signals, and recording the time difference of applying left and right excitation signals when the sum frequency signal amplitude is maximum;
5) fatigue crack positioning: the fatigue crack position calculation formula is as follows:
wherein:
b is the distance from the fatigue crack to the left signal excitation sensor;
a is the distance between the left and right signal excitation sensors;
delta t is the application time difference of the left and right excitation signals when the sum frequency signal amplitude is maximum;
cgis the group velocity of the excitation signal.
The invention has the advantages and beneficial effects that:
1. the invention discloses a microcrack positioning system based on nonlinear ultrasonic different-side time-delay mixing signals, and further exploration of microcrack detection in a metal plate structure by applying different-side mixing effect is completed.
2. The method has scientific and reasonable design, can quickly and accurately discover and determine the position of the microcrack in the structure, reduces waste caused by replacing materials without damaged structures too early, improves the utilization rate of the materials, avoids safety accidents caused by failing to discover the existence of the damaged structures in time, and has good reference significance for the research of predicting the residual life of the metal materials.
Drawings
FIG. 1 is an overall flow chart of the technical solution of the present invention;
FIG. 2 is a schematic diagram of the connection of the positioning system of the present invention;
FIG. 3 is a schematic diagram of the location where the excitation signals meet;
FIG. 4 is a schematic diagram of the relative position of a fatigue crack and a signal-excited sensor.
Description of the reference numerals
The device comprises a 1-left side attenuator, a 2-right side attenuator, a 3-low pass filter, a 4-sample left side signal excitation sensor to be tested, a 5-fatigue crack, a 6-high pass filter, a 7-sample right side signal excitation sensor to be tested, a 8-computer, a 9-oscilloscope, a 10-first radio frequency output end, a 11-second radio frequency output end, a 12-radio frequency input end, a 13-nonlinear ultrasonic instrument, a 14-sample to be tested and a 15-duplexer.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.
A microcrack positioning system based on nonlinear ultrasonic different-side time-delay mixing signals is innovative in that: the device comprises a computer 8, an RAM-5000-SNAP nonlinear ultrasonic instrument 13, an attenuator, a low-pass filter 3, a signal excitation sensor, a sample piece to be tested 14, a duplexer 15, a high-pass filter 6 and an oscilloscope 9, wherein the computer is connected to the nonlinear ultrasonic instrument which is provided with two radio frequency output ends and a radio frequency input end 12, the two radio frequency output ends comprise a first radio frequency output end 10 and a second radio frequency output end 11, the first radio frequency output end and the second radio frequency output end are respectively connected with a left side attenuator 1 and a right side attenuator 2, the left side attenuator and the right side attenuator are respectively connected to the low-pass filter and the duplexer, the signal excitation sensor 7 is symmetrically arranged on two sides of the sample piece to be tested, the low-pass filter is connected to the left side signal excitation sensor 4 of the sample piece, the other end of the duplexer is connected to the high-pass filter, the high-pass filter is connected to the radio frequency input end of the nonlinear ultrasonic instrument, and the nonlinear ultrasonic instrument is connected to the oscilloscope.
And signal excitation sensors symmetrically arranged on two sides of the sample piece to be detected are modulated by adopting a Hanning window.
A micro-crack positioning method based on nonlinear ultrasonic different-side delay mixing signals is innovative in that: the positioning method comprises the following steps:
1) system construction: adhering a signal excitation sensor to two sides of a sample piece to be detected through a high vacuum silicone grease coupling agent, and connecting a computer, a nonlinear ultrasonic instrument, an attenuator, a low-pass filter, the signal excitation sensor, the sample piece to be detected, a duplexer, a high-pass filter and an oscilloscope;
2) excitation of different-side delay signals: the computer generates excitation signals and transmits the excitation signals to the nonlinear ultrasonic instrument, the excitation signals are respectively acted on a sample to be tested through two paths of radio frequency output ends, 20 periodic 800kHz signals are applied to a signal excitation sensor on the left side of the sample to be tested in an initial state, and 15 periodic 600kHz signals are applied to a signal excitation sensor on the right side of the sample to be tested;
3) excitation signal conditioning: the signal application time of the left and right signal excitation sensors is changed, so that the excitation signals meet at different positions, such as: the left sensor applies excitation first, and signals meet at the right side of the midpoint of the board; the right sensor firstly applies excitation, and signals meet at the left side of the midpoint of the board; the left sensor and the right sensor apply excitation simultaneously, and signals meet at the middle point of the board; the difference between the left signal excitation sensor excitation application time and the right signal excitation sensor excitation application time varies from-50 microseconds to 50 microseconds, with 1 microsecond interval;
4) signal processing: using MATLAB software to carry out fast Fourier transform on the acquired signals, and recording the time difference of applying left and right excitation signals when the sum frequency signal amplitude is maximum;
5) fatigue crack positioning: the fatigue crack position calculation formula is as follows:
wherein:
b is the distance from the fatigue crack 5 to the left signal excitation sensor;
a is the distance between the left and right signal excitation sensors;
delta t is the application time difference of the left and right excitation signals when the sum frequency signal amplitude is maximum, and when the application time difference is greater than 0, the signals meet at the right side of a/2; when it is less than 0, the signals meet at a/2 on the left;
cgis the group velocity of the excitation signal.
The embodiment of the invention does not limit the types of the RAM-5000-SNAP nonlinear ultrasonic instrument and the signal excitation sensor, and only needs devices capable of completing the functions.
Although the embodiments of the present invention and the accompanying drawings are disclosed for illustrative purposes, those skilled in the art will appreciate that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and therefore the scope of the invention is not limited to the disclosure of the embodiments and the accompanying drawings.