CN106950282A - A kind of fiber reinforced plastics rod defect inspection method and system based on longitudinal ultrasonic guided wave - Google Patents

A kind of fiber reinforced plastics rod defect inspection method and system based on longitudinal ultrasonic guided wave Download PDF

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Publication number
CN106950282A
CN106950282A CN201710264917.6A CN201710264917A CN106950282A CN 106950282 A CN106950282 A CN 106950282A CN 201710264917 A CN201710264917 A CN 201710264917A CN 106950282 A CN106950282 A CN 106950282A
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fiber reinforced
reinforced plastics
wave
plastics rod
defect
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邓红雷
何战峰
陈力
夏桥
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South China University of Technology SCUT
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South China University of Technology SCUT
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04Analysing solids
    • G01N29/048Marking the faulty objects
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00Indexing codes associated with group G01N29/00
    • G01N2291/02Indexing codes associated with the analysed material
    • G01N2291/023Solids
    • G01N2291/0232Glass, ceramics, concrete or stone

Abstract

The invention discloses a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave and system, method and step is:Calculate the group velocity dispersion curve that supersonic guide-wave is propagated in fiber reinforced plastics rod;The mode, frequency and periodicity of supersonic guide-wave are determined according to group velocity dispersion curve, for programming modulation and obtaining pumping signal;Pumping signal is read by function signal generator, and is connected to after being amplified by power amplifier to pumping signal on the piezoelectric patches at fiber reinforced plastics rod excitation end, the supersonic guide-wave of plug defect is produced with this;The piezoelectric patches of fiber reinforced plastics rod receiving terminal receives ultrasonic guided wave signals, and fiber reinforced plastics rod receiving terminal is connected into digital oscilloscope, and the digital oscilloscope is used for the wave character for showing supersonic guide-wave;The wave character shown according to digital oscilloscope, judges particular location and size of the fiber reinforced plastics rod with the presence or absence of defect and defect.The present invention realizes the low cost of fiber reinforced plastics rod defect, fast and accurately detected.

Description

A kind of fiber reinforced plastics rod defect inspection method and system based on longitudinal ultrasonic guided wave
Technical field
Lack the present invention relates to electric device maintenance field, more particularly to a kind of fiber reinforced plastics rod based on longitudinal ultrasonic guided wave Fall into detection method and system.
Background technology
Since 1980s, silicon rubber compound insulator is because of its excellent performance, in China's high voltage power transmission engineering In obtained increasingly being widely applied.In the reasons such as increase and manufacturing process however as the operation time limit, working line Composite insulator can occur various accidents, the harm thereby resulted in will be extremely serious.Data is shown according to the relevent statistics, is being caused Mandrel fracture account for very big proportion in the reason for insulator is damaged.Therefore, realize that plug defect is fast and accurately detected, for Ensure that electric power netting safe running seems extremely important.
At present, for the detection of composite insulator defect, domestic and foreign scholars have done substantial amounts of research, conventional detection method Have:Purplish red outside line imaging method, Electric Field Distribution method, Leakage Method, ultrasonic method etc..These lack both for whole composite insulator Detection method is fallen into, what is predominantly detected is that sheath internal porosity caused by the reasons such as manufacturing process, natural environment, sheath and plug are de- The problems such as viscous, outer layer silicon rubber pollution level, but plug defects detection is not appropriate for, in the quality inspection of plug manufacturer also not It is practical.Liang Xidong of Tsing-Hua University et al. utilizes special ultrasonic probe, and the extension of crackle is detected during to core brittle fracture, With higher sensitivity.But ultrasound examination needs point by point scanning, the consuming time is longer, and can exist in detection process Blind area, detection is will be unable to for the defect in blind area.The Lu Xin of Jilin University proposes a kind of plug based on machine vision and lacked Fall into detecting system, this method automaticity is higher, but can only detection plug surface defect, and system is excessively complicated, detection Effect is easily influenceed by ambient light.
Supersonic guide-wave technology is a kind of quick, accurate, lossless detection method of relatively low cost of rising in recent years.Relatively For the spot scan of ultrasound examination, what supersonic guide-wave was carried out is that line is scanned, and inside and outside defect can be detected, the technology mesh It is preceding to be widely used in the detection of industrial pipeline, steel pole etc..Supersonic guide-wave is applied to insulator fiber reinforced plastics rod defect Detection be rarely reported.
The content of the invention
In order to overcome the shortcoming that prior art is present and a kind of not enough, glass based on longitudinal ultrasonic guided wave of present invention offer Steel core bar defect inspection method and system, to overcome and improve the deficiencies in the prior art, realize fiber reinforced plastics rod defect it is low into Originally, fast and accurately detect.
In order to solve the above technical problems, the present invention provides following technical scheme:A kind of glass based on longitudinal ultrasonic guided wave Steel core bar defect inspection method, comprises the following steps:
S1, physical dimension and material parameter according to required detection fiber reinforced plastics rod, calculate supersonic guide-wave in fiberglass The group velocity dispersion curve propagated in plug;The mode, frequency and periodicity of supersonic guide-wave are determined according to group velocity dispersion curve, For programming modulation and obtaining pumping signal;
S2, pumping signal read by function signal generator, and pumping signal is amplified by power amplifier On the piezoelectric patches for being connected to fiber reinforced plastics rod excitation end afterwards, the supersonic guide-wave of plug defect is produced with this;
S3, the piezoelectric patches of fiber reinforced plastics rod receiving terminal receive ultrasonic guided wave signals, and fiber reinforced plastics rod receiving terminal are connected To digital oscilloscope, the digital oscilloscope is used for the wave character for showing supersonic guide-wave;
S4, the wave character shown according to digital oscilloscope, judge fiber reinforced plastics rod with the presence or absence of defect and defect Particular location and size.
Further, in the step S1, the physical dimension includes the diameter of fiber reinforced plastics rod, the material parameter bag Include density, elastic modelling quantity and Poisson's ratio;
It is described to calculate the group velocity dispersion curve that supersonic guide-wave is propagated in fiber reinforced plastics rod, be specially:
Fiber reinforced plastics rod is considered as individual layer bar class component, when solving the group velocity dispersion curve of supersonic guide-wave, by plug Calculated in the frequency equation for the longitudinal mode that physical dimension and material parameter substitute into individual layer bar class, its frequency equation is as follows:
In formula, d is the diameter of plug, and J is Beseel functions;α, β and k meet following relational expression respectively:
Wherein, CL、CTThe respectively longitudinal wave velocity and transverse wave speed of fiber reinforced plastics rod, the longitudinal wave velocity and transverse wave speed Determined by the material parameter of fiber reinforced plastics rod;ω is circular frequency;It is to obtain C using above-mentioned various progress numerical solutionpWith f's Relation, recycles CpAnd CgRelation obtain CgWith f relation, CgRelation with f is group velocity dispersion curve;CpAnd CgPass System is as follows:
Further, the pumping signal in the step S1 is the sinusoidal signal modulated by Hanning window, and its expression formula is such as Under:
In formula, f is the centre frequency of signal, and n is the periodicity of signal.
Further, the piezoelectric patches in the step S2 has direct piezoelectric effect and reversed piezoelcetric effect, for realizing telecommunications Number and mechanical oscillation mutual conversion;The piezoelectric patches be both the exciter of supersonic guide-wave and also be supersonic guide-wave receiver.
Further, the fiber reinforced plastics rod encourages the piezoelectric patches at end, and its quantity is according to the actual geometry of fiber reinforced plastics rod Size is determined, and quantity is 4 multiple;The fiber reinforced plastics rod encourages the piezoelectric patches at end;It is axially symmetric equally spacedly to glue It is attached to mandrel surface;The piezoelectric patches quantity piezoelectric patches quantity of the fiber reinforced plastics rod receiving terminal is 1, and plug is pasted onto vertically Surface.
Further, judge fiber reinforced plastics rod with the presence or absence of the particular location of defect and defect and big in the step S4 Small, its foundation is:If tail end the waveform that receives and reflects between the waveform received for the second time through head end for the first time and has ripple Bag, as flaw echo, then judge that fiber reinforced plastics rod defect is present;Using flaw echo and tail end receive for the first time waveform it Between time difference judge the defective locations of fiber reinforced plastics rod;The ratio between supersonic guide-wave amplitude that flaw echo amplitude and head end are loaded and Defect size is directly proportional, the defect size for judging fiber reinforced plastics rod.
Further, in the step S4, when fiber reinforced plastics rod existing defects, flaw echo is had between main ripple bag, The time interval between flaw echo and main ripple bag is measured by adjusting the cursor of digital oscilloscope, according to the ripple of supersonic guide-wave Calculate out the particular location of defect quickly, the size of defect then judges according to the amplitude of its flaw echo.
It is a further object of the present invention to provide a kind of fiber reinforced plastics rod defect detecting system based on longitudinal ultrasonic guided wave, bag Include computer, function signal generator, power amplifier, digital oscilloscope, fiber reinforced plastics rod and some piezoelectric patches, the meter Calculation machine and the function signal generator, the function signal generator are connected with the power amplifier, digital oscilloscope; The fiber reinforced plastics rod includes excitation end and receiving terminal, and the excitation end connects the power amplifier by piezoelectric patches, described Receiving terminal connects the digital oscilloscope by piezoelectric patches;Wherein
The computer is used to program out required pumping signal by software program;
The function signal generator is used to read pumping signal;
The power amplifier is used to pumping signal being amplified;
The digital oscilloscope is used for the wave character for showing supersonic guide-wave;
The piezoelectric patches is used for:Piezoelectric patches at fiber reinforced plastics rod excitation end is used to convert electrical signals to mechanical signal, So as to encourage guided wave in fiber reinforced plastics rod;Mechanical signal is converted into telecommunications by the piezoelectric patches of the fiber reinforced plastics rod receiving terminal Number, the guided wave in fiber reinforced plastics rod is included on oscillograph.
After adopting the above technical scheme, the present invention at least has the advantages that:Supersonic guide-wave is that one kind can be carried out Over long distances, on a large scale, quick and precisely, the lossless detection method of relatively low cost, the present invention use ultrasonic guided wave detecting insulator With fiber reinforced plastics rod, overcome the deficiency of most of detection techniques, such as complicated and time consumption, sensitivity are low, testing result easily by Ambient influnence etc.;Compared with conventional ultrasound detection, ultrasonic guided wave detecting ability is stronger, speed faster, plug in detection process Inside and outside (upper and lower) surface have particle vibration, sound field, in the absence of check frequency, is so greatly reduced throughout whole plug Missed detection risk;Meanwhile, the waveform of ultrasonic guided wave detecting is more directly perceived, and the requirement and dependence to testing staff are low, and to detection The body fanout free region of personnel, is especially suitable for the quality check process of plug manufacturer.
Brief description of the drawings
Fig. 1 is a kind of structural representation of the fiber reinforced plastics rod defect detecting system based on longitudinal ultrasonic guided wave of the present invention;
Fig. 2 is the longitudinal mode phase velocities dispersion curve figure that diameter 18mm fiber reinforced plastics rods are used in the embodiment of the present invention;
Fig. 3 is the longitudinal mode group velocity dispersion curve map that diameter 18mm fiber reinforced plastics rods are used in the embodiment of the present invention;
Fig. 4 is the sinusoidal signal schematic diagram that Hanning window is modulated in the embodiment of the present invention;
Fig. 5 is the waveform that 10 cycle 40KHz supersonic guide-waves are propagated in zero defect fiber reinforced plastics rod in the embodiment of the present invention Figure;
Fig. 6 is the waveform that 10 cycle 40KHz supersonic guide-waves are propagated in defective fiber reinforced plastics rod in the embodiment of the present invention Figure.
Embodiment
It should be noted that in the case where not conflicting, the feature in embodiment and embodiment in the application can phase Mutually combine, the application is described in further detail with specific embodiment below in conjunction with the accompanying drawings.
As shown in figure 1, the present invention provides a kind of fiber reinforced plastics rod defect detecting system based on longitudinal ultrasonic guided wave, including Computer, function signal generator, power amplifier, digital oscilloscope, fiber reinforced plastics rod and some piezoelectric patches, the calculating Machine and the function signal generator, the function signal generator are connected with the power amplifier, digital oscilloscope;Institute Stating fiber reinforced plastics rod includes excitation end and receiving terminal, and the excitation end connects the power amplifier by piezoelectric patches, described to connect Receiving end connects the digital oscilloscope by piezoelectric patches.Wherein, piezoelectric patches has reversed piezoelcetric effect due to existing direct piezoelectric effect again, It can realize the mutual conversion of electric signal and mechanical oscillation, therefore not only can be as the generator of pumping signal but also can be as receiving Device.The number of piezoelectric patches is determined by the physical dimension of plug, is typically advisable with 4 multiple.The piezoelectric patches at excitation end need to be along core Mandrel can so suppress the interference of F mode in pumping signal to a certain extent to equidistantly mandrel surface is symmetrically distributed in.Connect The piezoelectric patches of receiving end only needs one, with encouraging that the piezoelectric patches at end is equidirectional to be pasted onto mandrel surface, excitation end and receiving terminal Position can determine as the case may be.
There is provided a kind of base using a kind of above-mentioned fiber reinforced plastics rod defect detecting system based on longitudinal ultrasonic guided wave by the present invention In the fiber reinforced plastics rod defect inspection method of longitudinal ultrasonic guided wave, step includes:
S1, physical dimension and material parameter according to required detection fiber reinforced plastics rod, calculate supersonic guide-wave in fiberglass The group velocity dispersion curve propagated in plug;The mode, frequency and periodicity of supersonic guide-wave are determined according to group velocity dispersion curve, For programming modulation and obtaining pumping signal;Selecting suitable guided wave modal, the standard of guided wave frequency is:It is right under the guided wave frequency The guided wave modal answered has the spread speed of maximum, and other guided wave modal spread speeds are small, and in certain guided wave frequency range Guided wave modal group velocity change is little.The selection standard in guided wave cycle is:Dispersion phenomenon is small, propagation attenuation is small, ripple bag waveform Clearly, amplitude is easy to observation;Wherein, the physical dimension includes the diameter of fiber reinforced plastics rod, the material parameter include density, Elastic modelling quantity and Poisson's ratio;
It is described to calculate the group velocity dispersion curve that supersonic guide-wave is propagated in fiber reinforced plastics rod, be specially:
Fiber reinforced plastics rod is considered as individual layer bar class component, when solving the group velocity dispersion curve of supersonic guide-wave, by plug Calculated in the frequency equation for the longitudinal mode that physical dimension and material parameter substitute into individual layer bar class, its frequency equation is as follows:
In formula, d is the diameter of plug, and J is Beseel functions;α, β and k meet following relational expression respectively:
Wherein, CL、CTThe respectively longitudinal wave velocity and transverse wave speed of fiber reinforced plastics rod, the longitudinal wave velocity and transverse wave speed Determined by the material parameter of fiber reinforced plastics rod;ω is circular frequency;It is to obtain C using above-mentioned various progress numerical solutionpWith f's Relation, recycles CpAnd CgRelation obtain CgWith f relation, CgRelation with f is group velocity dispersion curve;CpAnd CgPass System is as follows:
The pumping signal is the sinusoidal signal modulated by Hanning window, and its expression formula is as follows:
In formula, f is the centre frequency of signal, and n is the periodicity of signal;
S2, pumping signal read by function signal generator, and pumping signal is amplified by power amplifier On the piezoelectric patches for being connected to fiber reinforced plastics rod excitation end afterwards, the supersonic guide-wave of plug defect is produced with this;The piezoelectric patches tool There are direct piezoelectric effect and reversed piezoelcetric effect, the mutual conversion for realizing electric signal and mechanical oscillation;The piezoelectric patches had both been super The exciter of guided Waves is also the receiver of supersonic guide-wave;
S3, the piezoelectric patches of fiber reinforced plastics rod receiving terminal receive ultrasonic guided wave signals, and fiber reinforced plastics rod receiving terminal are connected To digital oscilloscope, the digital oscilloscope is used for the wave character for showing supersonic guide-wave;
S4, the wave character shown according to digital oscilloscope, judge fiber reinforced plastics rod with the presence or absence of defect and defect Particular location and size.Wherein, particular location and size of the fiber reinforced plastics rod with the presence or absence of defect and defect, its foundation are judged For:If tail end the waveform that receives and reflects between the waveform received for the second time through head end for the first time and has ripple bag, as lack Echo is fallen into, then judges that fiber reinforced plastics rod defect is present;Receive the time between waveform for the first time using flaw echo and tail end Difference judges the defective locations of fiber reinforced plastics rod;The ratio between supersonic guide-wave amplitude that flaw echo amplitude is loaded with head end and defect size It is directly proportional, the defect size for judging fiber reinforced plastics rod., can be defective between main ripple bag when fiber reinforced plastics rod existing defects Echo, the time interval between flaw echo and main ripple bag is measured by adjusting the cursor of digital oscilloscope, is led according to ultrasound The velocity of wave of ripple calculates the particular location of defect, and the size of defect then judges according to the amplitude of its flaw echo.
Embodiment
Fiber reinforced plastics rod test specimen in this example is that (Guangzhou Maclean Power Co., Ltd. produces, type by composite insulator Number it is FXBW4-110/100-A) excision two ends gold utensil and obtain after peelling off outer layer silicon rubber, length is a diameter of 18mm of 1.06m, Density 2176.17kgm-3, Poisson's ratio is 0.30, and elastic modelling quantity is 57GPa.
Plug can be considered as individual layer bar structure, and material parameter and physical dimension are substituted into the longitudinal mode frequency side of individual layer bar Cheng Zhong, the dispersion curve of phase velocity can be obtained as shown in Fig. 2 can using the relation of phase velocity and group velocity by numerical solution It is as shown in Figure 3 with the dispersion curve for obtaining group velocity.As can be seen from Figure 3:In 0-1MHz frequency range, a total of 7 Individual mode, each mode has cut-off frequency outside L (0,1) mode;Frequency is higher, and corresponding mode number is also more, inspection It is bigger to signal extraction and identification difficulty during survey;For L (0,1) mode, group velocity curve is more in the range of 0-70KHz Gently, illustrate that the frequency dispersion in the frequency range is smaller, and the value of group velocity is maximum in the frequency range, therefore in the frequency range L (0,1) mode be adapted to detection.
It is 40KHz that pumping signal centre frequency is selected in this example, and periodicity is 10, uses the sine of Hanning window modulation Signal, its oscillogram is as shown in Figure 4.In the frequency spectrum using Hanning window modulated signal, the energy comparison collection near centre frequency In, decay in communication process small, it is higher to the identification susceptibility of signal, beneficial to detection.
Pumping signal is stored in USB flash disk by computer programming, USB flash disk is inserted on function signal generator read afterwards Modulation, the excitation signal amplitude of function signal generator output is smaller, can't be used for actually detected.Pumping signal is put through power The piezoelectric patches of straight fiber reinforced plastics rod surface of test piece (is produced, material number is PIC151) phase by German PI Corp. after big device amplification Even, the multiple of this example intermediate power amplifier is 42db, and its actual waveform and amplitude are as shwon in Figures 5 and 6.
The number for encouraging end piezoelectric patches in this example according to determined by the diameter of fiber reinforced plastics rod is 8,8 piezoelectric patches etc. Away from, symmetrical be pasted onto close to plug end.Receiving terminal is selected in close to another end, and the piezoelectric patches number of receiving terminal is 1. The pumping signal of power amplifier output is carried on 8 piezoelectric patches at excitation end simultaneously by 8 sub-lines, is strengthened with this super The amplitude of guided Waves.
Fig. 5 show the oscillogram that 40KHz supersonic guide-wave is propagated in flawless fiber reinforced plastics rod test specimen, can see Go out within 2ms time, tail end have received the ripple bag of 4 L (0,1) mode supersonic guide-waves, and ripple bag amplitude because of decay by It is decrescence small.Between ripple bag in addition to other less interference modals containing amplitude, substantially into horizontality, it can be surveyed by cursor The time interval for obtaining adjacent wave parlor is about 410us, and the distance that supersonic guide-wave is propagated during this is 2 times of plug length and is 2.12m, the theoretical value 5046m/s's that the group velocity of supersonic guide-wave under the frequency can be calculated to draw in 5171m/s, with Fig. 3 Relative error only has 2.5%.
Fig. 6 show the oscillogram that 40KHz supersonic guide-wave is propagated in defective fiber reinforced plastics rod, the size of defect Size is:Axial length 2mm, circumferential lengths 20mm, depth 5mm, defective locations distance signal excitation end 53cm.It can be seen that by Substantially there is flaw echo between the presence of defect, first ripple bag of tail end and second ripple bag.It can be measured by cursor scarce The time interval fallen between echo-peak and first ripple bag peak value is 215us, has drawn the group velocity of supersonic guide-wave under the frequency For 5171m/s, during this in the distance of guided waves propagation arrived for receiving terminal twice of fault location distance, therefore obtain fault location finally away from connecing Receiving end is 56cm, i.e., distance excitation end is 50cm, there was only 5.6% with the error of physical location.
Although an embodiment of the present invention has been shown and described, for the ordinary skill in the art, can be with Understand, can carry out a variety of equivalent changes to these embodiments without departing from the principles and spirit of the present invention Change, change, replace and modification, the scope of the present invention is limited by appended claims and its equivalency range.

Claims (8)

1. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave, it is characterised in that comprise the following steps:
S1, physical dimension and material parameter according to required detection fiber reinforced plastics rod, calculate supersonic guide-wave in fiber reinforced plastics rod The group velocity dispersion curve of middle propagation;The mode, frequency and periodicity of supersonic guide-wave are determined according to group velocity dispersion curve, is used for Programming is modulated and obtains pumping signal;
S2, pumping signal read by function signal generator, and connected after being amplified by power amplifier to pumping signal On the piezoelectric patches for being connected to fiber reinforced plastics rod excitation end, the supersonic guide-wave of plug defect is produced with this;
S3, the piezoelectric patches of fiber reinforced plastics rod receiving terminal receive ultrasonic guided wave signals, and fiber reinforced plastics rod receiving terminal are connected into number Word oscillograph, the digital oscilloscope is used for the wave character for showing supersonic guide-wave;
S4, the wave character shown according to digital oscilloscope, judge fiber reinforced plastics rod with the presence or absence of the specific of defect and defect Position and size.
2. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1, its feature It is that in the step S1, the physical dimension includes the diameter of fiber reinforced plastics rod, and the material parameter includes density, elasticity Modulus and Poisson's ratio;
It is described to calculate the group velocity dispersion curve that supersonic guide-wave is propagated in fiber reinforced plastics rod, be specially:
Fiber reinforced plastics rod is considered as individual layer bar class component, when solving the group velocity dispersion curve of supersonic guide-wave, by the geometry of plug Calculated in the frequency equation for the longitudinal mode that size and material parameter substitute into individual layer bar class, its frequency equation is as follows:
2 α d ( β 2 + k 2 ) J 1 ( α d ) J 1 ( β d ) - ( β 2 - k 2 ) 2 J 0 ( α d ) J 1 ( β d ) - 4 k 2 αβJ 1 ( α d ) J 0 ( β d ) = 0
In formula, d is the diameter of plug, and J is Beseel functions;α, β and k meet following relational expression respectively:
α 2 = ω 2 C L 2 - k 2
β 2 = ω 2 C T 2 - k 2
k = ω C p = 2 π f C p
Wherein, CL、CTThe respectively longitudinal wave velocity and transverse wave speed of fiber reinforced plastics rod, the longitudinal wave velocity and transverse wave speed by The material parameter of fiber reinforced plastics rod is determined;ω is circular frequency;It is to obtain C using above-mentioned various progress numerical solutionpWith f pass System, recycles CpAnd CgRelation obtain CgWith f relation, CgRelation with f is group velocity dispersion curve;CpAnd CgRelation It is as follows:
C g = C p 2 C p - ( f d ) dC p d ( f d ) .
3. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1, its feature It is that the pumping signal in the step S1 is the sinusoidal signal modulated by Hanning window, its expression formula is as follows:
f ( t ) = 0.5 · ( 1 - ( c o s 2 π f t n ) ) · s i n ( 2 π f t )
In formula, f is the centre frequency of signal, and n is the periodicity of signal.
4. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1, its feature It is that the piezoelectric patches in the step S2 has direct piezoelectric effect and reversed piezoelcetric effect, for realizing electric signal and mechanical oscillation Mutual conversion;The piezoelectric patches be both the exciter of supersonic guide-wave and also be supersonic guide-wave receiver.
5. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1 or 4, it is special Levy and be, the fiber reinforced plastics rod encourages the piezoelectric patches at end, its quantity is determined according to the actual geometry of fiber reinforced plastics rod, And quantity is 4 multiple;The fiber reinforced plastics rod encourages the piezoelectric patches at end;It is axially symmetric to be equally spacedly pasted onto plug table Face;The piezoelectric patches quantity piezoelectric patches quantity of the fiber reinforced plastics rod receiving terminal is 1, and mandrel surface is pasted onto vertically.
6. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1, its feature It is the particular location and size that fiber reinforced plastics rod is judged in the step S4 with the presence or absence of defect and defect, its foundation is: If tail end the waveform that receives and reflects through head end for the first time and has ripple bag between the waveform received for the second time, as defect is returned Ripple, then judge that fiber reinforced plastics rod defect is present;The time difference between waveform is received for the first time using flaw echo and tail end to sentence The defective locations of disconnected fiber reinforced plastics rod;The ratio between supersonic guide-wave amplitude that flaw echo amplitude is loaded with head end and defect size are into just Than the defect size for judging fiber reinforced plastics rod.
7. a kind of fiber reinforced plastics rod defect inspection method based on longitudinal ultrasonic guided wave according to claim 1 or 6, it is special Levy and be, in the step S4, when fiber reinforced plastics rod existing defects, flaw echo is had between main ripple bag, by adjusting number The cursor of word oscillograph measures the time interval between flaw echo and main ripple bag, and defect is calculated according to the velocity of wave of supersonic guide-wave Particular location, the size of defect then judges according to the amplitude of its flaw echo.
8. a kind of fiber reinforced plastics rod defect detecting system based on longitudinal ultrasonic guided wave, it is characterised in that including computer, function Signal generator, power amplifier, digital oscilloscope, fiber reinforced plastics rod and some piezoelectric patches, the computer and the letter Number signal generator, the function signal generator is connected with the power amplifier, digital oscilloscope;The glass steel core Rod includes excitation end and receiving terminal, and the excitation end connects the power amplifier by piezoelectric patches, and the receiving terminal passes through pressure Electric piece connects the digital oscilloscope;Wherein
The computer is used to program out required pumping signal by software program;
The function signal generator is used to read pumping signal;
The power amplifier is used to pumping signal being amplified;
The digital oscilloscope is used for the wave character for showing supersonic guide-wave;
The piezoelectric patches is used for:Piezoelectric patches at fiber reinforced plastics rod excitation end is used to convert electrical signals to mechanical signal, so that Guided wave is encouraged in fiber reinforced plastics rod;Mechanical signal is converted into electric signal by the piezoelectric patches of the fiber reinforced plastics rod receiving terminal, will Guided wave in fiber reinforced plastics rod is shown on oscillograph.
CN201710264917.6A 2017-04-21 2017-04-21 A kind of fiber reinforced plastics rod defect inspection method and system based on longitudinal ultrasonic guided wave Pending CN106950282A (en)

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