A kind of tools for bolts ' pretension torque supersonic guide-wave monitoring method based on improvement time reversal
Technical field
The present invention relates to structural health monitoring technology, and in particular to a kind of tools for bolts ' pretension torque monitoring based on supersonic guide-wave
Method.
Background technology
Bolt connection is widely present in machinery, building, the energy and Aerospace Engineering field.To ensure the peace of engineering structure
Complete to be on active service, it is an important prerequisite that the moment, which ensures that bolt is in normal operating conditions,.However, the outside mechanical ring such as vibration, impact
Bolt stress relaxation during border, and long service may all cause tools for bolts ' pretension torque to decline, connection loosens, serious prestige
Coerce structure safety.At present, the detection of tools for bolts ' pretension torque can be realized by conventional lossless detection technique in engineering, such as ultrasonic body
Wave method.However, non-destructive testing technology needs large scale equipment to support, there is unsuitable real time on-line monitoring.Can also
Pressure sensor is installed on bolt to measure Bolt Torque.And pressure sensor is installed on each bolt, work as number of bolts
To bring huge Cost Problems when huge, and for aerospace vehicle, by numerous sensors and cable tie Lai it is additional
Quality problems are also insufferable.
To implement to monitor on-line to bolt looseness, current scholar is proposed based on vibration-testing, based on impedance and based on super
The structure health monitoring method of guided Waves etc..Structural health monitoring technology is reduced cumbersome compared to conventional lossless detection method
Detecting step, and can be applied to real-time online monitoring scheme.However, the method based on vibration-testing can only be recognized such as spiral shell
Bolt such as comes off at the macrolesion, does not possess the ability of quantitative judge tools for bolts ' pretension torque;And the method based on impedance is needed using expensive
High-precision electric impedance analyzer, and its monitoring range is limited only to less region around probe.For tools for bolts ' pretension torque
Monitoring problem, the method based on supersonic guide-wave has unique advantage:Required piezoelectric transducer can be launched and connect simultaneously
Ultrasonic guided wave signals are received, while supersonic guide-wave can propagate larger distance in thin-wall construction, resolution ratio is higher, and not by week
The influence of collarette border low-frequency vibration.
But, due to the frequency dispersion of guided wave, the influence of multi-modal and border reflection so as to the analysis of guided wave compared to bulk wave
For it is more complicated and difficult.Therefore scholar proposes time reversal to handle guided wave signals.Time reversal can
To compensate due to frequency dispersion, multipath, the multi-modal interference to response signal, when the information of bolt looseness is embodied a concentrated reflection of
In anti-focus wave bag.This causes the supersonic guide-wave method based on time reversal to have higher monitoring accuracy, and with can
The advantage applied in complicated bolt fastening structure.
According to being disclosed document ([1] Tao W, Shaopeng L, Junhua S, et al.Health monitoring
of bolted joints using the time reversal method and piezoelectric transducers
[J].Smart Materials&Structures,2016,25(2):025010.[2]Parvasi S M,Ho S C M,Kong
Q,et al.Real time bolt preload monitoring using piezoceramic transducers and
time reversal technique—a numerical study with experimental verification[J]
.Smart Materials and Structures,2016,25(8):085015.), it is currently based on the guided wave side of time reversal
Method use sign bolt looseness characteristic parameter it is also relatively simple, that is, use only based on when anti-focus wave bag amplitude feature
Parameter.The shortcoming of characteristic parameter based on amplitude is mainly reflected in the saturated phenomenon of the characteristic parameter under high pretightening force square.This leads
Cause under high pretightening force square, characteristic parameter can not react pretightning force away from situation of change.This shortcoming seriously limits guided wave side
Monitoring range of the method to tools for bolts ' pretension torque.
In fact, the change of tools for bolts ' pretension torque is in addition to it can influence the amplitude of guided wave signals, the phase of signal can be also influenceed
Position.But traditional time reversal due to monitoring every time when when bob-weight transmission signal (the time that reversely launch
Reversed reemitting signal) it is different from, therefore, it is difficult to the phase place change of comparison signal.The present invention is directed to this
Problem, improves time reversal, bob-weight transmission signal when unique standard is employed in monitoring process so as to signal phase
Relatively being possibly realized for position, and then improves the monitoring range to tools for bolts ' pretension torque and the degree of accuracy.
The content of the invention
The technical problem to be solved
In view of the above-mentioned problems, a kind of based on the tools for bolts ' pretension torque for improving time reversal it is an object of the invention to propose
Supersonic guide-wave monitoring method, the amplitude and phase of anti-reconstruction signal, are improved to tools for bolts ' pretension torque when this method considers
Monitoring range and the degree of accuracy.
Technical scheme
A kind of tools for bolts ' pretension torque supersonic guide-wave monitoring method based on improvement time reversal, it is characterised in that step is such as
Under:
Step 1:Set up reference database offline:
Step 1.1:Gluing two panels piezoelectric ceramics PZT A and PZT B elements, are respectively at bolt to be measured in attachment structure
The dominant shape of both sides, bolt-center and two panels PZT element is changed direction collinearly;
Step 1.2:Bolt to be measured is tightened to the specified pre-fastening moment of bolt using force moment spanner with digital display;
Step 1.3:One Hanning window modulation sine pulse signal is exported by AWG, centre frequency is according to even
The frequency thickness product selection of binding structure, generally 100~300kHz;After Hanning window modulation sine pulse signal amplifies through power amplifier
The PZT A element electrodes two ends as driver are acted on, the signal pulse peak-to-peak value after described power amplifier amplification is
50~100V;
Step 1.4:When bolt is in specified torque, the voltage of the PZT B element two end electrodes as sensor is gathered
Signal, high-pass filtering is carried out to voltage responsive signal, and multi collect is averaged, and obtains a filtered average response letter
Number;
Step 1.5:Obtained average response signal is overturn in time domain, is then stored in signal generator, is made
For when bob-weight transmission signal, be designated as Vr;
Step 1.6:By VrRow energization is entered to PZT B as pumping signal, after backpropagation, PZT A electrodes two ends are gathered
Response signal;The maximum amplitude of anti-focus wave bag, is designated as A when meeting with a response in signal0, and when being calculated using cross zero detecting method
The arrival time of anti-focus wave bag, it is designated as T0;
Step 1.7:Thorough loose bolts, then uniform design several be less than the tools for bolts ' pretension torque of nominal torque value;
For each tools for bolts ' pretension torque value, repeat step 1.6n times, obtain the n groups tools for bolts ' pretension torque values it is corresponding when anti-focus wave
The maximum amplitude A of bagiWith arrival time Ti;Normalized characteristic parameter TIAAnd TIt:
TIt=Ti-To
Then, the average and variance of the n group standardized feature parameters measured under each tools for bolts ' pretension torque value are calculated successively,
According to average and variance, the nonoverlapping reference operating mode of 95% confidential interval is marked off, obtains referring to operating mode and spy by pre-fastening moment
Levy the reference database of parameter confidential interval composition;
Step 2:Monitor tools for bolts ' pretension torque on-line:
Waveform generator is repeated V at set time intervalsrExported with impulse form, then monitor PZT A two ends
The voltage signal of electrode;Calculate characteristic parameter TIA' and TIt′;Obtained characteristic parameter is compared with reference database, spiral shell is obtained
The estimate of bolt pre-fastening moment.
Beneficial effect
A kind of tools for bolts ' pretension torque supersonic guide-wave monitoring method based on improvement time reversal proposed by the present invention, according to
Embodiments of the invention, should the method based on the active ultrasonic guided wave quantification monitoring bolt pre-fastening moment for improving time reversal method
It can accomplish the end in view.With prior art contrast, the monitoring scheme of negative side's method is turned round for bolt when the present invention is than based on tradition
Away from bigger monitoring range, and improve accuracy of detection.
Brief description of the drawings
Fig. 1:Tools for bolts ' pretension torque monitoring system;
Fig. 2:Tools for bolts ' pretension torque monitoring system measurement procedure;
Fig. 3:The test specimen physical dimension and PZT element position of example;
Fig. 4:Each excitation and the modulation sine pulse excitation of 5 cycle of response signal (a) Hanning window;(b) in modulation sine pulse
Response signal under excitation;(c) bob-weight transmission signal V during the standard obtained after time reversalr;(d) in VrResponse letter under excitation
Number;
Fig. 5:The characteristic parameter TI of exampleAStatistical result and reference pretightning force operating mode under each pre-fastening moment operating mode are really
It is fixed;
Fig. 6:The characteristic parameter TI of exampletStatistical result and reference pretightning force operating mode under each pre-fastening moment operating mode are really
It is fixed;
Fig. 7:The reference pretightning force operating mode of example and corresponding characteristic parameter TIAScope (reference database);
Fig. 8:The reference pretightning force operating mode of example and corresponding characteristic parameter TItScope (reference database).
Embodiment
In conjunction with embodiment, accompanying drawing, the invention will be further described:
As shown in Fig. 2 method includes two large divisions:
Step 1:Set up reference database offline:
Step 1.1:With the industrial glue two panels PZT elements of 3MDP460 in attachment structure, respectively as driver and biography
Fig. 3 is seen in sensor, position;PZT size is 10mm × 8mm × 1mm, and model P5H, manufacturer is the grand several electronics in Baoding
Equipment Co., Ltd.Wherein two panels PZT element is respectively at bolt both sides to be measured, respectively away from bolt-center 134mm and 30mm, spiral shell
The dominant shape of bolt center and two PZT elements is changed direction collinearly.3MDP460 industrial glue glue-lines are uniform and thin, and bondline thickness is
0.04-0.06mm, and two hours of solidification at a temperature of 50 DEG C~60 DEG C.
Step 1.2:Bolt to be measured is screwed to by specified torque using force moment spanner with digital display, the present embodiment employs M6 bolts,
Specified torque is set to 10Nm.
Step 1.3:As shown in figure 1, being sequentially connected power amplifier and waveform generator as the PZT A of driver;Make
Data acquisition equipment and computer are sequentially connected for the PZT B of sensor.
Step 1.4:The sinusoidal signal that 5 cycles modulated through Hanning window, sinusoidal signal center frequency are stored in waveform generator
Rate is 100kHz;Waveform generator exports the sinusoidal signal of storage according to pulse form, and output signal is through power amplifier
The after-applied PZT A electrodes two ends given as driver of amplification, the signal pulse peak-to-peak value after power amplifier amplification is 50V.
Step 1.5:The voltage signal of the PZT B two end electrodes as sensor is gathered, and the signal collected is carried out
High-pass filtering, the cut-off frequency of high-pass filtering is not less than 1.5 times of the centre frequency in step 1.4;Repeatedly measurement is averaged,
Filtered response signal is obtained, shown in such as Fig. 4 (b).
Step 1.6:The signal that will meet with a response is carried out time reversal, shown in such as Fig. 4 (c), is believed as bob-weight transmitting during standard
Number Vr, it is stored in waveform generator.
Step 1.7:By VrEncouraged again at PZT B, after backpropagation, gather the response signal at PZT A.Response letter
Anti- focus wave bag when number including one, shown in such as Fig. 4 (d).The maximum amplitude of anti-focus wave bag, is designated as when meeting with a response in signal
A0, and using the arrival time of anti-focus wave bag during cross zero detecting method (zero-crossing method) calculating, it is designated as T0.Meter
Calculate standardized feature parameter TIAAnd TIt:
TIt=Ti-To
Step 1.8:By the thorough loose bolts of spanner, 1Nm~10Nm totally 10 equally distributed torsions are then set
Away from operating mode;For each tools for bolts ' pretension torque value, repeat step 1.7 obtains the corresponding characteristic parameter of tools for bolts ' pretension torque value
TIAAnd TIt;Set up the reference database being made up of pre-fastening moment and characteristic parameter.In the present embodiment, for each tools for bolts ' pretension
Moment values, repeat step 1.7 5 times calculates the corresponding characteristic parameter average value of tools for bolts ' pretension torque value and variance, such as Fig. 5 and
Shown in Fig. 6.According to experimental result, reference database sets 10Nm, 7.26Nm, 5.08Nm, 3.15Nm and
Five Bolt Torque operating modes of 1.25Nm, 95% confidential interval of each operating mode be not present it is overlapping, with reference to pre-fastening moment operating mode and
As shown in Figures 7 and 8, Fig. 7 and Fig. 8 are reference database to its fiducial interval range of characteristic parameter 95%.
Step 2:Monitor tools for bolts ' pretension torque on-line:
Waveform generator each second is by VrWith impulse form output once, it is ensured that last guided wave effectively declines in structure
Subtract, then monitor the voltage signal of PZT A two end electrodes, and high-pass filtering is carried out to the signal monitored, obtain filtered
Response signal;Anti- focus wave bag during interception, calculates characteristic parameter TIAAnd TIt;By obtained characteristic parameter and reference database ratio
Compared with obtaining tools for bolts ' pretension torque value.
In the present embodiment, certain measures characteristic parameter TI twiceA=0.9806,8TIt=-0.8993 and TIA=0.30943,
TIt=-1.12452, as shown in Figure 7 and Figure 8, then the pre-fastening moment estimated by query graph 7 and Fig. 8 for 7.26Nm and
1.25Nm, and actual torque spanner reading is 7Nm and 2Nm, estimated accuracy meets expection.