阅读说明：本技术 基于压电换能器的玻璃幕墙松动检测装置和方法 (Glass curtain wall looseness detection device and method based on piezoelectric transducer ) 是由 徐佳文 张鑫 严如强 唐志文 于 2020-06-30 设计创作，主要内容包括：本发明公开了一种基于多片压电换能器的玻璃幕墙松动检测装置和方法,所述监测装置包括：包括激励产生模块、若干压电换能器和数据采集系统。其中一片或者多片压电换能器作为驱动器使用,另外一片或者多片压电换能器作为传感器使用,数据采集系统解耦两者的电压信号得到电压相应曲线,并依据输出电压响应曲线找到被测结构的固有频率,以此判断被测玻璃幕墙是否松动。本发明使用压电换能器,通过主动激励传感的方式获取被测结构振动特征,并通过压电换能器将其转换为电压信号,获得结构固有频率,并且对结构松动状况做出判断,具有结构简单、准确率高、灵活度高、适应性强、安全性强等优点。(The invention discloses a device and a method for detecting looseness of a glass curtain wall based on a plurality of piezoelectric transducers, wherein the monitoring device comprises: the device comprises an excitation generation module, a plurality of piezoelectric transducers and a data acquisition system. One or more piezoelectric transducers are used as a driver, the other one or more piezoelectric transducers are used as sensors, the data acquisition system decouples voltage signals of the two transducers to obtain a voltage corresponding curve, and finds out the natural frequency of the tested structure according to the output voltage response curve, so as to judge whether the tested glass curtain wall is loosened. The invention uses the piezoelectric transducer to obtain the vibration characteristics of the structure to be detected by an active excitation sensing mode, converts the vibration characteristics into voltage signals by the piezoelectric transducer to obtain the inherent frequency of the structure, judges the loosening condition of the structure, and has the advantages of simple structure, high accuracy, high flexibility, strong adaptability, strong safety and the like.)

1. The utility model provides a glass curtain wall is not hard up detection device based on piezoelectric transducer which characterized in that: comprises an excitation signal generating module for generating an excitation signal; the number of the piezoelectric transducers (3) is not less than two, the piezoelectric transducers (3) are fixedly connected to the curtain wall glass (1), one or more piezoelectric transducers are used as drivers to receive the excitation signals, and the other one or more piezoelectric transducers are used as sensors; and the data acquisition system is used for acquiring and processing output signals of the piezoelectric transducers, obtaining an impedance characteristic curve of the glass curtain wall through decoupling, and analyzing to obtain the natural frequency of the glass curtain wall.

2. The device for detecting looseness of glass curtain wall based on the piezoelectric transducer as claimed in claim 1, wherein: the data acquisition system comprises a signal conditioning module and a signal analysis module, wherein the signal conditioning module is used for decoupling the acquired response signal Vp and the excitation signal Vs and outputting two paths of decoupled digital signals to the signal analysis module for analysis.

3. The piezoelectric transducer-based glass curtain wall looseness detection device as claimed in claim 2, wherein: the signal conditioning module amplifies the collected response signal Vp through a preamplifier and then respectively inputs the amplified response signal Vp into two balanced modems, the signal conditioning module divides the collected excitation signal into two paths, one path is used as a reference signal and input into one balanced modem, the other path is input into the other balanced modem through a phase shifter, the outputs of the two balanced modems pass through a low-pass filter, and a direct current amplitude V is obtained_o1、V_o2I.e. the two paths of decoupled digital signals are obtained, the response signal amplitude V of the glass curtain wall to be measured_oIs composed of

4. The device for detecting looseness of glass curtain wall based on the piezoelectric transducer as claimed in claim 1, wherein: piezoelectric transducer (3) adopt two piezoelectric transducers, two piezoelectric transducer rigid couplings are on curtain wall glass, and one of them piece piezoelectric transducer (31) is received as the driver excitation signal produces vibration excitation, and another piece piezoelectric transducer (32) is as the sensor.

5. The device for detecting looseness of glass curtain wall based on the piezoelectric transducer as claimed in claim 1, wherein: the piezoelectric transducers are mutually parallel, arrayed or dispersedly and fixedly connected on the curtain wall glass.

6. The device for detecting looseness of glass curtain wall based on the piezoelectric transducer as claimed in claim 1, wherein: the piezoelectric transducer (3) is a piezoelectric ceramic, a high-molecular piezoelectric film or a single-crystal piezoelectric transducer and is fixedly connected to the surface of the curtain wall glass by using an adhesive, a fastening bolt or a magnet.

7. A glass curtain wall looseness detection method applied to the detection device of claim 1 is characterized by comprising the following steps of:

(1) the data acquisition system acquires output signals of each piezoelectric transducer under different excitation signal frequencies, and impedance response signals of the glass curtain wall structure are obtained through decoupling, so that an impedance characteristic curve of the glass curtain wall is calculated;

(2) obtaining the natural frequency of the glass curtain wall according to a response signal expression of a piezoelectric transducer as a sensor, wherein the response signal expression is as follows:

in the formula, M, C, K, K₁₂₁，k₁₂₂Respectively the mass, damping and rigidity of the system, the electromechanical coupling coefficient matrix of the first piezoelectric transducer, the electromechanical coupling coefficient matrix of the second piezoelectric transducer, K_c＝1/C_p，C_pIs the capacitance of a piezoelectric transducer, V_eIs the excitation voltage, ω is the excitation signal frequency, i represents the imaginary part; the natural frequency of the glass curtain wall is the frequency corresponding to the peak value of the measured impedance characteristic curve;

(3) and the detection device is used for measuring the natural frequency of the glass curtain wall in a healthy state as a reference, and analyzing the safety state of the glass curtain wall to be detected.

Technical Field

The invention relates to a building structure health monitoring device and method, in particular to a device and method for detecting looseness of a glass curtain wall based on a piezoelectric transducer.

Background

The glass curtain wall is widely applied to urban high-rise buildings, such as a central television station headquarters building and the like, due to the attractive and novel appearance, and becomes one of the marks of modern urban buildings. But because of the error in the production, transportation and installation processes and the effect of natural force and thermal stress in the long-term natural environment, the glass is likely to crack inside, so that the glass 'self-explosion' accident occurs, and along with the long-term use of the glass curtain wall and the influence of the natural environment, the structural adhesive in the glass curtain wall is easy to age and lose efficacy, so that the glass curtain wall is loosened, and the glass curtain wall falls and other accidents are caused. The above problems are serious safety hazards, and once the problems occur, the consequences which are difficult to estimate are caused. Therefore, an effective health monitoring system for the glass curtain wall is established, the health state and the residual service life of the glass curtain wall are reasonably analyzed and predicted, the part damaged in a short period by a large probability is replaced in time, the damage probability of the glass curtain wall is reduced, and the safety of the glass curtain wall is improved. In the mode of measuring by adopting the single piezoelectric sheet, the measured signal is coupled with a mechanical structure signal and a capacitance signal of the piezoelectric sheet, and the mechanical signal is easily submerged in the capacitance signal and is difficult to decouple under the condition that the piezoelectric transducer is small in size or a high-molecular piezoelectric transducer is adopted. Therefore, a new solution to solve the above technical problems is urgently needed.

Disclosure of Invention

The purpose of the invention is as follows: aiming at the problems, the invention provides a device and a method for detecting the looseness of a glass curtain wall based on a piezoelectric transducer, which improve the accuracy of the detection of the natural frequency of the glass curtain wall, realize the identification of the early failure of the structure and help to improve the accuracy of the service life prediction.

The technical scheme is as follows: the technical scheme adopted by the invention is that the glass curtain wall looseness detecting device based on the piezoelectric transducer comprises an excitation signal generating module, a detecting module and a detecting module, wherein the excitation signal generating module is used for generating an excitation signal; the number of the piezoelectric transducers (3) is not less than two, the piezoelectric transducers (3) are fixedly connected to the curtain wall glass (1), one or more piezoelectric transducers are used as drivers to receive the excitation signals, and the other one or more piezoelectric transducers are used as sensors; and the data acquisition system is used for acquiring and processing output signals of the piezoelectric transducers, obtaining an impedance characteristic curve of the glass curtain wall through decoupling, and analyzing to obtain the natural frequency of the glass curtain wall. The piezoelectric transducer is made of piezoelectric ceramics, a high-molecular piezoelectric film or a single-crystal piezoelectric transducer and is fixedly connected to the surface of the curtain wall glass by using an adhesive, a fastening bolt or a magnet; the piezoelectric transducers are mutually parallel, arrayed or dispersedly and fixedly connected on the curtain wall glass.

Because discrete elements are used as a driver and a sensor, the data acquisition system comprises a signal conditioning module and a signal analysis module, the signal conditioning module is used for decoupling the acquired response signal Vp and the excitation signal Vs, and outputting two paths of decoupled digital signals to the signal analysis module for analysis.

The signal conditioning module amplifies the collected response signal Vp through a preamplifier and then respectively inputs the amplified response signal Vp into two balanced modems, the signal conditioning module divides the collected excitation signal into two paths, one path is used as a reference signal and input into one balanced modem, the other path is input into the other balanced modem through a phase shifter, the outputs of the two balanced modems pass through a low-pass filter, and a direct current amplitude V is obtained_o1、V_o2I.e. the two paths of decoupled digital signals are obtained, the response signal amplitude V of the glass curtain wall to be measured_oIs composed of

A typical glass curtain wall looseness detection device based on above-mentioned scheme is, piezoelectric transducer adopts two piezoelectric transducers, and two piezoelectric transducer rigid couplings are in curtain wall glass surface, and wherein a slice piezoelectric transducer receives as the driver excitation signal, another piece piezoelectric transducer is as the sensor.

The invention also provides a glass curtain wall looseness detection method applied to the detection device, which comprises the following steps:

(1) the data acquisition system acquires output signals of each piezoelectric transducer under different excitation signal frequencies, and impedance response signals of the glass curtain wall structure are obtained through decoupling, so that an impedance characteristic curve of the glass curtain wall is calculated;

(2) obtaining the natural frequency of the glass curtain wall according to a response signal expression of a piezoelectric transducer as a sensor, wherein the response signal expression is as follows:

in the formula, M, C, K, K₁₂₁，k₁₂₂Respectively the mass, damping and rigidity of the system, the electromechanical coupling coefficient matrix of the first piezoelectric transducer, the electromechanical coupling coefficient matrix of the second piezoelectric transducer, K_c＝1/C_p，C_pIs the capacitance of a piezoelectric transducer, V_eIs the excitation voltage, ω is the excitation signal frequency, i represents the imaginary part; the natural frequency of the glass curtain wall is the frequency corresponding to the peak value of the measured impedance characteristic curve;

(3) and the detection device is used for measuring the natural frequency of the glass curtain wall in a healthy state as a reference, and analyzing the safety state of the glass curtain wall to be detected.

Has the advantages that: compared with the prior art, the invention has the following advantages: the method and the device for detecting the looseness of the glass curtain wall based on the piezoelectric transducer are provided, so that the relative ratio of the natural frequency of the glass curtain wall under the health condition is compared, and whether the detected glass curtain wall is loosened or not is judged. Compared with the traditional glass curtain wall natural frequency measuring method, the traditional method needs a manual knocking force hammer to provide excitation for a measured structure, and the measuring method has a great safety problem for the glass curtain wall located in high altitude. The traditional unmanned aerial vehicle inspection method is difficult to find problems timely and effectively. The piezoelectric transducer measuring device does not need to be excited manually, and only needs to lead out a lead from the glass and place a measuring circuit at a safe position, such as a lower position, so that the glass curtain wall measurement can be realized. In addition, the method for measuring the natural frequency of the structure by using the impedance method is sensitive to small changes of the measured structure, can more accurately measure the natural frequency of the glass curtain wall, realizes the identification of early faults of the structure and helps to improve the service life prediction accuracy. The double piezoelectric transducer is used for measuring the structure, so that the PVDF high-molecular piezoelectric film can be used as a driver to be applied to structural impedance measurement. PZT piezoelectric ceramics are fragile and can not be bent, and PVDF polymer piezoelectric films are soft and can be bent, so that the film is suitable for various glass surfaces with irregular shapes and curved surfaces. The output response signal of the double piezoelectric transducer measuring structure does not contain direct current bias, the inherent frequency peak value is more obvious, and the signal processing processes such as signal amplification and the like are facilitated.

Drawings

FIG. 1 is a flow chart of a double piezoelectric transducer glass curtain wall looseness detection device according to the invention;

FIG. 2 is a structural block diagram of a double piezoelectric transducer glass curtain wall looseness detection device;

FIG. 3 is a block diagram of a signal conditioning architecture;

FIG. 4 is a pre-amplification circuit diagram;

FIG. 5 is a circuit diagram of a band pass filter;

FIG. 6 is a cross-correlation phase-locked amplification circuit diagram;

fig. 7 is a low-pass filter circuit diagram.

Detailed Description

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

Referring to fig. 1, the device for detecting looseness of a glass curtain wall by using dual piezoelectric transducers comprises two piezoelectric transducers and a data acquisition system. The two polymer piezoelectric films are parallelly adhered to the surface of the curtain wall glass 1 by using epoxy resin, firstly, the response signal output by the piezoelectric transducer 32 is amplified without damage, the output amplified signal and the excitation signal received by the piezoelectric transducer 31 output two paths of direct current signals through the phase-locked amplifying circuit, and the signal analysis module acquires the direct current signals and analyzes the direct current signals by using an impedance method to obtain the natural frequency of the measured glass curtain wall 1.

One piezoelectric transducer 31 is used as a driver to receive an excitation signal, the other piezoelectric transducer 32 is used as a sensor, and the two piezoelectric transducers are used simultaneously to decouple and output a structural impedance response signal. The data acquisition system adopts an instrument amplifier to perform lossless amplification on a measured analog signal, and uses a digital signal processing mode or an analog circuit to realize cross-correlation phase-locked amplification of an excitation signal and a response signal, so that noise in the measurement signal is fully suppressed, and vibration characteristics directly related to the excitation signal are extracted. And the signal analysis system finds the natural frequency of the detected glass curtain wall 1 according to the response frequency curve of the detected structure, compares the natural frequency with the structural natural frequency in a healthy state, obtains whether the detected structure is loosened and predicts the service life of the glass curtain wall according to the safety level frequency interval of the glass curtain wall.

In this embodiment, two polymer piezoelectric films 31 and 32 are adhered to the surface of the curtain wall glass 1 of the structure to be tested, the polymer piezoelectric film 31 applies excitation to the structure, and due to the inverse piezoelectric effect, an alternating excitation electric field is applied to the piezoelectric material, and the piezoelectric material is mechanically deformed along with the change of the electric field. When the excitation signal applied to the polymer piezoelectric film 31 is a swept sine signal, the polymer piezoelectric film 31 deforms along with the change of the excitation signal, the deformation degree of the polymer piezoelectric film is in direct proportion to the voltage of the excitation signal, the piezoelectric transducer deforms to drive the structure to be measured to vibrate at the same frequency, and the vibration amplitude is in direct proportion to the deformation degree of the piezoelectric ceramic.

The structure to be measured vibrates, the polymer piezoelectric film 32 adhered to the structure to be measured senses the vibration of the structure to be measured, a voltage signal is output through a positive piezoelectric effect, and the output response voltage is in direct proportion to the vibration amplitude of the structure to be measured.

Starting from a constitutive equation of the piezoelectric transducer, establishing a mechanical model for a piezoelectric-structure coupled system by using a method of assuming a mode, and establishing a finite element model for the system by using finite element simulation software to obtain a kinetic equation:

wherein M, C, K, K₁₂₁，k₁₂₂Respectively the mass, damping and rigidity of the system, the electromechanical coupling coefficient matrix of the first piezoelectric transducer, the electromechanical coupling coefficient matrix of the second piezoelectric transducer, and C_pIs the capacitance of a piezoelectric transducer, and K_c＝1/C_p，V_eIs the excitation voltage, Q, Q₁And Q₂The system mechanical response matrix and the two-piece transducer response charge are respectively, omega is the excitation signal frequency, and i represents the imaginary part. In the case where the two piezoelectric transducers are of the same size and are attached together, the measured voltage signal is

V (omega) completely represents the dynamic response of the system, the response signal has no direct current bias, and the response signal can be directly amplified and analyzed.

When the structural adhesive of the supported frame 2 and the adhered curtain wall glass 1 looses, ages and fails, the solid structure of the glass curtain wall 1 changes, specifically, the structural vibration characteristic changes according to the formula (3), namely M, C, K, K₁₂₂，k₁₂₁，C_pWhen the isoparametric changes, the V (omega) change curve also changes correspondingly, and the natural frequency of the structure shifts. And applying an excitation signal to the structure to be tested by using the data acquisition system. Meanwhile, the data acquisition system analyzes the response signal processed by the signal processing circuit, and obtains the natural frequency of the glass curtain wall 1 to be tested according to the impedance characteristic curve of the structure. The system is used for measuring the natural frequency of the glass curtain wall in a healthy state as a reference, and analyzing whether the measured glass curtain wall 1 is loosened and the current safety state.

The excitation signal is a sine sweep frequency alternating current signal, the amplitude of the excitation signal is unchanged, the frequency changes along with the step length such as time, and the frequency range is determined by the material characteristics of the structure to be measured.

The data acquisition system comprises an instrument amplifier and a cross-correlation phase-locked amplification circuit, and the amplification factor of the instrument amplifier and the low-pass filtering parameter of the cross-correlation phase-locked amplification circuit need to be adjusted according to actual conditions, so that the sampling precision and amplitude requirements of the sampling system are met.

FIG. 3 shows a block diagram of a signal conditioning module, responding to a signal V_pAfter lossless amplification by a pre-amplification circuit, respectively inputting the signals into two high-precision balance regulators AD630 to obtain V_p1、V_p2Excitation signal V_sAfter 90 degrees phase shift, V is obtained_s2Wherein:

V_p＝Asin(ωt+α)+n(t)

V_p1＝V_p2＝kV_p

V_s＝Bsin(ωt+β)

V_s1＝V_s

V_s2＝Bcos(ωt+β) (4)

A. b is the signal amplitude, the excitation signal amplitude B is known, α, β are both signal phases, n (t) is the noise signal, and k is the amplification factor.

V_s1、V_s2The signals are respectively used as reference signals to be input into two high-precision balance regulators AD630, in a cross-correlation phase-locked amplifying circuit, the reference signals and response signals are subjected to multiplication operation, the frequency spectrum of the signals is shifted to a direct current position, and then the signals are subjected to low-pass filtering to obtain:

V_o1＝mAB cos(ω′)

V_o2＝mAB sin(ω′) (5)

where m is the coefficient, V_o1、V_o2Input data acquisition system solving

As shown in fig. 4, a pre-amplification circuit diagram is obtained by directly amplifying a response signal by using an amplifier INA128 for a high-precision instrument, and adjusting a voltage amplification factor by changing a resistance value of an adjusting resistor, wherein the voltage amplification factor is adjusted according to the sampling precision and amplitude requirement of an actual circuit.

As shown in fig. 5, in the bandpass filter circuit diagram, the amplified response signal is input from a terminal P5, and the filter circuit uses a TL082 dual operational amplifier to build a fourth-order active filter, so that the interference of the signal component input at a high frequency or a low frequency in the signal can be better removed.

As shown in fig. 6, the circuit diagram is an AD630 cross-correlation amplification module, and the other path has the same structure, a response signal is input through an SMA interface P1, a reference signal is input through an SMA interface P6, a signal passes through an AD630 demodulation circuit to transfer a same-frequency signal related to an excitation signal to a direct current, and an output signal is accessed to a low-pass filter to obtain direct current amplitude information.

As shown in fig. 7, it is a low-pass filter circuit diagram. A low-pass filter is built by using a low-noise double-operational amplifier TL082 and is used for filtering high-frequency signals in output signals of the cross-correlation amplification circuit to obtain V containing amplitude information of the detected response signal_o1、V_o2。

Two-path signal V output by signal modulation system_o1、V_o2According to the formula (6), the curve V of the impedance information of the measured structure along with the frequency change in the sweep frequency range is obtained_oAnd (omega), analyzing the position of the peak point on the curve to obtain the natural frequency of the measured glass curtain wall 1.

When the structural adhesive of the supported frame 2 and the adhered curtain wall glass 1 is loosened, aged and invalid, the solid structure of the glass curtain wall 1 is changed, specifically, the structural vibration characteristic is changed, and the inherent frequency of the structure deviates. And applying an excitation signal to the structure to be tested by using the data acquisition system. Meanwhile, the data acquisition system analyzes the response signal processed by the signal processing circuit, and obtains the natural frequency of the glass curtain wall 1 to be tested according to the impedance characteristic curve of the structure. The system is used for measuring the natural frequency of the glass curtain wall in a healthy state as a reference, and analyzing whether the measured glass curtain wall 1 is loosened and the current safety state.

The embodiment utilizes the mechanical impedance characteristic curve of the measured structure to obtain the natural frequency of the structure, and then analyzes the health condition of the structure, and the structure is simple and convenient to operate when in use, high in sensitivity, high in safety, strong in practicability, small in influence on the structure, and suitable for measurement of various material structures.

The piezoelectric transducer in this embodiment may be a piezoelectric ceramic, a polymer piezoelectric film, or a single crystal piezoelectric transducer, and is fixed to the surface of the curtain wall glass 1 by an adhesive, a fastening bolt, or a magnet, preferably, a detachable magnet is used for connection.

The present embodiment can also be generalized to the case of multiple (greater than or equal to three) piezoelectric transducers. Among the piezoelectric transducers, one piezoelectric transducer is used as a driver to receive an excitation signal, the other piezoelectric transducer is used as a sensor, a data acquisition system acquires output signals of each piezoelectric transducer, multi-path output signals are processed by adopting the existing signal processing methods such as averaging, error elimination and the like to improve the measurement accuracy, and response signals of structural impedance are obtained through decoupling. The arrangement of a plurality of piezoelectric transducers can be fixedly connected to the curtain wall glass in a mutually parallel, array or dispersed mode.