CN203432772U - Testing device capable of identifying natural vibration frequency of hydraulic concrete structure - Google Patents

Abstract

The utility model discloses a testing device capable of identifying the natural vibration frequency of a hydraulic concrete structure. The testing device comprises PCB (Printed Circuit Board) accelerometers (1), a vibration table (2), CPSMs (Concrete PZT Smart Modules) (3), a tested structure body (4), a digital filter (5), a signal digitalizing gatherer (6) and a modal parameter identifying system (7), wherein the tested structure body (4) is arranged on the vibration table (2), and the PCB accelerometers (1) and the CPSMs (3) are all arranged in the tested structure body (4). The testing device capable of identifying the natural vibration frequency of the hydraulic concrete structure has the advantages including high precision, high efficiency, simple layering and monitoring, and strong engineering applicability.

Description

A kind of proving installation of Hydro-concrete Structures natural frequency of vibration identification

Technical field

The utility model relates to a kind of proving installation of Hydro-concrete Structures natural frequency of vibration identification.

Background technology

Since 1954, the event that breaks down of generation has 3496, has caused massive losses to people's lives and properties and national economy.In 8.7 ten thousand reservoir dams that China builds, have 43.7% for dangerously weak reseroirs, be exactly by the end of the end of the year in 2007, also still there are the dangerously weak reseroirs of more than 30,000 nearly, therefore, keep safe operation and the use of buildings to become very severe and urgent, need to the running status under each running status monitor buildings, the monitoring materials of collecting is analyzed to the safe condition of Real-Time Evaluation buildings.Hydro-structure inevitably can produce structural damage in this operational process, therefore, need in structure, bury certain sensor underground with the condition of monitoring of structures.Lay traditional monitoring instrument and there is the shortcomings such as economic input is large, precision is lower.

Hydro-concrete Structures not only can be subject to the effect of dead load in operational process, and can be subject to the effect of dynamic load; The utilization of piezoelectric intelligent material can reduce economic input to a certain extent, can be simultaneously for active monitoring and the passive monitoring of structure, and it has feature that many other materials such as Hz-KHz is wide, fast response time do not have.From Structural Dynamics, vibration is the sensitive display of structural intergrity, and the damage of structure can cause the physical and mechanical parameter of structure to change, and then causes the variation of structure dynamic response.In the dynamic monitoring of structural health, the identification of modal parameters is an important link, is also prerequisite and difficult point place simultaneously, whether accurate the carrying out that directly has influence on follow-up work of its recognition result.

Utility model content

Goal of the invention: the purpose of this utility model is for the deficiencies in the prior art, and a kind of proving installation of Hydro-concrete Structures natural frequency of vibration identification is provided, and the dynamic monitoring field of hydraulic concrete structure for health is had to most important theories and practical significance.

Because vibration is the sensitive display of structural intergrity, the damage of structure can cause the physical and mechanical parameter of structure to change, and then cause the variation of structure dynamic response, in the dynamic monitoring of structural health, the identification of modal parameters is an important link.The utility model is the recognition principle based on the natural frequency of vibration just, the recognition methods of the natural frequency of vibration has been proposed, based on concrete piezoelectric ceramics smart module (CPSM, Concrete PZT Smart Module) technology that realizes of the identification Hydro-concrete Structures natural frequency of vibration, studies and has proposed the recognition methods of the natural frequency of vibration.The utility model be take forefathers' research and is basis, sure forefathers, designing, using on the basis of monitoring instrument and sensor, introduced piezoelectric ceramics intellectual material, utilize piezoceramic material design to be applicable to the piezoelectric ceramics smart module of dam safety monitor, and explore its utilization aspect dam safety monitor.

Technical scheme: the proving installation of the Hydro-concrete Structures natural frequency of vibration described in the utility model identification, comprises digital collection device and the Modal Parameter Identification system of PCB accelerometer, shaking table, concrete piezoelectric ceramics smart module sensor, tested structure, digital filter, signal; Described tested structure is arranged on described shaking table; Described PCB accelerometer and concrete piezoelectric ceramics smart module sensor are all arranged in described tested structure, concrete piezoelectric ceramics smart module sensor is embedded in to tested structure inner, can weakens to a certain extent the external environments such as temperature, humidity and change the impact on piezoelectric ceramic piece;

Described shaking table output signal encourages tested structure to produce the natural frequency of vibration; Under equivalence acceleration, PCB accelerometer and described concrete piezoelectric ceramics smart module sensor obtain vibration signal, and the digital collection device by digital filter and signal is transferred to Modal Parameter Identification system by signal;

Described concrete piezoelectric ceramics smart module sensor comprises piezoelectric ceramic piece, sulphurated siliastic layer, signal wire and external wrapping concrete, described sulphurated siliastic layer is coated on the periphery of described piezoelectric ceramic piece, and the piezoelectric ceramic piece that is coated with sulphurated siliastic layer is embedded in external wrapping concrete; One end of described signal wire is welded on piezoelectric ceramic piece, and the other end is connected with other components and parts through external wrapping concrete.

Modal Parameter Identification system for the signal obtaining mainly by Time Domain Analysis in the recognition methods of modal parameter, when measuring-signal be one steadily, during the random time sequence of normal distribution, zero-mean, the feature of reflected signal itself exactly.Time Domain Analysis is applicable to the analyzing and processing compared with short data.In Modal Parameter Identification system, mainly adopt NExT method to obtain under arbitrary excitation the cross correlation function of any two points in structure, then utilize ITD method that above-mentioned cross correlation function is carried out to Experimental Modal Parameters extraction as input to structure.

DSPACE(digital Signal Processing And Control Engineering) system is for the digital collection of signal, it consists of the large member of hardware and software two, and wherein software systems comprise the instrument automatically generating from Simulink model to dSPACE real-time code and experiment is carried out to a series of softwares visual, automatic management.

Piezoelectric ceramic piece is a kind of piezoelectric of manual manufacture, is the material of ferroelectrics one class; The concrete covering of piezoelectric ceramic piece, it mainly consists of sand-cement slurry; Signal wire, be generally after the dry tack free of piezoelectric ceramic piece welding and on; Single component sulphurated siliastic quality is soft, good waterproof performance, and can avoid preferably the stress concentration phenomenon that may occur in piezoelectric ceramic piece Transducers Embedded in Concrete, consider that piezoelectric ceramic piece self material is more crisp, generally in piezoelectric ceramic piece periphery, cover one deck single component sulphurated siliastic to reach the effect of the piezoelectric ceramic piece in protection Transducers Embedded in Concrete; Stress, displacement from piezoelectric ceramic piece to outer concrete transmittance process along rounded equipotential surface in polarised direction, so the right build of piezoelectric ceramics smart module generally can be used right cylinder.

Described tested structure by adhering with epoxy resin on described shaking table, by the random noise signal of shaking table output signal, frequency is compared with horn of plenty, be convenient to motivate the different order natural frequency of structures within the scope of this, by inputting different equivalent acceleration, carry out the energy size of control inputs signal, adopt dSPACE data acquisition system (DAS) to gather Monitoring Data, get vibration signal that under exciting equivalence acceleration, CPSM and PCB accelerometer obtain as analyzing samples.

The method of testing that the proving installation that utilizes the utility model Hydro-concrete Structures natural frequency of vibration to identify carries out the identification of the Hydro-concrete Structures natural frequency of vibration, comprises the steps:

(1) shaking table output drive signal, encourages tested structure to produce the natural frequency of vibration;

(2) by inputting different equivalent acceleration, carry out the energy size of control inputs signal;

(3) vibration signal that under equivalent acceleration, PCB accelerometer and concrete piezoelectric ceramics smart module sensor obtain, after digital filter denoising, is gathered by the digital collection device of signal;

(4) signal is delivered to Modal Parameter Identification system, first select reference point, then by NExT method, obtain vibration signal that under arbitrary excitation, PCB accelerometer and concrete piezoelectric ceramics smart module sensor obtain with respect to the cross correlation function of reference point, the input data of identification using the cross-correlation function value calculating as ITD Time-Domain Modal parameter, obtain impulse response function, realized the test of Hydro-concrete Structures natural frequency of vibration identification.

NExT method (Natural Excitation Technique) is called again natural excitation technique, its ultimate principle be under arbitrary excitation between 2, structure the cross correlation function of response have similar expression formula with impulse response function, after trying to achieve the cross correlation function of response between 2, then carry out Modal Parameter Identification by Time-Domain Modal Parameter Identification method.The expression formula of the cross correlation function between two responses is:

$R_{\mathrm{ijk}}\left(\mathrm{\τ}\right)=E\left[x_{\mathrm{ik}}(t+\mathrm{\τ})x_{\mathrm{jk}}\left(t\right)\right]=\underset{r=1}{\overset{2N}{\mathrm{\Σ}}}\underset{s=1}{\overset{2N}{\mathrm{\Σ}}}{\mathrm{\φ}}_{\mathrm{ir}}{\mathrm{\φ}}_{\mathrm{js}}{a}_{\mathrm{kr}}{a}_{\mathrm{ks}}{\∫}_{-\∞}^t{\∫}_{\∞}^{t-\mathrm{\τ}}{e}^{{\mathrm{\λ}}_r(t+\mathrm{\τ}-p)}{e}^{{\mathrm{\λ}}_s(t-p)}E\left[f_k\left(p\right)f_k\left(q\right)\right]\mathrm{dpdq}$

In formula: δ (t) is impulse function; a _kfor only relevant with point of excitation k constant term, φ _irbe the r rank Mode Shape of i measuring point, a _krfor only with point of excitation k and the relevant constant term of mode order r.

By formula E[f _k(p) f _k(q)]=a _kexpression formula the integration of the cross correlation function between two responses of δ (p-q) substitution formula, can obtain $R_{\mathrm{ijk}}\left(\mathrm{\τ}\right)=\underset{r=0}{\overset{2N}{\mathrm{\Σ}}}{\mathrm{\φ}}_{\mathrm{ir}}{b}_{\mathrm{jr}}{e}^{{\mathrm{\λ}}_r\mathrm{\τ}}\text{,}$ Wherein $b_{\mathrm{jr}}=\underset{s=1}{\overset{2N}{\mathrm{\Σ}}}{\mathrm{\φ}}_{\mathrm{js}}{a}_{\mathrm{kr}}{a}_{\mathrm{ks}}{a}_k(-\frac{1}{{\mathrm{\λ}}_r+{\mathrm{\λ}}_s})$ For only with reference point j and the relevant constant term of mode order r.

The multivariant structural vibration equation of ITD method (The Ibrahim Time Domain Technique) is:

$\left[M\right]\left\{\stackrel{\·\·}{\mathrm{\δ}}\right\}+\left[C\right]\left\{\stackrel{\·}{\mathrm{\δ}}\right\}+\left[K\right]\left\{\mathrm{\δ}\right\}=0$

In formula: [M], [C], [K] are respectively mass matrix, damping matrix and stiffness matrix, { δ } is transposed matrix, the eigenwert V that order is tried to achieve _rmeet

can obtain thus the model frequency ω of system _rwith damping ratio ξ _r, have $R_r=\ln V_r,{\mathrm{\ω}}_r=\frac{\left|R_r\right|}{\mathrm{\Δt}},{\mathrm{\ξ}}_r=\sqrt{\frac{1}{1+{\left(\frac{\mathrm{Im}\left(R_r\right)}{\mathrm{Re}\left(R_r\right)}\right)}^2}}.$

The utility model compared with prior art, its beneficial effect is: basic theories and elastic construction self the intrinsic mode of oscillation feature of the utility model proving installation based on analysis of natural vibration frequency, according to the modal analysis method of structural dynamic feature, by model analysis, understand the fundamental characteristics of each the rank mode of works in some susceptible frequency ranges, obtain structure in this frequency range externally or the actual vibration response condition producing under inner various vibration source effect.This utility model is by based on numerical value modal parameter (natural frequency of structures), Experimental Modal Parameters comparative analysis based on CPSM and PCB accelerometer, verified and utilized concrete piezoelectric ceramics smart module as rationality and the feasibility of the passive monitoring xoncrete structure of the sensor mode natural frequency of vibration, and then researched and developed a set of novel proving installation for the identification of the Hydro-concrete Structures natural frequency of vibration and realized technology.Proving installation of the present utility model has precisely, efficient, lay and the many merits such as monitoring is simple and engineering adaptability is stronger.

Accompanying drawing explanation

Fig. 1 is the utility model device workflow schematic diagram;

Fig. 2 is gravity dam segment model three-dimensional model diagram in embodiment;

Fig. 3 is CPSM and PCB layout schematic diagram in gravity dam model;

Fig. 4 is the basic composition schematic diagram of CPSM.

Embodiment

Below technical solutions of the utility model are elaborated, but protection domain of the present utility model is not limited to described embodiment.

Embodiment 1: the proving installation of the utility model Hydro-concrete Structures natural frequency of vibration identification, comprises digital collection device 6 and the Modal Parameter Identification system 7 of PCB accelerometer 1, shaking table 2, concrete piezoelectric ceramics smart module sensor 3, tested structure 4, digital filter 5, signal; Described tested structure 4 by adhering with epoxy resin on described shaking table 2; Described PCB accelerometer 1 and concrete piezoelectric ceramics smart module sensor 3 are all arranged in described tested structure 4; Described shaking table 2 output signals encourage tested structure 4 to produce the natural frequency of vibration; Under equivalence acceleration, PCB accelerometer 1 and described concrete piezoelectric ceramics smart module sensor 3 obtains vibration signals, and the digital collection device 6 by digital filter 5 and signal is transferred to Modal Parameter Identification system 7 by signal;

Described concrete piezoelectric ceramics smart module sensor 3 is right cylinder, comprise piezoelectric ceramic piece 10, sulphurated siliastic layer 12, signal wire 11 and external wrapping concrete 9, described sulphurated siliastic layer 12 is coated on the periphery of described piezoelectric ceramic piece 10, and the piezoelectric ceramic piece 10 that is coated with sulphurated siliastic layer 12 is embedded in external wrapping concrete 9; One end of described signal wire 11 is welded on piezoelectric ceramic piece 10, and the other end is connected with other components and parts through external wrapping concrete 9.

In the utility model device, tested structure 4 selects gravity dam model to test, accompanying drawing 2 is shown in by its three-dimensional model, in concrete gravity dam model, bury 6 PCB acceleration transducers 1 and 4 CPSM sensor PZT-1-1, PZT-1-2, PZT-2-1, PZT-2-2 underground, specifically referring to accompanying drawing 3, by the concrete gravity dam model bottom of making by adhering with epoxy resin on shaking table, adopt white-noise excitation, by dSPACE data acquisition system (DAS), Monitoring Data is gathered, utilize NExT method and the time-domain analysis of ITD method to extract concrete gravity dam model modal parameter.

By the proving installation of above-mentioned structure, it is as follows that the utility model utilizes piezoelectric ceramics smart module to carry out the proving installation implementation method of Hydro-concrete Structures natural frequency of vibration identification:

Determining of step 1, piezoelectric ceramic piece and body construction combination and manufacturing of CPSM.It is water that piezoelectric ceramics smart module adopts water cement ratio: fine sand: cement=1:2.9:2.09, utilize piezoelectric ceramic piece to be embedded in concrete gravity dam model ontology inside configuration as main sensors element, therefore can weaken to a certain extent the external environments such as temperature, humidity, change the impact on piezoelectric ceramic piece.

The design of step 2, the monitored structure of concrete and preparation.According to the needs of scientific research or Practical Project, the condition that can provide based on laboratory, preparation needs the concrete body to be monitored of size and quantity.In order to improve the signal quality of CPSM, adopt the water cement ratio identical with CPSM to build concrete gravity dam model as shown in Figure 3, its model parameter is specifically shown in accompanying drawing 3.By the concrete gravity dam model bottom of making by adhering with epoxy resin on shaking table, keep concrete gravity dam and shaking table rigidity cementing, so that by the output signal excitation concrete gravity dam model of shaking table, it by shaking table output signal, is the random noise signal of frequency range 100Hz～2000Hz, frequency, compared with horn of plenty, is convenient to motivate the different order natural frequency of structures within the scope of this.By inputting different equivalent acceleration, carry out the energy size of control inputs signal, in the present embodiment, adopt 0.5g, 1.0g, 1.5g, 2.0g, 2.5g, 3.0g totally 6 equivalent acceleration carry out the energy size of control inputs.In theory, the equivalent acceleration of shaking table output is larger, and the order of the natural frequency of structures that gravity dam model can be energized is higher.

Step 3, gather Monitoring Data information and obtain comparative analysis sample.Adopt white-noise excitation, excitation frequency is 100Hz～2000Hz, adopts dSPACE data acquisition system (DAS) to gather Monitoring Data, and sample frequency is 4000Hz.The direction of excitation of excitation white noise signal is perpendicular to axis of dam direction.Get vibration signal that under exciting equivalence acceleration 2.0g, CPSM and PCB accelerometer obtain as analyzing samples.Because the frequency range of white-noise excitation is 100Hz～2000Hz, consider that within the scope of this, impact of low frequency is larger, Selection Model is greater than the model frequency of 200Hz and analyzes as a comparison.

The recognition methods system of step 4, structure modal parameter, realizes Hydro-concrete Structures natural frequency of vibration identification test.During based on NExT method identification modal parameter, need to select reference point, the arrangement mode of the CPSM piezoelectric ceramics smart module in concrete gravity dam model shown in accompanying drawing 3, wherein, PZT-1-1, PZT-1-2, PZT-2-1, PZT-2-2 all represent sensor, and known PZT-2-2 position is near shaking table, yo-yo effect is less, can be used as reference value, in such cases, the cross correlation function relation of being ordered with respect to PZT-2-2 by the available PZT-1-1 of NExT method, PZT-1-2 and PZT-2-1.Using the cross-correlation function value calculating as ITD Time-Domain Modal parameter, the input data of identification, obtain respectively impulse response function curve map.Obtain utilizing the signal of the passive monitoring xoncrete structure of CPSM through the result of NExT method and ITD matching, according to same method, choosing 2# measuring point is reference point, acceleration signal to the collection of PCB accelerometer is analyzed, utilize NExT method and the time-domain analysis of ITD method to extract concrete gravity dam model modal parameter, consider in CPSM manufacturing process and unavoidably leaky can occur, the frequency content that contains ac frequency 50Hz in frequency content is removed.With structural integrity state, encouraging equivalent acceleration is under 2.0g, utilizes respectively CPSM and PCB acceleration transducer to obtain modal parameter, and is analyzed, and finally realizes Hydro-concrete Structures natural frequency of vibration identification test.

As mentioned above, although represented and explained the utility model with reference to specific preferred embodiment, it shall not be construed as the restriction to the utility model self.Not departing under the spirit and scope prerequisite of the present utility model of claims definition, can make in the form and details various variations to it.

Claims (3)

1. a proving installation for Hydro-concrete Structures natural frequency of vibration identification, is characterized in that: the digital collection device (6) and the Modal Parameter Identification system (7) that comprise PCB accelerometer (1), shaking table (2), concrete piezoelectric ceramics smart module sensor (3), tested structure (4), digital filter (5), signal; Described tested structure (4) is arranged on described shaking table (2); Described PCB accelerometer (1) and concrete piezoelectric ceramics smart module sensor (3) are all arranged in described tested structure (4);

Described shaking table (2) output signal encourages tested structure (4) to produce the natural frequency of vibration; PCB accelerometer (1) and described concrete piezoelectric ceramics smart module sensor (3) acquisition vibration signal under equivalence acceleration, and the digital collection device (6) by digital filter (5) and signal is transferred to Modal Parameter Identification system (7) by signal;

Described concrete piezoelectric ceramics smart module sensor (3) comprises piezoelectric ceramic piece (10), sulphurated siliastic layer (12), signal wire (11) and external wrapping concrete (9), described sulphurated siliastic layer (12) is coated on the periphery of described piezoelectric ceramic piece (10), and the piezoelectric ceramic piece (10) that is coated with sulphurated siliastic layer (12) is embedded in external wrapping concrete (9); It is upper that one end of described signal wire (11) is welded on piezoelectric ceramic piece (10), and the other end is connected with other components and parts through external wrapping concrete (9).

2. the proving installation of Hydro-concrete Structures natural frequency of vibration identification according to claim 1, is characterized in that: described concrete piezoelectric ceramics smart module sensor (3) is right cylinder.

3. the proving installation of the Hydro-concrete Structures natural frequency of vibration according to claim 1 identification, is characterized in that: described tested structure (4) by adhering with epoxy resin on described shaking table (2).

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