CN104655727A - Concrete nondestructive testing equipment based on nonlinear second harmonics theory - Google Patents

Abstract

The invention discloses concrete nondestructive testing equipment based on a nonlinear second harmonics theory. The equipment consists of an ultrasonic testing system, a maneuvering system, a wireless data transmission system and a computer terminal, wherein the computer terminal transmits an instruction by virtue of wireless transmission; the maneuvering system is controlled to carry the ultrasonic testing system to reach a to-be-tested area; the computer terminal transmits an instruction to a signal generator by virtue of the wireless transmission, transmitted ultrasonic signal parameters are set, the ultrasonic testing system generates an initial ultrasonic signal and receives the ultrasonic signal penetrating concrete, and the received ultrasonic signal is stored in a storage device in a temporary mode or is transmitted to the computer terminal by virtue of a wireless transmitter and is processed in real time; and moreover, because the ultrasonic testing system is separated from the computer terminal, only the instruction needs to be manually transmitted to the ultrasonic detection equipment by virtue of the computer terminal, so that the detection process is simple and convenient. Because the ultrasonic system is carried onto the maneuvering system with wheels, the ultrasonic system can rapidly move on the surface of the concrete, and the rapid large-area concrete detection is realized.

Description

A kind of concrete nondestructive testing equipment based on nonlinear second harmonic theory

Technical field

The present invention relates to a kind of concrete nondestructive testing equipment based on nonlinear second harmonic theory, belong to concrete field of ultrasonic nondestructive detection.Specifically, be exactly theoretical based on nonlinear second harmonic, adopt Air Coupling ultrasonic non-destructive inspection techniques, thus carry out detecting concrete damage fast, in large area.

Background technology

Existing Nondestructive Methods for Testing Concrete mainly contains rebound method, ultrasonic method, ultrasonic-rebound synthetic method etc.Rebound method due to cost low, the feature such as simple to operate, is most widely used in engineer applied, but due to rebound value can only the quality of representative structure surface concrete, cannot detect inner concrete quality, therefore its reliability is quite limited.Although traditional ultrasonic method and ultrasonic-rebound synthetic method can detect concrete inner structure, its principle utilizes traditional parameters,acoustic, as sound time, the parameter such as the velocity of sound detects the larger defect of inside concrete.But, relate to toward contact the damage type that concrete produces distributed microfracture under physics or chemical action in engineering, during tradition sound, the parameter such as the velocity of sound do not have enough susceptibility for the detection of this distributed microfracture, and therefore traditional ultrasonic method or ultrasonic-rebound synthetic method can not be applied to the detection of concrete microfracture and earlier damage.

Summary of the invention

The technical matters that patent of the present invention will solve:

For solving the vacancy of existing concrete Ultrasonic NDT on microfracture detects, solve existing detection technique reliability simultaneously, sensitivity, the problems such as convenience is not enough, the invention provides a kind of concrete nondestructive testing equipment based on nonlinear second harmonic theory, the non-linear ultrasonic Dynamic Non-Destruction Measurement that it adopts is the feature obviously increased based on nonlinear parameter after concrete damage, show through numerous experimental, this checkout equipment has high sensitivity and fiduciary level, be not only applicable to concrete large fracture detect, also be applicable to concrete at physical action (pressurized, tension etc.) or chemical action (freeze thawing, corrode etc.) under produce distributed microfracture concrete damage detect.In addition, the present invention increases the maneuvering system of band roller on ultrasonic device, improves equipment operating, therefore, it is possible to move at concrete surface rapidly, easily, thus carries out large area concrete detection.

The present invention solves its technical matters and is achieved through the following technical solutions:

A kind of concrete nondestructive testing equipment based on nonlinear second harmonic theory of the present invention, it is made up of four parts: ultrasonic testing system; Maneuvering system; Data radio transmission system; With terminal.Relation between them is: first terminal sends instruction by wireless transmission, control maneuvering system lift-launch ultrasonic testing system and arrive region to be detected, then terminal sends instruction by wireless transmission to signal generator, the ultrasonic signal parameter that setting is launched, ultrasonic testing system produces initial ultrasound signal and receives through concrete ultrasonic signal afterwards, the ultrasonic signal received can be temporary in storer or pass to terminal by Wireless Transmitter, processes in real time.Because ultrasonic testing system is separated with terminal, only need manually to send instruction by terminal to ultrasonic detection equipment, and do not need manually to lift, mobile detection apparatus, thus testing process is more simple and convenient, because ultrasonic system is equipped in the maneuvering system with wheel, can move at concrete surface fast, realize fast, concrete NDT in large area.

Described ultrasonic testing system is by signal generator, and high-power transmitting transducer, receiving transducer and signal processor composition, be interconnected each other.Ultrasonic testing system adopts Air Coupling ultrasonic transduction technology, and signal generator produces signal, sends signal by high-power transmitting transducer, ultrasonic signal is through air and concrete, again by receiving transducer acknowledge(ment) signal, by signal processor processes, the ultrasonic signal received can be obtained.Because this system is with air as ultrasonic coupling agent, in order to make up air and concrete acoustic impedance does not mate the ultrasonic attenuation caused, therefore adopt high-power transmitting transducer.Signal generator and signal processor, wireless transmitting system are integrated in a polypropylene box, and the external interface of signal generator overlaps high-power transmitting transducer, the external interface overlap joint receiving transducer of signal processor.

Described maneuvering system is made up of drive system, chassis frame, telechirics.Drive system comprises the motor of propulsion system, electron speed regulator, 2 axles 4 take turns kinematic train composition.Chassis is designed for aluminium alloy, and telechirics is integrated in Wireless Transmitter, and its principle is similar with remote-control car, and telechirics can the instruction that sends of receiving computer terminal running.The polypropylene box bolt entirety that ultrasonic system is housed is fixed on chassis frame, and chassis frame is used for through high-power transmitting transducer and receiving transducer with two circular opens.

Described data radio transmission system comprises storer and Wireless Transmitter.Storer is used for the ultrasonic signal that obtains of storage signal processor, Wireless Transmitter can receiving computer terminal to the instruction of signal generator and maneuvering system, also the ultrasonic signal of signal processor processes can be passed to terminal simultaneously.

Described terminal is made up of wireless transmitting system and portable computer.Wireless transmitting system is used for sending instruction to signal generator and maneuvering system and receiving waveform signal, and portable computer carries out scene process in real time by existing program to the signal received.

Principle of the present invention:

The present invention is theoretical based on non-linear ultrasonic for the Underwater Acoustic channels received, and has obviously different from traditional ultrasonic detection equipment, mainly by the change of concrete material nonlinear parameter, characterizes damages of concrete structures.

Concrete nonlinear characteristic generally can introduce second order modulus in constitutive relation, has

$\mathrm{\σ}=E(\mathrm{\ϵ}+\frac{\mathrm{\β}}{2}{\mathrm{\ϵ}}^2)$

In formula, E is single order material constant, is concrete Young's modulus of elasticity, and β is second order nonlinear coefficient, is in the present invention the parameter being used for characterizing concrete damage.Theoretical research shows, the damage that second order nonlinear coefficient occurs xoncrete structure is very responsive, and the increase of its numerical value has the raising of 1-2 the order of magnitude compared to the change of Young's modulus of elasticity.Therefore, key of the present invention is and how measures second order nonlinear coefficient quickly and accurately.

Concrete Nonlinear Constitutive Equation is substituted into one dimension fluctuation governing equation, obtain nonlinear wave equations and be expressed as

$\frac{{\∂}^{2}u}{\∂t^2}-c^2\frac{{\∂}^{2}u}{\∂t^2}=\mathrm{\β}{c}^2\frac{\∂\mathrm{\σ}}{\∂x_2}$

In formula, c is one dimension phase velocity of wave, and it is relevant with density p with the elastic modulus E of material:

$c=\sqrt{\frac{E}{\mathrm{\ρ}}}$

If the starting condition of equation is

u(x,t)＝A ₀cos(ωτ)

In formula, τ=t-x/c, then the approximate solution can trying to achieve wave equation is

$u(x,t)=A_0\cos \left(\mathrm{\ω\τ}\right)-\mathrm{\βx}\frac{A_0^{2}k}{8}\cos \left(2\mathrm{\ω\τ}\right)$

Fundamental voltage amplitude is made to be A ₁, secondary harmonic amplitude is A ₂, namely

A ₁＝A ₀

$A_2=\mathrm{\βx}\frac{A_0^{2}k}{8}$

Then second order nonlinear coefficient is

$\mathrm{\β}=\frac{8A_2}{x{A}_0^{2}k}$

Can see, when we can obtain fundamental voltage amplitude and the second harmonic amplitude simultaneously, can calculate the quadratic nonlinearity coefficient characterizing concrete damage, this is theoretical foundation of the present invention.

Key technical feature of the present invention is:

1) ultrasonic probe adopts Air Coupling, and the coupling of unconventional couplant, convenient operation, is applicable to the detection of nonplanar structure, and without the need to processing couplant.

2) ultrasonic device is with maneuvering system, adds equipment operating, saves manpower, therefore can detect large area concrete fast.

3) adopt nonlinear acoustics principle to detect concrete, relative to traditional concrete NDT technology, the damage that concrete microfracture causes can be detected.

Beneficial effect of the present invention:

Damages of concrete structures can be detected in large face fast, and it is easy to operate, produce the damage check in distributed crack under being specially adapted to detect concrete physics, chemical action, as the concrete damage under freeze thawing, fatigue, alkali-aggregate reaction, compensate for the vacancy of concrete NDT in this one side.

Accompanying drawing explanation

Fig. 1 concrete nondestructive testing device model and signal transduction process

Fig. 2 non-linear ultrasonic theoretical principle figure

Fig. 3 equipment workflow diagram

Below in conjunction with accompanying drawing, the present invention is further described.

Fig. 1 is that the present invention is for detecting concrete structure model.Dotted arrow is transmission of wireless signals process, and solid arrow is electric signal, command process, and filled arrows is ultrasonic signal communication process.

Fig. 2 is data handling procedure to the received signal, carries out the FFT conversion process that time domain turns frequency domain, analyze, obtain the amplitude components A of base frequency to frequency domain the ultrasonic signal received ₁with the amplitude components A of second harmonic ₂, use A ₁than removing A ₂square, can obtain characterizing the nonlinear parameter β of concrete damage.By changing ultrasonic signal amplitude, can obtain the β under different amplitude, do linear regression to these β value, the straight slope obtained is the nonlinear parameter β in surveyed region.By recording each β detecting position in surveyed area, surveyed area damage profile can be obtained.

1. wireless transport modules in Fig. 1,2. signal generator module, 3. transmitting transducer, 4. signal processor, 5. maneuvering system, 6. receiving transducer.

Embodiment

See Fig. 1-Fig. 3, as shown in Figure 1, (2) are signal generator modules to device model of the present invention, and (5) are maneuvering systems, and (1) is wireless transport module.Wireless transport module (1) receives the instruction that terminal sends, and control maneuvering system (5) and arrive concrete region to be detected, after equipment arrives appointed area, the ultrasound parameter information that wireless transport module (1) receiving computer terminal sends, and control signal generator module (2) sends ultrasonic signal by transmitting transducer (3).Ultrasonic signal is by air and concrete, by receiving transducer (6) Received signal strength, signal processor (4) process obtains the time domain waveform of Received signal strength, and pass to wireless transport module (1), waveform signal can be temporary in the storer of wireless transport module (1), also directly can pass to terminal by wireless transmissions module (1).Terminal receives waveform signal, carries out time domain turn frequency domain process by existing program to waveform signal.And obtain nonlinear parameter β according to non-linear ultrasonic principle.

Change check point position, obtain each region to be detected nonlinear behavior of concrete parameter beta.Draw degree of impairment and the distribution plan of surveyed area according to β value, provide corresponding maintenance scheme thus.Fig. 2 is non-linear ultrasonic theoretical principle figure; Fig. 3 is equipment workflow diagram.

Claims (1)

1. based on a concrete nondestructive testing equipment for nonlinear second harmonic theory, it is characterized in that: it is made up of four parts: ultrasonic testing system; Maneuvering system; Data radio transmission system and terminal; First terminal sends instruction by wireless transmission, control maneuvering system lift-launch ultrasonic testing system and arrive region to be detected, then terminal sends instruction by wireless transmission to signal generator, the ultrasonic signal parameter that setting is launched, ultrasonic testing system produces initial ultrasound signal and receives through concrete ultrasonic signal afterwards, the ultrasonic signal received is temporary in storer or passes to terminal by Wireless Transmitter, processes in real time; Because ultrasonic testing system is separated with terminal, only need manually to send instruction by terminal to ultrasonic detection equipment, and do not need manually to lift, mobile detection apparatus, thus testing process is simple and convenient, because ultrasonic system is equipped in the maneuvering system with wheel, can move at concrete surface fast, realize fast, concrete NDT in large area;

Described ultrasonic testing system by signal generator, high-power transmitting transducer, receiving transducer and signal processor composition, be interconnected each other; Ultrasonic testing system adopts Air Coupling ultrasonic transduction technology, and signal generator produces signal, sends signal by high-power transmitting transducer, ultrasonic signal is through air and concrete, again by receiving transducer acknowledge(ment) signal, by signal processor processes, namely obtain the ultrasonic signal received; Because this system is with air as ultrasonic coupling agent, in order to make up air and concrete acoustic impedance does not mate the ultrasonic attenuation caused, therefore adopt high-power transmitting transducer; Signal generator and signal processor, wireless transmitting system are integrated in a polypropylene box, and the external interface of signal generator overlaps high-power transmitting transducer, the external interface overlap joint receiving transducer of signal processor;

Described maneuvering system is made up of drive system, chassis frame, telechirics; Drive system comprises the motor of propulsion system, electron speed regulator and 2 axles 4 and takes turns kinematic train; Chassis is designed for aluminium alloy, and telechirics is integrated in Wireless Transmitter, and its principle is identical with remote-control car, and the instruction that telechirics receiving computer terminal sends also runs; The polypropylene box bolt entirety that ultrasonic system is housed is fixed on chassis frame, and chassis frame is used for through high-power transmitting transducer and receiving transducer with two circular opens;

Described data radio transmission system comprises storer and Wireless Transmitter; Storer is used for the ultrasonic signal that obtains of storage signal processor, and the ultrasonic signal of signal processor processes, to the instruction of signal generator and maneuvering system, is also passed to terminal by Wireless Transmitter receiving computer terminal simultaneously;

Described terminal is made up of wireless transmitting system and portable computer; Wireless transmitting system is used for sending instruction to signal generator and maneuvering system and receiving waveform signal, and portable computer carries out scene process in real time by existing program to the signal received.