CN1258078C - Nondestructive pressure testing method and its device based on Rayleigh surface wave - Google Patents

Abstract

The present invention discloses a nondestructive pressure testing method and a device based on a Rayleigh surface wave. In the method, a middle and low pressure vessel is used as an object, and a relation model of the transmitting speed and the vessel pressure of the Rayleigh surface wave is used as a basis; in a testing system composed of a Rayleigh surface wave energy converter, an ultrasonic wave receiving and transmitting device, a sampling device and a computer, the magnitude of a pressure value is obtained by extracting a Rayleigh surface wave signal transmitted at the surface of a vessel to be tested. The present invention has the advantages that the trouble of hole drilling for testing the pressure on the vessel is prevented, and various potential safety hazards due to hole drilling in the use process of the vessel are reduced. Simultaneously, application occasions of pressure tests of the existing vessel are expanded by the present invention, and thus, the present invention establishes a foundation for realizing the remote test of the pressure of the vessel.

Description

Nondestructive pressure testing method based on Rayleigh surface wave

Technical field

The present invention relates to the harmless pressure measurement technology of pressure vessel, relate in particular to a kind of nondestructive pressure testing method based on Rayleigh surface wave.

Background technology

Pressure vessel is indispensable a kind of specific installation in the modern industry production run, and it is widely used in aspects such as oil, chemical industry, metallurgy, light industry, energy industry, outer space, scientific research and war industry.Along with rapid development of national economy, the quantity of pressure vessel and usable range also increase day by day.Most of pressure vessels are to move under high temperature, high pressure, deep cooling, strong corrosive medium or alternate load effect, need monitor the size of working pressure in the container at any time, to obtain to produce required information, also can in time avoid simultaneously the explosion accident that causes owing to hypertonia, so the pressure of pressure vessel is detected is design of pressure vessels and essential important component in service.

Industrial pressure survey at present almost is contact type measurement, as: the liquid column pressure meter, flexible type pressure gauge etc., this class instrument need perforate connect pressure guiding pipe in use on chamber wall, this just can bring some negative influences to container inevitably, mainly shows: (1) perforate has destroyed the original stress distribution of container and has caused that stress is concentrated; (2) adapter place shell of tank forms the structure uncontinuous stress with adapter; (3) housing with take over the corner is connected and cause that because of unequal section transition (being little fillet) stress is concentrated.And stress to concentrate be the one of the main reasons that cracks, facts have proved that the explosion accident overwhelming majority of pressure vessel originates from the expansion of crackle or other defect.Because perforate also needs to consider problems such as sealing, installation, also brought inconvenience for design and use in addition.Therefore study contactless pressure measurement method, for the performance that promotes the commercial plant that has a large capacity and a wide range as pressure vessel, the support equipment safe operation has the economy and the social effect of particular importance.

Non-contact measuring technology is the focus of studying both at home and abroad in recent years, belongs to front subject, also is a difficult point in the sensor technology.Aspect contactless tonometric research, existing certain methods, adopt resistance strain gage as detecting element as resistive pressure sensor, adhering resistance strain sheets on the component surface specified point, resistance strain gage convert the mechanical quantity of experiencing to electric weight along with member is out of shape together, convert voltage or electric current to by specialized equipment again, and amplified, through ovennodulation, demodulation, calculating, change into force value then and indicate.Though this method is without perforate, be subject to the influence of environment (as electromagnetic field, temperature, humidity, chemical corrosion etc.) as the resistance strain gage of detecting element, the life-span is shorter, and its application is subjected to certain restriction.

Ultrasound wave is meant frequency greater than the sound wave more than the 20kHz, and it not only can be used as a kind of media of nondestructive examination, and can also the sensitive stress information that reflects material internal [1～2].Since Crecraft in 1967 proposes to utilize ultrasound wave to measure stress state the member, this development has caused the concern of Chinese scholars, the research that characterizes stress with the ultrasound wave parameter obtained developing by leaps and bounds in nearly decades, and ultrasound wave stress test technology that some are practical and instrument also occur in succession.Railway industry is that first harmless ultrasound wave stress detects the industry that is converted into practical application, and its application mainly contains three aspects: 1. detect by the longitudinal residual stress in the rail after the straightener straightening; 2. detect the stress in the solid wheel wheel rim; 3. detect the thermal (temperature difference) stress in the welded long rail, thereby brought into play vital role on the raising traffic safety, the instrument of developing uses on the U.S., Europe and Japan and other places.Current comparative maturity and another example of practical application is arranged is the ultrasonic measurement of bolt stress, it can provide the size of bolt axial stress rapidly accurately, as the main foundation of analytical equipment operation conditions.

Summary of the invention

The purpose of this invention is to provide a kind of nondestructive pressure testing method based on Rayleigh surface wave.

The step of pressure testing method is:

Calibration phase:

1). the employing frequency is that one one of the piezoelectric type of 2.5MHz is received the Rayleigh surface wave transducer as probe, and two probes are fixed on vessel surface along the testing container axis of symmetry, and remain on up and down on the same straight line, and the distance between two probes is 10cm;

2). measure the testing container ultrasonic signal that the Rayleigh surface wave receiving transducer receives under pressure-less state earlier, with this as the reference signal;

3). measure the ultrasonic signal that the Rayleigh surface wave receiving transducer of testing container under the various criterion pressure state receives again, and with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation;

4) obtain relational expression between mistiming variable quantity and the pressure by least square fitting;

Measuring phases:

5) when tested container is in running order, the ultrasonic signal that receives by the Rayleigh surface wave receiving transducer, with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation, the relational expression of substitution step 4) then calculates testing container working pressure at that time.

Pressure tester: transmitting probe and receiving transducer join with ultrasound wave receiving and transmitting unit, sampling apparatus, computing machine successively, and transmitting probe and receiving transducer adopt the Rayleigh surface wave transducer, one one receipts, and frequency is 2.5MHz, sampling apparatus adopts oscillograph.

The present invention is research object with the middle and low-pressure vessel, based on the relational model of ultrasonic propagation time difference and container inner pressure, calculates the size of force value by the Rayleigh surface wave signal that is extracted in the Surface Pressure Vessel propagation.Its essence of reservoir pressure measuring method based on Rayleigh surface wave is to obtain the size of container inner pressure value by the travel-time variable quantity of meter ground roll on specified length.Not only avoided the trouble of perforate on container, reduced in the container use because the various potential safety hazards that perforate causes, and the present invention enlarges the application scenario that existing container pressure is measured, for the remote measurement that realizes container pressure is laid a good foundation.

Description of drawings

Fig. 1 is based on the nondestructive pressure testing device block diagram of Rayleigh surface wave;

Fig. 2 ultrasound wave receiving and transmitting unit of the present invention block diagram;

Fig. 3 adopts the nondestructive pressure testing measurement device synoptic diagram based on Rayleigh surface wave;

The Rayleigh surface wave signal graph that Fig. 4 the present invention collects;

One group of data fitting graph of a relation in Fig. 5 the present invention test;

Direction synoptic diagram between Fig. 6 Rayleigh surface wave direction of propagation and the principle stress;

The pressure vessel synoptic diagram of pressing in Fig. 7 bears.

Embodiment

As shown in Figure 1, transmitting probe and receiving transducer join with ultrasound wave receiving and transmitting unit, sampling apparatus, computing machine successively, transmitting probe and receiving transducer adopt the Rayleigh surface wave transducer, the Rayleigh surface wave transducer adopts the Rayleigh surface wave flaw detection transducer, one one receipts, frequency is 2.5MHz, and its model parameter is 2.5P 13 * 13MC, and can be from Changzhou big flat ultrasonic instrument company limited buys.Sampling apparatus adopts oscillograph, selects the TDS430A of Tektronix company for use, and sample frequency is chosen as 500MHz, and the data of collection leave in the computing machine with the form of dat file, use for correlation computations.

As shown in Figure 2, the ultrasound wave receiving and transmitting unit has synchronizing circuit, radiating circuit, attenuator, the radio-frequency amplifier that connects successively; After joining, power circuit and DC converter join with synchronizing circuit, radiating circuit, attenuator, radio-frequency amplifier respectively again.It mainly finishes following function: the pulse de-energisation transmitting probe with one 600 volts of the frequency emission of 150Hz produces R wave, receive to such an extent that the Rayleigh surface wave signal amplifies and filtering to receiving transducer simultaneously, signal after the amplification is directly sent into sampling apparatus through lead, and also can be from Changzhou big flat ultrasonic instrument of ultrasound wave receiving and transmitting unit company limited buys.

As shown in Figure 3, the step based on the reservoir pressure measuring method of Rayleigh surface wave is:

Calibration phase:

1). the employing frequency is that one one of the piezoelectric type of 2.5MHz is received the Rayleigh surface wave transducer as probe, and two pop one's head in along testing container axis of symmetry fixed container surface, and remain on up and down on the same straight line, and the distance between two probes is 10cm;

2). measure the testing container ultrasonic signal that the Rayleigh surface wave receiving transducer receives under pressure-less state earlier, with this as the reference signal;

3). measure the ultrasonic signal that the Rayleigh surface wave receiving transducer of testing container under the various criterion pressure state receives again, and with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation;

4) obtain relational expression between mistiming variable quantity and the pressure by least square fitting;

Measuring phases:

5) when tested container is in running order, the ultrasonic signal that receives by the Rayleigh surface wave receiving transducer, with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation, the relational expression of substitution step 4) then calculates testing container working pressure at that time.

Said time-delay calculation method concrete steps are as follows:

1) make signal A, the amplitude of B beginning ripple part is zero;

2) to A1, B1 does cross-correlation calculation and obtains time variation amount.

The relational expression that obtains between mistiming variable quantity and the pressure by least square fitting is:

p＝KΔt

Wherein p is the working pressure of testing container, and Δ t is the variable quantity in Rayleigh surface wave travel-time.K is a coefficient for the treatment of that match obtains.

By step 1), 2) can obtain p, many groups sample value [p of Δ t ₁, p ₂, p ₃], [Δ t ₁, Δ t ₂, Δ t ₃], obtain the K value by least square fitting, promptly obtain the relational expression between mistiming variable quantity and the pressure.

Be an instantiation below:

During test, the material of pressure vessel is 16MnR, and the container inside radius is 150mm, wall thickness 3mm, and the couplant between transducer and the sample is selected glycerine for use, and environment temperature is 23 ℃ during experiment.Calibration phase, Figure 4 shows that collect under the container pressure-less state Rayleigh surface wave signal, by step 1), 2) many groups sample value that can obtain p, Δ t is [0,0.4,0.8,1.2,1.6,2.0,2.4,2.8,3.2], the Mpa of unit; The time corresponding variable quantity is [0,2,4,6,9,11,14,16,20], the ns of unit.By step 4), the K=0.162 that least square fitting obtains, as shown in Figure 4, then the relational expression between mistiming variable quantity and the pressure is:

p＝0.162Δt

Measuring phases, by the time variation amount Δ t that measures, substitution above-mentioned relation formula is calculated and just can be obtained testing container working pressure at that time.

Principle of the present invention:

Stress mainly shows change to velocity of wave to hyperacoustic influence, and document [3～4] has provided the complete derivation of Rayleigh surface wave velocity of wave and stress relation, directly provides conclusion here.If surface wave is along X ₁Direction is propagated, principle stress σ ₁And σ ₃Direction is as shown in Figure 6:

When Rayleigh surface wave along X ₁And X ₃When direction is propagated, can get:

$\frac{\mathrm{\Δ}{v}_1}{v_1^o}=A_{R1}^1{\mathrm{\σ}}_1+A_{R1}^3{\mathrm{\σ}}_3---\left(1\right)$

$\frac{\mathrm{\Δ}{v}_3}{v_3^o}=A_{R3}^1{\mathrm{\σ}}_1+A_{R3}^3{\mathrm{\σ}}_3---\left(2\right)$

In the formula, A _R1 ¹, A _R1 ³, A _R3 ¹, A _R3 ³Be second order and the relevant amount of three rank acoustic elasticity constants with material, the visible list of references of detailed computing formula [3～4]; v ₁ ⁰, v ₃ ⁰Be illustrated respectively under the unstress state Rayleigh surface wave along X ₁And X ₃The speed that direction is propagated; Δ v ₁=v ₁-v ₁ ⁰Δ v ₃=v ₃-v ₃ ⁰Wherein, v ₁And v ₃Be illustrated respectively in stress state following table ground roll along X ₁And X ₃The speed that direction is propagated.

By formula (1) and (2) as can be known, if the second order of known test specimen material and three rank acoustic elasticity constants promptly can calculate A _R1 ¹, A _R1 ³, A _R3 ¹, A _R3 ¹, A _R3 ³The size of 4 values, and then just can be by measuring Rayleigh surface wave unstressed and the speed of propagating under the stress situation is arranged, simultaneous formula (1) and (2) solve principle stress σ ₁And σ ₃

For the mesolow thin-walled pressure vessel, by boundary-layer theory as can be known, the force analysis of pressure vessel can only be considered axial stress σ With tangential stress σ _θ, and be easy to derive σ And σ _θAnd the relation between the working pressure p.If with σ And σ _θBe intermediate variable, just can derive the relation between Rayleigh surface wave velocity of propagation and the working pressure p.Figure 7 shows that the container of pressing in bearing.When interior pressure is p, can get [5] by boundary-layer theory:

σ in the formula , σ _θAxial stress when representing the pressure vessel pressurized respectively and tangential stress, R ₁, R ₂Represent first and second principal radiuses of curvature of tube face respectively, δ represents that wall of a container is thick.

For the housing of hydrostatic column, because of R ₁=∞, R ₂=R is so got by formula (3)

R represents the external diameter of container in the formula.

It is very little that radial stress and axial stress are compared with tangential stress, is approximately zero promptly:

σ _r＝0

With formula (4) substitution formula (1), (2) can obtain

A in the formula _R , A _R ^θ, A _{R θ}, A _{R θ} ^θExpression and material second order and the relevant amount of three rank acoustic elasticity constants.

$\mathrm{\Δ}{v}_{\mathrm{\θ}}=v_{\mathrm{\θ}}-v_{\mathrm{\θ}}^o$

V in the formula , v _θWith v ⁰, v _θ ⁰Respectively expression have ultrasound wave under stress and the unstress state along vessel axis to the velocity of wave of propagating with tangential direction.If order

Then

$\frac{\mathrm{\Δ}{v}_{\mathrm{\θ}}}{v_{\mathrm{\θ}}^o}=K_{\mathrm{\θ}}\frac{\mathrm{Rp}}{\mathrm{\δ}}---\left(7b\right)$

Thus, derived relational model between Rayleigh surface wave and the tested working pressure p.As can be known for given pressure vessel, velocity of wave changes and to be directly proportional with tested working pressure p by formula (7), as long as measure under the pressurized state the poor of velocity of propagation under the Rayleigh surface wave velocity of propagation and pressure-less state, just can obtain corresponding tested pressure p.

Because the measurement that ultrasonic velocity changes is generally relatively more difficult, and velocity of propagation itself can not be measured as direct amount.Consider that ultrasound wave all will propagate in the material of certain distance, the variable quantity of velocity of wave can be changed into the variable quantity of ultrasonic propagation time, the variation delta t by travel-time of ultrasound wave being determined in the processing of ultrasonic signal in sample (the poor of stress and the travel-time when unstressed arranged).But for the material of certain volume, the effect owing to stress will inevitably cause strain, thereby cause the variation of ultrasonic propagation distance L, further has influence on the measurement to ultrasonic propagation time.Though the variation delta L of distance is very little, find that in experiment the variation of the ultrasonic velocity that is caused by stress is also quite little, therefore must revise strain.Axially propagating along pressure vessel with surface wave is example, has in elastic strain range

E and μ represent the Young modulus and the Poisson ratio of material respectively in the formula.

Rayleigh surface wave is having under the stress state and unstress state is propagated the used time and is

And

T in the formula And t ⁰Represent that respectively ultrasound wave has the time of propagating under stress and the unstress state at material.With formula (9) substitution formula (8), and further get after substitution formula (7) arrangement

In the formula

K generally speaking Very little, K is arranged in YIELD STRENGTH σ ＜＜1, so formula (10) can further be reduced to:

In like manner can also obtain ultrasound wave when pressure vessel is tangentially propagated, Δ t _θAnd the simplification relational expression between the p is

$\mathrm{\Δ}{t}_{\mathrm{\θ}}=(\frac{2-\mathrm{\μ}}{2E}-K_{\mathrm{\θ}})t_{\mathrm{\θ}}^o\frac{\mathrm{Rp}}{\mathrm{\δ}}---\left(12\right)$

In the formula $\mathrm{\Δ}{t}_{\mathrm{\θ}}=t_{\mathrm{\θ}}-t_{\mathrm{\θ}}^o$

t _θAnd t _θ ⁰Represent tangentially direction of ultrasound wave respectively, the time of propagating under stress and the unstress state is arranged in the material.

Thus, formula (11), (12) have provided corresponding change corrected relational model between the time variation amount of Rayleigh surface wave when pressure vessel axially and is tangentially propagated certain distance and the tested pressure p respectively.By model as can be known, as long as record Δ t _θOr Δ t , under the known situation of sonoelastic coefficient, just can obtain tested pressure p.Propagate and the velocity of wave [6] of polarization along different directions but need measure several different wave modes usually for the mensuration of elastic properties of materials constant, too complexity and practicality are not strong for the engineering application.But can be ((2-μ)/2E-K _θ) do as a whole, by the test method determine, thereby determine Δ t _θAnd the relation between the p.Utilize this relation then, by calculating the mistiming that obtains earlier in all cases, substitution relational expression then calculates the size of force value to the data of collection in worksite.

List of references

(1)M.Duquennoy，M.Ouaftouh，M.Ourak.Ultrasonic?Evaluation?of?Stress?inOrthotropic?Materials?Using?Rayleigh?Waves.NDT&E?International，1999，32：189～199.

(2)M.Hirao，H.Fukuoka，K.Hori，Acoustoelastic?Effect?of?Rayleigh?Surface?Wavein?Isotropic?Material.Journal?of?Applied?Mechanics，1981，48：119～124.

(3)Y.H.Pao，W.Sachse，H.Fukuoka.Acoustoelasticity?and?Ultrasonic?Measurementsof?Residual?Stress.Physical?Acoustics，Mason?and?Thurston?edit?17(1984)：61～143.

(4)M.Duquennoy，M.Ouaftouh，M.Ourak，etc.Theoretical?Determination?ofRayleigh?Wave?Acoustoelastic?Coefficients：Comparison?with?Experimental?Values.Ultrasonics，2002，39：575～583.

(5) Wang Zhiwen. Design of Chemical Pressure Vessel. Chemical Industry Press, 1993.

(6)Sato?H，Nishino?H，Cho?H，et?al.Estimation?of?Elastic?Constants?from?SurfaceAcoustic?Wave?Veloctity?by?Inverse?Analysis?Using?the?Downhill?Simplex?Method.Janpanese?Journal?of?Applied?Physics，Part1，1998，37(5B)：3116～3119.

Claims (2)

1, a kind of nondestructive pressure testing method based on Rayleigh surface wave, it is characterized in that: the step of method is:

Calibration phase:

1). the employing frequency is that one one of the piezoelectric type of 2.5MHz is received the Rayleigh surface wave transducer as probe, and two probes are fixed on vessel surface along the testing container axis of symmetry, and remain on up and down on the same straight line, and the distance between two probes is 10cm;

2). measure the testing container ultrasonic signal that the Rayleigh surface wave receiving transducer receives under pressure-less state earlier, with this as the reference signal;

3). measure the ultrasonic signal that the Rayleigh surface wave receiving transducer of testing container under the various criterion pressure state receives again, and with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation;

4) obtain relational expression between mistiming variable quantity and the pressure by least square fitting;

Measuring phases:

5) when tested container is in running order, the ultrasonic signal that receives by the Rayleigh surface wave receiving transducer, with step 2) reference signal obtain the variable quantity in travel-time as time-delay calculation, the relational expression of substitution step 4) then just can calculate testing container working pressure at that time.

2, a kind of nondestructive pressure testing method based on Rayleigh surface wave according to claim 1 is characterized in that: the said relational expression that obtains between mistiming variable quantity and the pressure by least square fitting of step 4) is:

p＝KΔt

Wherein p is the working pressure of testing container, and Δ t is the variable quantity in Rayleigh surface wave travel-time, and K is for treating fitting coefficient,, 2) can obtain many groups sample value [p of p, Δ t by step 1) ₁, p ₂, p ₃], [Δ t ₁, Δ t ₂, Δ t ₃], obtain the K value by least square fitting, promptly obtain the relational expression between mistiming variable quantity and the pressure.

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