CN102818621B - Non-contact collecting probe - Google Patents
Non-contact collecting probe Download PDFInfo
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- CN102818621B CN102818621B CN201110153530.6A CN201110153530A CN102818621B CN 102818621 B CN102818621 B CN 102818621B CN 201110153530 A CN201110153530 A CN 201110153530A CN 102818621 B CN102818621 B CN 102818621B
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Abstract
The invention provides a non-contact collecting probe and belongs to the field of ultrasonic vibration detection. The non-contact collecting probe comprises a base and piezoelectric ceramic. The base is in an elastic arc structure with concave front and convex back. The piezoelectric ceramic is adhered to the back of the arc base, and a polarization direction of the piezoelectric ceramic is along through-thickness direction of the base, namely normal direction of the base. By the aid of the non-contact collecting probe, an emitting point medium is never damaged, and nondestructive testing is achieved. The non-contact collecting probe is a non-contact emission source, an emitter is not lifted or lowered at the moving position, and accordingly production efficiency of the non-contact collecting probe is high. A focus of the non-contact collecting probe on a model can be diminished to 0.2mm by focusing, the requirement for scaling down of a field focus is met, and simulation is more vivid.
Description
Technical field
The invention belongs to ultrasonic vibration detection field, be specifically related to a kind of noncontact accumulation type probe.
Background technology
Seismic physical modeling research refers to utilizes physical model to study earthquake and Related Phenomena (particularly wave phenomenon), and it is an important component part of experimental geology, and model geology is otherwise known as.The method of the most generally using in the research of model geology is ultrasonic method, is therefore often called as ultrasonic earthquake simulation.Ultrasonic earthquake physical model experiment by ultrasound wave the propagation in geologic model observation to seismic event the propagation in various complex geologic bodies carry out lab simulation observation, and carry out study of seismology according to observed result.It is explained and has solved the practical problems occurring in many geophysical surveys, thereby has greatly promoted the development of seismology theory.
Ultrasonic inspection is also in ultrasound examination, is a kind of of Non-Destructive Testing.Non-Destructive Testing is under the prerequisite of not defective work piece or starting material duty, to being verified the surface of parts and a kind of detection means that internal soundness checks.
Conventional ultrasonic detection method mainly contains two kinds, contact type measurement and non-cpntact measurement at present.
1. contact type measurement
The probe that contact type measurement adopts piezoelectric ultrasonic probe or other materials to make conventionally.This probe is comprised of piezoelectric chip or other materials (as compound substance) conventionally, and it is relatively simple for structure, easy for installation, receives and dispatches interchangeable.What Fig. 1 provided is the cut-away view of piezoelectricity contact probe.
When solid material is measured, transmitting probe and receiving transducer are close to testee surface.Emitting head is converted to ultrasonic signal by electric signal (being generally burst pulse); Receiver is converted to electric signal by ultrasonic signal.
2. non-cpntact measurement
The non-cpntact measurement using is at present comprised of intense pulse laser source and laser vibration measurer conventionally.
Ultrasound wave radiating portion adopts intense pulse laser source.When model is tested, intense pulse laser source is to model point (being called again shot point) Emission Lasers pulse, and this point is heated thermal expansion or fusing can occur, and produces thus ultrasound wave and transmits to model is inner.Ultrasound wave receiving unit adopts laser vibration measurer, and it can detect vibration velocity or the displacement on testee surface.
When detecting for geologic model, there are certain shortcomings and limitations in existing ultrasonic detection method.
1. piezoelectric ultrasonic probe is relatively simple, and price is lower, but when carrying out geologic model detection, while using piezoelectric type probe to transmit and receive, can produce some problems.
Piezoelectric ultrasonic probe is when detecting solid geologic model (especially to complex surface model), due to the reason device of process aspect, test section surface of contact is larger, when curved surface model is detected, probe and model surface coupling effect are poor, sometimes even cannot be coupled; Because existing ultrasonic probe can only carry out narrow emission and reception, therefore measure the actual conditions that can not reflect that field construction wideband receives.In addition owing to being contact type measurement, adopt manual mode to measure that efficiency is low, low precision; When moving mechanically, all will repeat to pull up and place this process, and that each set-point probe and contact between model are difficult to accomplish is consistent, the poor repeatability of therefore measuring, easily damages and pops one's head at every turn.Often the complete test of a sleeve solid geologic model needs the some months time at present, and piezoelectric ultrasonic probe can not meet the needs of research and production far away.
2. laser-ultrasound wave measurement
Laser-ultrasound wave measurement is a kind of non-contact ultrasonic measuring method.It can overcome the problem that piezoelectric type probe exists effectively, but it also exists some problems.Because ultrasound wave radiating portion adopts intense pulse laser source, when nonmetallic materials are irradiated in intense pulse laser source, the high temperature of instantaneous generation can damage surface, measured point, makes this point and is burnt in the neighbourhood, and producing distortion.The damage of this point, can affect next time the stimulation effect at this point.And when carrying out physical model detection, requirement can repeatedly be launched ultrasonic signal on same launching site (we are referred to as shot point), this just means that this point is repeatedly irradiated by intense pulse laser source, and require the state of this point of each pre-irradiation can not change, reproducible, and adopt intense pulse laser source to be difficult to accomplish this point.If reduction emitted energy, the ultrasound wave emitted energy producing is inadequate, and signal cannot arrival mode deep layer.
Summary of the invention
The object of the invention is to solve the difficult problem existing in above-mentioned prior art, a kind of noncontact accumulation type probe is provided, for Dynamite, carry out Non-Destructive Testing.
The present invention is achieved by the following technical solutions:
A kind of noncontact accumulation type probe, comprises matrix and piezoelectric ceramics, and described matrix is the arcuate structure that front is recessed, the back side is protruding, flexible; Described piezoelectric ceramics sticks on the back side of curved base, and its polarised direction is along the thickness direction of matrix, i.e. the normal direction of matrix.
When the operation mode of matrix is flexural vibrations, the crest place of matrix and the sense of displacement at trough place (being the normal direction at crest or trough place) all point to same focus; Piezoelectric ceramics sticks on crest place or the trough place at the back side of matrix.
When the operation mode of matrix is flexural vibrations, the crest place of matrix and the sense of displacement at trough place all point to same focus; Piezoelectric ceramics sticks on crest place and trough place simultaneously; In the polarised direction of the piezoelectric ceramics at crest place, be contrary with the polarised direction of piezoelectric ceramics at trough place.
Front at described matrix is provided with matching layer, and the material of described matching layer adopts microporous materials, comprises the high fibrous composite of aerogel or porous or porous polymeric materials.
Compared with prior art, the invention has the beneficial effects as follows:
1. utilize the noncontact accumulation type of the present invention probe can Dynamite, and launching site medium can not be damaged, therefore belong to Non-Destructive Testing; If add the laser head simulated earthquake wave detector with laser vibration measurer, just can simulate the complete gatherer process of ground observation;
2. because noncontact focused transducer is noncontact emissive source, when shift position, emitting head does not have handling process, and its production efficiency is higher;
3. the focus of noncontact focused transducer on model can be little of the 0.2mm (diameter of that when referring to shot point diameter or referring to that ultrasound wave is transmitted into model surface by focusing on, this focuses on light is the same in essence), meet the scaled requirement of field focus, make simulate effect more true to nature.
Accompanying drawing explanation
Fig. 1 is the cut-away view of piezoelectricity contact probe of the prior art.
Fig. 2-1st, the schematic rear view of noncontact focused transducer of the present invention.
Fig. 2-2nd, the front schematic view of noncontact focused transducer of the present invention.
Fig. 3 is the principle schematic that the piezoelectric ceramics on noncontact focused transducer of the present invention excites probe flexural vibrations and focused sound waves.
In figure, 1-1 is ultrasonic radiation face, and 1-2 is acoustic matching layer, and 1-3 is piezoelectric ceramics, and 1-4 is metal case, 1-5 base, and 1-6 is shielding material, 1-7 is lead terminal;
2-1 is high-performance PZT, and 2-2 is radiating surface, and 2-3 is matrix, and 2-4 is acoustic irradiation, and 2-5 is polarised direction.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail:
A kind of noncontact focused transducer is designed to as shown in Figure 2, what Fig. 2 provided is the overall diagram of noncontact focused transducer under off position, positive recessed, the structure that the back side is protruding, described curved base 2-3 is flexible, at the back side (as shown in Fig. 2-1) of matrix 2-3, be pasted with polylith piezoelectric ceramics (high-performance PZT) 2-1, the equal through-thickness of polarised direction of every piezoelectric ceramics 2-1, the i.e. normal direction of curved base 2-3.When piezoelectric ceramics 2-1 is applied along polarised direction electric field time, rely on the d31 effect of piezoelectric ceramics 2-1 can be first in piezoelectric ceramics 2-1 to produce displacement response tangentially, thereby make electric energy effectively convert mechanical energy to.Because piezoelectric ceramics 2-1 and flexible arc matrix 2-3 are cemented together, from deformation compatibility condition, the two will produce same distortion at boundary (place that pottery and matrix are pasted), piezoelectric ceramics 2-1 will pull matrix 2-3 to be out of shape together, can produce tensile force to matrix 2-3 and produce thus mechanical stress.If piezoelectric ceramics 2-1 is applied to specific signal (alternation or pulse), just can make piezoelectric ceramics 2-1 be subjected to displacement because of inverse piezoelectric effect, drive the matrix 2-3 bonding together with piezoelectric ceramics 2-1 to deform, inspire the dither of matrix 2-3, as shown in Figure 3, Fig. 3 provides is the schematic diagram that noncontact focused transducer has a plurality of Wave crest and wave troughs in working order.
The criterion of design matrix is, selected flexural vibrations are as operation mode, and the sense of displacement at its crest and trough place all points to same focus (do not pasting before piezoelectric ceramics, can, by finite element analysis and design, make it to meet the demands).For increasing output power, piezoelectric ceramics can stick on crest place or trough place simultaneously or stick on crest place and trough place simultaneously.Only be attached to trough place or be only attached to crest place, also can excite needed vibration mode, if but be only attached to crest or trough place, piezoelectric unit is very few, may make emittance not and impact effect is realized final sound radiation energy output because be after all by piezoelectric unit.It should be noted that especially the deformation direction at crest or trough place piezoelectric ceramics is contrary all the time, this can guarantee on the contrary by the polarised direction 2-5 of the piezoelectric ceramics pasted at crest and trough place, as shown in Figure 3.During work, all piezoelectric ceramics are applied to the pumping signal of alternation, and the frequency of alternating electric field and the vibration modal frequency of matrix consistent.Owing to being distributed in the polarised direction 2-5 at crest and trough place, be contrary, its distortion is also reverse, just can inspire operation mode.On curved base, each crest or trough place produce displacement response and all can bring out sound wave and pass.The crest and the trough place sense of displacement that due to probe matrix, vibrate all point to same focus, and the energy of the acoustic irradiation 2-4 that dither brings out will reach maximum in focus, and the acoustic wave energy that can realize on certain distance focuses on.Rely on the advantage of this method of d31 effect to be, because do not have the interference of reflection wave, therefore without the need for the design of backing, fairly simple in structure.
Concrete design key is the concrete configuration parameters of curved base, and concrete configuration parameters is to determine according to following principle: (1) crest and the displacement of trough place are pointed to a bit, focus on; (2) obtain the amplitude output of trying one's best large.The layout of piezoelectric ceramics and quantity (can accelerate according to power demand), radiating surface 2-2 (the front that refers to matrix, surface that face that there is no piezoelectric ceramics) is provided with matching layer, and the design of material of described matching layer and selection will guarantee to produce the sound wave of the enough energy that meet the demands.
For the selection of matching layer, mainly consider acoustic impedance coupling, decay littlely etc., and can meet processing request, as some material is just very crisp, cause being difficult to be processed into the needed parallel and smooth surface that has.In the present invention, matching layer can concentrate on microporous materials by material selection, therefore generally can select as aerogel the high fibrous composite of porous, porous polymeric materials.
Principle of work of the present invention is: when tested geologic model is tested, start high-voltage pulse generator and send high drive burst pulse to noncontact focused transducer, and this noncontact focused transducer is to certain point (being called shot point) transmitting focusing pulse of tested geologic model, at this point (referring to shot point place), produces ultrasound wave (noncontact focused transducer converts pulse voltage signal to ultrasonic signal and sends) and transmit to model is inner.In this process, launching site medium can not be damaged, and therefore belongs to Non-Destructive Testing.Because noncontact focused transducer is noncontact emissive source, when shift position, emitting head does not have handling process, and its production efficiency is higher; And the focus of noncontact focused transducer on model can be little of the 0.2mm (diameter of that when referring to shot point diameter or referring to that ultrasound wave is transmitted into model surface by focusing on, this focuses on light is the same in essence), meet the scaled requirement of field focus.
Technique scheme is one embodiment of the present invention, for those skilled in the art, the invention discloses on the basis of application process and principle, be easy to make various types of improvement or distortion, and be not limited only to the described method of the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.
Claims (4)
1. a noncontact accumulation type probe, is characterized in that: described noncontact accumulation type probe comprises that matrix and piezoelectric ceramics, described matrix are the arcuate structure that front is recessed, the back side is protruding, flexible; Described piezoelectric ceramics sticks on the back side of matrix, and its polarised direction is along the thickness direction of matrix, i.e. the normal direction of matrix; When the operation mode of described matrix is flexural vibrations, the crest place of matrix and the sense of displacement at trough place all point to same focus.
2. noncontact accumulation type probe according to claim 1, is characterized in that: piezoelectric ceramics sticks on crest place or the trough place at the back side of matrix.
3. noncontact accumulation type probe according to claim 1, is characterized in that: piezoelectric ceramics sticks on crest place and trough place simultaneously; In the polarised direction of the piezoelectric ceramics at crest place, be contrary with the polarised direction of piezoelectric ceramics at trough place.
4. according to the noncontact accumulation type probe one of claims 1 to 3 Suo Shu, it is characterized in that: the front at described matrix is provided with matching layer, the material of described matching layer adopts microporous materials, comprises the high fibrous composite of aerogel or porous or porous polymeric materials.
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| CN104122331B (en) * | 2014-07-24 | 2016-08-17 | 北京大学 | A kind of nondestructive detection system based on piezo disc contact vibration and detection method thereof |
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| CN201304188Y (en) * | 2008-12-11 | 2009-09-09 | 王敏岐 | Focused ultrasonic transducer |
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