CN101285679A - Crack depth test method and device - Google Patents

Abstract

The invention relates to a method and a device for measuring crack depth. The method comprises the following steps that: a. sound velocity v in a measured solid medium is measured; b. a transmitting transducer and a receiving transducer are respectively arranged on two sides with a crack as symmetry; the space between the transmitting transducer and the receiving transducer is l1; the propagation time of read sound wave is t1; the crack depth is calculated through the following formula: (see formula); c. the space between the transmitting transducer and the receiving transducer is set as l2, wherein l2 is more than or equal to 0.1h1 and less than or equal to 10h1, or l2 is more than or equal to 30mm and less than or equal to 500mm; sound-time value t2 is read; crack depth value h2 is calculated; the mean value h of d<h1> and h2 is the crack depth. The method can obtain high-precision measurement result by utilizing few measuring points. The invention also provides a crack depth tester comprising that: a main control system is connected with the transmitting transducer through a high-voltage transmitting module; the high-voltage transmitting module allows the transmitting transducer to generate a sound wave signal; the receiving transducer processes the received signal through a signal receiving-conditioning module, and then the signal is converted into a digital signal by an analog-digital conversion module and transmitted to the main control system; the main control system processes the received digital signal and works out the crack depth directly.

Description

A kind of crack depth test method and device

Technical field

The present invention relates to the sonic detection technical field, relate in particular to a kind of method and device that utilizes the acoustic wave diffraction method to measure the penetration of fracture in the solid dielectric.

Background technology

Usually can utilize the acoustic wave diffraction method to come the penetration of fracture of solid surface is measured in the productive life, especially can be used for the extensively detection of the crack depth of concrete of existence of construction work.The crack is modal a kind of defective in the concrete works, the reinforced concrete in the construction work and the destruction of masonry structure are often all relevant with the development in crack, the existence in crack can reduce the load-bearing capacity of engineering structure, have influence on the anti-permeability performance of structure, cause moisture and objectionable impurities to be infiltrated, bring out steel bar corrosion, thereby security is exerted an influence.

Detect the degree of depth in the non-penetrability of concrete crack at present, mainly adopt the acoustic wave diffraction method, as shown in Figure 1, concrete method of testing has following two kinds:

First kind is " computing method during diffraction sound ".This method is adopted by British standard (BS) BS-4408 and China Engineering Construction Standardization Association's standard " ultrasonic method detects concrete defect technical regulation " (CECS 21:2000 is hereinafter to be referred as " survey and lack rules "), and concrete measuring process is:

1. there be not the concrete surface at crack place, when the spacing of multimetering transmitting transducer and receiving transducer and propagation sound, when obtaining with linear regression method-and the regression coefficient of piano wire sexual intercourse, promptly concrete velocity of sound v

2. will launch with receiving transducer place respectively with the crack be the symmetry both sides, the spacing l between two transducers _iGet 100mm, 150mm, 200mm, 250mm ... the time, read duration t respectively _i, as shown in Figure 2, penetration of fracture calculating formula is:

$h_i=\frac{l_i}{2}\&times;\sqrt{{\left(\frac{t_i\&times;v}{l_i}\right)}^2-1}$ $m_h=\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{h}_i$

In the formula: h _iThe penetration of fracture value (mm) that-Di i point calculates

l _iSpacing (mm) between-Di i point two transducers

t _i-Di i point acoustic transit time (μ s)

m _h-different spacing measuring point penetration of fracture mean value

N-measuring point number

3. determine the penetration of fracture: with the distance values l of each spacing measuring point correspondence _iWith the dark m of average seam _hCompare, this mortal world is apart from l _iLess than m _hOr greater than 3m _h, should reject this group data, get remaining h _iMean value as the penetration of fracture.

Second kind is " Mintrop wave phase reversal method ".This method is also adopted by " survey lack rules ", and the concrete testing procedure of this method, penetration of fracture computing formula are identical with " computing method during diffraction sound ", but to the choice method difference of different spacing penetration of fracture value.Concrete measuring process is: in the test of different spacing measuring point, observe the variation of Mintrop wave phase place.When certain spacing measuring point finds that Mintrop wave is anti-phase, with the mean value of the penetration of fracture measured value of this spacing measuring point and two adjacent spacing measuring points as penetration of fracture value.As shown in Fig. 3 a, T1, R1 and T2, R2 are respectively two adjacent emissions and receive measuring point.In the oscillogram of T1-R1, the phase place of Mintrop wave is upwards seen Fig. 3 b.In the oscillogram of T2-R2, the phase place of Mintrop wave becomes downwards, sees Fig. 3 c, and then T2-R2 is and the anti-phase measuring point of Mintrop wave occurs.

In addition, adopt diffraction approach to detect penetration of fracture computing formula, the certain physical condition is satisfied in requirement, be that diffraction sound wave answers straight line to walk around the terminal propagation in crack, can not cause that sound ray departs from, also should guarantee the consistance of the velocity of sound in the travel path scope because of the reinforcing bar of crack vicinity or the defective of inside concrete.

Chinese utility model patent related to the present invention: " distress in concrete tester " (patent No.: ZL200420016797.6, hereinafter to be referred as the contrast patent), this patent adopts a plurality of transducers that transmit and receive to transmit and receive a plurality of acoustic signals successively, utilizes the phase change of measuring point directly to calculate the degree of depth that determines tested crack.Its adopt with " survey lack rules " in " Mintrop wave phase reversal method " similar method, promptly in a plurality of acoustic signals, find the anti-phase point position of Mintrop wave, and with 2 times of the average headway of these former and later two measuring points of measuring point as the penetration of fracture.

Recommends in " survey lack rules " method of testing used and with " surveying scarce rules " similar method in, exist following problem and defective:

(1) when diffraction sound in the computing method, because the variation of physical condition and the influence of various test errors, the dark calculated value of the seam of different spacing measuring point there are differences, and is a problem that is difficult to judge and handle to the choice of misdata wherein.Computing method is according to measuring point spacing l during " survey lack rules " employed diffraction sound _iWith the dark m of average seam _hRatio l _i/ m _hCarry out the choice of data, regulation ratio l _i/ m _hShould be 1～3, the data that exceed this scope are then disallowable.Therefore, adoptable test spacing range is very little when seam is more shallow deeply, is difficult to arrange measuring point.

For example, as the dark m of average seam _h=20mm, transducer spacing l _iOnly allow for 20mm～60mm; The dark m of average seam _h=30mm, spacing l _iOnly allow for 30mm～90mm.In addition, before the unknown seam is dark, if by spacing 100mm, the 150mm of " survey and lack rules " suggestion, 200mm, 250mm ... after testing, then most of the even whole test datas of possibility are because spacing l _iWith the dark m of average seam _hRatio disallowable greater than 3; And on the other hand, when seam is deeply dark, test by the spacing of " surveying scarce rules " suggestion, a lot of test datas again can be owing to spacing l _iWith the dark m of average seam _hRatio disallowable less than 1, for example, as the dark m of average seam _h=300mm, spacing l _iAllow for 300mm～900mm, then the spacing data below the 300mm is all with disallowable.

The problem that above situation is brought is: the rejecting of too much test data must mean will carry out too much invalid test.

(2) dark when dark when seam, transducer spacing that " survey and lack rules " requires is bigger, causes that to walk around crack propagation very faint to the signal of receiving transducer, even loses ripple, and reading is difficult or can't interpretation when causing, causes big error.For example, as the dark h of seam _i=300mm, transducer spacing l _iShould be 300mm～900mm, the diffracted wave propagation distance of walking around the crack end in the actual concrete will reach 670～1080mm.

(3) in the dark method of definite seam of " survey lack rules " suggestion, to the not in addition requirement of the number that remains the dark data of seam that are used to be averaged and discreteness, therefore two kinds of situations may take place: first kind is that only surplus data, second kind are that the data discrete that is used to be averaged is excessive.The data that have gross error all can not be found and be rejected to both of these case.Obviously, can not reduce test error to data or the excessive data of discreteness that comprise gross error with the method that is averaged.

(4) Mintrop wave phase reversal method requires to observe the variation of Mintrop wave phase place in test process, because in test, it is unforeseen the anti-phase measuring point of Mintrop wave when can occurring, therefore must make on-the-spot test work become very loaded down with trivial details, and the test experience to the tester also requires higher simultaneously.In addition, a large number of experiments show that just occurred when anti-phase at Mintrop wave, first wave amplitude can obviously reduce, the measuring accuracy in the time of at this moment can directly influencing sound as not examining, even may be lost ripple, in case lose ripple, measuring accuracy is obviously descended.Therefore Fig. 4 a, Fig. 4 b, Fig. 4 c are the sample waveform of the anti-phase front and back of Mintrop wave, and what adopt in the above-mentioned test is the amplification system of fixing, the size that the wave-shape amplitude among three width of cloth figure can the reflected signal amplitude.Mintrop wave upwards is waveform before anti-phase in Fig. 4 a, and the Mintrop wave amplitude reaches the full width of cloth above (peak value that is Mintrop wave exceeds screen); Mintrop wave is downward in Fig. 4 b, begins to occur anti-phase, and the Mintrop wave amplitude becomes very little; Mintrop wave is downward in Fig. 4 c, is anti-phase back waveform, and the Mintrop wave amplitude strengthens gradually.

(5) carry out the acoustic wave diffraction method according to " survey and lack rules " at present and detect the penetration of fracture, on-the-spot test work is loaded down with trivial details, and the point position that need draw is measured range finding, generally arranges 4～5 measuring points at least, is worth h deeply thereby obtain a plurality of seams _iTry to achieve the dark m of average seam _h, again according to ratio l _i/ m _kShould be 1～3, to different spacing l _iThe data of gained are screened and are rejected.When needing interpretation record sound in the test, observe wave form varies, and data are screened etc., and the testing tool that uses is general Ultrasound Instrument, the price height also needs to carry out the training of ultrasound wave rudimentary knowledge, testing tool using method and data processing method to the tester.

Summary of the invention

Because the method for the penetration of fracture exists error big in the existing detection solid dielectric, length consuming time, the high and numerous and diverse data of technical requirement are rejected defectives such as step, therefore need searching a kind of more easy, the new method that measuring accuracy is higher.

(select from " Electromagnetic andAccoustic scattering by simple shapes " Edited by J.J.BowmanT.B.A.Senior P.L.E.Uslenghi, Radiation laboratory from document " electromagnetism of simple shape object and acoustic scattering ", The Universityof Michigan, USA, Authors J.S.Asvestas D.l.Sengupta J.J.BowmanT.B.A.Senior etc.) in, can obtain sound wave and produce the diffractional field approximate formula of diffraction (diffraction) around splitting (wedge):

In the formula (referring to Fig. 5):

$v=\frac{2\mathrm{\&pi;}-2\mathrm{\&Omega;}}{\mathrm{\&pi;}},$ 2 Ω are the drift angle of splitting

-angle of diffraction

K=2 π/λ λ is a wavelength

ρ, ρ ₀Be the distance of launching, the acceptance point distance is split the top, angle,

R ₁=ρ ₀+ ρ=2 ρ ₀Be the propagation distance of emission with acceptance point

This approximate formula is applied to diffraction approach detects crack depth of concrete, further considered the decay of sound wave, the directive property of transducer and the multiple frequency characteristic of pulsating wave, derive the acoustic wave diffraction number of fields that is applicable to the crack test and learn approximate expression:

In the formula, Q is the directive property factor

A is a decay factor

∑ is the summation to the single-frequency diffracted wave of forming multiple frequency ripple

It is asked mould (absV ^d) be the amplitude of diffractional field

According to the requirement of penetration of fracture computing formula physical condition, when determining that suitable transducer spacing is suitable angle of diffraction, obviously the scope of diffractional field is the smaller the better, and promptly angle of diffraction is the smaller the better.Because the sound field scope that less angle of diffraction relates to is little, the easier sound ray of avoiding contiguous reinforcing bar or other defect to cause departs from the consistance of the also easier assurance velocity of sound.Can but the small-angle diffraction wave amplitude guarantee measuring accuracy? therefore the key of problem ascribes that need what to go out from the sound diffraction field expression parsing be only angle of diffraction to, makes it to guarantee enough amplitudes, can obtain the little angle of diffraction of trying one's best again.Angle of diffraction

With spacing l _iWith the dark h of seam _iRatio l _i/ h _iBe directly related,

Obviously, l _i/ h _iMore little, angle of diffraction

More little.L for example _i/ h _iBe 0.5 o'clock, angle of diffraction is 14 °; l _i/ h _iBe 1.5 o'clock, angle of diffraction is 37 °; l _i/ h _iBe 2.5 o'clock, angle of diffraction is 51 °.

Figure 6 shows that the amplitude A and the angle of diffraction of Crack Detection sound diffraction field

The example (seam deeply be 10cm, dominant frequency is the multiple frequency ripple of 50kHz) of graph of a relation, transverse axis is an angle of diffraction among the figure, the longitudinal axis is the diffractional field amplitude of correspondence.Amplitude A and angle of diffraction that other seams are dark

Graph of a relation similarly, just the crack is dark more, the pairing angle of diffraction of amplitude peak is more little among the figure, the order of magnitude of longitudinal axis amplitude is more little.

According to sound field amplitude and angle of diffraction graph of a relation and crack test result, can obtain following qualitative conclusion:

(1) diffracted wave can produce in little angle of diffraction, and test shows (spacing l when angle of diffraction is 10 ° _iWith the dark h of seam _iRatio l _i/ h _i=0.35), still can obtain comparatively ideal amplitude.For example, waveform shown in Figure 7, it stitches dark 316mm, transducer spacing 111mm, corresponding l _i/ h _i=0.35, angle of diffraction is 10 °, the interpretation requirement when first wave amplitude is enough to satisfy sound.

(2) for shallow fracture, it is short to propagate sound path, and it is little to decay, and therefore all can obtain stronger amplitude on a large scale in the angle of diffraction, can be for the spacing l of test use _iWith the dark h of seam _iRatio l _i/ h _iScope is bigger, can reach that (for example stitch dark 23mm, the measurement spacing is 120mm, l more than 5 _i/ h _iBe 5.2, the wave-shape amplitude ideal); And for deep crack, propagate sound path to strengthen, amplitude obviously descends, l _i/ h _iTherefore big more, sound path is big more, and amplitude is more little, must test in the pairing angle of diffraction scope than large amplitude, otherwise can't guarantee the amplitude of received signal, the measuring accuracy when influence sound wave and walking, so the crack is dark more, and can be for the l that tests use _i/ h _iRatio range more little.

(3) crack is dark more, and the represented energy distribution of the amplitude curve of sound field amplitude and angle of diffraction graph of a relation is offset to little angle of diffraction direction more, and the little angle of diffraction test of usefulness preferably is described for darker seam.

Under the situation that above-mentioned sound diffraction number of fields scientific principle opinion is supported, the inventor is through a large amount of tests and discovered the method for the penetration of fracture in a kind of new measurement solid dielectric, and this method may further comprise the steps:

Step a: measure the velocity of sound v in the tested solid dielectric;

Step b: first measuring point is measured,

It is the both sides of symmetry that emission and receiving transducer are placed respectively with the crack, and emission is l with the spacing of receiving transducer ₁, read duration t ₁, and calculate the penetration of fracture by following formula:

${\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">h</figure-callout>}}_1=\frac{{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">l</figure-callout>}}_1}{2}\&times;\sqrt{{\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">t</figure-callout>}}_1\&times;v}{l_1}\right)}^2-1},$

Wherein: h ₁Be the penetration of fracture value that first measuring point calculates, l ₁Be the spacing of the first measuring point transducer, t ₁It is the first measuring point acoustic transit time;

Step c: second measuring point is measured,

The spacing of emission and receiving transducer is changed to l ₂, l ₂Scope be: 0.1h ₁≤ l ₂≤ 10h ₁Perhaps 30mm≤l ₂≤ 500mm; All the other conditions are identical with the situation that first measuring point is measured, and read duration t ₂Adopt following formula to calculate the second measuring point penetration of fracture value h ₂

${\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">h</figure-callout>}}_2=\frac{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">l</figure-callout>}}_2}{2}\&times;\sqrt{{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">t</figure-callout>}}_2\&times;v}{l_2}\right)}^2-1}$

Wherein: h ₂Be the penetration of fracture value that second measuring point calculates, l ₂Be the spacing of second measuring point, two transducers, t ₂It is the second measuring point acoustic transit time;

Steps d: calculate h ₁With h ₂Mean value $\stackrel{\&OverBar;}{h}=\frac{1}{2}({\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+h_2),$ H is the penetration of fracture.

Said method other measuring method in compared to existing technology can be a large amount of the minimizing measuring process, to arrange a plurality of measuring points when need not the computing method, calculate a plurality of seams and be worth h deeply as diffraction sound _iMean value m _h, again according to ratio l _i/ m _kScope data are screened and are rejected; It is anti-phase also to need not need to observe Mintrop wave as Mintrop wave phase reversal method.The inventive method only need be got distance values l within the specific limits ₁, calculate the dark h of seam ₁, then with h ₁Get distance values l in the relevant scope ₂, calculate the dark h of seam again ₂, h then ₁With h ₂Mean value be the penetration of fracture, avoided the screening of data and rejected step, it is anti-phase also to need not to observe Mintrop wave.Because this method utilization measuring point seldom just can obtain high-precision measurement result and have bigger measuring point span, and measuring speed is obviously accelerated, cost reduces, and is more conducive to the working-yard and implements to measure.

Further, in above-mentioned steps d, can also continue to calculate discrete Δ=| h ₁-h ₂|, if this discrete value is less than a certain limit value Δ _x, then be the penetration of fracture with h; Otherwise, increase a measuring point again, up to the discrete value of the depth value of this measuring point and other any one measuring point depth values before less than the limit value Δ _x, then with the mean value of two measuring point depth values under this discrete value as the penetration of fracture.

Further, in the described step of leading portion, the limit value Δ of described discrete value _xBe 5mm～150mm or 30% * h.

Further, in the described step of leading portion, the limit value Δ of described discrete value _xFor:

When h＜30mm, Δ _xBe taken as 9mm; When h=30mm, Δ _xGet 9mm or 30% * h; When 30mm＜h＜300mm, Δ _xBe taken as 30% * h; When h=300mm, Δ _xGet 90mm or 30% * h; When h＞300mm, Δ _xBe taken as 90mm.

Further, among the step b, described l ₁Scope be 30mm≤l ₁≤ 500mm.

Further, in the described step of leading portion, described l ₁Scope be 50mm≤l ₁≤ 250mm.

Further, in the described step of leading portion, described l ₁Scope be 80mm≤l ₁≤ 150mm.

Further, in the described step of leading portion, described l ₁Can be 80mm or 100mm or 110mm or 120mm or 130mm.

Further, in step a, the method for the velocity of sound v in the tested solid dielectric of described measurement is in seamless district transmitting transducer and receiving transducer to be fixed in a certain spacing l, t when measuring propagation sound, calculating concrete velocity of sound v=l/t.

Further, in the described step of leading portion, described spacing l is: 50mm～300mm.

Further, in the described step of leading portion, described spacing l is 200mm.

Further, in step c,

Work as h ₁During≤50mm, l ₂Be h ₁0.6～8 times or 30mm≤l ₂≤ 200mm;

Work as h ₁During＞50mm, l ₂Be h ₁0.1～5 times or 50mm≤l ₂≤ 400mm.

Further, in the described step of leading portion, work as h ₁During≤50mm, l ₂=50mm; Work as h ₁During＞50mm, l ₂=150mm.

On the basis of method of testing of the present invention, the invention allows for a kind of penetration of fracture tester, comprise master control system, transmitting transducer, receiving transducer, power module; Described master control system is connected with transmitting transducer by the high pressure transmitter module, and described high pressure transmitter module makes transmitting transducer produce acoustic signals by applying high-voltage pulse; Receiving transducer receives the acoustic signals that receives that conditioning module is amplified, Filtering Processing by signal, be converted to digital signal transfers by analog-to-digital conversion module then and give master control system; Master control system handles and directly calculates the penetration of fracture to the digital signal that receives; Described master control system is undertaken by human-machine interface module and user alternately.

Penetration of fracture tester with said structure can adopt the method among the present invention to measure, and can directly obtain measurement result, promptly just can directly obtain stitching dark value by this instrument at the scene.And needn't in " survey and lack rules ", stipulate, need to use general Ultrasound Instrument to measure, and need artificial on-the-spot interpretation and record to test the parameter (phase change that promptly needs artificial field observation measuring point, find the anti-phase point position of Mintrop wave), do not need the later stage manually to calculate or call analysis software yet and carry out data processing.Penetration of fracture tester among the present invention is compared with general Ultrasound Instrument, and structure is more simple, and equipment cost obviously reduces.Compare with the contrast patent, its structure of penetration of fracture tester of said structure is simpler, can only adopt a pair of transducer that transmits and receives, and can directly obtain stitching dark value, and equipment cost obviously reduces, and operates more easy.Use penetration of fracture tester of the present invention, the tester does not need to understand ultrasound wave rudimentary knowledge, does not need can grasp and use this equipment fast through the complicated testing tool using method and the training of data processing method yet.

Further, the computing formula of the penetration of fracture of described master control system employing is as follows:

$h=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">l</figure-callout>}}{2}\&times;\sqrt{{\left(\frac{t\&times;v}{l}\right)}^2-1},$

Wherein: h is a penetration of fracture value, and l is the spacing of two transducers, and t is an acoustic transit time, and v is the velocity of sound in the tested solid dielectric.

Further, the high pressure exciting circuit in the described high pressure transmitter module is a single high pressure exciting circuit, and what described single high pressure exciting circuit made the transmitting transducer generation is the single pulse acoustic signals.

Further, described signal receives conditioning module and adopts fixed gain amplifier.

Further, described signal reception conditioning module adopts enlargement factor to be higher than 600 times high-gain amplifier.

Further, described signal is accepted conditioning module to adopt enlargement factor is 1000 times high-gain amplifier.

Further, described master control system is made up of master cpu module, Logic control module; The master cpu module is electrically connected respectively with between Logic control module, human-machine interface module, the power management module, is used to realize the scheduling between each functional module; The master cpu module is electrically connected with the high pressure transmitter module by Logic control module; Analog-to-digital conversion module is electrically connected with the master cpu module by Logic control module.

Further, described master control system is by carrying out data transmission between data communication module and the external equipment.

Further, described a kind of penetration of fracture tester also comprises at least one transducer mount, and at least one pair of transmitting transducer and receiving transducer are fixed on the support both sides respectively, and can move along the slide rail on the transducer mount respectively.

Further, on the described transducer mount, along being provided with scale marker on the slide rail direction.

Further, on described transducer mount, be provided with a center sign.

Further, the scale marker on the described transducer mount is made up of paired tag line, the sign both sides, the center that is distributed in of every pair of scale marker line symmetry.

Further, described scale marker line has four pairs, and the distance between the every pair of scale marker is respectively 50mm, 100mm, 150mm, 200mm, and indicates ident value in the relevant position.

Further, described transducer mount is provided with locating device, and this locating device can be fixed on transducer on the slide rail.

Further, described transducer mount is provided with locating device, and this locating device can be fixed on transducer the scale marker place.

Further, described center is designated a poly (methyl methacrylate) plate that indicates the cross groove, is provided with an aperture at cross groove center.

Description of drawings

Fig. 1 utilizes sound wave to stitch the synoptic diagram of dark test.

Fig. 2 is that computing method is stitched the synoptic diagram of dark test when utilizing diffraction sound.

The synoptic diagram of dark test is stitched in the wave phase reversal process headed by Fig. 3 a.

Fig. 3 b is the waveform of T1-R1.

Fig. 3 c is the T2-R2 waveform.

Fig. 4 a is the anti-phase preceding waveform of Mintrop wave.

Fig. 4 b is Mintrop wave waveform when anti-phase for beginning to occur.

Fig. 4 c is the anti-phase back of a Mintrop wave waveform.

Fig. 5 is a sound diffraction field synoptic diagram.

The amplitude A of sound diffraction field and angle of diffraction when Fig. 6 is Crack Detection Graph of a relation.

Oscillogram when Fig. 7 is 10 ° for angle of diffraction.

Fig. 8 adopts method of the present invention to measure the dark process flow diagram of seam for a kind of.

Fig. 9 is a crack of the present invention tester principle schematic

Figure 10 is a crack of the present invention tester structural representation.

Figure 11 a is a single high pressure exciting circuit synoptic diagram of the present invention.

Figure 11 b is the single pulse signal waveform.

Figure 12 is a fixing big gain amplifying circuit synoptic diagram of the present invention.

Figure 13 is a penetration of fracture tester operational flowchart of the present invention.

Figure 14 a is a transducer mount synoptic diagram of the present invention.

Figure 14 b is a transducer mount synoptic diagram of the present invention.

Embodiment

In order to make those skilled in the art can further understand feature of the present invention and technology contents, see also following about detailed description of the present invention and accompanying drawing, accompanying drawing only provide with reference to and explanation, be not to be used for limiting the present invention.

Below in conjunction with accompanying drawing, embodiments of the present invention are described.

Fig. 8 is a kind of embodiment of measuring method of the present invention.Transmitting transducer and receiving transducer are placed on tested solid surface, and the spacing l of two transducers is fixed as 200mm, and t when measuring propagation sound calculates the velocity of sound v=l/t in the tested solid dielectric, carries out according to step as shown in Figure 8 then.

Step 101: the both sides that place the crack that transmitting transducer is symmetrical respectively with accepting transducer, the spacing l of two transducers ₁Be 100mm, measure, according to spacing l ₁, read duration t ₁, obtain penetration of fracture h by following formula ₁:

${\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">h</figure-callout>}}_1=\frac{{\mathrm{<figure-callout\; id="1"\; label="l"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">l</figure-callout>}}_1}{2}\&times;\sqrt{{\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">t</figure-callout>}}_1\&times;v}{l_1}\right)}^2-1}$

If h ₁≤ 50mm turns to step 201, if h ₁＞50mm then turns to step 202;

Step 201: choose another test point, the spacing of two transducers is l ₂=50mm measures, and obtains penetration of fracture h respectively according to following formula ₂And h ₁With h ₂Mean value:

${\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">h</figure-callout>}}_2=\frac{{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">l</figure-callout>}}_2}{2}\&times;\sqrt{{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">t</figure-callout>}}_2\&times;v}{l_2}\right)}^2-1}$ $\stackrel{\&OverBar;}{h}=\frac{1}{2}({\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="A20081011464800221.png"\; state="\{\{state\}\}">h</figure-callout>}}_1+h_2),$

Turn to step 301 then;

Step 202: choose another test point, two transducer spacings are l ₂=150mm tests, and obtains penetration of fracture h respectively according to the formula in the step 201 ₂And h ₁, h ₂Mean value h, turn to step 302 then;

Step 301: calculate the discrete Δ of two test point penetration of fracture values=| h ₁-h ₂|, check discrete whether less than the limit value Δ _xWhen h＜30mm, Δ _xBe taken as 9mm; When h=30mm, Δ _xGet 9mm or 30% * h; When 30mm＜h＜300mm, Δ _xBe taken as 30% * h; When h=300mm, Δ _xGet 90mm or 30% * h; When h＞300mm, Δ _xBe taken as 90mm.If less than described limit value, the h that then calculates is the penetration of fracture; Otherwise turn to step 401.

Step 302:, calculate the discrete value Δ of two test point penetration of fracture values and check that whether the gained discrete value is less than the limit value Δ according to the formula and the span of step 301 _x,, otherwise turn to step 402 if be the penetration of fracture less than mean value h then;

Step 401: select another test point again, two transducer spacings are l ₃, be h ₁0.6～8 times or 30mm≤l ₂≤ 200mm tests, and obtains penetration of fracture h respectively according to following formula ₃Mean value h with any two penetration of fracture values:

$h_3=\frac{l_3}{2}\&times;\sqrt{{\left(\frac{t_3\&times;v}{l_3}\right)}^2-1},$ $\stackrel{\&OverBar;}{h}=\frac{1}{2}(h_i+h_j)$

Wherein, h _i, h _jBe respectively the penetration of fracture of i and j test point, and i ≠ j, turn to step 501 then;

Step 402: select another test point again, spacing is l ₃, be h ₁0.1～5 times or 50mm≤l ₂≤ 400mm tests, and obtains penetration of fracture h respectively according to two formula in the step 401 ₃Mean value h with any two penetration of fracture values turns to step 502 then;

Step 501: calculate the discrete Δ of any two test point penetration of fracture values=| h _i-h _j|, wherein, h _i, h _jBe respectively the penetration of fracture of i and j test point, and i ≠ j.According to the limit value Δ in the step 301 _x, whether each of inspection gained be discrete less than the limit value Δ _x, if less than described limit value, then discrete two penetration of fracture values less than limit value, averaging is the penetration of fracture.Otherwise repeating step 401, less than described limit value, the mean value of getting discrete two penetration of fracture values less than limit value is as the penetration of fracture up to the discrete value that obtains;

Step 502: obtain the discrete value Δ of any two test point penetration of fracture values according to the discrete formula of step 501, according to the limit value Δ in the step 301 _x, check that gained is discrete whether less than the limit value Δ _x, if less than then dispersing less than two penetration of fracture values of limit value, averaging is the penetration of fracture; Otherwise repeating step 402, less than described limit value, the mean value of getting discrete two penetration of fracture values less than limit value is the penetration of fracture up to the discrete value that obtains.

Concrete also above-mentioned steps can be adjusted and change when implementing the inventive method, be with the difference of the embodiment described in Fig. 8: in step 501 (or 502), if calculate the discrete limit value Δ that all is not less than of any two measured values _xThe time, repeating step 401 (or 402) no longer, but reselect a new measuring point, repeat above-mentioned steps 101 again to step 502, less than described limit value, the mean value of getting discrete two penetration of fracture values less than limit value is the penetration of fracture up to the discrete value that obtains.

Also above-mentioned steps can be adjusted and changes when specifically implementing the inventive method, be with the difference of the embodiment described in Fig. 8: behind the completing steps 101, repeating step 401 or 402 repeatedly, do not calculate its mean value, and only according to the formula in the step 501, calculate the discrete value of any two measured values and compare, choose two penetration of fracture values of the discrete value minimum of acquisition, get its mean value again as the penetration of fracture.

Concrete also can adjust and change above-mentioned steps when implementing the inventive method, be with the difference of the embodiment described in Fig. 8: behind the completing steps 101, repeating step 401 or 402 repeatedly be with the penetration of fracture h that repeatedly measures ₁, h ₂, h ₃... average, as the degree of depth in crack.

Concrete also can adjust and change when implementing the inventive method above-mentioned steps, be with the difference of the embodiment described in Fig. 8: behind completing steps 101 and 201 (or 202), can directly adopt the degree of depth of the mean value of the penetration of fracture that draws as the crack.

When enforcement the inventive method was tested the concrete velocity of sound, the test point spacing can be 50mm～300mm.During the test penetration of fracture, in the step 101, the spacing l of test point ₁Can be at 30mm≤l ₁Select in≤500mm the scope, the scope of choosing commonly used is 50mm≤l ₁≤ 250mm or 80mm≤l ₁≤ 150mm; In the step 201, the spacing l of test point ₂Selectable scope is h ₁0.6～8 times or 30mm≤l ₂≤ 200mm.In the step 202, the spacing l of test point ₂Selectable scope is h ₁0.1～5 times or 50mm≤l ₂≤ 400mm.The limit value Δ of described discrete value _xCan be 5mm～150mm or 30% * h.

Fig. 9 is a crack of the present invention tester principle schematic.This test macro is by penetration of fracture tester main frame 1, and transmitting transducer 2 and receiving transducer 3 are formed.Master control system 1 applies high-voltage pulse in transmitting transducer 2 by the high pressure exciting circuit of high pressure transmitter module, produce the acoustic signals of single pulse, enter concrete, the terminal diffraction through the crack, being received transducer 3 receives, the signal that receives instrument signal after tested receives the fixed gain amplification system of conditioning module, amplifies, after the Filtering Processing, is converted to digital signal by modulus (A/D) modular converter.The tester main frame also comprises the synchro control element, realizes synchronously with the output of realization high pressure exciting circuit and the received signal of A/D modular converter.Master control system to the digital signal that receives gather, interpretation, t when obtaining sound wave and walking, the transducer spacing l that determines according to predefined concrete acoustic velocity value v and transducer mount, calculate and show the penetration of fracture by following formula:

$h=\frac{\mathrm{<figure-callout\; id="2"\; label="l"\; filenames="A20081011464800281.png"\; state="\{\{state\}\}">l</figure-callout>}}{2}\&times;\sqrt{{\left(\frac{t\&times;v}{l}\right)}^2-1}$

Described transmitting transducer 2 and receiving transducer 3 can adopt the planar transducer of 50kHz.Because the acoustic signals that adopts is the single pulse signal, and the adjustable gain amplification system changed into the fixed gain amplification system, and significantly reduced synchronous control component in the tester and gain amplifier element, simplified operation steps, reduce technical difficulty, reduced instrument cost.

Figure 10 is a crack of the present invention tester structural representation.Main frame receives conditioning module, modulus (A/D) modular converter, human-machine interface module, data communication module and power management module by master cpu module, Logic control module, high pressure transmitter module, signal and forms.

The master cpu module is the nucleus module of test macro, and embedded intellectual analysis software is realized the scheduling between each functional module, by C language and assembly language hybrid programming, mainly contains that crack test, data are checked, data dump and four program modules of data transmission.Crack test procedure module is carried out analyzing and processing to gathering the signal of returning, and draws the velocity of sound in the tested crack of sign and the degree of depth in crack thereof, and stores.Data check that program module realizes the playback and the paging of depositing test data are browsed.The data dump program module realizes emptying of data space, for test data provides enough storage spaces.The data distributing program function realizes the function of the data upload of test macro to computing machine, to realize long-term data backup.

Logic control module is an important carrier of realizing master cpu module schedules function.By Logic control module, the master cpu module is loaded into transmitting transducer with the high pressure pumping signal, again the digital signal after the received signal A/D conversion is reached CPU for further analyzing and processing simultaneously.In this test macro, Logic control module is realized with CPLD (programmable logic device (PLD)).

The high pressure transmitter module is mainly realized from low-voltage to high-tension conversion, to the excitation of transmitting transducer generation high pressure.The conditioning module that receives signal mainly realize to the signal from receiving transducer amplify, processing such as filtering.Modulus (A/D) modular converter is mainly realized the conversion of simulating signal to digital signal.Human-machine interface module mainly refers to the direct mutual functional module of LCD (LCDs) and keyboard etc. and user.Data communication module is to realize the hardware carrier of test macro institute deposit data to the PC transmission, and described master control system in embodiment, can have two kinds of communication modes of USB and RS232 by carrying out data transmission between data communication module and the external equipment.Power management module partly is made up of power supply, DC-DC power source conversion etc.The conversion and the distribution of realization each functional module required voltage from original power supply to main frame, original power supply can be lithium ion chargeable battery, rechargeable Ni-H 2 battery or general dry battery etc.

Figure 11 a is a single high pressure exciting circuit synoptic diagram of the present invention.In the present embodiment, single high pressure exciting circuit by the appearance value be 0.47 μ F hold C2 every straight-through alternating current, switch triode Q1 BU806, the appearance value is that the storage capacitor C1 of 0.47 μ F forms, realize the conversion of from the low-voltage to the high voltage (more than the 500V) by a voltage doubling rectifing circuit, the single activation pulse is through holding the base stage B of C2 to switch triode Q1 every straight-through alternating current, the control high pressure by the collector C of switch triode Q1 to emitter E, make storage capacitor C1 discharge, transmitting transducer is produced single high pressure excitation pulse signal, and its waveform is shown in Figure 11 b.Figure 12 is a fixing big gain amplifying circuit synoptic diagram of the present invention.Fix big gain amplifying circuit by amplifier OP37, proportion resistor R21 and R22, filtering circuit resistance R 23 and C20 form.The acoustic signals that transmitting transducer produces is the resistance R 23 of 1k Ω through resistance by receiving transducer, the appearance value is the filtering circuit that the capacitor C 20 of 0.022 μ F is formed, filter unwanted signal, again through amplifier OP37, resistance is that the proportion resistor R21 of 1k Ω and proportion resistor R22 that resistance is 1M Ω make input signal amplify 1,000 times, and feeble signal can be simulated/digital quantizer collection identification.

Figure 13 is a penetration of fracture tester operational flowchart of the present invention.After opening tester, to variable-definition and initialization, to the display screen cls, enter sound velocity test then, the laggard crack test pattern of going into is finished in test, selects not, then returning the sound velocity test pattern, is then to carry out the test first time if select, after the test, enter next step test for the first time, select not, then return test for the first time, if select to be, then carry out the test second time, check after finishing whether test result is satisfied with, if discrete value is less than limit value, then select to be, otherwise select not return test pattern again the 2nd time, change the test point spacing, duplicate measurements less than limit value, is derived test result up to measured value gained result's discrete value then.

Figure 14 is a kind of embodiment of transducer mount of the present invention.Transducer mount is made up of transducer 1, transducer cover 2, sound insulating material 3, transducer lid 4, spring 5, slide rail 6, locating device 7, test board 8 and scale marker 9.

Figure 14 a left side is the cut-open view of transducer mount, and transducer mount is made by nonmetallic materials, and even effectively weight reduction when testing winter, does not have ice-cold sensation yet, still has feel preferably.Two transducers 1 place in the two transducers cover 2, and transducer overlaps the mode that cooperates with annular sound insulating material 3 between 2 hoop inwalls and the transducer 1, has prevented that effectively transducer 1 and transducer from overlapping 2 acoustic short circuit.Transducer overlaps the mode that cooperates with spring 5 between 2 top inner wall and transducer 1 top, transducer lid 4 withstands transducer 1 bottom, be fixed on the transducer cover 2 by modes such as screw threads, make transducer 1 and test surfaces under the situation of injustice, still can guarantee good coupling.Two transducers cover 2 is fixed on the support two ends respectively, and can move along the slide rail on the transducer mount 6 respectively.It can guarantee transducer and the good coupling of test surfaces, and can directly fast, accurately test the crack.Right figure is the back view of transducer mount, and slide rail 6 is provided with locating device 7, also can adopt locating device 7 is arranged on transducer cover 2 or the first-class multiple mode of support.

Figure 14 b is the vertical view of transducer mount, the support symmetria bilateralis is printed on four paired scale markers 9 such as 50mm, 100mm, 150mm, 200mm, and be provided with locating device 7 in corresponding scale marker 9 positions, when transducer cover 2 moves to corresponding scale marker, transducer cover 2 can be fixed automatically by locating device 7, makes that to transmit and receive the transducer spacing accurate.An organic glass test board 8 that indicates the cross groove is equipped with in the frame bottom center, and the center is a hole, support can be placed on a certain definite position in tested crack exactly during with the assurance test, the inaccurate error that causes is placed in the position in the time of can avoiding manual ranging line and handheld transducer so effectively, has improved the efficient of measurement and the precision of measured value greatly.Support can be made different length as required, such as 100mm～600mm.In concrete enforcement, if seam deeply below 50mm, can adopt symmetria bilateralis to be printed on the support of four paired scale markers such as 50mm, 100mm, 150mm, 200mm, the total length of support is convenient to operation and is carried about 250mm～300mm.

When using transducer mount, select the spacing of first test point earlier, with two transducers cover, 2 center pits with test board 8 is the centrosymmetric relevant position that places on the slide rail scale marker 9, central aperture crack to be measured, to prop up frame sliding track and compress test surfaces, make the good coupling of transducer and test surfaces, carry out the first time and measure.Carry out the second time or when measuring for the third time, keep a frame sliding track motionless, the position of the change two transducers cover 2 of symmetry, thus change the spacing of second, third or a plurality of measurement points, measure.

Following table is the penetration of fracture tester of the using this patent test findings on the dark distress in concrete model of known seam, and wherein each group test data of each fractured model is an embodiment of the inventive method:

Test findings by last table as can be seen, the measuring error of the inventive method is smaller, relative error is only between-5%～9%.

The inventive method and penetration of fracture tester and transducer mount also can be used for the detection in all kinds of nonmetal solid materials crack, singly are not confined to the detection to the concrete material crack.

Claims (29)

1. penetration of fracture measuring method may further comprise the steps:

Step a: measure the velocity of sound v in the tested solid dielectric;

Step b: first measuring point is measured,

It is the both sides of symmetry that emission and receiving transducer are placed respectively with the crack, and emission is l with the spacing of receiving transducer ₁, read duration t ₁, and calculate the penetration of fracture by following formula:

$h_1=\frac{l_1}{2}\&times;\sqrt{{\left(\frac{t_1\&times;v}{l_1}\right)}^2-1},$

Wherein: h ₁Be the penetration of fracture value that first measuring point calculates, l ₁Be the spacing of first measuring point, two transducers, t ₁It is the first measuring point acoustic transit time;

Step c: second measuring point is measured,

The spacing of emission and receiving transducer is changed to l ₂, l ₂Scope be: 0.1h ₁≤ l ₂≤ 10h ₁Perhaps 30mm≤l ₂≤ 500mm; Read duration t ₂, and by following formula calculating penetration of fracture value h ₂:

$h_2=\frac{l_2}{2}\&times;\sqrt{{\left(\frac{t_2\&times;v}{l_2}\right)}^2-1},$

Wherein: h ₂Be the penetration of fracture value that second measuring point calculates, l ₂Be the spacing of second measuring point, two transducers, t ₂It is the second measuring point acoustic transit time;

Steps d: calculate h ₁With h ₂Mean value $\stackrel{\&OverBar;}{h}=\frac{1}{2}(h_1+h_2),$ H is the penetration of fracture.

2. a kind of method as claimed in claim 1 is characterized in that:

In described steps d, the discrete Δ of further continuation calculating=| h ₁-h ₂|, if this discrete value is less than a certain limit value Δ _x, then be the penetration of fracture with h; Otherwise,

Increase a measuring point again, repeating step b, up to the discrete value of the depth value of this measuring point and other any one measuring point depth values before less than the limit value Δ _x, then with the mean value of two measuring point depth values under this discrete value as the penetration of fracture.

3. a kind of method as claimed in claim 2 is characterized in that: the limit value Δ of described discrete value _xBe 5mm～150mm, or 30% * h.

4. a kind of method as claimed in claim 2 is characterized in that: the limit value Δ of described discrete value _xFor:

When h＜30mm, Δ _xBe taken as 9mm; When h=30mm, Δ _xGet 9mm or 30% * h; When 30mm＜h＜300mm, Δ _xBe taken as 30% * h; When h=300mm, Δ _xGet 90mm or 30% * h; When h＞300mm, Δ _xBe taken as 90mm.

5. a kind of method as claimed in claim 1 is characterized in that: described l ₁Scope be 30mm≤l ₁≤ 500mm.

6. a kind of method as claimed in claim 5 is characterized in that: described l ₁Scope be 50mm≤l ₁≤ 250mm.

7. a kind of method as claimed in claim 6 is characterized in that: described l ₁Scope be 80mm≤l ₁≤ 150mm.

8. a kind of method as claimed in claim 7 is characterized in that: described l ₁Be 80mm or 100mm or 110mm or 120mm or 130mm.

9. a kind of method as claimed in claim 1, it is characterized in that: the method for measuring the velocity of sound v in the tested solid dielectric in step a is, in seamless district transmitting transducer and receiving transducer are fixed in a certain spacing l, t when measuring propagation sound calculates concrete velocity of sound v=l/t.

10. a kind of method as claimed in claim 9 is characterized in that: described spacing l is: 50mm～300mm.

11. a kind of method as claimed in claim 10 is characterized in that: described spacing l is 200mm.

12. a kind of method as claimed in claim 1 is characterized in that:

Work as h ₁During≤50mm, l ₂Be h ₁0.6～8 times or 30mm≤l ₂≤ 200mm;

Work as h ₁During＞50mm, l ₂Be h ₁0.1～5 times or 50mm≤l ₂≤ 400mm.

13. a kind of method as claimed in claim 12 is characterized in that: work as h ₁During≤50mm, l ₂=50mm; Work as h ₁During＞50mm, l ₂=150mm.

14. a penetration of fracture tester comprises master control system, transmitting transducer, receiving transducer, power module, it is characterized in that:

Described master control system is connected with transmitting transducer by the high pressure transmitter module, and described high pressure transmitter module makes transmitting transducer produce acoustic signals by applying high-voltage pulse;

Receiving transducer receives the acoustic signals that receives that conditioning module is amplified, Filtering Processing by signal, be converted to digital signal transfers by analog-to-digital conversion module then and give master control system;

Master control system is handled the digital signal that receives, and directly calculates the penetration of fracture;

Described master control system is undertaken by human-machine interface module and user alternately.

15. a kind of penetration of fracture tester as claimed in claim 14 is characterized in that: the computing formula of the penetration of fracture that described master control system adopts is as follows:

$h=\frac{l}{2}\&times;\sqrt{{\left(\frac{t\&times;v}{l}\right)}^2-1},$

Wherein: h is a penetration of fracture value, and l is the spacing of two transducers, and t is an acoustic transit time, and v is the velocity of sound in the tested solid dielectric.

16. a kind of penetration of fracture tester as claimed in claim 14, it is characterized in that: the high pressure exciting circuit in the described high pressure transmitter module is a single high pressure exciting circuit, and what described single high pressure exciting circuit made the transmitting transducer generation is the single pulse acoustic signals.

17. a kind of penetration of fracture tester as claimed in claim 14 is characterized in that: described signal receives conditioning module and adopts fixed gain amplifier.

18. a kind of penetration of fracture tester as claimed in claim 17 is characterized in that: described signal receives conditioning module and adopts enlargement factor to be higher than 600 times high-gain amplifier.

19. a kind of penetration of fracture tester as claimed in claim 18 is characterized in that: described signal is accepted conditioning module, and to adopt enlargement factor be 1000 times high-gain amplifier.

20. a kind of penetration of fracture tester as claimed in claim 14, it is characterized in that: described master control system is made up of master cpu module, Logic control module; The master cpu module is electrically connected respectively with between Logic control module, human-machine interface module, the power management module, is used to realize the scheduling between each functional module; The master cpu module is electrically connected with the high pressure transmitter module by Logic control module; Analog-to-digital conversion module is electrically connected with the master cpu module by Logic control module.

21. a kind of penetration of fracture tester as claimed in claim 14 is characterized in that: described master control system is by carrying out data transmission between data communication module and the external equipment.

22. a kind of penetration of fracture tester as claimed in claim 14, it is characterized in that: also comprise at least one transducer mount, at least one pair of transmitting transducer and receiving transducer are fixed on the support both sides respectively, and can move along the slide rail on the transducer mount respectively.

23. a kind of penetration of fracture tester as claimed in claim 22 is characterized in that: on the described transducer mount, along being provided with scale marker on the slide rail direction.

24. a kind of penetration of fracture tester as claimed in claim 22 is characterized in that: on described transducer mount, be provided with a center sign.

25. a kind of penetration of fracture tester as claimed in claim 23, it is characterized in that: the scale marker on the described transducer mount is made up of paired tag line, the sign both sides, the center that is distributed in of every pair of scale marker line symmetry.

26. a kind of penetration of fracture tester as claimed in claim 25 is characterized in that: described scale marker line has four pairs, the distance between the every pair of scale marker is respectively 50mm, 100mm, 150mm, 200mm, and indicates ident value in the relevant position.

27. a kind of penetration of fracture tester as claimed in claim 22, it is characterized in that: described transducer mount is provided with locating device, and this locating device can be fixed on transducer on the slide rail.

28. a kind of penetration of fracture tester as claimed in claim 22, it is characterized in that: described transducer mount is provided with locating device, and this locating device can be fixed on transducer the scale marker place.

29. a kind of penetration of fracture tester as claimed in claim 24 is characterized in that: described center is designated a poly (methyl methacrylate) plate that indicates the cross groove, is provided with an aperture at cross groove center.

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