CN206787474U - A kind of bending-type strains enlarger - Google Patents

Abstract

The utility model discloses a kind of bending-type to strain enlarger, including rigid rod, one end of rigid rod is fixedly connected with one end of spring beam, application method is that 2 points of bending-type strain enlarger are fixed on testee to be arranged on rigid rod as fixing point, wherein at least one fixing point；The spring beam being fixedly connected with rigid rod is connected with strain gauge means.The utility model mechanism is simple, easy to make, light and handy easy-to-use, after sticking on foil gauge, the mechanism can be fixed on into the various body surfaces for needing to measure small strain along should changing direction for measured object, install simple and fast, fixed, use is very flexible.Relative error caused by ambient noise is constant compared with directly using foil gauge to measure when the mechanism measures, but the ratio of systematic error relative measurement reduces, and reduces the relative error of measurement, further improves precision.

Description

A kind of bending-type strains enlarger

Technical field

The utility model belongs to engineering measurement field, sensor field, be specially it is a kind of by linear become strain value press than Example is enlarged into Bending Deformation strain value and makes signal to noise ratio constant, but the bending-type strain enlarger that systematic error reduces.

Background technology

Abbreviation and Key Term definition：

(1) (Bending Strain Amplification Mechanism, can be abbreviated as bending-type strain enlarger BSAM)。

(2) relative error (relative error)：Relative error refers to measuring caused absolute error with being tested Measure the ratio between (agreement) true value.The numerical value of 100% gained is multiplied by, is expressed as a percentage.In general, relative error can more reflect survey The credibility of amount.Relative error is equal to the poor absolute value divided by true value that measured value subtracts true value, multiplied by with 100 percent.

(3) systematic error (system error, abbreviation SE)：Systematic error is under certain measuring condition, to same When individual measured size be repeated several times measurement, the size and symbol of error amount keep constant；Or when condition changes, by one The error of set pattern rule change.Systematic error be with it is some fixed during analysis the reason for caused a kind of error, it have weight Renaturation, one-way, measurability.The characteristics of systematic error is that measurement result deviates to a direction, and its numerical value becomes according to certain rules Change.

(4) (strain) is strained：Object can produce certain deformation in the case where being acted on by external force, and the degree of deformation claims should Become.Strain has normal strain (line strain), shear strain (angular strain) and body strain.Mentioned herein is normal strain, i.e. unit length Elongation, represented with ε, calculation formula isδ=L_b-L₀, L in formula₀It is the length before deformation of body, L_bIt is deformation of body Length afterwards, δ are the elongations after deformation, and ε units are that 1, AD directions generation strain size is ε₀, D point measuring points (are placed on high order end Or low order end) produce strain size be ε₁。

(5) δ is the elongation after deformation, referring to (4), the same long measure of unit.

(6) derive in example schematic：L₁:A, D distance；L₂：BC beam lengths；2y is BC beam widths；Block arrow represents quilt Survey in deformation of body direction (measuring point A, D line direction).

(7) k is the strain amplification coefficient that this bending-type strains enlarger, represents that mechanism measuring strain value is relatively actual The multiplication factor of strain value size, unit 1, θ occur for structure measuring point：It is by what rigid rod and spring beam connected mode determined Number, is fixedly connected as 24, and freely-supported is connected as 12, and demarcation θ is determined by experiment between 12~24 in remaining connected mode, and then It is determined that strain amplification coefficient k.

In engineering measurement field, it is necessary to measure the power and torque of all directions, and conventional method measures bullet by foil gauge Property beam tension and compression, it is curved recessed and reverse three kinds of modes of texturing under strain value, to obtain required stress data.But work as mechanism rigidity Strain very little very big, that mechanism occurs, if foil gauge is pasted directly on mechanism measuring point carrys out measuring strain size, due to existing The sensitivity of foil gauge is inadequate, and the measured value degree of accuracy can be caused not high.And this problem can be solved by straining enlarger, the mechanism Principle refers under conditions of test specimen strain is not influenceed, and makes a part (generally elastomer) machinery should by displacement transfer Become with certain proportion amplification test specimen strain, so as to meet the sensitivity requirement of foil gauge.

It is tired that the application field of strain amplification includes weighing sensor, mechanical mechanism deformation monitoring, various heavy construction mechanisms Labor damage monitoring.When measure using strain amplifying technique engineering mechanism surface strain, strain enlarger need to meet it is large-scale Engineering mechanism has long-life, the engineering characteristic of low stress strain.

Existing strain enlarger mainly includes middle shrinkage variable cross-section enlarger, enlarger, groove are concentrated in displacement Shape enlarger, arch strain enlarger, simple component strain enlarger.Middle shrinkage variable cross-section enlarger makes the section Strain is produced at diminution to concentrate and play strain amplification；It is big rigid metal piece that strain enlarger both ends are concentrated in displacement, Centre is soft stuffing material, and packing material is fatigue design emphasis, and its both ends is pasted onto on metal；Flute profile deformation element strains Enlarger, center section corrosion processing are applied in above groove into mechanism groove, foil gauge；Simple component strains enlarger Surrounding is the very big beam of rigidity, and centre sets elastic strain beam to amplify the strain of assigned direction measuring point on framework.

Variable cross-section multiplier mechanism rigidity is excessive, and amplification coefficient is small, and fatigue rupture easily occurs；Enlarger is concentrated in displacement Mechanism it is complicated, reliability and globality poor, manufacturing process are difficult to control, fragile；Flute profile deformation element strains enlarger Multiplication factor and life-span by groove quantity number influenceed with factors such as dimensioned precision, the stress concentrations being connected out, amplify The scope of multiple is only 2-10 times, and difficulty of processing is big, and cost is high, and structure easily produces fatigue rupture in itself；Simple component strain is put Great institutions are overall heavy, and installation makes inconvenience, limits its use range, because around vertical perturbed force is numerous, it is by noise Influence is very big, can increase the systematic error of measured value.

In summary it is excessively complicated to there is mechanism in existing strain enlarger, and can be increased system by ambient noise interference misses Difference, fatiguability destroy, and cause erection support difficult, and the strain value of measurement is inaccurate, and measurement sensitivity reduces, and measurement apparatus uses The shortcomings of short life.When measuring the small strain of heavy construction structure, the measured value and circumstance of temperature difference of existing mechanism amplification should Variate is an order of magnitude, causes relative error excessive, and existing strain measurement by magnification device is difficult to meet that heavy construction structure is grown Life-span, the engineering characteristic of low stress strain are, it is necessary to redesign new measuring mechanism form.

Utility model content

To solve the above problems, the utility model provides a kind of bending-type strain enlarger, the utility model mechanism Simply, it is easy to make, it is light and handy easy-to-use, after sticking on foil gauge, the mechanism can be fixed on along should changing direction for measured object The various body surfaces for needing to measure small strain, install simple and fast, fixed, use is very flexible.The mechanism Relative error caused by ambient noise is constant compared with directly using foil gauge to measure during measurement, but systematic error relative measurement Ratio reduce, reduce the relative error of measurement, further improve precision.This patent also passes through the change of means of structural connection Improve the fatigue life of measurement apparatus.This patent can measure the small strain of heavy construction structure, because the system of measurement is missed Subtractive is small, ensures good measurement sensitivity, improves the accuracy of measured value, has very high engineering application value.

To reach above-mentioned technique effect, the technical solution of the utility model is：

A kind of bending-type strains enlarger, including rigid rod, one end of rigid rod are fixedly connected with one end of spring beam.

Further to improve, the rigid rod is two, and the both ends of one end of two rigid rods respectively with spring beam are fixed.

Further to improve, the rigid rod is two, and one end of two rigid rods interfixes, the other end respectively with bullet The both ends of property beam are fixedly connected to form triangle, and mounting hole is formed with the middle part of spring beam.

Further to improve, the ratio between the length of the spring beam and width are.

Further to improve, the rigid rod and spring beam are bolted mechanism and are connected.

Further to improve, the rigid rod and spring beam are welded and fixed.

Further to improve, the rigid rod is steel pole.

Further to improve, the spring beam is aluminium bar.

The utility model has the following advantages that:

(1) existing strain enlarger is contrasted, bending-type strain enlarger device is simple, easy to make, light and handy easy With, can along measured object should change direction by the mechanism be fixed on it is various need measure small strain body surfaces.By In simple in construction, component, convenient maintenance are conveniently replaceable；If bearing circulating pressure requirement, component can be connected by screw bolts, and be reduced Stress concentration, increase the fatigue life of measuring mechanism.

(2) bending-type strain enlarger can directly be surveyed actual strain value measurement by magnification relative to using foil gauge Amount and existing strain enlarger, relative error caused by mechanism ambient noise is constant, but systematic error reduces, further Improve measurement accuracy.

(3) this patent can measure the small strain of heavy construction structure, can also apply weighing measurement, medical measurement, machine Tool structure measurement etc..Existing strain enlarger is contrasted, because mechanism systematic error reduces, ensures measurement spirit well Sensitivity, improve the accuracy of measured value.This patent has great engineering application value, has potentially in other many fields Application value.

Brief description of the drawings

Fig. 1 is that the bending-type of embodiment 1 strains enlarger schematic diagram；

Fig. 2 is that the bending-type of embodiment 2 strains enlarger schematic diagram；

The bending-type strain enlarger schematic diagram of Fig. 3 embodiments 3；

Fig. 4 is that rigid rod and spring beam are bolted the structural representation that mechanism is connected；

Fig. 5 is the structural representation of experimental calibration device.

This patent scope of authority is not limited to embodiment 1-3 three kinds of schemes.

In figure：1st, 2- rigid rods, 3- spring beams strain measuring point on 4-BC beams, 5- mounting holes, 6- fixing points, and 7- bolts connect Connection mechanism；A, D, A1, E1, A2, D2 are the point position being fixed in mechanism；B, C, B1, C1, B2 are that spring beam connects with rigid rod Contact, the modes such as welding, bolt connection can be used；D1 is B1C1 midpoints；C2 is B2D2 midpoints；Straining the position of measuring point 4 can basis Need to choose, be not limited in spring beam midpoint and edge, block arrow represents testee deformation direction with the line of measuring point Direction expression, L₁:A, D distance；L₂：Elastic beam length is the length of BC beams, the length of B1C1 beams；L₃:The length of rigid rod 1,2 Degree；L₅:A2, D2 distance.

Embodiment

Illustrated below by way of embodiment and with reference to accompanying drawing to the technical solution of the utility model.

Embodiment 1

A kind of bending-type strain enlarger as shown in Figure 1, including rigid rod 1, one end of rigid rod 1 are fixedly connected with One end of spring beam 3.

In use, the other end of rigid rod and spring beam 3 is separately fixed at the diverse location of article to be measured, on spring beam 3 Strain gauge means such as strain gauge etc. is installed.Article to be measured is stressed when deforming upon, and rigid rod 1 is fixed on spring beam 3 and treated The two fixing points 6 surveyed on article are that the distance between 2 points of A2, D2 changes.Because rigid rod 1 does not deform upon, and two Individual fixing point 6 and rigid rod 1 constitute stable triangle with the junction of spring beam 3, then A2, D2 change causes spring beam 3 bend.Arrow in Fig. 1 represents the Impact direction of article to be measured, namely its deformation direction.

Because the length of spring beam 3 is much smaller than testee, therefore the strain of testee is amplified by spring beam 3, so as to Easily and more accurately measured by strain gauge.The amplification system for data divided by bending-type the strain enlarger that strain gauge measures Number, that is, obtain the strain size of testee.

And the length of the distance due to 2 points of A2, D2, rigid rod 1 and spring beam 3 is measurable, rigid rod 1 and spring beam 3 Between θ values can by experiment measure, therefore can by be calculated bending-type strain enlarger amplification coefficient k.

The amplification coefficient k of bending-type strain enlarger can also be surveyed to obtain by experimental calibration method.

Strain amplification coefficient in embodiment 1 is derived：

As shown in figure 1, B2D2 is spring beam, its width is 2y, and E is the modulus of elasticity of B2D2 beams, and I is beam the moment of inertia, B2D2 beams bending rigidity is E and I product, is designated as EI.A2B2 is rigid rod；

By A2, D2,2 points are fixed on mechanism to be measured, are ε when in A2D2 directions size occurs for mechanism₀Strain when, D2 points will It is δ=ε that size, which occurs, with respect to A2 points₀L₅Deformation, A2B2 is rigid rod, is not deformed, i.e. B2 points do not become relative to A2 Shape, by symmetry, it is δ that with respect to D2 points along A2D2 directions size, which will occur, for C2 points₂=ε₀L₅/ 2 deformation.

For clamped beam B2D2, B2D2 is divided into two unit Bs 2C2 and D2C2, is easy to get the curved of C2 points using displacement method Square M is：

Then C2 points, which strain, is：

Similarly it is easy to get, if B2D2 is simply supported beam,

Noteθ is that θ is 12 when 6, B2D2 is clamped beam when B2D2 is simply supported beam, and θ is 6~12 for remaining situation Between, then ε₁=k ε₀.Then pass through reasonable selection L₅,L₂, y value, the reading strain that can be amplified.

Example：

To meet beam theory, takeI.e. span-depth radio is 3.It can obtain

Take L₅=20cm, L₂=3cm, y=5mm, θ can obtain k=6.67-13.33 between 6~12, and the amplification coefficient is also It is bigger.

Embodiment 2

As shown in Fig. 2 on the basis of embodiment 1, the rigid rod 1,2 is two, one end point of two rigid rods 1,2 Both ends not with spring beam 3 are fixedly connected；The other end of two rigid rods is separately fixed at the different parts of testee such as；Should Become measurement apparatus and be arranged on the middle part of spring beam 3.Work as A1, when being strained between E1, be amplified on spring beam 3, then answered Change measures, and is the strain size that can obtain testee according to the amplification coefficient k of strain enlarger afterwards.

Strain amplification coefficient in embodiment 2 is derived：

As shown in Fig. 2 B1C1 is spring beam, its width is 2y, and E is the modulus of elasticity of B1C1 beams, and I is beam the moment of inertia, B1C1 beams bending rigidity is E and I product, is designated as EI.E1B1 and A1C1 is rigid rod, and bending rigidity is designated as E₁I₁；

By A1, E1,2 points are fixed on mechanism to be measured, are ε when in A1E1 directions size occurs for mechanism₀Strain when, E1 points will It is δ=ε that size, which occurs, with respect to A1 points₀L₂Deformation.

For clamped beam E1B1, know that relative to E1A1 midpoints δ occurs for E1 by structural symmetry₂=ε₀L₂/ 2 deformation, utilize The be easy to get moment M of B1 points of displacement method is：

Structural mechanics knowledge：The moment M of D1 points₁=M.

Then D1 points, which strain, is：

NoteThen ε₁=k ε₀.Then pass through reasonable selection L₂,L₃, y,Value, can be amplified Reading strain.

Example：

To meet beam theory, takeI.e. span-depth radio is 3.

Take L₃=10cm, L₂=3cm, y=5mm,It can obtain

K=18 can be obtained, the amplification coefficient or bigger.

Embodiment 3

As shown in figure 3, both ends of the one end of two rigid rods respectively with spring beam 3 are fixedly connected；Two rigid rods it is another One end interfixes；A points and D points are fixed on testee.Mounting hole 5 is provided with spring beam 3；Two rigid rods it is mutual D points are fixed on testee at bearing A points and mounting hole 5；Strain gauge means are arranged on the middle part of spring beam 3.

The principle of this patent is told about as example：

As shown in figure 3, AB, AC are rigid rod；BC is that spring beam is referred to as BC beams, and its width is 2y, and E is the springform of BC beams Amount, I are BC beam the moment of inertias, and BC beams bending rigidity is E and I product, is designated as EI.

By A, D, 2 points are fixed on mechanism to be measured, are ε when in AD directions size occurs for mechanism₀Strain^[1]When, D points are by phase It is δ=ε that size, which occurs, to A points₀L₁Deformation^[2]。

For clamped beam BC, BC is divided into two unit Bs D and DC, is using the be easy to get moment M of D points of displacement method：

Then D points, which strain, is：

Similarly it is easy to get, if BC is simply supported beam,

Noteθ is shown in annotation 7, then ε₁=k ε₀.Then pass through reasonable selection L₁,L₁, y value, can obtain The reading strain of amplification.

Example：

To meet beam theory, takeI.e. span-depth radio is 3.It can obtain

Take L₁=10cm, L₂=3cm, y=5mm, θ can obtain k=6.67~13.33 between 12~24, the amplification coefficient Still it is more considerable.

As described above, the utility model discloses a kind of bending-type to strain enlarger, the mechanism includes two rigid rods AB and AC, and a spring beam BC, derived from above-mentioned theory, A, D point are fixed in mechanism to be measured, D points can be converted into Strain, i.e., former strain is multiplied by an amplification coefficient.

In the present embodiment, because of D points by borehole to be fixed in the measurement point of structure so that spring beam is uneven, this Coefficient k is caused to be directly obtained by theory deduction, but the value can survey to obtain in laboratory by experimental calibration method, it is real Standard inspection determines schematic diagram and sees Fig. 5, and loading force F on beam is withstood on hydraulic jack, pastes foil gauge at strain measuring point 5 and measures reality Strain, specific scaling method method are：First, work as F=0, that is, when being not loaded with, as the control group of measure ambient noise, measure 5 The strain value ε of point₀；2nd, foil gauge is pasted at 5 again, F is not equal to 0, multistage loadings F, sequential reads out 4 points of strain value ε₁And Record；3rd, laid at 5 and fix strain enlarger, strained and paste foil gauge on enlarger measuring point, with two Loading force F, sequential read out the strain value ε on strain enlarger measuring point 4₂And record；To corresponding to loading force F phases in two and three Same strain value substitutes into following formula and calculates amplification coefficient K successively, and draws differently strained corresponding K value curves, finds out linear change Scope is as effective strain amplification range.

If AD extensional rigidity is too big may to influence mechanism mechanical behavior, but need not worry for large corporation, and optional BC bars are made with softer material.In the present embodiment, described rigid rod, spring beam use different materials, as AB, AC can So that aluminium can be used using Steel material, spring beam.Rigid rod AB, AC can be made to reduce deformation as far as possible, spring beam BC is obtained reality Test conceivable deformation effects.Meet that beam of the span-depth radio more than 3 is non-deep beam, but deep beam can also use this mechanism, and will obtain Bigger multiplication factor.

The connection of 4 foil gauges of full-bridge should be selected.Air China's electrical measurement has 0.02 grade of high-precision foil gauge and welded type strain Piece, the latter, which is used for hardware, should be more convenient and stably.Can certainly with bolt mechanism substitute welding come simplify assembling and Maintenance, such as accompanying drawing 4

If connecting rigid rod and spring beam with bolt arrangement, because bolt connection is slightly better than the turning power being welded to connect, By structural mechanics knowledge, junction is transmitted moment of flexure ability and reduced, and the moment of flexure of measurement point can reduce among spring beam, and foil gauge is surveyed Value can also reduce, i.e., multiplication factor reduces.But bolt arrangement connection can avoid welded weld defect and stress collection In, the fatigue life of measuring mechanism will improve, suitable for situation about being had higher requirements under circulation to measuring mechanism fatigue life, It can be needed to choose different connected modes according to Practical Project measurement.

In the present embodiment, wherein rigid rod and spring beam are the integrated model being fixed together, and rigid rod is tried one's best not Deform upon, for rigid rod along answering nyctitropic deformation to be reacted by the deformation of spring beam, the strain amplification that spring beam occurs is anti- The strain of object being measured is answered, is needing this bending strain enlarger of the object exterior pasting of measurement small strain, and should Become the side that meter is affixed on same position, carry out contrast test, test result indicates that, gathered using bending-type strain enlarger Data precision is apparently higher than the data precision for directly pasting strain gauge, and sensitivity is also higher.

In summary, bending-type strain enlarger has the advantages that simple mechanism, high sensitivity, precision are high, can be wide It is general to be used for the fields such as small strain measurement.Most important significance is in the presence of multiplication factor, and versus environmental noise is constant, but relatively System noise reduces.

Bibliography：

[1] Hu Mingmin, Zhang Ming, Luo Yanli, Lee instruct great waves Design of fatigue gauge for bridge monitoring [J] sensors and micro- system System, 2007, (04):64-66+69.

[2]Ueda,Jun；Secord,Thomas W.；Asada,H.Harry.Large effective-strain piezoelectric actuators using nested cellular architecture with exponential strain amplification mechanisms [J].IEEE/ASME Transactions on Mechatronics,v 15,n 5,p770-782,October 2010.

[3]S.C.Cowin,S.Weinbaum,,Yu Zeng.A case for bone canaliculi as the anatomical site of strain generated potentials[J].Journal of Biomechanics, Volume 28,Issue 11,November 1995,Pages1281–1297.

It the above is only the representative embodiment in the numerous concrete application scopes of the utility model, to protection of the present utility model Scope is not limited in any way, and bending-type strain enlarger proposes a kind of machine for straight line deformation being changed into Bending Deformation Structure, tested small strain amount is amplified by the change of mechanical mechanism, for from different materials, size, shape Or the limitation such as form, welding or bolt mechanism, all technical schemes formed using conversion or equivalence replacement, protected in right Within the scope of shield.

Above are only one of the present utility model it is specific be oriented to embodiment, but design concept of the present utility model not office It is limited to this, all changes for carrying out unsubstantiality to the utility model using this design, all should belongs to and invade guarantor of the present utility model Protect the behavior of scope.

Claims (8)

1. a kind of bending-type strains enlarger, it is characterised in that including rigid rod, one end of rigid rod is fixedly connected flexible One end of beam (3).

2. bending-type as claimed in claim 1 strains enlarger, it is characterised in that the rigid rod is two, and two just Both ends of the one end of property bar respectively with spring beam (3) are fixed.

3. bending-type as claimed in claim 2 strains enlarger, it is characterised in that the rigid rod is two, and two just One end of property bar interfixes, and the other end is fixedly connected to form triangle with the both ends of spring beam (3) respectively, spring beam (3) Middle part is formed with mounting hole (5).

4. bending-type as claimed in claim 1 strains enlarger, it is characterised in that the length of the spring beam (3) and width The ratio between degree is 3.

5. the bending-type strain enlarger as described in claim 1-4 is any, it is characterised in that the rigid rod and spring beam (3) mechanism (7) is bolted to be connected.

6. the bending-type strain enlarger as described in claim 1-4 is any, it is characterised in that the rigid rod and spring beam (3) it is welded and fixed.

7. bending-type as claimed in claim 1 strains enlarger, it is characterised in that the rigid rod is steel pole.

8. bending-type as claimed in claim 1 strains enlarger, it is characterised in that the spring beam (3) is aluminium bar.