CN205879104U - High resolution strain testing device - Google Patents

Abstract

The utility model discloses a high resolution strain testing device mainly comprises base, induction rod, transmission pole and resistance strain gauges. The connection combination that the device adopted two kinds of parts of different stiffness ratios and length ratio necessarily to construct will the interior deformation of effective distance be concentrated to a certain parts on through the mechanics principle, plays the effect that the enlarged bridge of machinery is met an emergency. Use the utility model discloses with corresponding test method, combine the inventor to meet an emergency through the high accuracy based on part parameter stiffness ratio, length ratio of mechanics of materials and the derivation of structural mechanics method and find the solution the formula to realize higher testing accuracy, it is higher even to reach 0.01 mu epsilon, can extensively be applicable to bridge load test, health monitoring and move technical field such as dynamic load based on dynamic strain discernment.

Description

High-resolution strain detection testing device

Technical field

This utility model belongs to strain testing method, particularly relates to a kind of high-resolution strain detection testing device.

Background technology

In current civil engineering industry, strain measurement is widely used in the knots such as building, railway, bridge, traffic, dam On structure.The stress-strain test of structure is that engineering staff understands structural stress state, ensures structural safety and carry out structure and set The important link that meter optimizes.Such as at work progress and the Long Period Health Monitoring of operation process of Longspan Bridge In, the ess-strain in crucial cross section is monitored, for bridge construction, operate, offer foundation be provided, it is ensured that structural safety is One requisite link of bridge construction.

Common strain testing method has fiber grating method, vibrating string type strain method of testing, extensometer or digital display dial gauge Method, resistance-type stain measuring technology etc..It is big etc. that fiber grating method has electromagnetism interference, preferable insulating properties, transmission capacity Advantage, shortcoming is that sensor processing technique is complicated, relatively costly, and required ancillary equipment is more, apparatus expensive, safeguards Replacement procedure Complicated, relatively costly, limit large-scale promotion and application；Vibrating string type strain method of testing directly exports the natural frequency of vibration of vibratory string Signal, reflects the strain size of tested component by the change of frequency, although vibrating string type strain test has capacity of resisting disturbance By force, the feature such as zero drift is little, temperature influence is little, long-time stability are good, at present for relatively in civil engineering strain testing For extensively, but only it is suitable for static strain testing, is not suitable for dynamic strain test；Draw secondary meter or digital display dial gauge method is long by gauge length Degree and the restriction installed, use fewer in Experiments of Machanics；The sensing used of resistance-type stain measuring technology is also called resistance should Become meter, be called for short foil gauge or resistor disc, utilize resistor disc that non electrical quantity is converted to electricity, then be amplified through electronic machine, show Show and record, so higher amplification can be obtained, thus reach higher sensitivity, have be easily achieved digitized, from Dynamicization, with low cost, operating technology is required the advantage such as relatively low, be the strain testing method being most widely used at present, carry out Long term monitoring it is applicable to after encapsulation process.

Owing to dynamic under Vehicle Load of bridge should be less, general three axle load automobiles cause about 10 Bridge moving strains, and the dynamic strain that station wagon causes is less；External environmental interference, as variations in temperature, wind etc. can draw 1-2 bridge The fluctuation of dynamic strain；But, current resistor straining testing precision is universal 1 strain, and this is by current circuit amplification system Technical merit determines, because of wiring technique and the difference of instrument hardware quality, circuit amplification system the most often can cause 0-2 strain Noise signal；In this context, to precisely test bridge moving strain, overcome environment and instrument system noise to become the most tired Difficult.

Utility model content

The technical problems to be solved in the utility model is to provide a kind of high-resolution strain detection testing device, and this device can realize Higher test accuracy, is widely used in Test on Bridge Loading, health monitoring and based on skills such as dynamic strain identification traveling loads Art field.

For solve above-mentioned technical problem, this utility model by the following technical solutions: high-resolution strain testing method, Bridge member surface parallel strain direction steel planting or 2 bases that welding center distance is L, penetrate base by transmission lever Top perforate, and use nut transmission lever to be tightened in the both sides of base top perforate；It is the sensing of l in two ends perforate centre-to-centre spacing Difference adhering resistance formula foil gauge at bar lateral symmetry, and use protective material to be answered with being pasted with resistance-type by resistance strain plate Become the induction rod portion envelops protection of sheet；Abutting end two transmission levers uses bolt induction rod and transmission lever to be connected and tightens Fixing；Resistance strain plate accesses strain acquirement cabinet according to double foil gauge connections, adjusts nut and makes base, transmission lever and sensing The abundant stress of bar, the actual measurement strain reading induction rod is ε '；By formulaCalculate and obtain bridge structure The strain to be measured of part surface is ε；Wherein, to be respectively the area of section of transmission lever, elasticity modulus of materials, axial deformation firm for S, E, SE Degree；S, e, se are respectively the area of section of induction rod, elasticity modulus of materials, axial deformation rigidity；L is the perforate of induction rod both ends Centre distance, L is base center distance.

After induction rod adhering resistance formula foil gauge, put into the drying baker that temperature is 120 DEG C-150 DEG C and be no less than 3 hours, take Protective material parcel protection is used immediately after going out.

Induction rod and the axial rigidity ratio of transmission leverλ is less than 0.01；The centre-to-centre spacing of induction rod both ends perforate From l and base center distance L ratioβ is less than 0.1；Formula isDefinitionξ is and transmission lever and the material of induction rod, size, the relevant feature of cut-in method of foil gauge Coefficient, λ and β that the material chosen and size thereof draw, make ξ be less than 0.1.

High-resolution strain detection testing device, is mainly made up of base, induction rod, transmission lever and resistance strain plate；At the bottom of 2 The center distance of seat is L, and the top perforate of each base is also respectively interposed a transmission lever, uses in perforate both sides that nut is fixing to be passed Pass bar；Being provided with perforate centre-to-centre spacing in two ends between two transmission lever adjacent both ends is that the induction rod of l, transmission lever and induction rod pass through spiral shell Bolt is fixed；Difference adhering resistance formula foil gauge at induction rod lateral symmetry, resistance strain plate is according to double foil gauge connections and answers Become and gather cabinet and connect, resistance strain plate and post the induction rod part of resistance strain plate by protective material covering protection.

The area of section of induction rod is preferably less than 5mm², in the middle of its perforate, gap length is generally less than 20mm；Cutting of transmission lever Face area is preferably greater than 105mm², single effective length should be greater than 100mm.

Induction rod cross sectional shape is rectangle, and its long limit is more than 5 with the ratio of minor face.

Induction rod typically chooses the elastic modelling quantity alloy metal material less than 150GPa；Transmission lever is chosen elastic modelling quantity and is more than The alloy metal material of 200GPa, ceramic material, carbon fiber bar etc.；Protective material is epoxy resin mortar polymer.

Induction rod typically chooses magnalium；It is fine that transmission lever chooses the high model carbon that elastic modelling quantity is 300GPa, 450GPa Tie up or superelevation model carbon fiber, or elastic modelling quantity is the ceramic SiC etc. of 450GPa.

For the problem of the test accuracy deficiency that existing strain testing method exists, inventor establishes a kind of high-resolution Rate strain testing method, this method uses the connection combination that different-stiffness necessarily constructs than two kinds of parts with length ratio, logical Cross mechanics principle the deformation in coverage to be concentrated on a certain parts, play the effect of mechan-amplifier bridge strain.Accordingly, Inventor has also designed and produced corresponding test device.Use this method of testing and test device, in conjunction with inventor through the mechanics of materials And high accuracy based on parameters of operating part ratio of rigidity, the length ratio strain solution formula that structural mechanics method is derived, to realize relatively High test accuracy, reaches 0.01 μ ε the highest (accuracy of conventional strain testing method is only 1 μ ε), is broadly applicable In Test on Bridge Loading, health monitoring and based on technical fields such as dynamic strain identification traveling loads.Compared with prior art, this reality It is with novel outstanding advantage:

(1) by mechan-amplifier, by strain amplification decades of times to hundreds times, even thousand times, improve the identification of small strain Rate and accurate testing degree；

(2) amplification has highlighted the numerical value of structural strain, and Test System Noise does not changes, and is equivalent to reduce test system Noise jamming；

(3) test device instrument is simple, with low cost, it is easy to change；

(4) bridge Modal testing and analysis based on bridge moving strain can be realized.

Accompanying drawing explanation

Fig. 1 is that the structure using state diagram and test device thereof of this utility model middle high-resolution strain testing method is shown It is intended to (being perpendicular to induction rod and transmission lever).

Fig. 2 is that the structure using state diagram and test device thereof of this utility model middle high-resolution strain testing method is shown It is intended to (being perpendicular to bridge member surface).

Fig. 3 is the mechanics principle schematic diagram of this utility model middle high-resolution strain testing method and device thereof

In Fig. 1 and Fig. 2: 1 beam surface, 2 bases, 3 transmission levers, 4 nuts, 5 induction rods, 6 resistance strain plates, 7 prevent Protective material, 8 bolts.

In Fig. 3: 1 transmission lever, 2 induction rods.

Detailed description of the invention

The ultimate principle of this utility model high-resolution strain testing method

1. operating procedure

As depicted in figs. 1 and 2, bridge member surface parallel strain direction steel planting or welding center distance be the 2 of L Individual base, penetrates transmission lever the top perforate of base, and uses nut transmission lever to be tightened in the both sides of base top perforate； It is difference adhering resistance formula foil gauge at the induction rod lateral symmetry of l in two ends perforate centre-to-centre spacing, and uses protective material by electricity Resistive foil gauge and the induction rod portion envelops protection being pasted with resistance strain plate；Abutting end two transmission levers uses spiral shell Induction rod and transmission lever connection are tightened fixing by bolt；Resistance strain plate accesses strain acquirement cabinet according to double foil gauge connections, Adjusting nut and make the abundant stress of base, transmission lever and induction rod, the actual measurement strain reading induction rod is ε '；By formulaCalculate and obtain bridge member surface strain stress to be measured；Wherein, S, E, SE are respectively cutting of transmission lever Face area, elasticity modulus of materials, axial deformation rigidity；S, e, se are respectively the area of section of induction rod, elasticity modulus of materials, axle To deformation rigidity；L is the centre distance of induction rod both ends perforate, and L is base center distance.

Wherein, after induction rod adhering resistance formula foil gauge, put into the drying baker that temperature is 120 DEG C-150 DEG C little no less than 3 Time, use protective material (epoxy resin mortar polymer) parcel protection after taking-up immediately.

2. the derivation of equation

As it is shown on figure 3, under the effect of two ends axial force F, induction rod and transmission lever strain are respectively ε, ε ', and axle power is F, the length of induction rod, area of section and elastic modelling quantity be respectively l, s, e, the length of transmission lever, area of section and elastic modelling quantity It is respectively l ', S, E.Thus can obtain formula (1)

Se ε=F, SE ε '=F, be i.e.

Se ε=SE ε ' (1)

The ratio of strain stress, ε ' can be obtained, order by formula (1)See formula (2)

$\frac{\mathrm{\ϵ}}{{\mathrm{\ϵ}}^{\′}}=\frac{SE}{se}=\frac{1}{\mathrm{\λ}}---\left(2\right)$

Component total length is L, L=l+2l ', and under axial force F effect, total Zhongchang amount Δ L is formula (3)

L ε+2l ' ε '=Δ L (3)

Formula (3) both sides, with divided by L, can obtain formula (4)

$\frac{l}{L}\mathrm{\ϵ}+2\frac{l^{\′}}{L}{\mathrm{\ϵ}}^{\′}=\frac{\mathrm{\Δ}L}{L}---\left(4\right)$

OrderFormula (2) is brought into formula (4) and obtains formula (5)

$\mathrm{\β}\mathrm{\ϵ}+\frac{L-l}{L}\mathrm{\λ}\mathrm{\ϵ}=\frac{\mathrm{\Δ}L}{L}---\left(5\right)$

Mean strain in induction rod and transmission lever length range is the strain of structure, makes this mean strain numerical value be It is i.e.Formula (6) is obtained after formula (5) abbreviation

$(\mathrm{\β}+\mathrm{\λ}-\mathrm{\β}\mathrm{\λ})\mathrm{\ϵ}=\stackrel{\‾}{\mathrm{\ϵ}}---\left(6\right)$

When resistance strain plate accesses strain acquirement cabinet according to double foil gauge connections, actual measurement strain is induction rod strain 2 times, then have formula (7)

$\frac{1}{2}(\mathrm{\β}+\mathrm{\λ}-\mathrm{\β}\mathrm{\λ})\mathrm{\ϵ}=\stackrel{\‾}{\mathrm{\ϵ}}---\left(7\right)$

This seasonξ is relevant to induction rod and transmission lever area of section, length and elastic modelling quantity Characteristic coefficient.

The strain of structure in formula (6)For a certain value, when induction rod and transmission lever area of section, length and elastic modelling quantity ginseng Array is closed when meeting particular kind of relationship so that when characteristic coefficient ξ is less than 1, must haveAnd induction rod and transmission lever area of section, When length and elastic modelling quantity are definite value, characteristic coefficient ξ is also definite value, when characteristic coefficient ξ is 0.1,It it is i.e. induction rod Strain be 10 times of structural strain；When characteristic coefficient κ is 0.01,Be i.e. the strain of induction rod be structural strain 100 times；The structural strain that structure is less cannot be accurately tested when using existing method of testingTime, use this practicality new The test device that type is combined by specific induction rod and transmission lever, adhering resistance formula foil gauge on induction rod, can record and compare structure StrainThe ε of big several times, can be scaled, by characteristic coefficient ξ, the structural strain that conventional method can not accurately obtainIts base Present principles is, by induction rod and the particular combination of transmission lever, utilizes the principle of deformation consistency of structural mechanics and the mechanics of materials, also It is exactly to be presented on distinctive parts after mechanical method amplifies several times less strain, then by characteristic coefficient ξ inverse Structural strain accuratelyGenerally, when using milimeter scale to go the length measuring 1.31mm, the length data measured is probably 1.0mm or 1.5mm, it is impossible to accurately reflect actual length.But after the magnifier of employing 10 times, 100 times amplifies, then use millimeter Chi removes the image after measuring and amplifying, and the length data measured is respectively 13.0mm, 131.0m.Now when the amplification knowing magnifier Multiple is 10 times, 100 times respectively, can try to achieve physical length and be respectively 1.3mm, 1.31mm after inverse).

Application example

Illustrating this utility model below by way of application example, parallel employing traditional method carries out contrast test, wherein Application example is carried out with reference to said method operation, and traditional method is as follows:

(1) selecting sticking strength high (shear strength is typically not less than 3-4MPa), electrical insulation capability is good, chemical stability and The glue of good manufacturability.

(2) select foil gauge, with magnifier, foil gauge is checked, it is ensured that the foil gauge zero defect of selection and breakage. Select, with batch test chamber, the foil gauge that sensitivity coefficient is identical with resistance, use million to beat up table or circuit tester and its resistance is measured, Ensure that error is not more than 0.5 Ω；

(3) location, tentatively draws patch location, is polished flat the position of paster with emery cloth or emery wheel, concrete surface Without laitance, it is coated with primer if desired and processes, the most again polish, accurately draw the longitudinal and transverse of measuring point at the position polished flat Centrage and the direction of stickup foil gauge；

(4) paster, dips acetone or ethanol with tweezers folder rayon balls and paster is obtained position cleans up.Grasping should Become sheet lead-out wire, at one layer of glue of its back side uniform application, be then placed on measuring point, adjust the position of foil gauge so that it is can be accurate Determine position.Foil gauge covers small pieces cellophane finger roll gently, extrusion surplus glue and bubble.It is careful not to make to answer Become sheet position to move.Gently press 1-2min with finger, after glue primary solidification, can loose one's grip.

(5) weld, check, dry solidification and the protection of foil gauge.

Application example 1

At 2 bases that parallel strain direction, bridge member surface steel planting center distance is 166mm；Diameter 18mm's Transmission lever penetrates the perforate on the top of base, and uses nut transmission lever to be tightened in the both sides of base top perforate；At two ends Perforate centre-to-centre spacing is the induction rod lateral symmetry adhering resistance formula foil gauge respectively of 16mm, and induction rod cross section is 6mm × 0.5mm square Shape；And use protective material by resistance strain plate and the part induction rod parcel protection being pasted with resistance strain plate；Passing The abutting end passing bar uses bolt to tighten fixing by induction rod and transmission lever connection；Resistance strain plate is according to double foil gauge connections Access strain acquirement cabinet, adjust nut and make the abundant stress of base, transmission lever and induction rod.The face, cross section of steel material transmission lever Long-pending, elasticity modulus of materials, axial deformation rigidity are respectively 254.47mm²、200GPa、5.0894×10⁴kN/mm；Aluminum alloy materials The area of section of induction rod, elasticity modulus of materials, axial deformation rigidity are respectively 3.00mm²、71GPa、2.13×10²kN/mm； Induction rod is 0.0041852 with the axial rigidity ratio of transmission lever, and the centre distance of induction rod both ends perforate is and base center Gap ratio is 0.09639, sensor characteristics coefficient ξ 0.050084.

Measured result compares and is shown in Table 1.

Table 1 application example 1 and traditional method test result

Class of loading	1	2	3	4	5	6	7	8	9	10
											Theoretical strain	1.0	2.0	3.0	4.0	5.0	6.0	7.0	8.0	9.0	10.0
Conventional actual measurement strain	1	1.5	3.0	4.5	5.0	6.5	7.5	8.0	9.0	9.5
											This method is surveyed	20	39	61	80	102	120	143	162	182	196
Actual measurement inverse strain	1.00	1.95	3.06	4.01	5.11	6.01	7.16	8.11	9.12	9.82

Application example 2

At 2 bases that parallel strain direction, bridge member surface steel planting center distance is 520mm；Diameter 23mm's Transmission lever penetrates the perforate on the top of base, and uses nut transmission lever to be tightened in the both sides of base top perforate；At two ends Perforate centre-to-centre spacing is the almag induction rod lateral symmetry adhering resistance formula foil gauge respectively of 10mm, and induction rod cross section is 4mm × 0.5mm rectangle；And use protective material by resistance strain plate and the part induction rod parcel being pasted with resistance strain plate Protection；Abutting end in transmission lever uses bolt to tighten fixing by induction rod and transmission lever connection；Resistance strain plate is according to double Foil gauge connection accesses strain acquirement cabinet, adjusts nut and makes the abundant stress of base, transmission lever and induction rod.The cross section of transmission lever Area, elasticity modulus of materials, axial deformation rigidity are respectively 415.48mm²、210GPa、8.7245×10⁴kN/mm；Induction rod Area of section, elasticity modulus of materials, axial deformation rigidity are respectively 2.00mm²、40GPa、0.80×10²kN/mm；Induction rod with The axial rigidity ratio of transmission lever is 0.0009169, and the centre distance of induction rod both ends perforate is for base center distance ratio to be 0.019231, sensor characteristics coefficient ξ is 0.01007.Embodiment 2 method compares with traditional method measured result and is shown in Table 2

Table 2 embodiment 2 test result

Class of loading	1	2	3	4	5	6	7	8	9	10
											Theoretical strain (μ ε)	1.0	2.0	3.0	4.0	5.0	6.0	7.0	8.0	9.0	10.0
Conventional actual measurement strain (μ ε)	1.5	2.0	3.0	4.5	5.5	6.0	6.5	8.0	9.5	11
											Conventional actual measurement strain error (%)	50.0	0	0	12.5	10.0	0.0	7.1	0	5.6	10.0
This method actual measurement (μ ε)	102	204	289	393	500	575	698	778	899	1005
											Actual measurement inverse strain (μ ε)	1.03	2.05	2.91	3.96	5.03	5.79	7.03	7.83	9.05	10.12
Actual measurement inverse strain error (%)	3.0	2.5	3.0	1.0	0.6	3.5	0.4	2.1	0.6	1.2

In Tables 1 and 2, each index parameter implication is as follows:

Theoretical strain: Theoretical Calculation strains, and is i.e. Utopian logarithmic strain.

Conventional actual measurement strain: the test result of conventional adhering resistance formula foil gauge, precision is only capable of reaching 0.5 μ ε.

Conventional actual measurement strain error: | theoretical strain-conventional actual measurement strain | × 100/ theoretical strain

This method is surveyed: uses the device actual measurement strain of this programme, by the method for mechan-amplifier, strain is exaggerated 100 times.

Actual measurement inverse strain: consider the inverse strain after device characteristic value, and the strain of the high accuracy of structure, high precision.

Actual measurement inverse strain error=| theoretical strain-actual measurement inverse strain | × 100/ theoretical strain.

Claims (5)

1. a high-resolution strain detection testing device, it is characterised in that mainly strained by base, induction rod, transmission lever and resistance-type Sheet forms；The center distance of 2 bases is L, and the top perforate of each base is also respectively interposed a transmission lever, adopts in perforate both sides With nut fixed delivery bar；Being provided with perforate centre-to-centre spacing in two ends between two transmission lever adjacent both ends is the induction rod of l, transmission lever and Induction rod is bolted；Difference adhering resistance formula foil gauge at induction rod lateral symmetry, resistance strain plate is answered according to double Become sheet connection to be connected with strain acquirement cabinet, resistance strain plate and post the induction rod part of resistance strain plate by protecting material Material covering protection.

High-resolution strain detection testing device the most according to claim 1, it is characterised in that: the area of section of described induction rod Less than 5mm², in the middle of its perforate, gap length is less than 20mm；The area of section of described transmission lever is more than 105mm², single effective length Degree is more than 100mm.

High-resolution strain detection testing device the most according to claim 2, it is characterised in that: described induction rod cross sectional shape is Rectangle, its long limit is more than 5 with the ratio of minor face.

High-resolution strain detection testing device the most according to claim 3, it is characterised in that: described induction rod chooses springform The amount alloy metal material less than 150GPa；Described transmission lever chooses elastic modelling quantity more than the alloy metal material of 200GPa, pottery Ceramic material, carbon fiber bar；Described protective material is epoxy resin mortar polymer.

High-resolution strain detection testing device the most according to claim 3, it is characterised in that: described induction rod is chosen magnalium and is closed Gold；Described transmission lever chooses the high model carbon fiber or superelevation model carbon fiber that elastic modelling quantity is 300GPa, 450GPa, or elastic Modulus is the ceramic SiC of 450GPa.