CN203148372U - Micro resistor type displacement meter based on full-bridge electrometric method - Google Patents

Abstract

The utility model relates to a micro resistor type displacement meter based on a full-bridge electrometric method, belonging to the technical field of a geomechanics model test. The displacement meter mainly comprises a thin copper piece, a test bolt, a protective shell, four strain gauges and conductive wires, and a base with holes. The test bolt is fixed at the upper end of the thin copper piece. The middle part and the lower end of the thin copper piece are placed in the protective shell. Opposite positions of two side surfaces of the middle part of the thin copper piece are adhered with the four strain gauges. The lower part of the thin copper piece is fixed with the base. The four strain gauges are respectively connected with the conductive wires to form a full bridge circuit. The micro resistor type displacement meter can measure the displacement of a dam body surface or the internal part of a rock body, has the advantages of miniature, lightweight, high sensitivity and good stability, and is especially suitable for the geomechanics model test.

Description

Miniature resistance-type displacement meter based on the full-bridge electrical measuring method

Technical field

The utility model belongs to the geomechanical model testing technology field; Specially refer to a kind of structural design of the simple and easy miniature resistance-type displacement meter for geomechanical model test.

Background technology

Geomechanical model test can the model engineering structure strain, displacement characteristics, again can approximate simulation rock mass tomography etc. geologic agent to the influence of engineering structure stability, therefore it has important role and has obtained using widely in engineering designs such as water conservancy, mining, tunnel, and for example Zhong Guo big-and-middle-sized arch dam was substantially all done geomechanical model test.

In the geomechanical model test, the displacement situation of body structure surface and basic rock mass inside is main measurement content under load action, can reflect the security and stability at stress, strained situation and each position of structure and basic rock mass by displacement, and then obtain the final safety analysis result of engineering.But geomechanical model test need be measured many some displacements, and sometimes measuring point need be arranged in the inside of strata model; But the size of model own is little, and displacement measuring device can not be excessive so that structure and rock mass stress distribution situation are exerted an influence.To sum up, geomechanical model test needs the displacement measuring device of a kind of miniature, lightweight, highly sensitive, good stability.Though emerge high-tech measurement mechanisms such as Fibre Optical Sensor in recent years, these costs are higher, and be subject to disturb, seriously hindered its popularization.

Shandong University once applied for " being used for the miniature built-in overarm formula displacement meter of geomechanical model test " (open (bulletin) day: 2009.01.14, openly (bulletin) number: CN101344372).This is a kind of miniature built-in cantilever beam type displacement gage for geomechanical model test, comprises spring leaf, wire rope, foil gauge, it is characterized in that: the two ends of wire rope are connected to the stator at spring leaf upper end and the inner measuring point of model body place; Be provided with the adjusting bolt in the spring leaf upper end, the spring leaf lower end is fixed on the thick steel bar, and foil gauge is arranged near the root of spring leaf lower end and by signal wire and is connected with the signal receiving and processing device.This displacement meter adopts the half-bridge method to measure, and measuring accuracy is not high; And this utility model more lays particular stress on the internal displacement value of measuring rock mass structure.

The utility model content

The purpose of this utility model is for overcoming the weak point of prior art, a kind of miniature resistance-type displacement meter based on the full-bridge electrical measuring method is proposed, the utility model can be measured the displacement on dam body or rock mass surface, and have the characteristics of miniature, lightweight, highly sensitive, good stability, be specially adapted to geomechanical model test.

A kind of miniature resistance-type displacement meter based on the full-bridge electrical measuring method that the utility model proposes is characterized in that, is used for the displacement measurement of geomechanical model test, this displacement meter mainly comprises scale copper, test bolt, containment vessel, 4 foil gauges and lead thereof, base with holes; Wherein, test is bolted to the upper end of scale copper, and middle part and the lower end of scale copper place containment vessel, bonding four foil gauges of the relative position of the middle part both side surface of scale copper, and bottom and the base of scale copper are fixed; 4 foil gauges composition full-bridge circuit that is connected with lead respectively.

This base can be plastic feet, can be made up of base plate and riser, and base plate one end is a circular hole, is used for fixing with geomechanics model, and the base other end also has a small sircle hole, is used for interspersed 4 leads; Riser is combined in and has two holes on base plate one end, is used for base and scale copper bottom are fixed by set bolt.

This scale copper is about the thick scale copper of 0.5mm, highly is about 3.6cm, and is up-narrow and down-wide, and the narrowest place, top is about 0.9cm, and bottom the widest part is about 1.5cm, and the scale copper bottom is fixed on the plastic feet; 4 foil resistance foil gauges place copper sheet both side surface middle part, wherein, first foil gauge and the 4th foil gauge, second foil gauge and the 3rd foil gauge are in copper sheet both sides same position respectively.

This each foil gauge surface is equipped with paraffin and adds the vaseline sealant, is used for protection against the tide and thermal insulation, to improve stability;

The size of population of this displacement meter can be 1cm*2cm*3.5cm.

Characteristics of the present utility model and useful result:

This displacement meter can be imbedded the inside of basic strata model, also can be arranged in the measuring point of body structure surface.This displacement meter one end is fixed on the brandreth, and when the other end was subjected to displacement, copper sheet can produce bending; Use the full-bridge method to measure the strain differential on copper sheet two sides, and then conversion obtain the shift value of copper sheet; This displacement meter is converted into extremely sensitive electric signal with shift value and measures; And this displacement meter only uses simple material such as resistor disc, scale copper, thin wire, plastic plate, and cost has been saved in processing, easy to use greatly.

This displacement meter constructs, uses simple, and cost is lower; Use the full-bridge method highly sensitive; The displacement meter arrangement convenience can be measured dam body or strata model surface displacement, also can measure the strata model internal displacement; The displacement meter size is less, and is less to the structural stress distribution influence; Measuring technique is easy to learn, and cost is low, is easy to promote the use of.

Description of drawings

Fig. 1 is displacement meter side view of the present utility model;

Fig. 2 is vertical view of the present utility model;

Fig. 3 is the positive view of the A-A section of Fig. 2;

Fig. 4 is displacement meter rear view of the present utility model;

Fig. 5 is circuit reduction figure of the present utility model;

Wherein, 1 scale copper, 2 test bolt (2-1 nuts, the 2-2 nut), 3 containment vessels, 4 foil gauges (4-1 foil gauge 1,4-2 foil gauge 2,4-3 foil gauge 3,4-4 foil gauge 4), 5 set bolts (5-1 set bolt 1,5-2 set bolt 2), 6 bases, 7 leads (lead A, lead B, lead C, lead D); R1, R2, R3, R4 be corresponding foil gauge 1,2,3,4 respectively, and A/C wire connecting power, B/D two ends connect surveying instrument.

Embodiment

The miniature resistance-type displacement meter based on the full-bridge electrical measuring method that the utility model proposes reaches embodiment by reference to the accompanying drawings and is described in detail as follows:

A kind of miniature resistance-type displacement meter based on the full-bridge electrical measuring method that the utility model proposes is characterized in that, is used for the displacement measurement of geomechanical model test, this displacement meter mainly comprises scale copper, test bolt, containment vessel, 4 foil gauges and lead thereof, base with holes; Wherein, test is bolted to the upper end of scale copper, and middle part and the lower end of scale copper place containment vessel, bonding four foil gauges of the relative position of the middle part both side surface of scale copper, and bottom and the base of scale copper are fixed; 4 foil gauges composition full-bridge circuit that is connected with lead respectively.

The structure of present embodiment is shown in Fig. 1～4, and the about 1cm*2cm*3.5cm of the size of population of this displacement meter can ignore than the dam body moulded dimension, so less to the stress distribution influence of model.Present embodiment mainly comprises scale copper 1, test bolt 2(is made up of nut 2-1 and nut 2-2), containment vessel 3,4 foil gauge 4(first foil gauge 4-1, the second foil gauge 4-2, the 3rd foil gauge 4-3 and the 4th foil gauge 4-4) and lead (lead A, lead B, lead C, lead D), base 6 with holes; Wherein, test bolt 2 is fixed on the upper end of scale copper 1, the middle part of scale copper 1 and lower end place containment vessel 3, bonding four foil gauges 4 of the relative position of the middle part both side surface of scale copper 1, and the bottom of scale copper 1 is fixing by gib screw 5-1,5-2 and base 6; The first foil gauge 4-1, the second foil gauge 4-2, the 3rd foil gauge 4-3 and the 4th foil gauge 4-4 respectively with lead A, lead B, lead C, the lead D composition full-bridge circuit that is connected.

The embodiment of each parts of this displacement meter is respectively described below:

The base 6 of present embodiment is plastic feet, shown in Fig. 2,3, formed by base plate and riser, the high about 0.6cm of base plate is about 3cm, thick about 0.8cm, base plate one end is a circular hole 6-1, diameter 0.5cm, the point of fixity that is used for interspersed bolt and geomechanics model outside is fixed, and base is placed on the point of fixity of model outside; The base other end also has a small sircle hole, and the about 0.3cm of diameter is used for interspersed 4 leads; Riser is combined on base plate one end, and high about 1cm is about 1.5cm, thick about 0.8cm,, have two holes, be used for scale copper 1 bottom is fixed by set bolt 5-1,5-2, as shown in Figure 3.

The thick scale copper of scale copper 1 thickness 0.5mm of present embodiment, highly about 3.6cm, up-narrow and down-wide, the narrowest 0.9cm of place in top, the bottom is the wideest to go out 1.5cm, the scale copper bottom use 2 fixedly universal source hook bolt 5 be fixed on the plastic feet 6; A test bolt 2 is settled at copper sheet 1 top, and screw is about 1cm, adopts general snap head bolt; 2 foil resistance foil gauges 4 that length is 0.5mm have respectively been arranged at copper sheet both side surface middle part, wherein, the first foil gauge 4-1 and the 4th foil gauge 4-4, the second foil gauge 4-2 and the 3rd foil gauge 4-3 are in the both sides same position respectively, as shown in Figure 2; Each foil gauge surface all scribbles paraffin and adds the vaseline sealing, is used for protection against the tide and thermal insulation, to improve stability; Present embodiment adopts 4 leads 7, and every lead is separated into 2 thin wires again, uses the full-bridge method to connect 8 thin wires are connected with 4 foil gauges, and connected mode is seen accompanying drawing 3,4 and Fig. 5; The thick thin plastic sheet of containment vessel 3 usefulness 0.5mm is made, and just the middle and lower part with copper sheet is trapped among wherein, is used for preventing dust etc. to the pollution of foil gauge and to the interference of test figure, and is glued fixing between containment vessel bottom and pedestal.

Measuring principle and the course of work of this displacement meter are described as follows: during use, when measuring the rock mass internal displacement, the bolt head on displacement meter top is imbedded the measuring position; When measuring the body structure surface displacement, the adjacent measuring position of the bolt head on displacement meter top makes copper sheet that less bending takes place simultaneously; Base is fixed on the outer point of fixity of model during measurement; When the measuring position was subjected to displacement, bolt was also along with the measuring position produces identical displacement together; Copper sheet is bent, the copper sheet two ends produce equal and opposite in direction, direction opposite strain stress ₁=ε ₂=-ε ₃=-ε ₄).

The foil gauge measure equation:

$\frac{\mathrm{\ΔR}}{R}=K\·\mathrm{\ϵ}---\left(1\right);$

Full-bridge method measure equation:

$\mathrm{\&Delta;U}=\frac{U}{4}(\frac{{\mathrm{\&Delta;R}}_1}{{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="HDA00002936549400011.png,HDA00002936549400021.png"\; state="\{\{state\}\}">R</figure-callout>}}_1}+\frac{{\mathrm{\&Delta;R}}_2}{R_2}-\frac{{\mathrm{\&Delta;R}}_3}{R_3}-\frac{{\mathrm{\&Delta;R}}_4}{R_4})=\frac{\mathrm{UK}}{4}({\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2-{\mathrm{\&epsiv;}}_3-{\mathrm{\&epsiv;}}_4)---\left(2\right);$

Strainmeter full-bridge method place in circuit, reading:

${\mathrm{\&epsiv;}}_{\mathrm{ds}}=\frac{4\mathrm{\&Delta;U}}{\mathrm{KU}}={\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2-{\mathrm{\&epsiv;}}_3-{\mathrm{\&epsiv;}}_4={4\mathrm{\&epsiv;}}_1---\left(3\right);$

(ε ₁, ε ₂, ε ₃, ε ₄Be respectively foil gauge 1,2,3,4 strain value; R ₁, R ₂, R ₃, R ₄Be respectively foil gauge 1,2,3,4 resistance value; U is magnitude of voltage; K is the coefficient of strain);

Because the displacement exact value of measuring in the model test is in a small amount with respect to the copper sheet size, so the bending value of the shift value of bolt and copper sheet can be approximated to be linearity, just shift value is similar to and ε again ₁Linear, just with strain-ga(u)ge reading ε _DsBeing linear closes.Before the use, use clock gauge, strainmeter that displacement meter is carried out calibration at the calibration frame, the data that record are carried out linear fit, obtain strain-displacement curve slope; During test, again the strainmeter difference of reading being multiply by slope is exactly the displacement difference of measuring.

(1) displacement meter is inserted in the strainmeter according to the full-bridge method, as shown in Figure 5, use clock gauge that displacement meter is carried out calibration at the calibration frame, the multi-group data that same displacement meter is recorded carries out linear fit, obtains strain-displacement curve slope;

When (2) measuring internal displacement, the top bolt of displacement meter is imbedded the measuring position; When measuring surface displacement, with the top bolt of the displacement meter surface near the measuring position, make copper sheet that less bending takes place simultaneously; Use bolt that the base of displacement meter is fixed on the point of fixity of model outside;

(3) full-bridge circuit and the strainmeter with displacement meter connects, as shown in Figure 5;

(4) read the initial measurement data that model does not have the strainmeter when loading;

(5) after model begins to load, the strain-ga(u)ge reading when reading each heap(ed) capacity;

(6) to multiply by slope be exactly twice displacement difference under the heap(ed) capacity situation to any twice strain-ga(u)ge reading difference, because initial displacement is 0, be exactly shift value under corresponding each the heap(ed) capacity situation that records so measure constantly slope that strain-ga(u)ge reading difference with initial time multiply by calibration.

Claims (5)

1. the miniature resistance-type displacement meter based on the full-bridge electrical measuring method is characterized in that, is used for the displacement measurement of geomechanical model test, and this displacement meter mainly comprises scale copper, test bolt, containment vessel, 4 foil gauges and lead thereof, base with holes; Wherein, test is bolted to the upper end of scale copper, and middle part and the lower end of scale copper place containment vessel, bonding four foil gauges of the relative position of the middle part both side surface of scale copper, and bottom and the base of scale copper are fixed; 4 foil gauges composition full-bridge circuit that is connected with lead respectively.

2. displacement meter according to claim 1 is characterized in that this base is plastic feet, is made up of base plate and riser, and base plate one end is a circular hole, is used for fixing with geomechanics model, and the base other end also has a small sircle hole, is used for interting 4 leads; Riser is combined in and has two holes on base plate one end, is used for base and scale copper bottom are fixed by set bolt.

3. displacement meter according to claim 1 is characterized in that this scale copper is the thick scale copper of 0.5mm, and height 3.6cm is up-narrow and down-wide, the narrowest 0.9cm of place in top, and the bottom is the wideest to go out 1.5cm, and the scale copper bottom is fixed on the plastic feet; 4 foil resistance foil gauges place copper sheet both side surface middle part, wherein, first foil gauge and the 4th foil gauge, second foil gauge and the 3rd foil gauge are in copper sheet both sides same position respectively.

4. displacement meter according to claim 1 is characterized in that this each foil gauge surface is equipped with paraffin and adds the vaseline sealant.

5. displacement meter according to claim 1 is characterized in that the size of population of this displacement meter is 1cm*2cm*3.5cm.

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