GB2175695A - Neutrally buoyant underwater elongate pressure or bending sensor - Google Patents

Neutrally buoyant underwater elongate pressure or bending sensor Download PDF

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Publication number
GB2175695A
GB2175695A GB08513249A GB8513249A GB2175695A GB 2175695 A GB2175695 A GB 2175695A GB 08513249 A GB08513249 A GB 08513249A GB 8513249 A GB8513249 A GB 8513249A GB 2175695 A GB2175695 A GB 2175695A
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GB
United Kingdom
Prior art keywords
tube
conductors
pair
wall surface
member according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08513249A
Other versions
GB2175695B (en
GB8513249D0 (en
Inventor
Lyndon Reginald Spicer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
STC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by STC PLC filed Critical STC PLC
Priority to GB08513249A priority Critical patent/GB2175695B/en
Publication of GB8513249D0 publication Critical patent/GB8513249D0/en
Publication of GB2175695A publication Critical patent/GB2175695A/en
Application granted granted Critical
Publication of GB2175695B publication Critical patent/GB2175695B/en
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/16—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge
    • G01B7/22—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring the deformation in a solid, e.g. by resistance strain gauge using change in capacitance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/28—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures
    • G01B7/281—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring contours or curvatures for measuring contour or curvature along an axis, e.g. axial curvature of a pipeline or along a series of feeder rollers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0026—Transmitting or indicating the displacement of flexible, deformable tubes by electric, electromechanical, magnetic or electromagnetic means
    • G01L9/003—Transmitting or indicating the displacement of flexible, deformable tubes by electric, electromechanical, magnetic or electromagnetic means using variations in capacitance

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

A neutrally buoyant underwater elongate member comprises an extruded resilient plastics tube 10 having at least one pair of diametrically opposed conductors 12 incorporated in ridges 11 formed on the inner wall surface of the tube. The distance between the conductors will vary according to bending or compression of the tube, affecting capacitance and characteristic impedance. These variations can be measured using pulse techniques, treating the conductors as balanced pair transmission lines. <IMAGE>

Description

SPECIFICATION Neutrally buoyant underwater elongate member This invention relates to a neutrally buoyant elongate member having a capability for detection and measurement of axial non-linearity and/or changes in external pressure due to changes in depth of immersion.
According to the invention there is provided a neutrally buoyant underwater elongate member comprising a tube of resilient material having at least one pair of diametrically opposed longitudinal conductors positioned on or adjacent the inner wall surface of the tube.
An embodiment of the invention will now be described with reference to the accompanying drawing which illustrates a cross section through a neutrally buoyant underwater elongate member.
The elongate member comprises an extruded tube 10 of plastics material, e.g. polythene, rubber, Neoprene, PVC, polyester, polyurethane, etc., the inner wall surface of which is formed with two diametrically opposed ridges 11. Embedded in each ridge 11 is an electrical conductor 12, e.g. of copper clad steel wire. The distance between the diametrically opposed conductors 12 will vary dependent on the longitudinal radius of curvature to which the tube will be subjected and/or variation in external pressure along the tube, e.g. due to depth of immersion in water. This variation in distance between the conductors will affect the capacitance and characteristic impedance when the conductors are treated as forming a balanced pair transmission line.
The capacitance C and characteristic impedance Z0 of such a line are given by:
D= Diameter under the outer screen (in our case sea water).
d= Diameter over the conductor.
h= Distance between conductor (x) divided by diameter under the outer screen (D).
e= Dielectric constant. (say 2.26).
As an example consider the following design parameters: Diameter (D) of tube =0.250 inches Wall thickness =0.040 inches Distance (nominal) between conductors =0.100 inches Diameter of conductors =0.010 inches Thickness of insulation round conductors =0.020 inches Bending of the tube on the plane of the conductor centres will cause the spacing between the conductors to decrease. Alternatively compression of the tube will cause the spacing to decrease. The amount of decrease for a given bending or compression will depend on the compressive or flexural strength of the tube wall.For the above example typical changes in transmission line parameters as the spacing between the conductors is decreased would be: Distance between Capacitance Impedance centre conductors pF/ft ohms .100 7.164 213.1 .090 7.282 209.7 .080 7.460 204.7 .070 7.716 197.9 .060 8.082 188.9 .050 8.616 177.2 In a modification of the design the tube is provided with two pairs of conductors in orthogonal relationship. This allows simultaneous measurement of both vertical and horizontal bending of the tube. At the same time pressure variation along the tube will affect the transmission parameters of both pairs of conductors. However these changes due to external pressures will be the same for both transmission line pairs as the tube collapses uniformly in cross section with increase in compression.
To control the buoyancy of the tube it may be necessary to fill the tube with a material of suitable specific gravity. For example the tube may be filled with liquid kerosene. Alternatively the filling may be a gel like material such as hydroxy terminated Polybutadiene. In the latter case the tube will bend, but is not readily compressible. If a foamed solid filler is used e.g., foamed polythene, then compression of the tube can be effected. The addition of barium titanate, which has a very high dielectric constant, to any of the aforementioned filler materials will provide much larger changes in capacitance and impedance.
To determine changes in capacitance and characteristic impedance the pairs of conductors are treated as balanced pair transmission lines and are connected at one end to apparatus for generating electrical pulses. The capacitance and impedance are then measured using time domain reflectometry (TDR) or pulse echo techniques.

Claims (8)

1. A neutrally buoyant underwater elongate member comprising a tube of resilient material having at least one pair of diametrically opposed longitudinal conductors positioned on or adjacent the inner wall surface of the tube.
2. A member according to claim 1 having a second pair of diametrically opposed longitudinal conductors positioned on or adjacent the inner wall surface of the tube in orthogonal relationship to the one pair of conductors.
3. A member according to claim 1 or 2 wherein the member comprises a tube of extruded plastics material and the conductors are incorporated within ridges formed on the inner wall surface of the extruded tube.
4. A member according to claim 3 wherein the extruded tube is of substantially circular cross section.
5. A member according to any preceding claim wherein the tube is filled with a buoyancy controlling medium.
6. A member according to claim 5 wherein the tube is filled with hydroxy terminated Polybutadiene.
7. A neutrally buoyant underwater elongate member substantially as described with reference to the accompanying drawing.
8. A method of determining axial non-linearity or changes in external pressure of a neutrally bouyant underwater elongate member comprising a tube of resilient material having at least one pair of diametrically opposed longitudinal conductors positioned on or adjacent the inner wall surface of the tube including the steps of connecting the conductors at one end of the tube to apparatus for propagating pulsed electrical signals in the conductors and measuring the capacitance and characteristic impedance between the conductors of a pair.
GB08513249A 1985-05-24 1985-05-24 Neutrally buoyant underwater elongate member Expired GB2175695B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08513249A GB2175695B (en) 1985-05-24 1985-05-24 Neutrally buoyant underwater elongate member

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08513249A GB2175695B (en) 1985-05-24 1985-05-24 Neutrally buoyant underwater elongate member

Publications (3)

Publication Number Publication Date
GB8513249D0 GB8513249D0 (en) 1985-06-26
GB2175695A true GB2175695A (en) 1986-12-03
GB2175695B GB2175695B (en) 1988-11-09

Family

ID=10579670

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08513249A Expired GB2175695B (en) 1985-05-24 1985-05-24 Neutrally buoyant underwater elongate member

Country Status (1)

Country Link
GB (1) GB2175695B (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0387180A1 (en) * 1989-01-23 1990-09-12 The University Of Melbourne Electronic transducer
FR2666408A1 (en) * 1990-09-05 1992-03-06 Framatome Sa Device for expanding a tubular member
EP1188033A1 (en) * 1999-04-29 2002-03-20 Didjiglove PY Ltd. Electronic transducer for measuring flexion
DE102008035746A1 (en) * 2008-07-31 2010-02-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Force effect spatial-resolution detection device for use during e.g. clamping protection of electric window lift, has signal processing device determining position of effect along waveguide based on time difference between time points
EP3575739A1 (en) * 2018-06-01 2019-12-04 Eolotec GmbH Method and device for determining a load or aging of a component

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0387180A1 (en) * 1989-01-23 1990-09-12 The University Of Melbourne Electronic transducer
FR2666408A1 (en) * 1990-09-05 1992-03-06 Framatome Sa Device for expanding a tubular member
EP1188033A1 (en) * 1999-04-29 2002-03-20 Didjiglove PY Ltd. Electronic transducer for measuring flexion
EP1188033A4 (en) * 1999-04-29 2006-03-01 Didjiglove Py Ltd Electronic transducer for measuring flexion
DE102008035746A1 (en) * 2008-07-31 2010-02-04 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Force effect spatial-resolution detection device for use during e.g. clamping protection of electric window lift, has signal processing device determining position of effect along waveguide based on time difference between time points
EP3575739A1 (en) * 2018-06-01 2019-12-04 Eolotec GmbH Method and device for determining a load or aging of a component
DE102018208689A1 (en) * 2018-06-01 2019-12-05 Eolotec Gmbh Method and device for determining a load or aging of a component

Also Published As

Publication number Publication date
GB2175695B (en) 1988-11-09
GB8513249D0 (en) 1985-06-26

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Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19940524