GB2036336A - Measuring stress and strain using optical fibres - Google Patents
Measuring stress and strain using optical fibres Download PDFInfo
- Publication number
- GB2036336A GB2036336A GB7933684A GB7933684A GB2036336A GB 2036336 A GB2036336 A GB 2036336A GB 7933684 A GB7933684 A GB 7933684A GB 7933684 A GB7933684 A GB 7933684A GB 2036336 A GB2036336 A GB 2036336A
- Authority
- GB
- United Kingdom
- Prior art keywords
- composite
- stress
- optical fibres
- optical
- fibres
- 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.)
- Withdrawn
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 27
- 239000002131 composite material Substances 0.000 claims abstract description 48
- 239000011521 glass Substances 0.000 claims abstract description 9
- 238000010998 test method Methods 0.000 claims abstract description 3
- 239000011159 matrix material Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 4
- 229920000642 polymer Polymers 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 abstract 1
- 239000000835 fiber Substances 0.000 description 3
- 239000013307 optical fiber Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000003365 glass fiber Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920000728 polyester Polymers 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- LNEPOXFFQSENCJ-UHFFFAOYSA-N haloperidol Chemical compound C1CC(O)(C=2C=CC(Cl)=CC=2)CCN1CCCC(=O)C1=CC=C(F)C=C1 LNEPOXFFQSENCJ-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 239000002952 polymeric resin Substances 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000003938 response to stress Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/08—Testing mechanical properties
- G01M11/083—Testing mechanical properties by using an optical fiber in contact with the device under test [DUT]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The present invention relates to a glass reinforced composite having incorporated therein filaments of optical fibres the transmission parameters of which vary with stress, one end of said filaments being accessible to a light source and the other end being accessible to a light detector. The invention also relates to a method of testing the strain of such composites.
Description
SPECIFICATION
Reinforced composites
The present invention relates to reinforced composites and to non-destructive methods of testing strain and stress on such reinforced composites and structures.
By the term "reinforced composites" is meant here and throughout the specification composites in which the reinforcements are substantially compatible with the matrix of the composite. For example, the matrix may be of polymeric resins such as epoxy resins or polyesters reinforced with glass fibres in which case the composites will be glass reinforced polymers known as GRP. On the other hand, the matrix may be a cementitious composition such as concrete which is reinforced with glass or polymeric fibres. Such composites have hitherto been used in a wide range of applications including the production of structures such as pipelines, beams, aircraft components, turbine blades, buildings and prefabricated units thereof.In many of these uses it is vital to ascertain whether such composites have been subjected to a strain above the desired safety iimit in respect of that particular use. In certain cases it is also necessary to know whether such composites would withstand a certain degree of stress either prior to or during use. Ideally, it would be desirable periodically to test the composites or structures either at regular intervals or during servicing of such composites and structures to ensure that they conform to the required safety limits. The methods available hitherto for such testing have often involved complete destruction of the composite or structure and have given results which are misleading and difficult to interpret.
It has now been found that by incorporating filaments of optical fibres in such composites or structures these problems may be overcome.
Accordingly, the present invention is a reinforced composite having incorporated therein optical fibres which are substantially compatible with the matrix of the composite, one end of said fibres being accessible to a light source and the other end being accessible to a light detector.
According to a further embodiment, the present invention comprises a method of testing a reinforced composite having incorporated therein optical fibres which are substantially compatible with the matrix of the composite and which fibres exhibit a change in optical transmissibility when subjected to stress said method comprising determining the stress to which the composite has been subjected by monitoring the change in optical transmissibility of the optical fibres in the composite.
The optical fibres may be of glass or of polymeric material. In the manufacture of a composite according to the present invention, the optical fibres may either be incorporated at specific points of stress within the composite or on the surface thereof or, alternatively, for example in the case of pipelines, be wound helically around said pipelines, so that any excessive strain or stress results in elongation and consequent deformation of the physical structure of the optical fibres. When such deformation occurs, the transmissibility of the optical fibre changes significantly and the change immediately gives an indication of the stress to which the composite has been subjected. Such fibres may be incorporated as single filaments, bundles of filaments or as a lattice network depending upon the use to which the composite is put and the stress to which it is likely to be subjected.The optical fibres used in the present invention may be produced with different stress or strain characteristics. Thus optical fibres may be produced which respond to different degrees of stress in terms of their optical transmissibility. By incorporating several filaments of optical fibres, each of which is responsive to a different degree of stress, the progressive effect of continued stress on a particular composite may be monitored. The selection of one or more grades of fibre would be dependent upon the type of information required and the safety limits for any particular end use of a composite.
One of the important features of the present invention is that the optical fibres are substantially compatible with the matrix because the elastic modulus of the optical fibres is similar to conventional reinforcements such as for instance glass. This is significant if the performance of the composite as a whole is not to be affected. Furthermore, conventional surface treatment of glass fibres in a matrix to vary the compatibility can also be carried out with optical fibres so that the degree of adhesion of the optical fibres to the matrix may be adjusted as required.
EXAMPLE
(i) Preparation of Reinforced Composite
A glass reinforced polyester polymer composite with the optical fibre incorporated therein was
made as follows: Six layers of a random chopped fibreglass mat (density 2 ozlsq foot) were laminated
with approximately 1 20 strands of optical fibre in a roving laid lengthwise between the central layers of
the mat such that the ends of the roving overlay the ends of the mat. A polyester resin, Cellobond
A253/67 (Regd. Trade Mark) was then applied thereon by hand. The resin was set using 0.5 ml/l 00 g of 1% of a cobalt containing coaccelerator and Butanox M-5D (Regd. Trade Mark) peroxide catalyst
(1 ml/l 00 g). The reinforced composite thus produced contained 30% glass by weight.
(ii) Measurement of response to stress
A piece of the composite made in (i) above was tested as follows:
A light emitting diode which generated red light was optically coupled to one end of the fibre-optic roving and the transmissibility of the roving monitored by means of a photodiode with an integral amplifier coupled at the other end of the roving.Varying loads were applied using an Instron machine with a three point bend flexural jig (ASTM 790) in which the parameters were as follows:
Thickness of composite, d = 8.9 mm
Length ,, ,, I = 82 mm
Breadth ,, ,, b=21 mm
The results of the effect of various loads applied are tabulated below:
Load in KN Deflection, a in mm Output mV 0 0 0.06 0.2 1 0.065 0.65 2 0.095 0.95 3 0.14 1.15 3.5 0.155 1.2 1st Fibre 1.21 Using the above parameters, the modulus E of the composite on application of a weight, W = 1.1 5
KN and for a flexion observed, a = 3.5 mm, was calculated by the formula: : Wl3 -E=
4 a bd3
For this particular case the modulus, E was 1.33 GN/m2.
The szme parameters can be used to calculate the strain on the sample which in the present case was the equivalent of about 1 5%/my output
Similarly, the maximum fibre stress, a can be calculated using the formula 3WI = 2bd2
Claims (7)
1. A reinforced composite having incorporated therein optical fibres which are substantially compatible with the matrix of the composite, one end of said fibres being accessible to a light source and the other end being accessible to a light detector.
2. A reinforced composite according to Claim 1 wherein the matrix is polymer or cementitious.
3. A reinforced composite according to Claim 1 or 2 wherein the optical fibres are made of glass or polymeric material.
4. A reinforced composite according to any one of the preceding Claims wherein said composite is a glass reinforced polymer.
5. A reinforced composite according to any one of the preceding Claims, wherein the optical fibres are incorporated at points of stress on the surface of the composite.
6. A reinforced composite according to any one of the preceding Claims wherein several filaments of optical fibres, each of which is responsive to a different degree of stress, are incorporated therein.
7. A method of testing reinforced composites having incorporated therein optical fibres which are substantially compatible with the matrix of the composite and which fibres exhibit a change in optical transmissibility when subjected to stress, said method comprising determining the stress to which the composite has been subjected by monitoring the change in optical transmissibility of the optical fibresin the composite.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7933684A GB2036336A (en) | 1978-09-29 | 1979-09-28 | Measuring stress and strain using optical fibres |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7838665 | 1978-09-29 | ||
| GB7933684A GB2036336A (en) | 1978-09-29 | 1979-09-28 | Measuring stress and strain using optical fibres |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2036336A true GB2036336A (en) | 1980-06-25 |
Family
ID=26269006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7933684A Withdrawn GB2036336A (en) | 1978-09-29 | 1979-09-28 | Measuring stress and strain using optical fibres |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2036336A (en) |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0038401A1 (en) * | 1980-04-22 | 1981-10-28 | Philips Kommunikations Industrie AG | Method of controlling the physical parameters of structural members |
| EP0071695A1 (en) * | 1981-08-12 | 1983-02-16 | Felten & Guilleaume Energietechnik GmbH | Element to be monitored in relation to rupture or stress by means of optical wave guides |
| DE3243026A1 (en) * | 1982-05-15 | 1984-05-24 | Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn | Measuring arrangement for detecting cracks |
| EP0116685A1 (en) * | 1982-11-20 | 1984-08-29 | Messerschmitt-Bölkow-Blohm Gesellschaft mit beschränkter Haftung | Optical measuring arrangement for detecting flaws |
| FR2559262A1 (en) * | 1984-02-07 | 1985-08-09 | France Etat | Method and device for non-destructive testing in a massive structure |
| DE3447122A1 (en) * | 1984-12-22 | 1986-06-26 | Messerschmitt-Bölkow-Blohm GmbH, 2800 Bremen | MEASURING ARRANGEMENT FOR DETECTING CRACKS IN TEST UNITS |
| US4654520A (en) * | 1981-08-24 | 1987-03-31 | Griffiths Richard W | Structural monitoring system using fiber optics |
| US4840481A (en) * | 1987-12-10 | 1989-06-20 | Simmonds Precision | Polarimetric optical frequency domain distributed strain sensor and method |
| US4927232A (en) * | 1985-03-18 | 1990-05-22 | G2 Systems Corporation | Structural monitoring system using fiber optics |
| AU597937B2 (en) * | 1985-03-18 | 1990-06-14 | G2 Systems Corporation | Structural monitoring system using fiber optics |
| US4936649A (en) * | 1989-01-25 | 1990-06-26 | Lymer John D | Damage evaluation system and method using optical fibers |
| FR2672681A1 (en) * | 1991-02-13 | 1992-08-14 | Mongliols Jean Claude | Fibre-optic pressure detector |
| US5479828A (en) * | 1991-12-11 | 1996-01-02 | Thomson-Csf | Structure with intrinsic damage control, manufacturing processes and method of use |
-
1979
- 1979-09-28 GB GB7933684A patent/GB2036336A/en not_active Withdrawn
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0038401A1 (en) * | 1980-04-22 | 1981-10-28 | Philips Kommunikations Industrie AG | Method of controlling the physical parameters of structural members |
| EP0071695A1 (en) * | 1981-08-12 | 1983-02-16 | Felten & Guilleaume Energietechnik GmbH | Element to be monitored in relation to rupture or stress by means of optical wave guides |
| DE3131870A1 (en) * | 1981-08-12 | 1983-02-24 | Philips Kommunikations Industrie AG, 8500 Nürnberg | COMPONENT-MONITORABLE COMPONENT BY means of fiber-optic cables |
| US4840480A (en) * | 1981-08-12 | 1989-06-20 | Philips Kommunikations Industrie A | Light conduit arrangement for monitoring a physical condition of a structural part |
| US4654520A (en) * | 1981-08-24 | 1987-03-31 | Griffiths Richard W | Structural monitoring system using fiber optics |
| DE3243026A1 (en) * | 1982-05-15 | 1984-05-24 | Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn | Measuring arrangement for detecting cracks |
| EP0116685A1 (en) * | 1982-11-20 | 1984-08-29 | Messerschmitt-Bölkow-Blohm Gesellschaft mit beschränkter Haftung | Optical measuring arrangement for detecting flaws |
| FR2559262A1 (en) * | 1984-02-07 | 1985-08-09 | France Etat | Method and device for non-destructive testing in a massive structure |
| FR2575290A1 (en) * | 1984-12-22 | 1986-06-27 | Messerschmitt Boelkow Blohm | MEASURING DEVICE FOR DETERMINING CRACKS IN SAMPLES |
| DE3447122A1 (en) * | 1984-12-22 | 1986-06-26 | Messerschmitt-Bölkow-Blohm GmbH, 2800 Bremen | MEASURING ARRANGEMENT FOR DETECTING CRACKS IN TEST UNITS |
| US4927232A (en) * | 1985-03-18 | 1990-05-22 | G2 Systems Corporation | Structural monitoring system using fiber optics |
| AU597937B2 (en) * | 1985-03-18 | 1990-06-14 | G2 Systems Corporation | Structural monitoring system using fiber optics |
| US4840481A (en) * | 1987-12-10 | 1989-06-20 | Simmonds Precision | Polarimetric optical frequency domain distributed strain sensor and method |
| US4936649A (en) * | 1989-01-25 | 1990-06-26 | Lymer John D | Damage evaluation system and method using optical fibers |
| FR2672681A1 (en) * | 1991-02-13 | 1992-08-14 | Mongliols Jean Claude | Fibre-optic pressure detector |
| US5479828A (en) * | 1991-12-11 | 1996-01-02 | Thomson-Csf | Structure with intrinsic damage control, manufacturing processes and method of use |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |