GB2169480A - A method of non-destructive testing of structural members - Google Patents
A method of non-destructive testing of structural members Download PDFInfo
- Publication number
- GB2169480A GB2169480A GB08500085A GB8500085A GB2169480A GB 2169480 A GB2169480 A GB 2169480A GB 08500085 A GB08500085 A GB 08500085A GB 8500085 A GB8500085 A GB 8500085A GB 2169480 A GB2169480 A GB 2169480A
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- fibre
- diaphragms
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/20—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials
- G01N23/205—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by using diffraction of the radiation by the materials, e.g. for investigating crystal structure; by using scattering of the radiation by the materials, e.g. for investigating non-crystalline materials; by using reflection of the radiation by the materials using diffraction cameras
Abstract
A method for the non-destructive testing of fibre-reinforced composite materials by means of monochromatic X-ray examination and detector image formation in which the method comprises examining the structure by X-ray microstructure examination and determining its variation in position and form of X-rays 3 scattered in image formable reflections by the polycrystalline material as a measure of variations and internal stresses in the test piece 4. <IMAGE>
Description
SPECIFICATION
A method of non-destrictive testing of structural members
The invention relates to a method of non-destructivetesting of structural members offibre-reinforced composite materials by means of monochromatic
X-ray examination and detector image-formation.
Non-destructive methods of testing structural members comprising fibre-reinforced composite materials, by means of X-rays, are fundamentally known. In such methods oftesting, it was hitherto usual to detect the so-called macrostructure ofthese composite systems with X-rays. It is known that X-rays a rein a position to showvariationsin density in test pieces so that irregularities can thus also be discovered in composite materials.
In composite materials, however, the densities of the fibres and of the resin binder arse very similar so thatthe same mass disposition may result even with very different proportions of these structural components. An X-ray examination of the macrostructure therefore does not provide any results which can evaluate unambiguously and thus does not provide any unambiguous indexforthe integrity ofthe structural member examined.
The invention seeks to provide a method of X-ray testing forthe examination offibre-reinforced composite materials which provides measurement results which can provide unambiguous indications.
According to the invention, there is provided a method of non-destructive testing of structural members offibre-reinforced composite materials by monochromatic X-ray examination and detectorim- age-formation, wherein the method comprises ex amining the structure by X-ray microstructure examination and determining the variation in the positionandform of th e X-rays scattered in image formable reflections by the polycrystalline material as a measure of variations and internal stresses of the test piece.
The testing method according to the invention can provide unambiguous measurement resultsforthe structural members examined. The method of X-ray microstructure examination used in this case does not, as intheso-called macrostructure examination, evaluate the weakening of the X-ray by the mass ofthe object examined but evaluates the scattering (bend
ing) ofthe X-ray on the individual atoms of the
material.Thus the capacity of monochromatic X-ray
radiation to be scattered in reflections in polycrystal
line material is used to draw conclusions about variations and internal stresses in a test piece from the
reflection Position. Thusinthetype of microstructure
examination used in the present invention, the positions of the reflections produced by a fibre in a
composite system are used to obtain information
aboutthe orientation and the mass density ofthe
fibres which have a high orientation ofthe micropar acrystalsto the fibre axis as a result ofthe paracrystal
line attribute of their long chain molecule.
The term "paracrystals" used here describes a structural distortion wherein the external dimensions of a crystal remain unaltered buttheindividual vectors between adjacent unit cells can vary in size and direction provided that these cells are clearly defined, that is to say are not amorphous. Considered physically, a microparacrystal represent a special form of crystal, the lattice ofwhich contains a large number of randomly distributed imperfections of which each imperfection causes a local microdisplacement. Since both the fibres, for example carbon fibres, and the resin of a composite material have distinct paracrystalline characteristics, it is possible to use these characteristics forthe evaluation of X-ray microstructure examinations.
The invention will now be described in greater detail, byway of example, with reference to drawings, in which:
Figure 1 shows the principle of X-ray microstructure examination of unorientated crystallites;
Figure 2 shows a diagrammatic illustration of X-ray microstructure wide-angle examination of a microparacrystallite orientated into a fibre structure;
Figure 3 shows an image-formation of possible reflections of a carbon-fibre composite system; and
Figures 4 to 6 show three X-ray photographs from different test pieces.
In the illustration shown in Figure 1, the principle of
X-ray microstructure examination of "powder preparations" or of substances composed of completely unorientated crystal lites can be seen, which has become known undertheterm "Debye-Scherrer method". In this case, an X-ray tube 1 radiates an
X-ray3through a diaphragm 2, which ray radiates through a test piece 4 of composite materials to be examined and reproduces the lattice structure of the composite system as a diffraction image 6 on a film 5 disposed round the test piece. This diffraction image 6 can be recognized on the film 5 indicated below when uncoiled and developed.
In the principle of X-ray microstructure wide-angle examination according to the invention, illustrated in
Figure 2, on the other hand, it is a question of "fibrous materials". Here all the crystallites or microparacrys tallites have the same orientation with respect to a crystal axis lying in the fibre direction. With this method, the X-ray 3 penetrates through the bundle of fibres of the test piece 4 and then falls on thefilm 5 acting as a detector. In the course ofthis,thefilm reproduces the reflections 7, 8 resulting during the wide-angle scattering, which reflections showthatthe carbon fibres ofthe test piece 4 are orientated in the direction ofthe arrow 9.In a physical consideration of a test piece comprising composite material (CFK,
Kevlar, polypropylene), such composite systems represent paracrystalline structures which are more or less well orientated in the fibre direction, and at the lattice planes ofwhich the X-rays are reflected. In the case of composite materials with carbon fibres, the carbon atoms also produce ordered, unambiguous reflections, as a result of their associated chain moleculestructure,whiletheresin,asafiller,formsa randomly distributed mass of molecules which does not have any specific privileged direction and there fore only produces circular reflections 10 as indicated in Figure 2.
As can be seen from the illustration of Figure 3, the reflections of a carbon4ibre composite system examined may, for example, assume the positions reproduced in this figure. In this case, it is a question of the so-called 002 reflections ofthe carbon with different fibres and angular directions of a composite system and of the halo ofthe resin surrounding the fibres. The spacing b of two adjacent graphite lattice planes 002 of a composite system is related to the reflection dista nces from the zero point, which in first approximation are reciprocal tothe spacing bofthe lattice planes, that is to saythey are reproduced with a spacing b on an X-ray diagram. In the illustration shown in Figure 3, the reflections with the index 0 indicate fibres which lie in the verticals ofthe drawing plane.Reflections with the index 1,that is to say b a on the other hand, indicate fibres which are orientated perpendicularthereto.
In the case of these reflections, the position of the reflections may also fluctuate by + 5". The reflections with the index 2, that is to say b 2, indicate fibre orientations in the diagonal djrect:;n. 2y indicates the half width ofthe reflections inthetangential direc.ion.
It is a measure ofthe quality ofthe parallel orientation ofthe microparacrystals in the fibre direction and depends on the structure of a fibrel (individual fibre) and on the quality ofthe shift of the rod. h indicates the position ofthe resin without any orientation direction.
It is possible to draw conclusions about the nature of the fibre orientation in a structural member of composite materials examined, from the position of the reflections. In this case, the tangential half-width (half angley) ofthe g reflections is a measure of the quality of the fibre windings, thus a measure ofthe degree of orientation ofthe corresponding fibres.
During the examination offibre-reinforced composite materials, the following measuring effects can be found as well as the results which can be derived therefrom.
Measurement Effect caused by Evidence of 1 Intensity of the Number of , Number of fibres per reflection lattice planes unit of area dependent (microparacrystels) on type of fibre in the test piece (proportional) 2 Angle of the Position of the Position of the fibre reflection to normals.of the direction to the axis an axis of lattice planes to of symmetry of the symmetry of the the fibre axis test piece (winding teat piece direction) 3 Azimuthal Scattering of the Orientation of the width of the position of the fibres reflection - lattice planes 4 Radial spacing Lattice plane Rvpe of material of the spacing (sorts of fibre) reflections internal stress, purity 5 Radial width Paracrystalline Impurities; density of reflection disturbances and of internal surfaces, size of the miero- mechanical stability paracrystala 6 Halo of Randomly distribu- Thickness of layer metallic ted lattice planes and purity of the coatings of vapour-deposited protective coatings (aluminium) crystals 7 Halo of the Random masses of Genuineness of the sorts of molecules sorts of resin + type resin As the following illustrations show, various statements with regard to the test pieces examined can be made using this measuring technique. Thus Figure 4, for example, shows a halo which can be interpreted as an index of a resin system without fibres. The spot in the middle ofthe halo and the interruption of the halo resultfromthe lead diaphragm to mask the primary X-ray.
Figure shows the reflections of afibre-reinforced composite system and the orientation of the fibres on the basis of the reflections reproduced.
Figure 6 likewise shows reflectionsofafibre- reinforced composite system examined, with fibres orientated in a plurality of directions.
The method according to the invention therefore enables fibre-reinforced composite materials to be examined non-destructively by means of X-rays and enables the results of the examination to be interpreted satisfactorily. In this case, a source having a plurality of ray exit windows may be used for the
X-ray source, and the ray exit windows for the primary rays and the reflections may have different diaphragm shapes (triangle, circle, star, square, etc) adapted to the composite pattern in each case. An
X-ray film may be used as the detector with the possibility of masking certain reflections or parts of reflections by diaphragms for checking purposes.
Electronic and/or scintillation counters provided with preceding special diaphragms and able to be positioned appropriately may be used, with recording devices, as detectors. These special diaphragms may also be aligned in the direction ofthe bundles of fibres, for example in the form of sI its, in order to achieve greater intensities. It is also possible, however,to providethedetectorswhichcan be positioned with automatic focussing devices to align the detectors in positions of maximum X-ray intensity.
In anotherform of embodiment, the test piece and the detector system may be moved in relation to one another while in a furtherform of embodiment a test piece consisting of composite material can be conveyed past a stationary detector orfilm, using a stationary X-ray source in order to test the total quality of the test piece.
When the method according to the invention is used fortubulartest pieces, these may be rotated continuously about their longitudinal axis in order to testthe uniform coverage ofthewound composite fibres as to their cross-sections and/ortheirtotal number. In this case, the tubulartest pieces may be moved pasta stationarydetectorwith a helical and/or meandering movement, the X-ray tube being situated at one side and the detector at the other side of the test piece. In the case of an X-ray tube constructed in rod form, it is also possible to dispose this inside a tubular test piece.
The evaluation ofthe measurements can be affected in continuous operation by simultaneous measurement of a plurality of, but at least two, reflections in an electronic differential circuit. In this case, it is also possible to record two base reflections (002) of a carbonfibre orof a polymerfibreusinga narrower and a wider diaphragm in a differential connection and to regard the difference in width resulting parallel to the fibre as information regarding the quality of the degree of orientation ofthe microparacrystals inside a fibre strand. In this connection,the difference in width ofthe diaphragms may be perpendicularto the fibre direction ofthetest piece and provide information about the size and lattice imperfections ofthe microparacrystals ofthe fibres.Two reflections of different fibre strands detected in a differential circuit may also count as information with regard to the constancy ofthefibre thickness or fibre strength on the basis of the mass of the microparacrystals in each thread cross-section.
Apart from evaluating the fibre thicknesses, the fibre direction and laying quality, it is also possible to record the proportion of randomly distributed molecules, particularly of fillers or binders, by a stationary measurement with an X-ray film or by adjustment of the counting apparatus used to the halo in question and to carry out an evaluation, for example by means of photometric evaluation. By this means, it is also possible to obtain information about the quality of the filler, for example resin.
In a further development of the invention, it is also possible to replace the recording device by an alarm device which releases a signal when a tolerance value of the measured quantities or differential quantities is exceeded. The alarm device may also have a device for position marking associated with it in orderto mark the positions on the test piece at which the alarm is activated during continuous checking.
The method according to the invention has a special application to composite fibre materials but it can also be usedfortesting vehicle tyres, particularly for testing the tyre carcases.
Claims (22)
1. A method of non-destructive testing of structural members offibre-reinforced composite materials by monochromatic X-ray examination and detector image-formation, wherein the method comprises examining the structure by X-ray microstructure examination and determining the variation in the position and form of the X-rays scattered in imageformable reflections by the polycrystalline material as a measure ofvariations and internal stresses ofthe test piece.
2. A method as claimed in Claim 1, wherein an X-ray source is used having a plurality of ray exit windows and the ray exit windows forthe primary rays and the reflections have different diaphragm shapes adapted to the composite pattern in each case.
3. A method as claimed in Claim 2, wherein the shape ofthe diaphragms are triangular, circular, star shaped or square.
4. A method as claimed in Claim 1,2 or 3, wherein an X-ray film is used as the detector and diaphragms are used to mask certain reflections or parts of reflectionsforchecking purposes.
5. A method as claimed in Claim 1,2 or3,wherein detectors are used which comprise electronic and/or scintillation counters, which can be appropriately positioned, have special preceding diaphragms and have recording devices associated therewith.
6. Amethod as claimed in Claim 5,whereinthe special diaphragms are aligned in the direction of the
bundles offibres in order to achievegreaterintensi- ties.
7. A method as claimed in Claim 6, wherein the special diaphragms are in the form of slits.
8. A method as claimed in any one of the Claims 1 to 7, wherein detectors which can be variably positioned are used, the detectors having automatic focussing devices for aligning the detectors in positions of maximum X-ray intensity.
9. A method as claimed in Claim 8, wherein a test piece comprising composite material is moved relative to a detector orfilm associated with an X-ray source,fortesting the quality ofthe whole object
10. A method as claimed in Claim 9, wherein the test piece is conveyed past a stationary detector or film and associated stationary X-ray source.
11. A method as claimed in any one of Claims 1 to 9, wherein the test-piece and detector system are moved continuously.
12. A method as claimed in any one of Claims 1 to 9,whereintubulartest-pieces are rotated continuously about a longitudinal axis to testthe uniform coverageofthewound compositefibresastotheir cross-section and/ortheirtotal number.
13. A method as claimed in any one of Claims 1 to 12, wherein a tubulartest piece is moved pastthe stationary detector with a helical and/or meandering movement andthe X-raytube is situated at one side of the test piece and the detector is situated at the other side ofthe test piece.
14. A method as claimed in Claim 12 or 13, wherein the X-ray tube is rod-shaped and is disposed insidethetubulartest piece.
15. A method as claimed in any one of Claims 1 to 14, wherein a plurality of reflections are measured
and evaluated simultaneously in an electronic differential circuit, in continuous operation.
16. A method as claimed in any one of Claims 1 to
14, wherein two base reflections (002) of a carbon fibre ortwo base reflections (110,200) of a polymer fibre are recorded with narrower and wider diaphragms in a differential connection whereby the difference in width existing paralleltothefibre provides information concerning the quality ofthe degree of orientation of the microparacrystals inside a fibre strand.
17. A method as claimed in any one of Claims 1 to 15, wherein two base reflections (002) of a carbon fibre orthe base reflections (110,200) of a polymer fibre are recorded with two diaphragms, one ofwhich is narrower and the otherofwhich is wider perpen diculartothefibre direction, in a differentiai connection whereby the difference in width provides information regarding the size and lattice imperfections ofthe microparacrystals ofthe fibres.
18. A method as claimed in any one of Claims 1 to 16,wherein two reflections of differentfibre strands detected in a differential circuit provide information with regardtotheconstancyofthefibrethicknessor fibre strength on the basis ofthe mass ofthe microparacrystals in each thread cross-section.
19. A method as claimed in any one of Claims 1 to 16,whereinthe proportion of randomly distributed molecules,such asfillersor binders is recorded by stationary measurement with X-ray film or by adjusting acounting apparatustothe halo in question and an evaluation which can be carried out by means of photo-metric evaluation renders possible a statement of quality of the particularfille binder etc.
20. A method as claimed in any one of Claims 1 to 19, wherein the recording device is replaced by an alarm device which produces a signal when a tolerance value ofthe measured quantities or differential quantities is exceeded.
21. A method as claimed in Claim 19, wherein the alarm device has a device for position marking associated with it in orderto mark the positions on the text piece at which the alarm was activated during continuous checking.
22. A method of non-destructive testing of structural members of fibre reinforced composite materials substantially as described herein with reference to the drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08500085A GB2169480B (en) | 1985-01-03 | 1985-01-03 | A method of non-destructive testing of structural members |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08500085A GB2169480B (en) | 1985-01-03 | 1985-01-03 | A method of non-destructive testing of structural members |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8500085D0 GB8500085D0 (en) | 1985-02-13 |
| GB2169480A true GB2169480A (en) | 1986-07-09 |
| GB2169480B GB2169480B (en) | 1988-12-07 |
Family
ID=10572353
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08500085A Expired GB2169480B (en) | 1985-01-03 | 1985-01-03 | A method of non-destructive testing of structural members |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2169480B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6907107B1 (en) | 1999-03-16 | 2005-06-14 | Qinetiq Limited | Method and apparatus for the analysis of material composition |
| US8617310B1 (en) | 2005-03-09 | 2013-12-31 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and a second region of a superabrasive volume |
| US8969833B1 (en) | 2011-12-16 | 2015-03-03 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and a second region of a superabrasive volume |
| FR3011321A1 (en) * | 2013-09-27 | 2015-04-03 | Airbus Operations Sas | METHOD FOR CONTROLLING A LOT OF MATERIAL USED TO OBTAIN FIBER LAYERS INTENDED FOR THE MANUFACTURE OF A COMPOSITE MATERIAL PART |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1119511A (en) * | 1964-10-12 | 1968-07-10 | Exxon Research Engineering Co | Elimination of the preferred orientation distortions of an x-ray diffraction pattern |
| GB1255644A (en) * | 1968-05-10 | 1971-12-01 | Rolls Royce | Method of determining the value of a mechanical property or properties of a fibre |
| GB1390710A (en) * | 1973-02-20 | 1975-04-16 | Rigaku Denki Co Ltd | X-ray diffraction instrument |
| GB2007479A (en) * | 1977-10-28 | 1979-05-16 | Born E | Method of and apparatus for preparing texture topograms |
| EP0034035A2 (en) * | 1980-02-05 | 1981-08-19 | The Commonwealth Of Australia | X-ray diffraction camera |
-
1985
- 1985-01-03 GB GB08500085A patent/GB2169480B/en not_active Expired
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1119511A (en) * | 1964-10-12 | 1968-07-10 | Exxon Research Engineering Co | Elimination of the preferred orientation distortions of an x-ray diffraction pattern |
| GB1255644A (en) * | 1968-05-10 | 1971-12-01 | Rolls Royce | Method of determining the value of a mechanical property or properties of a fibre |
| GB1390710A (en) * | 1973-02-20 | 1975-04-16 | Rigaku Denki Co Ltd | X-ray diffraction instrument |
| GB2007479A (en) * | 1977-10-28 | 1979-05-16 | Born E | Method of and apparatus for preparing texture topograms |
| EP0034035A2 (en) * | 1980-02-05 | 1981-08-19 | The Commonwealth Of Australia | X-ray diffraction camera |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6907107B1 (en) | 1999-03-16 | 2005-06-14 | Qinetiq Limited | Method and apparatus for the analysis of material composition |
| US8617310B1 (en) | 2005-03-09 | 2013-12-31 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and a second region of a superabrasive volume |
| US9453802B1 (en) | 2005-03-09 | 2016-09-27 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and a second region of a superabrasive volume |
| US8969833B1 (en) | 2011-12-16 | 2015-03-03 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and a second region of a superabrasive volume |
| US9423364B1 (en) | 2011-12-16 | 2016-08-23 | Us Synthetic Corporation | Method and system for perceiving a boundary between a first region and second region of a superabrasive volume |
| FR3011321A1 (en) * | 2013-09-27 | 2015-04-03 | Airbus Operations Sas | METHOD FOR CONTROLLING A LOT OF MATERIAL USED TO OBTAIN FIBER LAYERS INTENDED FOR THE MANUFACTURE OF A COMPOSITE MATERIAL PART |
| US9417167B2 (en) | 2013-09-27 | 2016-08-16 | Airbus Operations S.A.S. | Method for testing a batch of material used for obtaining layers of fibres intended for manufacturing a composite material component |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2169480B (en) | 1988-12-07 |
| GB8500085D0 (en) | 1985-02-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |