1、A.E.C.M.A. STANDARDNORME A.E.C.M.A.A.E.C.M.A. NORMDRAFTprEN2155-8Edition 1March HJaOENG L1SH VERSIONTEST METHODSFOR TRANSPARENT MATERIALSI=OR AIRCRAFT GLAZINGPART 8 DETERMINATION OF OPTICAL DISTORSIONAEROSPACE SERIESThe text of this standard, which exists in three equivalent versions English, French
2、, Gem18n has been drawnup under the responsibility of AECMA Association Europeenne des ConstlVcteurs de Materiel A6rospatia/ andhas been circularad to Official Services. Any reselvations expressed by OffIcIal ServIces and not resolved in thIsIssue, have beon incorporated in the history sheot which h
3、as accompanIed this prEN to CEN.ItIs publislwe on yeltow paper “s a draft European Standard intended to receivo, under the sam 0 presentation and,1ccording to its own rutes, the approval of CEN (European Committee for Standardization).LUFTUND RAUMFAHRTPRUFVERFAHRENFUR TRANSPARENTE WERKSTOFFEZUR VERG
4、LASUNG VON LUFTFAHRZEUGENTElL 8-BESTIMMUNG DER OPTISCHEN VERZERRUNGMI:THODES DESSAISPOUR MATt:RIAUX TRANSPARENTSPOUR VITRAGES AERONAUTIOUESPARTIE 8-DETERMINATION DE LA DISTORSION OPTIOUESERlE AEROSPATIALE1:;o.0gjI-l0J)ocr“-lUJCl:1If UJo(f)cr:JUJf- U:Jcr.liizoUrnuQu,ZZIIIill0oa:lUlZot:io:J0:Ul-eiuJAp
5、provod byCOM1Tf: DE NORMALISATIONof A.E.C.M.A. 7907-31JJEhe equivelent version. in French end Germon language. cnnbe supplied bV R.N.A.E 8. rue MoreauVauthier92100 ElOULOGNE-SIl.LANCOURT r-nANCE.-_._-prEN21SS-8 Page 2CONTENTS1 SCOPE AND FIELD OF APPLICATION2 REFERENCES3 DEFINITIONS4AlPARATUS5 SPECIM
6、ENS6 PROCEDURE7 EXPRESSION OF RESULTS8 TEST REPORTprEN2155-8 Page 3DRAfTEUROPEAN STANDARDAEROSPACE SERIESprEN2I.55-8TEST HETHODSFOR TRANSPARENT HATERIALSFOR AIRCRAFT GLAZINGPART 8 - DETERMINATIONOF OPTICAL DISTORTIONI SCOPE AND FIELD OF APPLICATIONThis standard specifies the method of measurement of
7、 optical distortion whichconsists of determining the change of deviation over the entire area of themater.ial. The method allows material to be vieved at differing angles which nrespecified according to the quality of the sheet under test.2REPERENC1SEN2l55-6, Test methods for transparent materials f
8、or aircraft glazing. Part 6 Determination of optical defects.3 DEFINITIONSOptical distortion is defined as local variation of optical deviation whichresults in distortion of the image perceived on viewing through the panel,ThuB known straight lines become crooked or curved,if APPARATUSA grid board h
9、aving line spacing of 25 mm is mounted vertically.A graticule having a system of equally spaced lines in two directions at 90 toeach other is designed to be used vith a suitable lantern projector so that at adistance of 4,5 m the projected image can be made coincident with the grid board,To avoid di
10、stortion of the image measurement shall be restricted to a square about1 x 1 m at the grid board. An iris diaphragm may be useful to reduce the apertureof the lems. The specimen shall be mounted so that the area being examined is 1,2 mfrom the grid board, The mounting arragement shall allow the spec
11、imen to be placedat varying inclination to the horizontal plane,5 SPECUlENSFor the purpose of tllis standard, the specimens are entire sheets,Theenti:esurface of each specimen shall be carefully cleaned avoiding scratchingor C1I1Z1.:1g.6 PROCEDUR;:6.1 Maximum gradientWith the specimen mounted at the
12、 specified viewing angle, the maximum gradientof the projected image with respect to the grid board lines in botl1 directionsshall be asseRsed.The specimen shall be rotated 90 in its own plane and the same assessmentrepeated. In cases of doubt the image of the defect shall be brought to theoptical a
13、xis of the apparatus and projector adjustments made to overcome lineshift due to displacement,prEN2155-B Page 46.2 Sharp discontinuitiesSharp discontinuities in the projected image shall be measured asindicated in figure 1FIGURE 1NOTE The examination for sharp discontinuities, typically shownin figu
14、re 1 is necessary in addition to the examination formajor and minor defects in EN21S5-6 since inhomogenitiesresulting in change of refractive index may not show up inEN2l55-6.7 EXPRESSION OF RESULTSThe gradient in each area of distortion shall be expressed as a slope eg 1 in 17;sharp discontinuities
15、 shall be expressed as measured as displacement in mm.8 TEST REPORTAt each of the specified viewing angles as specified in the material standard,the number of occasions when the gradient is steeper than the agreed limitsshall be reported; likewise the number of occasions when the discontinuity “eYexceeds the specified limit shall be reported,
