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Show Keeping Up Upcien Upf UpI UpO Upc f I cien cienfcdeuco O c n erv e eQ Q : . fcdeuco .clellCO clellCO cieuee Survlco Service ServicewU s rvlco -w\U w U - WNU 'VU 'V\ 'V V ' ' \ U SerMc Semite Scr\ Scr ScrIce \ Ice . * . , "Fingerprints Fingerprints " " ofMetals of o oMetals Mctals Metals Used to toFailure toForecast Forecast Failure FailureXRay ForecastXRay X-Ray X Ray - Test Will WiII Show Shoe Showthe ' the "Lane Lane "Laue Laue " Pattel Pattein Pattern n " Cleveland , OhioHow Ohio-How Ohio How Ohio -How How - How sci- sci science science sci science - ence is studying tlie the X-iay X iay X-lay lay X-ray ray - "fin fin "fin- "fingerprInts "fingerprints "fingerprints " - gerprints " of metals in the hope hopeof hopeof hopeof of being able to forecast theIfallure thefailure the thefailure failure Ifallure ! of airplane propellers propellersand propellersand propellersand and other metal structures was wasdescrIbed wasdescribed wasdescribed descrIbed at a meeting of the theIAmencan theAmerican theAmerican IAmencan American ( ! Society of Metals Metals'here Metals'here Metals'here Metalshere 'here here ' by Dr . Charles S Barrett Barrettof Barrettof Barrettof of the department of metallurgy metal metal- metalI metal.Iurgy metallurgy - I , lurgy .Iurgy Iurgy . of Carnegie C1.rncglc C1rncglc . Institute of ofTechnology ofTechnology ofTechnology Technology , Pittsburgh , Paw PawWIUun Pa . Within WIUun some 1m limits ts , explained explamed Dr Dr.Barrett DrBarrett . Barrett , it is now possible to e ex- ex examine ex examine - - amine amme by X Xra ra rays } s a piece of metal metalsuspected metalsuspected metalsuspected suspected of fatigue and possibleImpending possIble possIblefmpendmg possibleimpending fmpendmg impending failure , and obtain obtam some someidea someidea someidea idea of the internal mternal damagehich damage \\hich hich which whichhas \ whichhas \ hichhas has already occurred in ItlIow ithow it itHow How lIow the Test Tcst " florks "orks orks Works . , A specimen piece of metal from froman froman froman an airplane propeller ( for example exampleis ) is placed in front of an X ray tube tubeand tubeand tubeand and the piercing plercmg X radiation passed passedthrough passedthrough passedthrough through it The little hlUe metal crys crys- crystals crystals crys- crys crystals - - tals bend the X Xra ra rays ) s into a design designnamed designnamed designnamed named the Laue pattern a after ter their theirfamous theirfamous theirfamous famous European discoverer The Thepattern Thepattern Thepattern pattern , characteristic for each eachmetal eachmetal eachmetal metal , , , looks loohs like .e e l . rings rUlgs of tiny tmy spots spotsarranged spotsarranged spotsarranged arranged m In cIrcles1th circles \ with \\1th 1th \ somewhat somewhatthe somewhatthe somewhatthe the appearance of tree rmgsFresh ringsFresh rings rmgs ringsFresh Fresh new metal . which V.hlCh VhlCh nhich has hasnever hasnever hasnever never been stressed in m actual use useshows , shows one kind of Laue X ray pat pat- pattern pattern pattern - tern and a similar piece of ot the met met- metal metal metal - al , , except that it has been muse museill in use usewill , \\ill ill will \ \ show a slightly different pat pat- pattern pattern pattern - tern ternThis ternTlus ternThus This Tlus Thus change m in the X ray "finger finger "finger- "fingerprmts "fingerprints "fingerprints " - prints prmts " of metals with age is qUite qUitedlfferent quitedifferent quitedifferent dlfferent different from what happens to hu- hu human human hu human - - man fingerprints fingerprmts From ! infancy 1llancy to toold toold toold old age the pattern of fingerprmts fingerprints fingerprmtsremams fingerprintsremains fingerprintsremains remams remains unchanged and this is the thebasIs thebasis thebasis basIs of their use in m identification identificationand identificationand and police pollce workj workComprlson workComparison work j , Compinson Comp\rlson Comp rlson Comparison ' \ Is Necessary . Where it is possible posslble to have test testsamples test testsamples testsamples samples of metal in the laboratory laboratoryand laboratoryand laboratoryand and have on record an X ray pat pat- pattern pattern pattern - tern for vaI'j vaIj vary varying ' Ing lengths of metal metalWe metallife metallife We life and fatigue , the state of an- an another another an another - other piece of metal can roughly roughlybe roughlybe be compared , said Dr BarrettIn BarrettIn Barrett BarrettIn In theory at least , it If a piece of ofmetal ofmetal ofmetal metal broke after 2 000 000 flexmgswith flexmgs flexings flexmgsWlth flexingswith Wlth with a load of 29,000 29000 , , pounds to the thesquare thesquare thesquare square inch , and showed a charac charac- characterIstic characteristic characteristic - - teristic pattern , it \ would ould be possi POSSI- POSSIble possible possible - ble to tell roughly roughlj how near an- an another another an another - other piece of similar metal metal-used metal used metalusedm - usedin m an airplane propeller-might propeller might propeller - might beto beto be to fracture and failure . |