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Page|1 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
L A B O R A T O R Y L E A R N I N G A C T I V I T Y
Compositematerials
IntroductionToday’sLaboratoryunpackshowcompositematerialscanresponddifferentlytounbalancedforces.
VictorianCurriculumOutcomeChangetoanobject’smotioniscausedbyunbalancedforcesactingontheobject;Earth’sgravitypullsobjectstowardsthecentreofEarth(VCSSU103)
Checkouttheracingcarandsurfboard
GiedovanderGardedrivingtheCaterhamCT03atSepangInternationalCircuit.
AsurferattheCayucosPier,Cayucos,California.
Photo:"Mike"MichaelL.Baird.https://commons.wikimedia.org/wiki/File:Giedo_van_der_Garde_2013_Malaysia_FP1.jpg
https://commons.wikimedia.org/wiki/File:Surfer_at_the_Cayucos_Pier,_Cayucos,_CA.jpg
Page|2 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Whatcouldbethesamebetweenthematerialsusedamodernracingcarandsurfboard?(Hint:focusonthehoweachismade(manufactured).)
Thecarandsurfboardaremadefromlightmaterials,yetmadestrong.Thisallowsforshapingandrigidity.
CompositeMaterialsAcompositematerialismadefromtwoormorematerials,eachwithdifferentphysicalorchemicalproperties.Butwhencombined,thewholecompositehaspropertiesthataredifferentfromtheindividualmaterials.
Somecompositematerialsaremixtures,likecements,concrete,imitationgraniteandculturedmarblesinksandcountertops,andmetalalloys.
Somecompositematerialshaveonematerialembeddedinsidetheothermaterial,forexample,fiberglass,concretewithsteelreinforcement,andmudbrickswithstrawreinforcement.
Somecompositematerialshavetheindividualmaterialsinseparateanddistinctlayers.
Scientistsandengineersaredevelopingnewcompositematerialsbecausetheycanbestronger,lighter,orlessexpensivewhencomparedtotraditionalmaterials.
KeyideasForce–apushorapull
Compressionforce–apushthatsqueezesanobjecttotrytomakeitsmallerorshorter.
Tensionforce–apullstretchesanobjecttotrytomakeitbiggerorlonger.
Page|3 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
AimThecompositematerialsactivityenablesyoutoexperienceandinvestigatethewaycombiningthepropertiesoftwomaterials(polystyreneandgaffertape)canresultinaparticulartypeofcompositematerial.Thepropertiesofthecompositeareverydifferentfromthepropertiesoftheoriginal.Intheprocess,youwilllearnabouttensionandcompressionforces.
Whydowemakecompositematerials?
Thesestructuresarestrongerandlighter.
(Note: this question and answer is to test the students’ understanding of theinformationthathasbeenpresentedtothem.)
Considerthesimilaritybetweenthesetwopictures
Abacon,lettuceandtomatosandwichontoastedbread.
Photo:StevenGrovesfromDenver(CO),USA.
GlassAluminumReinforced(GLARE)honeycombcompositesandwichstructure.
Photo:NASA.http://en.wikipedia.org/wiki/Sandwich#/media/File:BLT_sandwich_on_toast.jpg
http://ballistics.grc.nasa.gov/Photographic%20Data/Images/glare_honeycomb.jpg
Page|4 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Howdoyouthinksandwichcompositematerialsaremade?
Layersofmaterialsare“glued”together.
YourchallengeTodayyouareascientistwhohasbeenpaidtodesignastrongercompositeproductforaslittlecostaspossible.Thefollowingdemonstrationistoprepareyouforthetask.
Part1:Demonstrationoftheeffectivenessofsandwichstructures
Thingstonotefromthedemonstration:
• Apolystyreneplankisnotverystrong.(Footnote1)
• Whenadditionalmaterialsarelayeredontothepolystyreneitbecomesacompositematerialanditspropertieschange–itbecomesstronger.
1 Styrofoamisaparticularbrandnameforpolystyrene.
Page|5 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Drawandlabeltheequipmentandwhathappened.
(etcetra)
Part2:Comparisonofthreeproducts:polystyreneonitsownand2compositematerialswithdifferentstructures
Thinkaboutthedemonstrationyouhavejustseen.Canyouthinkoftwodifferentwaysofmakingsandwichcompositestructuresusingthematerialsandequipmentavailabletoyou?
Manypossibleanswershere.Someinclude:
• Puttingtapeonbothtopandbottom
• Puttingtapeonlyontop
• Puttingtapeonlyonbottom
• Usingpartialstripsoftape,etc
Page|6 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Re-dothedemonstrationwithyourgroup.Youwillneedtoworkoutawayofmeasuringtherigidityorhowmuchbendingthereisforeachindividualweightadded.Talkwithyourpartnertodecidehowyouwillmeasuretheamountofbendingandhowyouwillrecordthedatainanappropriatetablebelow.Yoursupportstructuresneedtobe21cmapart(Footnote2).
Recordthedatainanappropriatetabletoshowthedifferencebetweenthepolystyreneandthecompositematerialstructures1and2.
Sometypicaldata
load(g)
bendingnotape(mm)
bendingtapetopandbottomfullwidth
bendingtapebottomandhalftop
0 0 0 0300 3 0400 5 0500 6 2 0600 8 2 1700 14 2 2750 50 2800 (break) 2 3900 3 4
1000 4 61100 6 71200 7 81300 10 91400 13 101500 13 121600 14 14
load(g)
bendingnotape(mm)
bendingtapetopandbottomfullwidth
bendingtapebottomandhalftop
1700 14 161800 15 221900 15 242000 16 262100 20 302200 20 322300 21 352400 22 (break)2500 222600 232700 242800 502900 (break)3000
2 21cmhasbeenchosenbecauseiotisthewidthofanA4cpageandiseasytosetup.Ifyouwish,youcouldusesomeotherseparationdistance.
Page|7 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Graphthedatatoshowthedifferencebetweenthepolystyreneandthecompositematerialstructures1and2.(Hint:putallthedataonasinglegraph.)
0
10
20
30
40
50
60
0 500 1000 1500 2000 2500 3000 3500
defle
ction(m
m)
massloadedontostructure(g)
Deflectionversusload
Page|8 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Describeinwordswhatwasrevealedthroughthedataanalysisofthegraph.
The graph shows the typical deflection of the polystyrene (vertical axis) as load(weights,horizontalaxis)areappliedtothecentreofthepolystyrene.
The left-hand-mostdataare forpolystyrenewithnotape.The lastdatapoint isat750g.Thepolystyrenebrokewithaloadof800g.
Theright-hand-mostdataareforpolystyrenewithfull-widthtapeonthebottomandtop.Thelastdatapointisat2800g.Thepolystyrenebrokewithaloadof2850g.
Part3:AnalysisofforcesRoofsandbridgeshavetospanlargegapswhilesupportingmassiveweight.
Considerthebridgebelow.Theschematicdiagramfollowingisofasimilarlydesignedbridge.
Steelframetrussbridge,locatedontheSouthernHighway,Belize,CentralAmerica.
Photograph©JohnReid&Sons(Strucsteel)Ltd.http://www.steel-bridges.com/under-truss-bridge.html
Steelframetrussbridgedesign.Theconcretedeckandthesteelstrussesformacomposite
structure.Diagram©JohnReid&Sons(Strucsteel)Ltd.
Page|9 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
http://www.steel-bridges.com/under-truss-bridge.html
Considertheroof/ceilingbelow.Theschematicdiagramfollowingisofasimilarlydesignedroof.
Compositetrussroof,TahoeRidgeHouse,California.Photograph©WADesignInc
http://www.wadesign.com/newbuilding#/tahoe-ridge-house/
Simplecompositetrussroof
Alltheseroofsandbridgeshaveoneelement(orpart)thatspansthetopofthestructureandoneelementthatspansthebottomofthestructure.
Page|10 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Canyourepresentthemainforcesthatyouthinkareactingonthesetwoelementsofthestructures?
Howmanyelementsspanyourpolystyrenestructure?Whydoyouthinkthepolystyrenestructureisrelativelyweak?
Thepolystyrenestructureonlyhasasingleelement.
Somestudentsmightrealizethatthetopofthepolystyrene isundercompression,whilethebottomisundertensionasweightisapplied.
Howmanyelementsspanyoursandwichstructure?Canyourepresentwhyyouthinkthesandwichstructureworkstoalterthestrengthandrigidity?
Effectivelyonly2elementsspanthesandwichstructure.
Thetapeonthebottomisundertensionasweightisapplied.
Like the roof andbridges, the (mostly) toppolystyrene is under compression. Thetapeonthetopiseffectivelydoingnothing.
Page|11 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Whatistheroleofthetapeandwhatpropertiesmakeitworkwell?
Thetapeprovidesthefibreandagluetofusethelayeredsandwichmaterials.Thetapeisstrongundertension.
Wouldonepieceoftapeaboveorbelowthepolystyrenebeaseffectiveastwopiecesoftapeinabridgestructure?
Onepiecebelowisallthatisneeded. Thetoplayeris ineffectiveat increasingthestrengthofthelayeredstructure.Thebottomlayercouldbereducedtoanoptimalamount(ofstrengthforcost).
Page|12 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
Discusswithyourteam,howacompositematerialmightbeusedinboathulls,swimmingpools,racecarbodies,surfboards,spacecraftandaircraft.Canyourepresentwhyyouthinkan“open-sandwich”structure(similartotapeonlyononesideofthepolystyrene)wouldperformbetterorworsethanaregularsandwichstructure(similartotapeonbothsidesofthepolystyrene)?
Inabridge,thegravitationalforcesactdownward.Hencethebottomlayerisalwaysunder tension, and putting tape on the top does nothing as the top layer alwaysundercompression.
However,inboathulls,swimmingpools,racecarbodies,surfboards,spacecraftandaircraft,panelsarebeing flexed: forcespushagainst thepanels inbothdirections.Hencethereinforcinglayerisneededonbothsides.
Part4:ChallengeYourjobasaScientististocreateastrongercompositematerialusingtheleastamountofmaterial(polystyreneandtape)toreducecost.
Workwithyourgrouptodesigntostrongestsandwichstructurecompositematerialusingtheleasttape.Testeachdesignforstrengthandrigiditytodecidethebestdesign.
Decidehowyouwillcollectyourdataforeachtrialandproduceareportthatdescribesthedesignthatworksbest.Includeevidence(data)andanexplanationastowhy(usingdiagramsandwords).
Page|15 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
CopyrightandCreativeCommonsExceptinglogos,trademarksorotherthird-partycontentasindicated,thisresourceisdistributedunderaCreativeCommons‘Attribution-NonCommercial-ShareAlike’4.0InternationalLicense.
• PhotographofGiedovanderGardedrivingtheCaterhamCT03atSepangInternationalCircuithasbeenusedandredistributedunderaCreativeCommons(CCBY-SA3.0)licence<creativecommons.org/licenses/by-sa/3.0/deed.en>.
• PhotographofasurferattheCayucosPier,Cayucos,California,hasbeenusedandredistributedunderaCreativeCommons(CCBY2.0)licence<commons.wikimedia.org/w/index.php?curid=10682743>bypermissionofMichaelL."Mike"Baird.
Page|16 Sampleanswers–Compositematerials–RemSTEP(DeakinUniversity)
• Photographofabacon,lettuceandtomatosandwichontoastedbreadhasbeenusedandredistributedunderaCreativeCommons(CCBY2.0)licence<creativecommons.org/licenses/by/2.0/deed.en>bypermissionofStevenGrovesfromDenver(CO),USA.
• PhotographofGlassAluminumReinforced(GLARE)honeycombcompositesandwichstructurehasbeenusedandredistributedunderaneducationalnon-commerciallicencebypermissionofNASA.
• PhotographsanddiagramsoftrussbridgeshavebeenusedandredistributedunderaCreativeCommons‘Attribution-NonCommercial-ShareAlike’4.0InternationalLicensebypermissionofJohnReid&Sons(Strucsteel)Ltd(UK).
• PhotographoftheTahoeRidgeHousehasbeenusedandredistributedunderaCreativeCommons‘Attribution-NonCommercial-ShareAlike’4.0InternationalLicensebypermissionofWADesignInc(USA).
Themoralrightsoftheauthors,StuartPalmer,IanBentley,KieranLim,PetaWhite,JohnLong,RussellTytler,andMaryVamvakas,havebeenassertedundertheAustralianCopyrightAct1968(Cth).