Development of press forming techniques for thermoplastic composites

127 Pages·2017·5.22 MB·English

by  Francisco Saraiva

Development of press forming
techniques for thermoplastic
composites
Investigation of a multiple step
forming approach
Francisco Saraiva
MSc Thesis in Aerospace Engineering
Structural Integrity & Composites

Development of press
forming techniques for
thermoplastic composites
Investigation of a multiple step forming
approach
by
Francisco Saraiva
toobtainthedegreeofMasterofScience
attheDelftUniversityofTechnology,
tobedefendedpubliclyonFridayMarch17,2017at01:30PM.
Studentnumber: 4413725
Thesiscommittee: Ir.J.Sinke, TUDelft,Supervisor
Dr.ir.R.C.Alderliesten, TUDelft,Chairman
Dr.ir.O.K.Bergsma, TUDelft
Dr.ir.J.M.J.F.vanCampen, TUDelft
Anelectronicversionofthisthesisisavailableathttp://repository.tudelft.nl/.

Summary
Thermoplasticcompositesareveryattractiveforaerospacestructuresduetotheirhighspecificstrength
andstiffness,enhancedtoughnessandhightemperatureresistance. Oneofthemanufacturingmeth-
odsusedtoproducethermoplasticcompositepartsispressforming.Pressformedpartstypicallyhave
constantthicknessandfibreorientation. However,compositepartsmaybeoptimizedbytailoringthe
stiffnessandstrength,therebyreducingstructuralweight. Inthisthesis,theprocessingtechniquesfor
thismanufacturingmethodweredevelopedbyinvestigatingthefeasibilityofamultiplestepforming
approachfortheproductionofpartswithvariablethicknessandfibreorientation.Thismanufacturing
approachwasprovenfrombothaformabilityandstructuralintegrityviewpoints.Byusinganefficient
blankholdersystemwithclampsandsprings,thermoplasticcompositelaminatescanbemultiplestep
formedintothree-dimensionalshapeswithnooccurrenceofvisualformingdefectssuchaswrinkling,
fibre buckling or ply folding. Furthermore, good quality bonds can be achieved between laminates
formedandco-consolidatedindifferentsteps. ToachieveahighdegreeofbondingbetweenGF/PEI
composite laminates, the co-consolidation process window was estimated to be between 270ºC and
300ºC.Theuseofapost-consolidationstageinahotpresswasneededtoimprovethedegreeofbond-
ing between co-consolidated laminates formed in different steps, which led to very long production
cycle times. For future research, the maximum temperature limit of the metal mould should be in-
creasedandtoolingactivecoolingmechanismsmustbeincorporatedtoallowthemouldtoberapidly
cooleddown,therebydecreasingproductioncycletimes. Withtheseimplementations,abetterinsight
onthefeasibilityoftheprocessinanindustrialenvironmentmaybegained.
iii

Contents
ListofFigures vii
ListofTables xi
ListofAcronyms xiii
ListofSymbols xv
1 Introduction 1
1.1 ResearchQuestions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 ThesisOutline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 LiteratureReview 5
2.1 DeformationMechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.1 Intra-plyshear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1.2 Fibrestraightening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 Inter-plyslippage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.4 Tool-plyslippage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.5 Resinpercolation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.1.6 Transversesqueezeflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2 Processvariants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1 Matcheddieforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.2 Rubberforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.3 Diaphragmforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3 Formabilityofthermoplasticcomposites . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.4 Processinduceddeformations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5 Effectsofstampinginmaterialmechanicalandphysicalproperties. . . . . . . . . . . . . 14
2.6 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3 DesignoftheExperimentalSetup 17
3.1 Experimentalsetupassemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1.1 Rig. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1.2 Blankholder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.1.3 Pressassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2 Designchoicesandconsiderationsofthepressassembly . . . . . . . . . . . . . . . . . . 21
3.2.1 Extensioncylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2.2 Topmountingplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2.3 Rubbermouldandrubbermouldbox. . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.2.4 Metalmould . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.5 Constrainingblocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.6 Bottommountingplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.2.7 Heatingplate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.3 Overviewofthepressassembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4 MultipleStepFormingofGF/PEIWovenCompositeLaminates 33
4.1 ExperimentalProcedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.1 Materialsandblankpreparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.1.2 PressForming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.1.3 Temperaturemeasurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.1.4 Microscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
v
vi Contents
4.2 ResultsandDiscussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.1 Temperaturecurves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.2 Formingbehaviour. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2.3 Demonstrator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.2.4 Microscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
5 ModeIInterlaminarFractureToughnessofCo-ConsolidatedGF/PEIComposites 51
5.1 ExperimentalProcedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.1.1 Preconsolidatedlaminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5.1.2 Co-consolidatedlaminates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.1.3 Specimenpreparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.1.4 Microscopy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.2 Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.2.1 Orthogonalarrayexperiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
5.2.2 DoubleCantileverBeamtests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.2.3 Statisticalanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
5.3 ResultsandDiscussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.3.1 DCBtestresults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5.3.2 ANOMresults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.3.3 ANOVAresults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.3.4 Interactionplots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
6 Multiplestepformingandpost-consolidationofGF/PEIcompositelaminates 71
6.1 ExperimentalProcedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.1.1 Materialsandblankpreparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.1.2 Multiplestepformingprocess. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
6.1.3 Post-consolidationprocess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
6.1.4 Specimenpreparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
6.2 ResultsandDiscussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.2.1 DCBtestresults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6.2.2 Qualitativeanalysisofpost-consolidatedformedshape. . . . . . . . . . . . . . . . . . 77
6.3 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
7 ConclusionsandRecommendations 79
A Designinganorthogonalarrayexperiment 83
B Statisticalmethods-AnalysisofMeansandAnalysisofVariance 85
B.1 Analysisofmeans(ANOM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
B.2 Analysisofvariance(ANOVA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
C DoubleCantileverBeamTestDataandLoad-DisplacementCurves 89
C.1 PreconsolidatedSpecimens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
C.2 Co-consolidatedSpecimensRun1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
C.3 Co-consolidatedSpecimensRun2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
C.4 Co-ConsolidatedSpecimensRun3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
C.5 Co-ConsolidatedSpecimensRun4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
C.6 Co-ConsolidatedSpecimensRun5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
C.7 Co-ConsolidatedSpecimensRun6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
C.8 Co-ConsolidatedSpecimensRun7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
C.9 Co-ConsolidatedSpecimensRun8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100
C.10 Co-ConsolidatedSpecimensRun9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101
C.11 Post-consolidatedspecimensfrommultiplestepformedshape . . . . . . . . . . . . . . .102
C.12 Preconsolidatedspecimensfromnewmaterial . . . . . . . . . . . . . . . . . . . . . . . .103
Bibliography 105
List of Figures
1.1 Boeing787materialstructuralweightdistribution[1] . . . . . . . . . . . . . . . . . . . . 1
1.2 Comparisonofthermosetandthermoplasticpolymerstructures[3] . . . . . . . . . . . . 2
1.3 Tandempresslineconfiguration[8]. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Multiplestepformingapproachforthemanufacturingofavariablethicknesspart . . . 3
2.1 Stagesofthepressformingprocess[11] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Intra-plyshearinfabriclayer[12] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Intra-plyshearinUDplies[9] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.4 Processwindowof90ºbends[23] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.5 Schematicexplanationofthebalancebetweentheapparentintra-ply(IR),frictional(FR),
andbending(BR)rigidityoftheplies[35] . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Overviewofexperimentalsetup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 (a) Rig with integrated IR-panels, ventilation system, moving frame, (b) rail and glass
platesusedtoprotectIR-lamps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3 (a) Blankholder holding the laminate through springs and crocodile clamps and (b)
loadedintothemovingframeoftherig . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.4 Overviewofthepressassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.5 Explodedviewofthepressassembly(obs: rubbermouldnotdepicted) . . . . . . . . . . 21
3.6 Topmountingplate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.7 Rubbermouldandtheexistinggapswithrespecttothemetalmould . . . . . . . . . . . 23
3.8 Materialruptureuponformingwithhighclampingpressures[20] . . . . . . . . . . . . . 24
3.9 Schematicrepresentationofmouldclosingsequence . . . . . . . . . . . . . . . . . . . . . 24
3.10 Laminatedeformations[34] . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.11 Metalmould . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.12 Constrainingblockpreventingmetalmouldfrombeingreleasedfrommountingplate . 26
3.13 Metalmouldconstrainedbyblocksandrubberpads . . . . . . . . . . . . . . . . . . . . . 26
3.14 (a)Schematicand(b)realrepresentationofmetalstripsactingasstoppers . . . . . . . . 26
3.15 GuidingPins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.16 Insulatingblockaroundmetalmould . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.17 Heatingplatewithfiveheatingelements . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.18 Heatingplatecavitiestoinsertthermalswitches . . . . . . . . . . . . . . . . . . . . . . . 29
3.19 Schematicrepresentationofelectricalcircuitintegratedintheheatingplate . . . . . . . 29
3.20 Technicalrepresentationofelectricalcircuitintegratedintheheatingplate . . . . . . . . 29
3.21 Powercontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.22 Overviewofpressassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.23 GuidingpinsfixedtothetopmountingplateandM12boltsusedtofixthebottompress
assemblytothepress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.1 Layupschematicrepresentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2 ConsolidationtemperatureandpressureprofilesofGF/PEIlaminate . . . . . . . . . . . 34
4.3 Blankcuttinglayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.4 Pressformingstagesandindicationoflaminateandmoulds’temperatures. . . . . . . . 36
4.5 Thermocouplesinstrumentedatthebottomsurfaceofthemetalmouldandatthecenter
ofthelaminatetobeformedinthefirststep . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.6 Dataacquisitionsystemandthermocoupleinstrumentedonthesidewalloftherubber
mould. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.7 Experimentalrunnº1&Formingstepnº1-Laminateandmoulds’temperaturecurves . 38
4.8 Heatsourcesduringtheconsolidationstageofapressformingprocess . . . . . . . . . . 39
vii
viii ListofFigures
4.9 Experimentalrunnº2&Formingstepnº1-Laminateandmoulds’temperaturecurves . 40
4.10 Experimentalrunnº3&Formingstepnº1-Laminateandmoulds’temperaturecurves . 41
4.11 Experimentalrunnº3&Formingstepnº2-Interfaceandmoulds’temperaturecurves . 41
4.12 Experimentalrunnº4&Formingstepnº1-Laminateandmoulds’temperaturecurves . 42
4.13 Experimentalrunnº4&Formingstepnº2-Interfaceandmoulds’temperaturecurves . 42
4.14 Blankspringbackandreleasefromthemouldinexperimentalruns1and2 . . . . . . . 44
4.15 Blanksformedin1stformingsteponruns3and4 . . . . . . . . . . . . . . . . . . . . . . 44
4.16 Largercornerradiiatthetwoedgesoftheformedshape . . . . . . . . . . . . . . . . . . 45
4.17 Constraint of rubber mould’s sides in order to reduce non-uniform pressure distribu-
tions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.18 Multiplestepformedshapewith2ndblankco-consolidatedto1stblank. . . . . . . . . . 46
4.19 FormingscenarioA,whereblankdoesn’tmakecontactwithmetalmould’ssurfacedur-
ingforming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.20 FormingscenarioB,whereblankmakescontactwithmetalmould’ssurfaceduringthe
entireformingprocess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.21 Run3-Multiplestepformedshapewith(a)novisualformingdefects,but(b)withvery
weakbond . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.22 Demonstratorpartafter(a)1stand(b)2ndformingsteps,showingaccuratedimensional
controlandalignmentwithrespecttothemould . . . . . . . . . . . . . . . . . . . . . . . 48
4.23 Demonstratorpartmanufacturedviathreeformingsteps . . . . . . . . . . . . . . . . . . 48
4.24 Cross-sections of co-consolidated flanges in runs (a) 3 and (b) 4 (10x magnification),
showingnoevidenceofaninterfacebetweenco-consolidatedlaminates . . . . . . . . . 49
5.1 Threemodesofloadingadelamination: (a)opening,(b)shearingand(c)tearing[60] . . 51
5.2 LongitudinaltensilefailureinSBStestspecimen . . . . . . . . . . . . . . . . . . . . . . . 52
5.3 Layupof14-plylaminatewithKaptonfilminsertedatthemidplane . . . . . . . . . . . 53
5.4 TemperatureandpressureprofilesofGF/PEIpreconsolidatedspecimens . . . . . . . . 53
5.5 Productionsequenceof14-plyco-consolidatedplateswith(a)layupandconsolidation
of7-plylaminate,(b)stackingoftwo7-plypreconsolidatedlaminateswith(c)aKapton
insertattheinterface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
5.6 Co-consolidationrun3-Programmedtemperatureandpressureprofiles . . . . . . . . . 55
5.7 Co-consolidationrun3-Measuredtemperature . . . . . . . . . . . . . . . . . . . . . . . 55
5.8 Specimencuttinglayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.9 Excessadhesiveafterpost-curing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.10 DCBspecimenconfiguration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
5.11 (a) DCB test load-displacement curve and (b) delamination resistance curve showing
higherG propagationvaluesthaninitiationvalues. . . . . . . . . . . . . . . . . . . . . 58
IC
5.12 Areaunderload-displacementcurveofDCBtestedspecimen . . . . . . . . . . . . . . . 59
5.13 (a)Schematicandreal(b)representationsofthevariablet. . . . . . . . . . . . . . . . . . 60
5.14 DCBtestresultsofpreconsolidatedandco-consolidatedlaminates . . . . . . . . . . . . 62
5.15 Thicknessresultsforpreconsolidatedandco-consolidatedlaminates . . . . . . . . . . . 63
5.16 Microscopycross-sectionsof14-plypreconsolidatedlaminateat320ºCwithlargeareas
offibre-fibrecontactatthemidplaneinterface(2.5xmaginification) . . . . . . . . . . . . 64
5.17 Microscopycross-sectionsof14-plyco-consolidatedlaminateat270ºCwithsmallareas
offibre-fibrecontactatthemidplaneinterface(2.5xmaginification) . . . . . . . . . . . . 64
5.18 Microscopycross-sectionsof14-plyco-consolidatedlaminateat300ºCwithlargeareas
offibre-fibrecontactatthemidplaneinterface(2.5xmaginification),butpossiblylower
thanpreconsolidatedlaminates’. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.19 G VISvsTime,TemperatureandPressurescatterplots . . . . . . . . . . . . . . . . . . 65
IC
5.20 MaineffectsplotsforG VISoutput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
IC
5.21 InteractionplotsforG VISoutput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
IC
5.22 Maineffectsplotsforthicknessoutput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
6.1 Multiplestepformingprocessfollowedbyapost-consolidationstep . . . . . . . . . . . 71
6.2 Blankcuttinglayout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72