NISA II Composites Flyer Brochure

7/27/2019 NISA II Composites Flyer Brochure

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NISA - Composite

NISA II/COMPOSITES is the most powerful and

economical general purpose finite element program to

solve a wide range of static, dynamic, buckling, heat

transfer, optimization and nonlinear (both geometric and

material) analysis problems encountered in Aerospace,

Mechanical and Civil Engineering environments. NISA

II/COMPOSITES, which is a part of NISA II, is tailored

specifically for accurate and efficient analysis of

composite structures using state-of-the-art solution

methods, convergence techniques and time integration

schemes. NISA II/COMPOSITES is considered to be the

world's best program for solving linear and nonlinear

structures made of composite materials. The composites

module is directly interfaced with DISPLAY III/ IV for post-

processing the results.


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NISA - Composite

COMPOSITE ELEMENT LIBRARY

ANALYSIS FEATURES

MODELING FEATURES

FAILURE THEORIES

OUTPUT

3D Layered Composite Shell

3D Layered Sandwich Shell

3D Solid

Axisymmetric Layered Composite Solid

No restriction on the laminationVariable thickness and rotation angles

Edge effects and delamination can be predicted

Nodal temperatures and temperature gradients may be

specified

Temperature dependent material properties

Interlaminar stresses satisfying 3D equilibrium equations

Graphical representation of lamina thickness and angles

across the laminate

Draping of fabric over surfaces of general curvature

Maximum stress

Modified Hill-Mises

Tsai-Wu

Delamination

Plots of original and/or deformed geometry

Contour plots in any layer of displacement, stress

components, and stress resultants

Filtered stress output

The ratio of actual to allowable stress is computed. The

output is suppressed if this ratio is below the user

specified filtering stress ratio

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Stress survey plots

This special survey plot searches for the most

critical stress ratio in all layers of each element. Itprints an integer number, representing the most

critical percentage of allowable stress on each

element

Largest magnitudes of the displacement vector

Highest stress resultants in descending order of

magnitude


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NISA - Composite

NISAComposite

NISAII/COMPOSITESisanintegratedpartofthegeneralpurposefinite element program NISA II. The elements of NISAII/COMPOSITES can be used with all the elements of NISA -including isotropic (or orthotropic) shells, solids, beams, spars,mass,andspringelementsandthuscompleteanalysiscapabilityisavailableforall compositeandhybridstructures.

The element library includes: Theseelementshave no restriction on the number of layers, and eachlayermayhavedifferentthickness, orientationangle andmaterialproperties. The lamination maybesymmetricor unsymmetric. For

shell elements, transverse (interlaminar) shear deformation and`bendingextensional'couplingareincluded.

- The

elementiscomposedofseveral layersoforthotropicmaterialswithvaryingthicknessesandmaterial properties. TheTsai-WuandHill-Misesfailuretheoriesareavailablefortheseelements.

- In sandwichcomposite elements, the face sheets are thin which resistextensional and inplane shear deformation and a thickcorematerial which resists transverse shear. The face sheetsthemselvescan be made of laminated compositesand the core

maybeorthotropic.Multiplecoresofmorethantwofacesheetsareallowedandthesandwichconstructionneednotbesymmetrical.

- In thiselement, solid isassumed to becomposed ofseverallamina,eachlaminamayhavedifferentmaterial propertiesand lamination angles. Each group of lamina is considered asa

solid element. Thenormal stressandinterlaminarshearstressaremostaccuratelydeterminedatanydesiredlocation.Theelementiscapableofpredictingdisplacementandstressvariations, includingedgeeffectsaccurately.

NISA/COMPOSITE

THREE-DIMENSIONAL LAYERED COMPOSITESHELL

THREE-DIMENSIONAL SANDWICH SHELL

THREE-DIMENSIONAL COMPOSITE SOLID (OVERLAY)

ELEMENT

Highlightsof theElementLibrary

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ConsistentorlumpedmassformulationsfordynamicanalysisDeformation dependent concentrated force and followerpressurefornon-linearanalysis.Materialnonlinearitywithelastoplasticmaterial modelSpecified nodal temperatures with temperature gradientsthroughthickness.

Input and modeling features for Compositestructures

BucklingandEigenvalueAnalysis

There isnorestrictiononthe lamination. Anynumberoflayersormaterialsmaybelaidupatanyangle. In themostgeneral case,each layer is a different material. Nodal temperatures andtemperaturegradientsmaybe specified and material propertiesmaybetemperaturedependent.

With the higher-order isoparametricformulation, largegeometrical regionsmaybe modeled with a single element, and

curved boundaries may be fit with apiecewisequadraticorcubiccurve.

Theshellelementsaredoublycurvedbutthesurfaceiscompletelydescribed byspecifyingonlythethreecoordinatesof eachnode.

Thus, theinputisassimpleasforplateelements.

Oneof thespecialproblemsofcompositeanalysiswhicharisesinmodeling curved structures is specifying the fiber orientations.Most programs give the user onlyone option - to measure theanglesfroma specifiedsideof theelement. If a detailedmodel isused, thisrequires theuser to prepare a

newsetofangledataforeachelement.

NISA II/COMPOSITEShasthisoptionas

well assixothers, including theoptionofdefining a rotationanglebased on localcoordinatesystem. Theseoptionssimplifythe analysis of singly or doubly curvedstructures by defining lines on the shell surface, which areprojectionsof theglobal axes. Rotationsarein everycase abouttheshell normal andmeasured fromthesewell defined referencelines. Fiberorientationscanbedefinedatelementornodelevelineitherlocal orglobalsystem. Several local coordinatesystemscan

bedefinedandreferencedfordefiningthefiberorientations.

The resultof all this isthatmodeling a composite structure turnsouttobenomoredifficultthanmodelingitsmetalcounterpart. Allthese unique capabilities of NISA saves tremendous amount oftimeinmodelingacompositestructure

Buckling analysis is used to extract natural frequencies andcorresponding mode shapes of a structure when there is nodissipationofenergyduetodamping. Bucklinganalysisisusedtofind critical load factorsat which a structure becomeselastically

unstable. This analysis is properlytermed `bifurcation buckling.'

Tennis racket with optimi zed fiber

orientation--first torsional mode

Tennis racket with optimi zed fiberorientation--combined bending torsionalmode


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NISA - Composite

(The post-buckling behavior of the structure can be analyzedusing NISA II/Non-linear analysis.) Determination of thesebifurcation points requires eigenvalue extraction. NISA IIprovidesseveral differentsolutiontechniquestofindthebucklingload factors, natural frequencies and mode shapes of thestructure. Very efficient and accurate techniques such assubspace iteration (conventional and accelerated), inverseiteration and Lanczos methods are available for the eigenextraction.

Modal DynamicAnalysis

DirectTransientAnalysis

AnalysisFeatures

NISAII/DYNAMICS isanindependentmoduleand canbeusedin conjunction with NISA II to solve a wide varietyof problemsencountered in dynamic analyses using Modal Superposition.

Thefollowinganalysisfeaturesareavailable:

Transient Dynamic Analysis to evaluate the response of agivenstructuretoanarbitraryloading.Shock Spectrum Analysis may be used to determine theresponseofastructuretoanarbitraryorientedshockinputFrequency Response Analysis can be used to compute thesteady state response of a structure to harmonic loadsdefinedbyamplitudeandphasespectra.Random Vibration Analysis can be used to obtain the

statistical parameters of response quantitiessuch as powerspectraldensities(PSD)andmeansquarevaluesofstructuressubjected to a stationary random loading or groundexcitation(suchasearth uake,etc.).

Direct Transient Analysis solves the coupled system of dynamicequilibrium equations. State-of-the-art numeric integrationschemes and iteration methods are employed to achieveaccurate and cost effective solutions for linear and nonlinearproblems. Geometric and material nonlinearities can be

considered.Thefeaturesinclude:

ImplicitandexplicittimeintegrationschemesConsistentorlumpedmassmatrixDiscrete damper elements and proportional (Rayleigh)damping Non-zero initial displacementsand velocities, andmovingboundaryconditionsSelf-adaptive time steps for implicit and explicit schemeGeometricandmaterialnonlinearbehavior

Movingframesofreference-centrifugalandCoriolisforces

NISA II/COMPOSITES is a general purpose finite elementprogram which is tailored specifically for the accurate andefficientanalysisofawiderangeofcompositestructures. O

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TheelementsinNISAII/COMPOSITESaccountfortheeffectsoftransverse(interlaminar)sheardeformation,material anisotropy,and all possiblebending- extensional - twist - shearcouplings.

Thermal loads maybecomputed, and residual stresses due tocuringmaybefound.Mostplateandshell analysisarebasedontheclassicalKirchofftheory, whichassumesthatlinesof material pointsnormal totheneutral surface before deformation remain normal to it afterdeformation. The theoretical basis of NISA II/COMPOSITESincludes transverse shear effects, which are accounted for by

allowingthesenormalstorotaterelativeto thedeformedneutralsurface.ConsiderthatG/Etheratioofshearingtoextensionalstiffness, isfixed for an isotropic material at1/(2 + 2v), orabout 0.40 formost metals. Bycontrast, for a unidirectional lamina of highmodulusgraphite-epoxy, thevaluecanbeaslowas0.01. Thus,itisapparentthatthesameloadingwill inducesignificantlymoretransverse shear deformation in composite structures than intheir metal counterparts. Indeed, it is not difficult to find

composite problems where transverse shear is the dominantresponsemodeofthestructure.NISAII/COMPOSITESalso includestheeffectsof rotaryinertia,the counterpart of transverse shear deformation for dynamicproblems.Forsteadystateandtransientdynamics, thishasbeen

shown to be an important response mode for compositestructures.

Manylevelsofstructuralidealizationarepossible.Anorthotropicmaterial model is available for plane stress, planestrain,axisymmetric, general shell, and solid elements. Thedirectionsoforthotropymaybeconstantwithineachelement,ormayvarycontinuouslyformnodetonode.

The heart of NISA II/COMPOSITES is a family of generallaminated shell elements based on shear deformation theoryandthreedimensional solid elementsbasedonelasticitytheory.

Theseelementsaresuitedfortheanalysisoflaminatedstructureswith anisotropy as well as the special cases of orthotropy,transverseisotropyandisotropy.Asinglecompositegeneralshell elementmaybeused to model

an arbitrary number of layers at any given angle. The finiteelementdiscretizationis justontheshell midsurface. Thisallowsadrasticreductioninbothmodelingandcomputationtime.A special modification of the isoparametric laminated shellelement hasproven to beapplicable to a verygeneral class of

sandwich structures, and this analysis capability is included inNISAII/COMPOSITESasa separatefamilyofelements.

The element consists of thin face sheets that resist extensionaland inplanesheardeformation and a thickcorematerial whichresiststransverseshear. Thefacesheetsthemselvescanbemadeof laminated composites and the core may be orthotropic.Multiplecoresand morethan two face sheetsare allowed and

theconstructionneednotbeSymmetrical.


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The 3D composite solid element is based on the threedimensional elasticitytheoryandso,conceptually, includes

all the possible bending, extensional, twist and shearcouplingsin theelement formulation. These elementsaresuitableforanalysisof thicktomoderatelythickcompositestructures in which considerable shear deformation ispresent. Theelementcanalsopredictthenormalstress(s )accuratelywhichplanestressbasedelementsneglect.

The ever increasing use of laminated composite structures inthe aerospace, automotive, chemical and sporting goods

industries, demandsbetterunderstandingof theirmaterial andstructural behavior notonlyin thelinear rangebutalso in thenonlinear range. To meet the increased application oflaminated composite structures in these industries, NISA II,known for itsoutstanding capabilitiesformodelingcompositestructures is now enhanced with nonlinear formulations.Currently, the four and eight noded degenerated compositeshell elementshavenonlinear capabilitywhereasfor thesolidelementdevelopmentisinprocess.

Geometrical nonlinearitywith total and updated Lagrangian

formulation which includes large displacements and largerotations.Materialnonlinearitywithelastoplasticmaterial modelandthefollowingyieldcriteria:

Hill'sanisotropic yield criterion withyield parameters thatareupdatedduringdeformationhistory.

Modified Hill'sanisotropic yieldcriterion (C.F. Shihand D.Lee) which takes into account the differential strength intensionandcompressionandBauschingereffect.Programaccepts individual effectivestress-straincurvesinthe principal material directions. Bilinear, piecewiselinearor Ramberg-Osgood options are available for curveddefinitions.

NonlinearSolutionProceduresSimpleincremental

Newton-RaphsonandModifiedNewton-RaphsonIterationBFGS, Aitken, and Modified Conjugate GradientTechniques

OUTPUT - The linearanalysisoutputandpost-processingarealso applicable to nonlinear analysis. In addition, both theeffective plastic strain and the effective stress are output atGaussaswell asnodal points. Historyplotsarealso availablethroughthepost-processor.

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Analysishighlightsfor nonlinear composites:

Nonlinear Analysis

LoadingandBoundaryConditions

KinematicConstraints

FailureTheories

NISA II/Composites allows the user a large variety of loadingconditionsasshownbelow:PointloadsFollowerpointloads(fornon-linearanalysis)Specifiednon-zerodisplacementsPressureloadsFollowerpressureloads(fornon-linearanalysis)Bodyforces(centrifugalandlinearaccelerations)

ThermalloadsThermalgradientthroughthicknessforshellandbeamelements

Kinematicconstraintsarerelationsamongtheunknownsthatmustbe satisfied during thesolution. The following forms of kinematicconstraintsareavailable:SpecifieddisplacementsRigidLinks(elements)

Multi-point-constraintsCoupleddisplacements

NISA-compositesincludesthefollowingfailuretheories:Maximumstress

ModifiedHill-VonMisesTsai-WuDelamination

Formaterialnonlinearity, thefollowingyieldcriteriaareavailable:Hill'sanisotropicyieldcriterionModifiedHill'sanisotropicyieldcriterion

All theories are applied on a ply-by-ply basis, in the principalmaterial coordinatesystemofeachlayer. Delamination failuresarepredictedon thebasisof interlaminarstressexceedinga specifiedallowablevalue.

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Optimization of Laminated Composites with STROPT

STROPT is a general purpose structural optimization programintegratedwiththefiniteelementanalysispackageNISAII. STROPTaccommodatesstatic and dynamic analysesandhasan extensivelibraryof finite elementscontaining 3D composite and sandwichelements. Listed below are the capabilities and features for theoptimizationof laminatedcomposites.

Objectivefunctioniseithervolume,massorweightConstraints maybe based on Hill-Mises and Tsai-Wu failure

theories. In addition, constraints on displacements, stresses,natural frequencies, buckling load factors and maximumamplitudescanalsobeimposed

NISA - Composite


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Design variables may be layer thicknesses and/or rotationangles. In addition, cross sectional dimensions can also betreatedasdesignvariablesControlsonthestatusofdesignsuchasfree,fixedorlinkedSensitivity analysis methods such as direct differentiation,adjointvariableandhybridOptimization algorithms such as Recursive QuadraticProgramming (RQP), Generalized Reduced Gradient (GRG),andOptimumCostBounding(OCB)

Multipleloadcasesandboundaryconditions

Outputand Post-processing

Output

Post-Processing

NISAII/Compositesoffersa numberofoutputandpost-processingoptionstomeetindividualneeds.Alloutputisinteractiveandcanbeprinted, very conveniently, from stress and displacement outputfiles. Theusermay, athisdiscretion, selectonlya fewoftheoptionsand select additional output through a restart after thedisplacementsolution.

The following output canbe selectivelycontrolled using the printcontroloptionsofNISAII

Nodaldisplacements

ReactionforcesatnodeswheredisplacementsarespecifiedElement strain energy, element internal forces - and rigidelementforcesElement centroidal strains in theorthotropic direction of eachlayerElement stresses in orthotropic direction at Gauss points and

nodepointsofeachlayerElement stress resultants in the direction of top layer at eachGausspointandnodepointAveragestressresultantsinthetoplayerdirectionateachnodeofthestructureLargestmagnitudeofdisplacementvectorHighest stresses and stress resultants in descending order ofmagnitude

Extensivepost-processing featuresof DISPLAY III canbeutilized tocontour and interpret the results of the analysis. Some of theoutstandingandfrequentlyusedcapabilitiesare:

LayerstressesStressresultantsDisplacementsOriginalanddeformedgeometryStresssurveyplots

ModeshapesMultipleloadcasedeformedplots

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FilteringtheOutput

FilteringStressOutput

Stresssurveyplot

Interpreting theresults of a compositestructural analysis canbe a

cumbersometaskforvariousreasonssuchas:Thevolumeofstressoutputincreasedwiththenumberoflayers.Maximumstressesmaynotnecessarilyoccuratthetop, middleorbottomsurfaceoftheshell.Strength of a composite lamina is direction-dependent andstresses must be transformed into a material coordinatesystem,which isdifferentfor eachlayer, before their significancecanbemeasured.

To overcome the above difficulties, filtering of output is very

essential incompositestructuralanalysis.

NISA II/ COMPOSITES incorporates a number of unique outputfeatures. For each layer, stress components are automaticallycomputed in the local material axes. The stress values, includingtransverseshea rcomponents, andtheratiosof actual to allowablestressesarecomputedatthemidsurfaceofeachlayer. Theusermaychoosetoprintall stressesandstressratiosormayspecifyathresholdstressratio andsuppressprintoutofall stresseslessthanthatfraction

ofallowable.In addition to filtering the stress output using the threshold stressratio, theoutputcan also befiltered using theNISA II printcontrol

options.Theseoptionsmaybeusedtocontrolthebulkofprintoutforthe output quantities such as displacements, reactions, stresses,strain,energy,etc.

Aspecialsurveyplotisavailablewhichsearchesforthemostcritical

stress ratio in all layersof each element. Thisplotprints an integernumber, representingthemostcriticalpercentageofallowablestressand thelayernumbers in eachelement. Guidedbya stress surveyplot,theanalystmaythenusethestressprintoutandcontourplotsoflayer stresses or stressresultants to examine structural response inmoredetail.

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Scopeof AnalysisNISA II/Composites comprise of a diverse group of analysistypesto solveproblemsthatarelinearornon-linear innature.NISAII/Compositescanbeusedtosolvethefollowingtypesofstructuralanalysisproblems:

StaticEigenvalue

SucklingNonlinearGeometric

materialDynamictransient dynamics (modal superposition or directintegration)randomvibrationfrequencyresponse

shockspectrumOptimizationoptimumthicknessesand/oroptimumrotationangles

HeatTransfersteadystatetransient

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NISA - Composite

CranesSoftwareInternationalLimitedisa leadingprovider of ComputerAided Engineering(CAE)servicesto theAutomotive, Aerospace, Energy&Power, Civil, ElectronicsaSportingGoodsindustries. Over70dedicatedscientists,technologyarchitectsandsoftwareengineersprovidingNISAbasedsolutionshavehelpedmajor engineeringcompanreduceanalysisturnaroundtime, improveuserproductivity, andensurefasterreturnoninvestments.TheCompanyhasitspresencein33 countriesacrosstheworldandhasaubaseofmorethan350,000.Withamissionstatementtoprovideitscustomersthebestinscientifictechnologyandtoenableitscustomerstodefinenewlimits,Cranesissettingnewstandardsinthescientificaengineeringfield. For more information,please visitw w w.nisasoftw are.com Email: nisa@cranessoftw are.com

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NISA II Composites Flyer Brochure