The document describes a FE-based methodology for simulating the vibration behavior of electronic products. This approach establishes calibrated analytical models through FE simulation that correlate well with test data. It has been implemented successfully on real projects, eliminating hardware testing and reducing costs and time. Key steps include understanding product geometry, simulating loads, analyzing results, evaluating design strength, and calibrating models to test data.

1. ANovelDesignApproachforElectronicEquipment
FEABased ethodology

2. ©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
Abstract
Abbreviations
Introduction
Problem Definition
SolutionandImplementation
FEA-to-ActualTestCorrelation
BusinessRelevance/PracticalImplementationonLiveProjectsBusinessRelevance/PracticalImplementationonLiveProjects
BestPractices
ConclusionandRecommendations
References
AuthorInfo
3
3
3
3
4
8
99
9
10
10
10
TableofContents

3. ©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
Thispaperdescribesthedesignapproachestablishedtostudyandsimulatethevibrationbehaviorofelec-
tronicproductsandprovidegoodcorrelationbetweentestdataandFEsimulationthroughawellcalibrated
analyticalmodel.Thisestablishedandvalidatedapproach/methodologyhasbeenpracticallyimplementedin
variousrealtimeprojectsforvariousHCLclients,therebyeliminating/minimizingtheactualhardwaretesting
andprototypingeffortsresultinginasignificantreductioninturnaroundtime,increasedproductcostsavings
andimprovedproductivity.Anaddedadvantagethatthisapproachprovidesisanopportunitytostudyand
validateseveralotherdesignconfigurationsresultinginarobustandreliableproduct.validateseveralotherdesignconfigurationsresultinginarobustandreliableproduct.
Sl.No
1
2
3
4
5
FEA
PSD
PCB
MPC
CAE
FiniteElementAnalysis
PowerSpectralDensity
PrintedCircuitBoard
MultiPointConstraints
ComputerAidedEngineering
FullFormAcronyms
Abstract
Inordertomeetstringentproductandfunctionalrequirements,allelectronicproductshavetocomplywith
variousthermal,structuralandvibrationstandardsandcatertootherchallengeslikeuniqueproductdesign
withenhancedfunctionalities,spaceconstraints,aesthetics,andmore.
Oneofthemostimportantrequirementsofanelectronicproductistowithstandsignificantlyhighshockand
vibrationlevelscausedduetovarioususerhandlingandenvironmentalsituationsviz.productshippingand
handling,transportation,enduserhandlingandabuse,earthquake/seismicloading,etc.
Introduction
Atraditionaldesignapproachdealswithdesigningandanalyzingtheproductandvalidatingitthereafter
usingthetypicalhardwaretestingwhichinvolvesaconsiderableamountofeffortandcost.Thiscostcanbe
ever-increasingincasevariousdesigniterationsaretobetriedout.
Problem Definition
Abbreviations
FEABasedMethodology|3

4. ©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
Thislatestdesignapproachdevelopedhere,resultsinprovidingasimulationbaseddesignwhichhelpsinvirtually
simulatingthestructuralandvibrationbehaviorfordifferentdesigniterationsandloadconditions.This,inturn,
eliminates/minimizestheneedforactualtestingandthussavescostandoverallturnaroundtime.
ExtensiveFEBasedApproach/Methodology
ToeffectivelyusethelatestFEbasedapproach,thestepsbelowhavebeenadoptedwhichresultsinbuilding
asimulationbaseddesignthatcompareswellwithtesting:
Understandingtheproductgeometryintermsofdistributionandplacementofdifferentcomponents/
sub-assembliesinordertoaccountforrightmassandstiffness.
Simulatingtherightloadingandboundaryconditionskeepinginmindthetestsetupconfigurationand
actualusagescenarios.
Analyzingandinterpretingthesimulationresults,mappingandcorrelatingtestdatawithanalytical
modelresults,andperform calibration.
Evaluatingthedesignstrengthandvibrationlevelsusingempiricalequationse.g.Steinberg'sequations
forthemaximum allowableoutofplanePCBdeflections,marginofsafetycalculationsforactualcompo
nentstresslevels,etc.
Figure1.ProductDesignCycle
SolutionandImplementation
FEABasedMethodology |4

5. FEASimulationfor"SHOCKandRandom Vibration"Loading
Shocksimulation(alsoknownastime-historysimulation)isatechniqueusedtodeterminethedynamic
responseofastructureundertheactionofanygeneraltime-dependentloadssuchasimpactloaddueto
shippingandhandling,end-userabuse,etc.
Thistypeofanalysisisusedtodeterminethetime-varyingdisplacements,strains,stresses,andforcesina
structureasitrespondstoanycombinationofstatic,transient,andharmonicloads.
Themaximum fairedaccelerationvaluethatisusedasaninputforshockFEAhasbeencalculatedusingthe
empiricalequationbelow:
∆V=0.24A*T
(EnvironmentalTestsProcedure-ProductShockTests-DocumentSection760)
where,
∆V=Velocitychange(in/s)
A=Max.FairedAcceleration(g)
T=Pulseduration(ms)T=Pulseduration(ms)
Figure2.FEASimulation
Figure3.FairedAccelerationValue
©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
FEABasedMethodology |5

6. Inordertocalculatetheloadcurveforhalfsinepulseloading,theempiricalequationbelowcanbeused:
Acceleration(g)=386.4*A*Sin(∏*n/R)
Where,
g :Accelerationing's
A :TotalShockpulse'g'valueobtainedusing∆Vequationshownpreviously
n :Datapoints1,2,3.....
RR :NumberofAccelerationresolutiondatapoints
Figure4.Input&OutputResponses,SimulationModelandTestUnit
Figure5.FEASimulationResults
©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
FEABasedMethodology |6
AnalysisResultsandModalCorrelation/CalibrationTechniques
Aftersimulatingtheproductassemblyforimpactshockloading,theun-calibratedresultsfrom thefirstitera-
tionmodelaremappedontothetestdatatogettheinitialbehaviorpredicted.Iftheinitialmatchshowsa
hugedisagreementofanalyticalmodelresultswithtestdata,thefollowingweakpointsshouldbetargeted/-
fine-tunedtocalibratethemodel:

7. Theboundaryconditions(constraintslocations)shouldberecheckedandsimulatedascloseaspossible
tothetestsetup.
Thedistributionofmassandstiffnessinthesimulatedmodelshouldbecheckedagainsttheactualtest
unitforplacementofvariouscomponents/sub-assemblies.
Ifaparticularcomponent/sub-assemblycontributesenoughtotheoverallstiffnessofthestructure,it
shouldnotbemodeledaslumpedmass.Instead,anapproximategeometrywithslightlyrealistic
materialpropertyvaluesshouldbeused.
TwoadjacentcomponentsshouldbetiedtogetherusingMPCs/Constraintsequationsonlyifthedistance
betweenthemisnegligiblysmall.DistantcomponentstiedtogetherusingMPCwillprovideunnecessary
©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
Figure6.DaveSSteinberg'sdeflectionequationsforShockandRandomVibrationsanalysis
FEABasedMethodology |7
AcceptanceCriteriafor'Shock'Loading
TheFEsimulationresults(PCBboardout-of-planedeflections,stresses,strains,etc.)arecomparedwith
variousacceptancecriteriabasedupontheempiricalequationsasshownbelow.Themaximum allowable
out-of-planeboarddeflectionsarecalculatedusingDaveSSteinberg'sdeflectionequationsforShockand
Random Vibrationsanalysis.MarginofSafetycalculationsarealsoperformedtogettheoverallboard
strengthagainstrandom andshockimpactloading.

8. Usingalltheabovementionedempiricalequationsforshockloadcalculation,responsepredictionandcom-
parisonwithacceptancecriteria,FEsimulationisperformedforinitialiterationwhichthengetscalibrated
usingtestdata.Afterincorporatingtheabovementionedcalibrationtechnique,agoodanalysis-to-testdata
matchhasbeenobtainedasshowninFigure8.
Figure7.MarginofSafetycalculations
Figure8.Test-to-FEAcorrelation
©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
FEA-to-ActualTestCorrelation
FEABasedMethodology |8

9. ThisextensiveFEAbaseddesignmethodologyhasactuallybeensuccessfullyimplementedforanumberof
HCLbusinesspartners/clientsoverthepasttwoyearsandhasgeneratednumeroussuccessfulcasestudies:
Successfulimplementationon“HydroMechanicalControlUnit”forarenownedAircraftsBrakesSystem
OEM worldwide.
Successfulimplementationon“ElectronicsServerDataStorageAssembly”forarenownedTier1supplier
ofDataServersworldwide.
SuccessfulimplementationandvalidationonvariousotherElectronicEnclosureAssembliesforaTier1
and2supplierofsensors,valves,actuators,etc.
©2015,HCLTechnologies.ReproductionProhibited.ThisdocumentisprotectedunderCopyrightbytheAuthor,allrightsreserved.
BusinessRelevance/PracticalImplementationonLiveProjects
Figure9.ImplementationofFEADesignMethodologyonActualRealtimeProjects@HCL
Themathematicalcalculationsaboveforthemaximum allowabledeflectionsandpeakaccelerationshelpthe
FEanalysttocross-checktheFEAresultsandvalidatethenumbersthroughsafetymargincalculations.The
SteinbergempiricalcalculationsforPCBmaxout-of-planedeformationcanbeusedtocalculatethesafety
marginsandvalidatethedesign,andareuniversallyacceptedbyEnclosureDesignEngineersasithasstrong
theoreticalandpracticalcorrelations.
BestPractices
FEABasedMethodology |9

10. Formoredetailscontact:ers.info@hcl.com
Followusontwitter:http://twitter.com/hclersand
Ourbloghttp://www.hcltech.com/blogs/engineering-and-rd-services
Visitourwebsite:http://www.hcltech.com/engineering-rd-services
Hello,I’m from HCL’sEngineeringandR&DServices.Weenabletechnologyledorganizationstogotomarketwithinnovativeproducts
andsolutions.Wepatnerwithourcustomersinbuildingworldclassproductsandcreatingassociatedsolutiondeliveryecosystems
to help bringmarketleadership.Wedevelop engineeringproducts,solutionsand platformsacrossAerospaceand Defense,
Automotive,ConsumerElectronics,Software,Online,IndustrialManufacturing,MedicalDevices,NetworkingandTelecom,Office
Automation,SemiconductorandServers&Storageforourcustomers.
ThiswhitepaperispublishedbyHCLEngineeringandR&DServices.
Theviewsandopinionsinthisarticleareforinformationalpurposesonlyandshouldnotbeconsideredasasubstituteforprofessional
businessadvice.TheusehereinofanytrademarksisnotanassertionofownershipofsuchtrademarksbyHCLnorintendedtoimply
anyassociationbetweenHCLandlawfulownersofsuchtrademarks.
FormoreinformationaboutHCLEngineeringandR&DServices,
Pleasevisithttp://www.hcltech.com/engineering-rd-services
Copyright@ HCCopyright@ HCLTechnologies
Allrightsreserved.
PraveenAhuja
HCLEngineeringandR&DServices
Reference
ConclusionandRecommendations
AuthorInfo
VibrationAnalysisofElectronicEquipment,DaveS.Steinberg,ThirdEdition,McGrawHillspublications
EnvironmentalTestsProcedure-ProductShockTests-DocumentSection760
ANSYS12.1HelpDocumentation
AIAAPaper,#2004-1535,A.BrownandD.McGhee
ThisextensiveFEAbaseddesignmethodology,substantiatedbytheusageofvariousempiricalequations,
Test-to-FEAcorrelationandmodelcalibration,hasbeensuccessfullyimplementedinvariousrealtimedesign
projectsleadingtothefollowingbusinessbenefits:
Iterativedesignusingparametricmodeling,leadingtoanoptimizedsolutionwithintheconstrained
designspace.
Fasterturnaroundtime,leadingtoanoverallreductioninproductdesigncycle.
Significantreductionintestingandprototypingcostandefforts.
Enhancedproductivityandefficiency.
Abilitytoidentifyunforeseenproblem areasinthesystem.
Theoverallsimulationtimecanbereducedfurtherwiththehelpofautomationtoolslikescripts/macros.Pro-
gramminglanguagescanalsobeusedforeasierandfasterpostprocessingofFEsimulationresults.
FEABasedMethodology |10