NUMERICAL SIMULATION OF IMPACT ON CERAMIC ARMOUR SYSTEMWord文档格式.docx

NUMERICAL SIMULATION OF IMPACT ON CERAMIC ARMOUR SYSTEMWord文档格式.docx

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Theballisticperformanceofthelightweightarmoursystemswasexaminedtoobtainanestimatefortheglobaldamageofthecompositeplates.

Materialmodels

TheMohr-Coulomb（MC）strengthmodelandlinearequationofstate（EOS）areusedtomodeltheceramiclayer.Themicromechanicalfailureofceramicismodelledusingacumulativedamagemodel.Sinceexperimentsindicatethatceramicsshowamarkedincreaseincompressivestrengthasthehydrostaticpressureisincreased,itismostlikelythatthismodelwillbeusedinconjunctionwiththeMohr-Coulombmodelwhichusesayieldstrengththatisafunctionofthelocalhydrostaticpressure.

Anadvancedorthotropicmodel[1]implementedinAutodynhydrocode,whichusenon-linearequationofstateinconjunctionwithanorthotropicstiffnessmatrixisusedtomodeltheKevlar29/Epoxylayer.

The4340steelusedforSTANAGfragmentswasrepresentedusingtheJohnsonCookstrengthmodel,whichincludestrainandstrainratehardeningandthermalsofteningeffects.

AmodeloftheNATO5.56bulletwasdevelopedusingmaterialdataavailablefromexistingAutodynmodellibrariesandparametersmodifiedbaseduponthemeasuredhardnessofthebullet´

sindividualcomponents.Thebulletisofthree-partconstructionwithahardsteeltiparelativelysoftleadcoreandacooper-alloygildingjacket.Thereisasmallgapbetweenthefrontofthesteeltipandthegildingjacket.Thenominalmassofthebulletis4.0gandithasanaveragevelocityof1100m/swhenfiredfromastandardproofmountandwithastandardcartridgecase.

AshockequationofstateandJohnson-Cookconstitutivemodelwasusedtosimulatethematerialresponsetodynamicloadingofbullet´

stipwithyieldstressYS=1539MPa.ThecoppergildingmetalwasmodelledusingsimplelinearequationofstateandJohnson-Cookconstitutivemodel,thetieldstressYS=330.75MPa.TheleadcorewasmodelledusingasimplelinearequationofstateandaSteinberg-Guinanconstitutivemodel,theyieldstresswassetatYS=20MPa.Thefailureofjacketwassimulatedusingaprinciplestrainfailuremodelsetat90%.

Thematerialmodelsanddataaresummedupinthefollowingtable.

Table2Materialdata

Ceramic-Gceramic（Autodynmateriallibraries）

StrengthModel:

Mohr-Coulomb

Pressure#1（kPa）–5.00E5

Pressure#2（kPa）0.00

Pressure#3（kPa）1.01E20

Pressure#4（kPa）1.01E20

YieldStress#1（kPa）0.00

YieldStress#2（kPa）3.80E6

YieldStress#3（kPa）3.80E6

YieldStress#4（kPa）3.80E6

Failure:

CumulativeDamage

Eff.Pl.StrainatZeroDamage:

0.01

Eff.Pl.StrainatMax.Damage:

0.03

MaximumDamage:

0.7

Equationofstates 

:

Linear

Referencedensity（g/cm3） 

3.43

Bulkmodulus（kPa）1.54E8

Strength 

Mohr-Coulomb

Shearmodulus（kPa）8.30E7

Failure 

ReferenceTemperature（K）300

KEVLAR/EPOXY-EMI

TensilefailureStress11（kPa） 

5.00E+04

MaximumShearStress12（kpa） 

1.00E+05

TensileFailureStrain11 

TensileFailureStrain22 

0.20

TensileFailureStrain33 

PostFailureResponse 

Orthotropic

Fail11&

11Only

Fail22&

22Only

Fail33&

33Only

Fail12&

12and11Only

Fail23&

23and11Only

Fail31&

31and11Only

ResidualshearStiff.Frac.0.20

Orthotropic

Sub-EquationofStates 

Polynomial

1.40

Youngmodulus11（kPa） 

2.392E+05

Youngmodulus22（kPa） 

6.311E+06

Youngmodulus33（kPa） 

Poisonsratio12 

0.115

Poisonsratio23 

0.216

Poisonsratio31 

3.034

Elastic

Shearmodulus（kPa）1.54E+06

MaterialStress/Strain

4340Steel

EquationofStates 

Referencedensity（g/cm3）7.83

Bulkmodulus（kPa）1.59E+07

Referencetemperature（K）300

Specificheatcapacity（J/kgK）477

Johnson-Cook

Shearmodulus（kPa）8.18E+07

YieldStress（kPa）7.92E+05

Hardeningconstant（kPa）5.10E+05

Hardeningexponent0.34

Strainrateconstant0.014

Thermalsofetningexponent1.03

Meltingtemperature（K）1793

Failuremodel 

None

Numericalmodels

Asthehighvelocityimpactphenomenonisoflocalisednature,theboundaryconditionsd