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Crash Simulations Using LS-DYNA

By: Levaughn Denton

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I. Bacgroun!I. Ls-Dyna

II. "ront #ail $esting

II. %ro&ect Design'(etho!sI. "ront rail e)am*le

II. Do!ge Neon e)am*le

III. S*eci+c AimsI. ,ua!tree hierarchical structure

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Several versions of LS DYNA◦ "indo#s $arallel (memory can be allocated di%erently)

Serial

◦ Uni& $arallel

Serial

◦  Linu&

$arallel Serial

'ach has its o#n set of ey#ords

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rontal rails play an interal role in crashtests

*esponsible for absorbin enery durin animpact

Amount of enery absorbed is directlyproportional to a vehicle+s deformation

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,uasi-Static Testin◦ rontal rail #ill e&perience deformation as a result

of a constant force

elocity at $ime

elocity at Time !

/

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.mpact Testin◦ rontal rail #ill e&perience deformation as a result

of an initial impact speed that decreases #ithtime

elocity at $ime

elocity at $ime 0 1 elocity at $ime

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"inite 2lement(o!el

•Split into planes of

symmetry in bar•/odel only aportion of the bar•0rash into a riid#all

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1iven the material parameters2 a rid ofnodes #ill be enerated◦ 3456 nodes

'ach node has an initial velocity in the 7direction

y&

7

(aterial (o!el Density 3g'cm456 7.872lastic (o!ulus 3g'microsec.40

cm6 .$angent (o!ulus 3g'microsec40cm6 .9)94-5 Yiel! Strength g'microsec40cm6 .9)94-5;ar!ing %arameter .9

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irst bloc of code de8nes output parameters  9 9 Units: m2 cm2 microsec2 3e;NT*>LET'*/.NAT.>N 9 endtim endcyc dtmin endne endmas   C!?3< 9 0>NT*>LE'N'*1Y 9 hen r#en slnten rylen   !

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Second bloc of code de8nes /esh and /aterial $arameters 9999 De8ne $arts and /aterials 9999999999999999999999999999999999999999999999999999999999999999999999999 9 9???@????3????@????!????@????4????@????????@????B????@????5????@????=????@????C 9 $A*T

9 pid sid mid eosid hid adpopt Far   3 3 3 9 9 /ATE$LAST.0EG.N'/AT.0 9 mid ro e pr siy etan beta   3 C?64< 3?3=

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y&

7

9999 .nitial 0onditions

9???@????3????@????!????@????4????@????????@????B????@????5????@????=????@????C99999 Nodes #ithin bo& ! are iven an initial velocity in the ne 7-direction?9999 These are all the nodes e&cept for those on the bottom of the bar?9.N.T.ALE'L>0.TY9 nsid nside& bo&id  < < !9 v& vy v7 v&e vye v7e 

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y&

7 Third bloc of code de8nes boundary de8nitions

99999999999999999999999999999999999999999999999999999999999999999999999

99999999999999 De8ne Nodes and 'lements99999999999999999999999999999999999999999999999999999999999999999999999999999999999999 /any nodes have boundary conditions to simulate symmetry?9

N>D'9 node & y 7 tc rc  3

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H$ $avilion dv!=

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15/19htt :II###?to crunch?or Ibenchmar results?sfe

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 The mesh storae structure has a directimpact on the:◦ the amount of memory used

◦ the 0$U time necessary for assembly

◦ the comple&ity of the prorammin

Suest the Juadtree hierarchical structureis used to store information

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•Locate part of the frontal rail thate&perienced deformation usin the boundary

coordinates of a node

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"ith a depth2 d2 a neihborin node can be found in >(d ; 3) time?

LULEÅ UNIVERSITY OF TECHNOLOGY  Department of Computer Science and Electrical Engineering

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