Rotordynamics with ANSYS Mechanical Solutions
Pierre THIEFFRY Product Manager ANSYS, Inc.
Agenda
• General feature
• Generali!ed a"i#$$etric ele$ent
• Rotord#na$ic %it& ANSYS 'or()enc& – An An ANSYS V2.0 e!a"ple e!a"ple – #$t$re plans
Agenda
• General feature
• Generali!ed a"i#$$etric ele$ent
• Rotord#na$ic %it& ANSYS 'or()enc& – An An ANSYS V2.0 e!a"ple e!a"ple – #$t$re plans
General features
Rotordynamics features • Pre-roceing – Appropriate ele"ent %or"$lation %or all geo"etries – &yroscopic "o"ents generated 'y rotating parts – (earings – )otor i"'alance and other e!citation %orces *synchrono$s and asynchrono$s+ – )otational velocities – Str$ct$ral da"ping – • Solution – o"ple! eigensolver %or "odal analysis – -ar"onic analysis – ransient analysis
Rotordynamics features
• Pot-roceing – a"p'ell diagra"s – /r'it plots – ode ani"ation – ransient plots and ani"ations – • 0er guide
• Adanced feature – o"ponent ode Synthesis %or static parts –
Appropriate element formulation • T&e follo%ing ele$ent are u--orted for rotord#na$ic anal#i 4tationar# reference fra$e5 –
New in ANSYS 12.0
Mass
MASS21
Beam
BEAM! "#"E1$ BEAM1%%! BEAM1%& "#"E 2%%'2%& S()#*+! S()#*&+ S()#*1%+! S()#*1%$! S-E))$. S()#*1%, S-E))1%1! S-E))2%1
Solid Shell General a/isymmetric elements
S()#*2,2! S()#*2,.
Generalied a/isymmetric element
T&e ne% 262726* ele$ent Are co"p$tationally e%%icient 1hen co"pared to 3 solid S$pport 3 non4 a!isy""etric loading Allo1 a very %ast set$p o% a!isy""etric 3 parts5
2D axisymmetric mesh
Slice an a!isy""etric 3 A3 geo"etry to get planar "odel esh 1ith 262726 ele"ents No need to calc$late e$ivalent 'ea" sections an 'e co"'ined 1ith %$ll 3 "odels,
3D representation
3 res$lts *not necessarily a!isy""etric+
Bearings • 29 -ring7da$-er %it& crocou-ling ter$ – )eal constants are sti%%ness and da"ping coe%%icients and can vary 1ith spin velocity ω – • :earing ele$ent c&oice de-end on – Shape *3, 23, 3+ – ross ter"s Description Stiffness and Damping cross – Nonlinearities terms – COMBIN14 COMBI214 MATRI2!
M"C1#4
Uniaxial 2-D spring/damper spring/damper No Unsymmetric General stiffness or damping matrix Multipoint constraint ymmetric for linear element characteristics - None for nonlinear characteristics
Nonlinear stiffness and damping characteristics
No Function of the rotational velocity Function of the displacement
#m3alance and other e/citation forces • Poi)le e"citation caued )# rotation elocit# are – 9n'alance * + – o$pling "isalign"ent *2: + – (lade, vane, no;;le, di%%$sers *s: + – Aerodyna"ic e!citations as in centri%$gal co"pressors *0.<: + – • In-ut $ade a a force on t&e $odel
F! !
F #
=
mr ω2
=
F"ω2
m r
t
ω
#
Fy
Rotating damping • =onidered if t&e rotating tructure &a
str$ct$ral da"ping *P, 3AP or (=A3+ or a locali;ed rotating visco$s da"per *'earing+
•
• T&e da$-ing force can induce unta)le i)ration. •
• T&e rotating da$-ing effect i actiated along %it& t&e =orioli effect 4=>RI>?IS co$$and5.
*amper
4(MB#21
Beam
BEAM! "#"E1$ BEAM1%%! BEAM1%& Solid S()#*+! S()#*&+ S()#*1%+! S()#*1%$! S()#*1%, General S()#*2,2! S()#*2,. a/isymmetri 5new in 6 120 7 c Elements supporting rotating damping
4amp3ell diagrams 8 whirl • @ariation of t&e rotor natural freuencie %it& re-ect to rotor -eed
• In $odal anal#i -erfor$ $ulti-le load te- at different angular elocitie
• A freuencie -lit %it& increaing -in elocit#, ANSYS identifie – %or1ard *#>+ and 'ac?1ard *(>+ 1hirl – sta'le 7 $nsta'le operation – critical speeds – • Alo aaila)le for $ulti-ool $odel
(r3it plots • In a -lane -er-endicular to t&e -in a"i, t&e or)it of a node i an elli-e •
• It i defined )# t&ree c&aracteritic e$i a"e A , : and -&ae in a local coordinate #te$ 4", #, !5 %&ere " i t&e rotation a"i •
$ Angle i t&e initial -oition of t&e node %it& re-ect to t&e $aBor e$ia"i A. •
$ >r)it -lot are aaila)le for )ea$ $odel •
PRINT ORBITS LOCAL y AX 0.0000
Rotordynamics analysis guide • Ne% at releae 12.< •
• Proide a detailed decri-tion of ca-a)ilitie •
• Proide guideline for rotord#na$ic $odel etu-
Sample models a9aila3le
Generalied a/isymmetric element
New Element :echnology :
$eneral A%i&s'mmetric (lement) 2!2*2!+ %D elements generated #ased on 2D mesh &oundary conditions applied in %D space Nonlinearities' Node to surface contact
?Y@
n a & c e M
ci
@ D
A
B@
I C
Benefits Multiple (xis can #e defined in any direction )a*e advantage of axi-symmetry #ut deformation is general in %D l + element in , hoop. direction a
r c u
ut
rt
S 3 vie1 o%
Application to rotordynamics
T&e ne% 262726* ele$ent Are co"p$tationally e%%icient 1hen co"pared to 3 solid S$pport rotordyna"ics analysis S$pport 3 non4 a!isy""etric loading Allo1 a very %ast set$p o% a!isy""etric 3 parts5
2D axisymmetric mesh
3D representation
Slice an a!isy""etric 3 A3 geo"etry to get planar "odel esh 1ith 262726 ele"ents No need to calc$late e$ivalent 'ea" sections
3 res$lts *not necessarily a!isy""etric+
Rotordynamics with ANSYS ;or<3ench An e/ample
Story3oard
• T&e geo$etr# i -roided in for$ of a Paraolid file • Part of t&e &aft $ut )e re-ara$etri!ed to allo% for dia$eter ariation • A di( $ut )e added to t&e geo$etr# • Si$ulation %ill )e -erfor$ed uing t&e generali!ed a"i#$$etric ele$ent, $i"ing ': feature and AP9? cri-ting • 9eign anal#i %ill )e $ade %it& ariation of )earing -ro-ertie and geo$etr# •
"ro=ect 9iew
•
0--er -art of t&e c&e$atic define t&e i$ulation -roce 4geo$etr# to $e& to i$ulation5
Para$eter of t&e $odel are gat&ered in one location 4geo$etr#, )earing tiffne5
•
?o%er -art of t&e c&e$atic contain t&e deign e"-loration tool
•
Geometry setup • Geo$etr# i i$-orted in 9eign Modeler • A -art of t&e &aft i redeigned %it& -ara$etric di$enion • Model i liced to )e ued %it& a"i#$$etric ele$ent • :earing location are defined • A dic i added to t&e geo$etr#
Initial 3D geometry
Final axisymmetric model
Additional disk
•
• •
Bearings location
Geometry details
Part of the original shaft is removed and recreated with parametric radius
Additional disk created with parameters the outer diameter will !e used for design analysis"
3D Model sliced to create axisymmetric model
Bearing locations and named selections are created named selections will !e transferred as node components for the simulation"
Mesh
• T&e $odel i $e&ed uing t&e ': $e&ing tool
Simulation • Si$ulation i -erfor$ed uing an AP9? cri-t t&at define – =le"ent types – (earings – (o$ndary conditions – Sol$tions settings *Crda"p solverD+ – Post4processing *a"p'ell plots and e!traction o% critical speeds+
Axisymmetric model with !oundary conditions
Expanded view
A"*) script
Mesh transferred as mesh2%% elements& converted to solid2'2
#pring$ component comes from named selection
Simulation results • T&e AP9? cri-t can create -lot and ani$ation • T&e reult can alo )e anal#!ed %it&in t&e Mec&anical AP9? interface • Reult are e"tracted uing get co$$and and e"-oed a ': -ara$eter 4&o%ing t&e -erfor$ance of t&e deign5
Mode animation 5e/panded 9iew7
*esign e/ploration • T&e $odel &a 2 geo$etr# -ara$eter 4dic and &aft radiu5 a %ell a a tiffne -ara$eter 4)earing tiffne5 •
• + out-ut -ara$eter are inetigated firt and econd critical -eed at 2"RPM and +"RPM 4o)tained fro$ t&e=a$-)ell diagra$ and *get co$$and5
Sample results • A re-one urface of t&e $odel i created uing a 9eign of E"-eri$ent •
Sensitivity plots5 the 'earing sti%%ness has no in%l$ence on the %irst and second critical speeds, the disc radi$s is the ?ey para"eter
• =ure, urface and enitiit# -lot are created and t&e deign can )e inetigated •
• >-ti$i!ation tool are alo aaila)le
=vol$tion o% critical speed 1ith sha%t and disc radi$s
(ptimiation • A $ulti o)Bectie o-ti$i!ation i decri)ed and -oi)le candidate are found 4uuall#, t&ere are $ulti-le acce-ta)le configuration 5 •
• Tradeoff -lot gie an indication a)out t&e ac&iea)le -erfor$ance
>uture plans 561. and 3eyond7
4amp3ell diagrams
$ltiple steps *$odal+
Rotational elocit# co-ed on )odie4 4$ulti-ool anal#i5 aaila)le in $odal anal#i
B a!is is rotational velocity /$tp$t C$antities5%re$encies or sta'ility val$es
Additional enhancements • Proide $odal oler c&oice 4R9AMP, ?AN:5 •
• T&e connection folder &oting )earing – Eocation – 3a"ping and sti%%ness *as %$nctions o% w+ – • =orioli o-tion aaila)le fro$ t&e Anal#i etting 4li(e t&e large deflection or inertia relief5
• >r)it -lot for )ea$ $odel
• E"-oure of generali!ed a"i#$$etric ele$ent
Modal post?processing 5already a9aila3le at 6127
o"ple! eigenshapes
ode ani"ation si"ilar to AN-A)
#or co"ple! "odes, ta'$lar data display 'oth i"aginary and real parts
