types of contact

8/18/2019 Types of Contact

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LOADS AND CONSTRAINTS

Beam PreloadA beam preload creates an axial load over the length of a beam element. This is useful for

simulating fasteners, wire rope, and other loads that are internal to the model or part (as

opposed to an external load such as a nodal force). Unlike external loads which are constant

throughout the analysis, the preload magnitude is the magnitude in the element if the rest of

the structure were infinitely stiff. ince the structure is not infinitely stiff, one result of a

preload is that the structure deforms and relieves a portion of the preload. ee !ractical

"onsiderations below.

Apply Preload Loads#n linear analyses, beam preloads are available only for static stress. They are not available

for $atural %re&uency ('odal) with oad tiffening nor "ritical uckling oad.

#n nonlinear analyses, beam preloads are available for '* and for tatic tress with

$onlinear 'aterial 'odels. #t is also possible to apply a beam preload in a $atural %re&uency

('odal) with $onlinear 'aterial 'odels analysis. +owever, it will produce no effect on the

results, since this analysis type does not account for load stiffening effects. eam preloads are

not available for an '* iks analysis.

1. Defne the Element Type or the part to be Beam elements.

. Sele!t one or more beam elements "s#n$ the Selection Select Lines!ommand.

%. R#$ht&!l#!' #n the d#splay area and !hoose the Add p"ll&o"t men" andsele!t the Beam Preload !ommand to add a preload load ea!h beamelement.

(. )nter the ma$n#t"de o the preload #n the Axial Force feld. A pos#t#*e*al"e #nd#!ates the element #s #n#t#ally #n tens#on+ so the analys#s dra,s the

beam ends to$ether. A ne$at#*e *al"e #nd#!ates the element #s #n#t#ally #n!ompress#on+ so the analys#s mo*es the beam ends apart.

-. A beam element ,#th a preload has the symbol B on the l#ne se$ment. Tomod#y the preload+ e#ther sele!t the preload entry #n the )A Ob/e!t0ro"ps bran!h o the tree *#e,+ or sele!t the B symbol #n the d#splay area,h#le #n the l#ne sele!t#on mode Sele!t#on Sele!t L#nes2.

Note3

• In add#t#on to the !onte4t men" !ommand+ yo" !an also !l#!' the Beam

Preload !ommand ,#th#n the Beam Loads panel o the r#bbon Setup tab.


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• The #n#t#al stra#n #s !ons#dered to be 5ero. Th"s+ the !al!"lated stra#n doesnot appear to a$ree ,#th the !al!"lated stress "nless yo" !ons#der theprestra#n.

• or l#near analyses+ the preload #s appl#ed to all load !ases #n the analys#s.

It #s not a6e!ted by any load m"lt#pl#ers.

• or plast#! mater#al models #n a nonl#near analys#s+ the pre&stra#n #s!al!"lated+ so the e6e!t appears #n the stra#n res"lts.

Pra!t#!al Cons#derat#onsAs noted above, some of the preload applied to the beam element is relieved in the analysis

because the members compress in response to the load. #f the preload provided is intended to

be the final load, such as the preload in a bolt due tor&uing it with a tor&ue wrench, then the

beam preload applied must be increased to compensate for the compression of the parts. #f the

stiffness of the members and the final load were known, the initial preload to apply to the

beam elements could be calculated as follows-

"onsider a beam (represented by red spring b ) that is stretch to create a preload of amount

!, and then attached to the members (represented by blue spring m ). The beam and member

then compress an amount /. ince the beam is stretched before attaching to and compressing

the member, the final load %0 in the beam e&uals the preload minus the stiffness times the

compression, while the e&ual (but opposite) load in the member e&uals the stiffness times thecompression. Thus, there are two e&uations and two unknowns (%0 and /).

%inal load in beam %0 1 ! 2 b/

%inal load in member %0 1 m/

olving these two e&uations for the final load %0 gives

%0 1 !3 m4( m 5 b)6


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where b is the stiffness of the beam, m is the stiffness of the member, and ! is the preload

applied to the beam.

%or a bolted connection, there are many formulas for calculating the stiffness of the members

depending on the assumptions about the pressure distribution under the bolt. 7ne such

formula is as follows which considers an apex angle of 89 degrees for the pressure

distribution and a washer diameter of :.; times the bolt diameter-

where is the total thickness of the bolted members and d is the diameter of the bolt and

hole. (eference- udynas, ichard < and $isbett, =. eith, higley0s 'echanical*ngineering >esign, 'c


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• I the members are !omposed o se*eral mater#als+ the st#6ness !an be!al!"lated as spr#n$s #n ser#es. Re!all that the e9"#*alent st#6ness : e9* #nth#s s#t"at#on #s o"nd rom

:4 e&v 1 :4 : 5 :4 ? 5 :4 8.

• I one mater#al #s m"!h ,ea'er than the others+ s"!h as a sot $as'etmater#al+ then the soter mater#al $o*erns and : e9* ; : $as'et.

• In some !r#t#!al !ases+ #t may be ne!essary to perorm the analys#s ,#th noloads appl#ed to the model e4!ept or the preload to determ#ne ,hatpreload P #s re9"#red to $et the fnal load


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• Rad#al loads are appl#ed #n a parabol#! d#str#b"t#on and are al,ays !onfnedto a ma4#m"m !yl#ndr#!al load 5one o =>&?7@ rom the rad#al *e!tord#re!t#on. Cons#der the #ma$es belo,+ ,h#!h e4pla#n ho, the rad#al load #sd#str#b"ted #n d#6erent s#t"at#ons3

a2 Rad#al load on a "ll %87@ !yl#ndr#!al s"ra!e.

• Important3 Re$ardless o the n"mber o part#al s"ra!es #n!l"ded #n as#n$le bear#n$ load+ the Magnitude spe!#fed #n the d#alo$ bo4 #s thetotal load ma$n#t"de. Th#s beha*#or d#6ers rom other A"todes'S#m"lat#on loads+ ,here the spe!#fed ma$n#t"de #s appl#ed to ea!hsele!ted ent#ty. or e4ample+ # a !yl#nder #s d#*#ded #nto o"r ?7@ s"ra!esand a 1+777 po"nd bear#n$ load #s defned ,#th all o"r s"ra!es sele!ted+the total load ,#ll be 1+777 po"nds. Con*ersely+ ,hen a 1+777 po"nds"ra!e or!e #s appl#ed+ the total load #s (+777 po"nds 1+777 lbs.>s"ra!e4 ( s"ra!es2.

• The a4#s or#entat#on o the !yl#ndr#!al s"ra!e #s !al!"lated a"tomat#!ally. The thr"st *e!tor d#re!t#on !annot be man"ally spe!#fed+ s#n!e #t #s al,ays#n the a4#al d#re!t#on. o,e*er+ #t !an be re*ersed by !l#!'#n$ the ToggleVector Direction b"tton.

• The rad#al load d#re!t#on !an be spe!#fed #n three d#6erent ,ays3

1. se X+ Y + or rad#o b"ttons to spe!#y a $lobal d#re!t#on.

. an"ally enter !"stom *e!tor !omponents #n the X+ Y + and felds.

%. Cl#!' the !adial Vector Selector b"tton and then !l#!' t,o po#ntson the model to #nd#!ate the d#re!t#on $raph#!ally.

#f the specified vector is skewed relative to the purely radial direction of the surface, it

is automatically adBusted to align with the purely radial direction.


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• A bear#n$ load may a!t a$a#nst an #nternal s"ra!e s"!h as the #ns#de o abear#n$ bore2+ or a$a#nst an o"ts#de s"ra!e s"!h as the shat e4tens#on,here a bear#n$ #s to be lo!ated2. The determ#nat#on o #nternal *ers"se4ternal loads o!!"rs a"tomat#!ally or sol#d elements+ as sho,n #n theollo,#n$ #ma$e3

$otice that the vector direction is the same for both parts. The selected surface

determines whether the load is internal or external. oth loads are applied in the 5C

direction for this example. The left load is applied to the inner surface of the bushing.

The right load is applied to the outer surface.

• or planar elements plates>shells2+ yo" m"st spe!#y ,hether the load #sto be appl#ed to the #ns#de or o"ts#de a!e. The pro$ram !annot #ner the

#ntended load rom the *e!tor alone. hen yo" apply a bear#n$ load to aplanar element+ the d#alo$ bo4 ,#ll !onta#n an add#t#onal #np"t feld Loadapplied to2+ ,h#!h #s not *#s#ble or other element types. Cons#der theollo,#n$ plate>shell e4ample3

Again, the vector direction is the same for both parts (5C). The left load occurs when

the Inside Face option is selected. The right load occurs when the Outside Face

option is selected.


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Note3 The spe!#f!at#on o #ns#de or o"ts#de a!e+ #n the Bearing Load

"#$ect d#alo$ bo4+ #s #ndependent o the Element Normal Point, ,h#!h #s

"sed to or#ent planar elements or other types o loads.

To Apply a Bear#n$ Load3

1. I yo" ha*e s"ra!es sele!ted+ yo" !an r#$ht&!l#!' #n the d#splay area andsele!t the Add p"ll&o"t men". Choose the Sur%ace Bearing Load

!ommand. Eo" !an also a!!ess th#s !ommand *#a the r#bbon SetupLoads Bearing&' Eo" !an #n*o'e th#s !ommand rom the r#bbon e#therpr#or to or ater sele!t#n$ the appl#!at#on s"ra!e.

. In the Load (ase ) Load (ur*e feld+ spe!#y the load !ase n"mber stat#!analys#s2 or load !"r*e n"mber trans#ent stress or nonl#near analys#s2 that,#ll !ontrol the bear#n$ load o*er t#me.

%. Spe!#y the thr"st or!e and>or rad#al or!e #n the Magnitude felds.

(. Cl#!' the Toggle Vector Direction b"tton # yo" ,#sh to re*erse thethr"st load d#re!t#on.

-. Choose one o the $lobal X+ Y + or rad#o b"ttons to spe!#y the rad#al loadd#re!t#onF or...

o A!t#*ate the (ustom rad#o b"tton and man"ally enter the G+ E+ andH *e!tor !omponents #n the X+ Y + and #np"t feldsF or...

o Cl#!' the !adial Vector Selector b"tton and then !l#!' t,o po#ntson the model to #nd#!ate the rad#al load d#re!t#on.

Dhether manually or graphically specified, the vector is automatically adBusted, if

necessary, to conform to the purely radial direction of the selected cylindrical surface.

8. or planar element s"!h as plates or shells2+ spe!#y ,hether to apply theload to the +nside Face or "utside Face "s#n$ the Load applied to men" b"tton.

. Opt#onally+ type a Description o the load #n the pro*#ded feld.

J. Cl#!' ", to apply the load or (ancel to abort the !ommand.

Centr#"$al Load

Note3 T-e in%ormation in t-is section applies to all linear and nonlinearanalyses t-at support centri%ugal loads'

A centrifugal load simulates the effect of the entire model spinning about an axis you specify.

7nly parts with a nonEero material mass density are affected. The model does not actually

experience rotation. ather, the e&uivalent forces that would occur as a result of angular

rotation and4or angular acceleration are calculated and applied to the nodes of each element.


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L#near AnalysesThree types of linear analysis support centrifugal loadsF Static Stress with Linear Material

Models, Natural Frequency (Modal) with Load Stiffening, and Critical Buckling. The model

can be spinning at a constant rate and4or can be undergoing a constant angular acceleration

rate.

The command implementation is slightly different among the linear analyses. #n all three

cases, the actual load is defined within the Centrifugal tab of the nalysis !ara"eters dialog

box, and the axes of rotation and angular acceleration can pass through any point is 8> space

(that is, the axes do not have to pass through the global coordinate origin). The differences

are as follows-

• Stat#! Stress ,#th L#near ater#al odels3

o The Centr#"$al load !an be a!!essed #n three ,ays...

1. R#$ht&!l#!' the Centr#"$al head#n$ "nder the Analys#s Typehead#n$ #n the bro,ser tree *#e,2 and !hoose the Edit !ommand.

. se the r#bbon !ommand+ Setup Loads (entri%ugal.

%. A!!ess the Analysis Parameters d#alo$ bo4 e#ther *#a thebro,ser or r#bbon2 and !l#!' on the (entri%ugal tab.

o 0lobal load !ase m"lt#pl#ers separately !ontrol ,hether or not the

An$"lar Kelo!#ty ."mega& and>or An$"lar A!!elerat#on .Alp-a& loads+ as defned ,#th#n the Centr#"$al tab+ are a!t#*e or ea!h load!ase.

o The a4#s o an$"lar *elo!#ty and the a4#s o an$"lar a!!elerat#on !anbe separately defned and !an be the same or d#6erent2.

o The a4es or an$"lar *elo!#ty and an$"lar a!!elerat#on !an be alon$any l#ne #n %D spa!e+ as spe!#fed *#a d#re!t#on *e!tors.

• Nat"ral re9"en!y odal2 ,#th Load St#6en#n$ and Cr#t#!al B"!'l#n$3

o The Centr#"$al load !an be a!!essed #n t,o ,ays...

1. se the r#bbon !ommand+ Setup Loads (entri%ugal.

. A!!ess the Analysis Parameters d#alo$ bo4 e#ther *#a thebro,ser or r#bbon2 and !l#!' on the (entri%ugal tab.

o There are no $lobal load !ase m"lt#pl#ers or the !entr#"$al load.Rather+ #t #s enabled solely *#a the +nclude speci/ed centri%ugalload !he!'bo4 ,#th#n the (entri%ugal tab o the Analys#sParameters d#alo$ bo4. I enabled+ the !entr#"$al load a6e!ts e*eryres"ltant mode shape+ modal re9"en!y+ and b"!'l#n$ m"lt#pl#er.


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o The a4#s o rotat#on and an$"lar a!!elerat#on m"st be the same notseparately spe!#fed2.

o The a4#s o rotat#on and an$"lar a!!elerat#on m"st be one o thethree $lobal a4es G+ E+ or H2.

Nonl#near AnalysesTwo types of nonlinear analysis support centrifugal loadsF M#S and Static Stress with

Nonlinear Material Models. oad curves control both the rotation speed and the angular

acceleration rate over time. The same load curve can be used for both, or you can specify two

different load curves for rotation and angular acceleration. The centrifugal load is defined

within the Centrifugal tab of the Advanced nalysis !ara"eters dialog box and can be

accessed using one of the following two methods-

1. se the r#bbon !ommand+ Setup Loads (entri%ugal.

. A!!ess the Analysis Parameters d#alo$ bo4 e#ther *#a the bro,ser orr#bbon2+ !l#!' the Ad*anced b"tton+ and !l#!' on the (entri%ugal tab.

%or either type of nonlinear analysis that supports centrifugal loads...

• The a4#s o rotat#on and the a4#s o an$"lar a!!elerat#on !an be separatelydefned and !an be the same or d#6erent2.

• The a4es o rotat#on and an$"lar a!!elerat#on !an pass thro"$h any po#nt#s %D spa!e that #s+ the a4es do not ha*e to pass thro"$h the $lobal

!oord#nate or#$#n2.

• The a4es or rotat#on and an$"lar a!!elerat#on !an be alon$ any l#ne #n %Dspa!e+ as spe!#fed *#a d#re!t#on *e!tors.

Apply Centr#"$al LoadsTo apply a centrifugal load to a model...

1. A!!ess the appropr#ate d#alo$ bo4 "s#n$ one o the methods des!r#bedabo*e d#6ers amon$ the *ar#o"s analys#s types2.

. I #n!l"ded ,#th#n the d#alo$ bo4+ a!t#*ate the +nclude speci/edcentri%ugal load !he!'bo4.

%. Spe!#y the appropr#ate ma$n#t"des "nder Angular Velocity ."mega& and Angular Acceleration .Alp-a&.

(. or nonl#near analyses+ sele!t the load !"r*e n"mbers to "se or an$"lar*elo!#ty and an$"lar a!!elerat#on.

-. Spe!#y the a4#s or#entat#on "s#n$ one o the methods des!r#bed abo*ed#6ers amon$ the *ar#o"s analys#s types2. or some analys#s types+ therotat#on and an$"lar a!!elerat#on a4es may be d#6erent+ and or others+the same a4#s m"st be "sed or both as deta#led abo*e2. In add#t#on+ someanalys#s types s"pport non&$lobal a4#s or#entat#ons and others do not also


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as deta#led abo*e2. se the Point on Axis !oord#nates and the Direction !oord#nates or p"ll&do,n $lobal a4#s l#st to spe!#y the lo!at#on andd#re!t#on o the a4#s or a4es2 . The an$"lar rotat#on ollo,s the r#$ht&handr"le abo"t the *e!tor yo" defne.

8. or l#near stat#! stress analyses+ set the "mega and>or Alp-a $lobal load!ase m"lt#pl#ers ,#th#n the Multipliers tab o the Analysis Parameters d#alo$ bo4.

T#p3 A non5ero m"lt#pl#er #s re9"#red to a!t#*ate the load. See the pa$e

Analysis Parameters: Stat#! Stress ,#th L#near ater#al odels.

%or example, take the circle centered at the origin in %igure :. To specify rotation about the G

axis at the origin, enter Point on Axis coordinates of (0,0,0) and Direction coordinates of

(0,0,1) 2 the circle rotates about its center and the center of the circle remains stationary.

Figure 1: Model 1 Rotating Aout Origin

+owever, if you have the circle as shown in %igure ? centered at (8,9,9) with the same

settings for the centrifugal load, the load is based on rotation of the circle about the origin. #n

other words, the center of the circle moves in a circular path about the global origin. %igure 8

shows a graphical depiction of the path of the circle from %igure ? under the specified

centrifugal load.

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Figure !: Model ! " Circle #it$ its Center %ot at t$e &loal Origin

Figure ': Interretation of Model ! Rotating Aout Origin

Note3 or all three l#near analyses that s"pport !entr#"$al loads+ remember that+

desp#te the s#m"lated mot#on e6e!ts+ these are st#ll stat#! analyses. Thereore+the model needs to be stat#!ally stable #n all d#re!t#ons. Typ#!ally+ a rotat#n$ part

or assembly #s atta!hed to a shat or le*er. T,o !ommon !onstra#nt s!hemes areas des!r#bed belo,3

• "lly&f4 the area or areas o atta!hment to the s"pport#n$ shat or le*er.

• Alternat#*ely+ !onstra#n tan$ent#al mot#on alon$ the s"ra!e o the hole,here the rotat#n$ parts are ft to the shat or le*er. Th#s !onstra#nt ta'es!are o t,o o the three translat#onal de$rees o reedom. In add#t#on+!onstra#n a po#nt+ ed$e+ or s"ra!e a$a#nst translat#on #n the a4#ald#re!t#on. or e4ample+ !onstra#n the area o !onta!t ,#th the shatsho"lder a$a#nst translat#on #n the normal d#re!t#on+ ,h#!h pre*ents a4#almot#on "nder thr"st loads and ta'es !are o the th#rd translat#onal DO.

D#str#b"ted Loads

A distributed load is a load that is applied over the length of a beam element. A distributed

load can be applied in any direction specified by a vector.


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#n the case of a inear analysis, for the distributed load to be applied to your model, you

must assign a Pressure multiplier in the Multiliers tab of the Anal*sis Para+eters dialog

box. The product of the Magnitude and the Pressure multiplier updates the magnitude of the

distributed load.

#n the case of a %onlinear analysis, a load curve controls the magnitude of the distributed

load during the event duration. Cou specify the load curve number within the Creating ea+

Distriuted oad O-ect dialog box.

Apply D#str#b"ted Loads#f you select one or more beam elements using the .election .elect ines command and

right2click in the display area, you can select the Add pull2out menu and select the ea+

Distriuted oads command to add a distributed load to each beam element.

#f the magnitude and direction of the load is constant across the length of each selected beam,

specify the magnitude of the load per unit of length in the Magnitude field and the direction

of the load in the Direction section. "lick the Fli$ %irection button ( ) to invert the sign of

the applied load, reversing its direction. #f the magnitude or direction of the load varies across

the length of each selected beam, deactivate the /nifor+ check box and specify the

magnitude of the force per unit of length at each end in the I%ode Magnitude and %ode

Magnitude fields and the direction in the I%ode Direction and %ode Direction sections.

The magnitude of the load varies linearly between the nodes. This is done on a per2beam

basis.

#f you are applying a non2uniform load to the beam, you can have the load start and end atany point along the beam. This is done by specifying a ratio of the length of the beam in two

ratio fro+ I%ode fields. The first field determines how far from the #2$ode the load starts.

The second field determines how far from the #2$ode the load ends. %or example, if you want

a load to be applied only along the third2&uarter of a beam, you specify 9.; in the first field

and 9.H; in the second field.

T#p3 The a4#s 1 or#entat#on o the beam elements !an be d#splayed "s#n$ the

Vie0 Visi#ility "#$ect Visi#ility Element Axis 1 !ommand. Th#s a4#s

l#es alon$ the d#re!t#on o the beam element l#ne and the pos#t#*e d#re!t#on #s

rom the I&Node to the &Node. I a4#s 1 needs to be re*ersed or some elements+th#s !an be done by sele!t#n$ the elements Selection Select Lines2+r#$ht&!l#!'#n$+ and !hoos#n$ Beam "rientations +n*ert + and 2 3odes.

or Nonl#near Analyses Onlypecify the load curve that will be used to multiply the distributed load in the oad Case 2

oad Cur3e field. !ress the Cur3e button to define a load curve in the oad "urve *ditor , or

use the Anal*sis: Para+eters dialog box. pecify an additional multiplier applied to this

load in the Multilier field.

%or the load to maintain the same orientation with respect to the element as it deforms,

activate the Follo#s Dislace+ent check box (and the arge >isplacement analysis type in

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the *lement >efinition). Dhen using Follows %is$lace"ent, the following additional

calculations are performed-

1. The "ser


14/103

distributed based on the relative area of each surface selected. ee the $$ly

Forces section below for more details.

4$at does a force do5

The data entered or the or!e #s appl#ed to ea!h ob/e!t sele!ted and #n thed#re!t#on yo" spe!#y. Thereore+ # yo" sele!t 17 nodes and spe!#y a 17 lb or!e

ma$n#t"de #n the G d#re!t#on+ yo" ha*e /"st appl#ed 177 lbs 17 ob/e!ts M 17 lbsper ob/e!t2 to yo"r model. The same #s tr"e # yo" apply the or!e to 17 s"ra!es

or 17 ed$es. The e4!ept#on to th#s r"le #s or surface or!es appl#ed to t,o or

more s"ra!es ,hen the Distribute magnitude across all surfaces opt#on #senabled. See the Apply Forces se!t#on belo, or more deta#ls.

Anal*sis.ecific Para+eters:

1. or Linear analyses3

o Nodal and ed$e or!es are appl#ed to a load !ase. The load !ase #sdefned #n the Load (ase) Load (ur*e feld. I yo" ,ant a nodal ored$e or!e to be appl#ed #n m"lt#ple load !ases+ yo" !an !opy #t to ane, load set and !han$e the *al"e #n the Load (ase) Load (ur*e feld.

o or a s"ra!e or!e to be appl#ed to a model a Pressure m"lt#pl#erm"st be defned #n the Multipliers tab o the AnalysisParameters d#alo$ bo4.

. or 3onlinear analyses3

o All or!es ,#ll ollo, a load !"r*e thro"$ho"t the analys#s. Sele!t theloads !"r*e #n the Load (ase) Load (ur*e feld.

Apply or!es#f you have nodes, edges or surface selected, you can right2click in the display area and select

the Add pull2out menu. elect the %odal Force, 6dge Force or .urface Force command.

Cou can also access this command from the ribbon (.etu oads Force). Cou can click

the ribbon command either before or after selecting the obBects to which you wish to apply

the force.

• Spe!#y the ma$n#t"de o the or!e that #s appl#ed to ea!h sele!ted ob/e!t#n the Magnitude feld. Alternat#*ely+ spe!#y the total or!e to bed#str#b"ted o*er m"lt#ple s"ra!es #n the Magnitude feld.

• Spe!#y the d#re!t#on o the load #n the Direction se!t#on.

• Cl#!' the Flip Direction b"tton 2 to #n*ert the s#$n o the appl#ed load+re*ers#n$ #ts d#re!t#on.

• I t,o or more s"ra!es are sele!ted+ the Distri#ute magnitude acrossall sur%aces opt#on ,#ll be a*a#lable. hen th#s opt#on #s a!t#*ated+ the

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spe!#fed ma$n#t"de #s d#str#b"ted on a pro rata bas#s depend#n$ "pon thearea o ea!h sele!ted s"ra!e. The e4ample #n the ollo,#n$ table e4pla#nsho, the load #s d#str#b"ted3

6xa+le:

Assume that a total force of ?,;99 $ is distributed over three surfaces (a, b, and c)

with areas of :99, 899, and @99 mm?, respectively.

Sur%ace

a

b

!

Ca"t#on3 Be !are"l ,hen r"nn#n$ a Parametr#! St"dy on models ,#th a

d#str#b"ted s"ra!e or!e appl#ed. The or!es appl#ed to #nd#*#d"al s"ra!eso a d#str#b"ted or!e $ro"p are not "pdated ,hen the model $eometry

!han$es. I any o the parameters yo" are man#p"lat#n$ a6e!t the area oa s"ra!e to ,h#!h a d#str#b"ted or!e #s appl#ed+ the or!e d#str#b"t#on ,#ll

no lon$er be !orre!t.

The arrows used to indicate applied forces point in the specified load vector direction,

including the Nor"al direction for forces applied normal to surfaces. +owever, the lengths of

the force arrows are not scaled to indicate the relative magnitude of the applied forces.

%or linear analyses, if you are applying an edge or nodal force, specify the load case or load

curve in which you want the force placed in the oad Case2oad Cur3e field. urface forces

are controlled by the global load case Pressure multiplier within the Analysis !arameters

dialog box. %or nonlinear analyses, specify the load curve number within the oad

Case2oad Cur3e field for all surface, edge, and nodal forces.

Note3 or #normat#on abo"t ho, nodal loads are appl#ed at d"pl#!ate *ert#!es+see the !omments "nder the Application of Loads and Constraints at DuplicateVertices head#n$ on the Loads and Constra#nts pa$e.

Import Rea!t#on or!es rom an )le!trostat#! Analys#sThe structural reactions to the electrostatic force between conductors (usually significant only

in '*' applications) can be calculated. #f an electrostatic analysis has been performed in a

different model, and if the reaction forces were calculated in the different model, then those

reaction forces can be applied to the structural model. To activate the output of the reaction

forces, see the Calculating the Forces and Charge Caused &y the #lectrostatic Field sectionon the nalysis !ara"eters' *lectrostatic %ield trength and Ioltage page. (Although the

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16/103

electrostatic forces in the binary results file are in units of voltage J current J time4length, the

software automatically converts this to force units when applying the loads to the model.)

Attent#on3 D"e to !han$es #n the sot,are+ ele!trostat#! or!es !al!"lated pr#or toK%.1 ebr"ary 77?2 sho"ld not be "sed ,#th sot,are *ers#ons K%.1 or ne,er.

I these res"lts are needed #n K%.1 or ne,er+ the analys#s m"st be perormeda$a#n.

The nodes in the stress model need to match the nodes in the electrostatic model where the

reaction forces were calculated. ut, the electrostatic parts do not need to be included in the

stress analysis. %or example, the force may be calculated on the surface of a part representing

the dielectric material between conductors (such as air). Air between conductors would not be

included in the stress analysis.

The method to apply the reaction forces to the stress model is as follows-

1. #th noth#n$ sele!ted+ r#$ht&!l#!' #n the d#splay area o the )A )d#tor.Sele!t the Loads %rom File !ommand.

. Press the Bro0se b"tton #n the !esults File !ol"mn. A d#alo$ bo4appears. se the Files o% type4 p"ll&do,n to sele!t the ElectrostaticReaction Forces !"efr# type o fle to read or the loads.

%. Sele!t the fle and !l#!' "pen'

(. S#n!e ele!trostat#! analyses !an only ha*e a s#n$le load !ase+ the Load(ase %rom File !ol"mn ,#ll sho, 5ero 72. o,e*er+ yo" !an #mport

m"lt#ple sets o loads #nto a s#n$le model by press#n$ the Add !o0 b"tton. The loads ass#$ned to the other ro,s o the spreadsheet !an berom the same fle and des#$n s!enar#o+ rom d#6erent fles+ or romd#6erent des#$n s!enar#os. or e4ample+ yo" may ,ant to apply the sameele!trostat#! or!es to more than one load !ase #n the stress analys#s. Or+yo" may ,ant to !al!"late stresses or ele!trostat#! or!e res"lts at t,od#6erent appl#ed *olta$es+ ea!h one be#n$ rom a d#6erent des#$ns!enar#o.

-. The loads are pla!ed #n a spe!#f! load !ase or load !"r*e #n the stressanalys#sF enter the load !ase>load !"r*e #n the Structural Load (ase

feld.

8. I yo" ,ant the loads to be m"lt#pl#ed by a !onstant *al"e beore be#n$appl#ed to the model+ spe!#y the !onstant *al"e #n the Multiplier !ol"mn.

. Press the ", b"tton.

Note3

• The #mported loads do not appear #n the )A )d#tor. They appear #n theRes"lts en*#ronment ater do#n$ a Che!' odel or perorm#n$ the analys#s.

• or l#near analyses+ don


17/103

and a load #mported rom an ele!trostat#! analys#s #s ass#$ned to load !ase-+ the load on load !ase - does not e4#st. The model has only t,o load!ases. To !reate the add#t#onal load !ases #n th#s e4ample+ add three ro,son the Multipliers tab o the Analysis Parameters d#alo$ bo4.

•

or nonl#near analyses+ donA!!elerat#onTo apply a gravity or acceleration load to a model, right2click the &ra3it*2Acceleration

heading under the Anal*sis 7*e heading in the tree view and select the 6dit command. $ote

that the text of this command will be gray before gravity is activated and defined. +owever, it

is not grayed2out. That is, the heading is still right2clickable and the 6dit command is

available. The heading text becomes black once gravity is set up.

Note3 Eo" !an also !l#!' the 5ra*ity !ommand ,#th#n the Loads panel o ther#bbon Setup tab. )#ther method d#splays the 0ra*#ty>A!!elerat#on tab o the

Analys#s Parameters d#alo$ bo4.

To apply the acceleration due to gravity on *arth, press the .et for standard gra3it* button.

The standard value for the acceleration of gravity is applied in the units of the model. To

apply a different acceleration magnitude, specify this in the Acceleration due to od* force

field. $ext, use the 8 +ultilier, 9 +ultilier, and +ultilier fields to define the vector

along which the acceleration is applied. pecifying a value in only one of these fields applies

the acceleration in that direction. pecifying values in more than one of these fields applies

the acceleration along an arbitrary vector. The value in the Acceleration due to od* force

field is multiplied by the values in these three fields before it is applied to the model in that

direction.

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The K, C, and G multiplier values are not normaliEed to a unit vector, as they are for many

other types of loads. "onsider the following two examples-

• I yo" ,#sh to apply standard $ra*#ty at a (-@ an$le bet,een the =G and&H d#re!t#ons+ !l#!' the Set %or standard gra*ity b"tton+ set the X

multiplier to 7.717 and set the multiplier to &7.717.

T#p3 !os (-@2 7.717

The resultant vector is :.9 and is in the desired direction.

• I yo" ,#sh to s#m"ltaneo"sly apply a %$ a!!elerat#on #n the &E d#re!t#onand a -$ a!!elerat#on #n the &H d#re!t#on+ !l#!' the Set %or standardgra*ity b"tton+ set the Y multiplier to &%+ and set the multiplier to &-.

#n the case of Nonlinear analyses, choose the load curve that will control the

gravity4acceleration load using the available pull2down list. The load curve must be previously defined and the model saved in order for it to appear in this list.

Dhen gravity is applied to the model, an arrow showing the direction of the gravity load

appears in the display area in both the %*A *ditor and the esults environment. The gravity

arrow can be shown in the display area at either of these locations-

• At the !enter o the bo4 that en!loses the model. I parts are h#dden+sho,n+ dea!t#*ated+ or a!t#*atedF the lo!at#on o the arro, "pdates ,henthe model #s en!losed Vie0 3a*igate Enclose&.

• S"permposed on the m#n#&a4#s. se the "ptions 5rap-icsMini6axis +nclude gra*ity .0-en applied& !he!' bo4 to !ontrol ,herethe $ra*#ty arro, appears at.

#n the %*A *ditor, the gravity arrow itself can also be shown or hidden by right2clicking on

the &ra3it*2Acceleration entry in the tree view which is located underneath the Anal*sis

7*e entry.

ydrostat#! Press"re

+ydrostatic pressure varies linearly from the level of the fluid in the direction of increasingdepth of the fluid. The magnitude of the hydrostatic pressure 1 (fluid density) x (depth below

the fluid surface).

Cou can apply hydrostatic pressure to plate, shell, brick, 8> kinematic, nonlinear membrane,

8> gasket, or tetrahedral elements. y default, the pressure is normal to the face of the

elements.

Apply ydrostat#! Press"res#f you have surfaces selected, you can right2click in the display area, select the Add pull2out

menu, and choose the .urface ;*drostatic Pressure command. This command is alsoavailable on the ribbon (.etu oads ;*drostatic Pressure).


19/103

To apply a hydrostatic pressure to any supported element type...

• Eo" m"st spe!#y the ,e#$ht dens#ty #n the Fluid Density feld2 o the"#d that !a"ses the hydrostat#! press"re.

• The hydrostat#! press"re !an #n!rease alon$ any d#re!t#on. Spe!#y a po#nton the top o the "#d #n the X+ Y + and felds #n the Point on FluidSur%ace se!t#on. Only elements belo, th#s po#nt re!e#*e a press"re.

• s#n$ the Sur%ace 3ormal o% Fluid se!t#on+ spe!#y a *e!tor that #snormal to the s"ra!e o the "#d and po#nts #nto the "#d that #s+ #n thed#re!t#on o #n!reas#n$ "#d depth and $ra*#ty2. hen the s"ra!e normal #sal#$ned to a $lobal a4#s+ only one o the *al"es or the Po#nt on l"#dS"ra!e #s !r#t#!al.

• or plate elements l#near analyses2 and $eneral shell elements nonl#near

analyses2+ a Side sele!tor #s pro*#ded ,#th#n the Creating $urface%ydrostatic Pressure &b'ect d#alo$ bo4. Choose the Top or Bottom s#derom the p"ll&do,n l#st. The bottom #s the s#de a!#n$ the element normalpo#nt+ as defned ,#th#n the Element De(nition d#alo$ bo4. or $eneralshell elements the add#t#onal t,o !ho#!es+ Bot- and 3eit-er+ are alsoa*a#lable rom the Side sele!tor. Re$ardless o ,hether the load #s appl#edto the top or the bottom s"ra!e+ the d#re!t#on #s to,ards the element.

• I yo" are perorm#n$ a trans#ent stress d#re!t #nte$rat#on2 analys#s or anonl#near analys#s+ sele!t the load !"r*e that the press"re ollo,s #n theLoad (ur*e feld.

Note3 Sot,are *ers#ons pr#or to 71% #n!l"ded an add#t#onal Multiplier feld orhydrostat#! loads #n nonlinear analyses only. Th#s opt#on has been el#m#nated.

)ssent#ally+ all ne, loads ,#ll be based on a non&!han$eable m"lt#pl#er o 1. orolder models opened #n *ers#on 71% or later+ the spe!#fed "#d dens#ty ,#ll be

#n!reased or de!reased a!!ord#n$ to the le$a!y m"lt#pl#er to ens"re ane9"#*alent res"ltant load. or e4ample+ ass"me yo" ha*e a nonl#near analys#s

model !reated #n *ers#on 71 or earl#er2+ ,here a hydrostat#! load ,#th a "#d

dens#ty o 7.7- and a m"lt#pl#er o % has been appl#ed. hen th#s model #sopened #n *ers#on 71% or ne,er+ the spe!#fed "#d dens#ty ,#ll be 7.7- % 4

7.7-2.

efer to %igure : below. !oint . represents any point along the top surface of the fluid. The

vector


20/103

Figure 1: ;*drostatic Pressure

#n the Creating ;*drostatic Pressure O-ect dialog box, there is a Pressure 7*e option.

The choices are as follows-

• 3ormal to t-e sur%ace3 The ma$n#t"de o the hydrostat#! press"re "#d dens#ty2 4 depth belo, "#d s"ra!e2+ and the d#re!t#on #s normal tothe s"ra!e o ea!h plate element. See #$"re a2 belo,.

• Full pressure in -ori7ontal4 The ma$n#t"de o the hydrostat#! press"re#s !al!"lated as "s"al+ b"t appl#ed #n the hor#5ontal plane. There #s no or!e!omponent parallel to the *e!tor defned by the S"ra!e Normal o l"#d*e!tor. In other ,ords+ the d#re!t#on #s normal to the S"ra!e Normal ol"#d+ re$ardless o the slope o the element s"ra!es. An e4ample o ,henth#s opt#on m#$ht be "sed #s to s#m"late the lateral so#l press"re a!t#n$

a$a#nst an #n!l#ned or !"r*ed reta#n#n$ ,all. See #$"re b2 belo,.

• 8ori7ontal component only3 Th#s #nd#!ates that only the hor#5ontal!omponent o the hydrostat#! press"re #s to be appl#ed *ert#!al!omponent 72. The ma$n#t"de o the press"re "#d dens#ty2 4 depthbelo, "#d s"ra!e2 4 s#nan$le bet,een the s"ra!e normal d#re!t#on othe element and the S"ra!e Normal o l"#d *e!tor2. The load d#re!t#on #snormal to the S"ra!e Normal o l"#d *e!tor+ re$ardless o the slope o theelement s"ra!es. See #$"re !2 belo,.

Note3 I the element s"ra!e #s hor#5ontal s"!h as alon$ the bottom o a at&bottomed tan'2+ then the normal d#re!t#on or the element s"ra!e and the "#d

normal d#re!t#on are parallel+ so the hor#5ontal !omponent o the hydrostat#!press"re #s 5ero. In th#s s#t"at#on+ the appl#ed hydrostat#! press"re #s 7 or

Pressure Type sele!t#ons o Full pressure in -ori7ontal or 8ori7ontalcomponent only.


21/103

(a) %or+al to t$e surface (b) Full ressure in

$ori=ontal

(c) ;ori=ontal co+onent

onl*

Figure 94 Types o% 8ydrostatic Pressure

2based models, ; glyphs are displayed along the surfaces in the %*A *ditor to

indicate hydrostatic pressure loads.

+ydrostatic pressures are converted to nodal forces during the solution phase. %or all models,

the esults environment displays arrows of varying length, indicating the load direction and

the pressure variation at different fluid depths. Cou can check a model prior to solving it to

verify the proper hydrostatic loads.

Notes on 0eneral Shell )lements3

$onlinear &eneral .$ell elements take the thickness of the element into account for pressureloading.

(The other planar elements that support hydrostatic pressure loads L plate, membrane, co2

rotational shell, and thin shell L consider the pressure to be applied at the midplane. The type

of shell element is set using the 6le+ent For+ulation selector within the Ad3anced tab of

the #le"ent %efinition dialog box.)

As mentioned previously, general shell elements have options to apply the hydrostatic

pressure to the 7o side, otto+ side, ot$ .ides, or %eit$er side.


22/103

Although the areas of the top and bottom sides of the element are e&ual in the stress2free

condition, large displacement effects can stretch the two surfaces differently. Thus, although

uniform pressures of 2:999 on the top and :999 on the bottom may appear to be identical

graphically, the results can be different. A similar situation occurs with hydrostatic loads. #n

addition, for inclined or curved surfaces, taking the thickness into consideration changes the

effective fluid depth where the fluid contacts the elements, and therefore affects the

hydrostatic pressure (depending upon whether the load is applied to the top or bottom face of

the elements). ee the figures below.

(a) !lanar element, one with a negative pressure applied to the top side of the element (left

side of figure) and one with a positive pressure applied to the bottom side of the element

(right side of figure). #n the stress2free condition, the area of the top side and bottom sides are

the same. (The element normal point is indicated by the K.)

(b) As the elements stretch, the area of the top and bottom sides also stretch. Thus, the total

force due the same pressure on the top as on the bottom may be different. #n this example, the

top side stretches more than the bottom side, so the force in the model with the pressure on

the top is higher than the force in the model with the pressure on the bottom.


23/103

(c) The above image demonstrates how the thickness can affect the hydrostatic pressure for

general shell and plate elements. The 8 represents the element normal point. $otice that the

range of fluid depth along the bottom surface (D1 through D!) differs from the range of

fluid depth for the top surface (Dt1 through Dt!). Therefore, the hydrostatic pressure load

will differ depending upon whether it is applied to the top or bottom surface of the planar

element. This effect will hold true for general shell elements along inclined, curved, or

horiEontal surfaces.

T#p3 o, to Comb#ne Constant and ydrostat#! Press"resA common occurrence is the combination of a constant pressure (!) and a hydrostatic

pressureFfor example, a tank partially filled with water and pressuriEed with air above the

water. %or ?9:8 and newer software versions, you can apply multiple surface loads to a single

surface, or group of surfaces, in a linear static stress analysis. Apply ! as a surface pressure

load and add the hydrostatic load to the same surface or surfaces.

+owever, if you are setting up a nonlinear analysis, or if you anticipate the possibility of both

linear and nonlinear analyses (using separate design scenarios, for example), a different

method is re&uired. $onlinear analyses do not support multiple surface loads. There are two

methods of applying the combined constant pressure and hydrostatic pressure loads.

1. The frst method #s to spe!#y a ree s"ra!e po#nt that #s at a h#$herele*at#on than the a!t"al "#d s"ra!e. At the top o the "#d and abo*e+the press"re #s P and the appl#!able e9"at#on #s...

! 1 (coordinate of higher free surface 2 coordinate of actual fluid surface)M(fluid

density).

All values are known except for the coordinate of the higher free surface, so calculate

this value and enter it for the hydrostatic pressure. earranging the terms of the prior

e&uation, solve for the higher free surface as follows-

"oordinate of higher free surface 1 ! 4 (fluid density) 5 (coordinate of actual fluid

surface)

constant ressure > $*drostatic ressure ? $*drostatic ressure of greater det$

$aturally, the surface numbers of the model may need to be adBusted so that the

hydrostatic pressure is only applied where needed (below the water level) and not in

the dotted region of the figure (above the water level). A constant pressure is appliedto the surface above the water level. %or "A>2based models, splitting the surfaces


24/103

within the "A> application is the preferred method of doing this, but the surface

attributes of the lines can also be changed in Autodesk imulation.

. The se!ond sol"t#on to th#s problem #s to apply a Sur%ace Varia#le Load.Defne an e9"at#on+ as a "n!t#on o the appropr#ate !oord#nate d#re!t#on+

that ,#ll prod"!e the des#red l#nearly #n!reas#n$ press"re. As or thepre!ed#n$ e4ample+ the s"ra!e o the CAD or )A model may ha*e to bespl#t to !onta#n the load to the des#red re$#on. or more #normat#onre$ard#n$ s"ra!e *ar#able loads+ reer to the Kar#able Press"res pa$e.

Loads rom #le

ometimes, you have loads from a source other than the software L or from the results of a

prior analysis L that you want to apply to the model. Cou can use oads fro+ File to do so.

oads fro+ File transfers loads from a text file L or from a prior analysis results file L to the

model. The command facilitates various multiphysics scenarios and is also useful when youfind it easier to calculate the load in a spreadsheet or other in2house program. #n such cases,

import the load L rather than entering it one2by2one through the interface. %or example, you

used an in2house program to calculate the temperature distribution of a model due to laser

light passing through the components, and you want to apply those temperature results to a

stress analysis model.

T#p3 Eo" !an also #mport rea!t#on or!es rom an ele!trostat#! model+ ortemperat"res rom a heat transer model+ "s#n$ the Loads %rom File d#alo$ bo4.

The procedure to apply a load from another file, whether an Autodesk imulation results file

or a text file, is as follows-

1. Sele!t Setup Loads Loads %rom File rom the r#bbon+ or+ ,#thnoth#n$ sele!ted+ r#$ht&!l#!' #n the d#splay area o the )A )d#tor and!hoose the Loads %rom File !ommand.

. Press the bro,se b"tton #n the !esults File !ol"mn. A d#alo$ appears,h#!h allo,s yo" to sele!t the res"lts fle. se the Files o% type4 p"ll&do,n to sele!t the appropr#ate type o fle to read or the loads. See thedeta#ls belo, or ea!h fle type.

%. Sele!t the fle and !l#!' the "pen b"tton.

(. Only the loads rom a s#n$le load !ase #n the sele!ted fle !an be appl#ed toa spe!#f! #nde4 ro, o the spreadsheet2. Sele!t the load !ase #n the Load(ase !ol"mn. In some !ases+ #t #s appropr#ate to #mport m"lt#ple sets oloads #nto a s#n$le model by press#n$ the Add !o0 b"tton. The loadsass#$ned to the other ro,s o the spreadsheet !an be rom d#6erent load!ases or t#me steps2 #n a s#n$le fle+ or the loads !an be rom d#6erentfles.

-. The loads ,#ll be pla!ed #n a spe!#f! load !ase or load !"r*e #n the

analys#s. )nter the load !ase>load !"r*e #n the Structural Load (ase feld. Note3 the name o the !ol"mn may !han$e ,#th the analys#s type.2

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8. or the loads to be m"lt#pl#ed by a !onstant *al"e beore be#n$ appl#ed tothe model+ spe!#y the !onstant *al"e #n the Multiplier !ol"mn.

. Cl#!' O:.

The imported loads do not appear in the %*A *ditor. They appear in the esults environmentafter doing a "heck 'odel or performing the analysis.

Note3

• Some loads+ s"!h as nodal or!es+ s"pport m"lt#ple loads at the samenode. or e4ample+ apply#n$ one nodal or!e o Q7+177+7 and anothernodal or!e o Q7+ -7+-7 ,#ll res"lt #n 1-7 #n the E d#re!t#on and -7 #n the Hd#re!t#on.

• Other loads+ s"!h as #n#t#al nodal temperat"res+ s"pport only one load at

the same node. I m"lt#ple #n#t#al temperat"res are loaded on the samenode+ the pro!essor ,#ll "se only one o the temperat"res.

Unless indicated otherwise, the results in the selected file are converted from the 'odel Units

of the results model to the 'odel Units of the current model. #f the 'odel Units of the results

model cannot be determined, then it is assumed that no conversion is re&uired.

Import#n$ an )le!trostat#! Rea!t#on or!es #le3The reaction forces from an electrostatic analysis can be imported into a stress analysis using

the oads fro+ File command. efer to the %orce page for details on this type of load

transfer.

Import#n$ Temperat"re Res"lts #le3The temperatures from a steady state or transient heat transfer analysis can be imported into

various stress analyses or transient heat transfer analyses using the oads fro+ File

command. efer to the Temperature page for details on transferring temperature results to a

structural analysis. %or more information regarding transferring temperatures to a transient

heat transfer analysis, see the nalyses !ara"eters' Transient +eat Transfer page.

Note3 There are t,o methods that !an be "sed to transer temperat"res #nto astr"!t"ral or thermal analys#sone *#a the Analysis Parameters d#alo$ bo4 and

one *#a the Loads %rom File !ommand. Both methods are d#s!"ssed ,#th#n the

abo*e&reeren!ed pa$es.

Import#n$ ASCII GEH Res"lts #le3electing a file type of A"## KCG esults %ile will import nodal2based loads specified by

K,C,G coordinate and apply the loads to the nodes in the model with the same coordinate. The

tolerance used for the comparison is :*2@. (#f more than one node has the same coordinate,

the load is applied to the first node.) The file to import must have an extension of .xyE to be

recogniEed.

Any type of nodal load supported can be defined in the A"## file.

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The format of this file must be as follows. 7ther than the addition of the K, C, G coordinate of

the load, the format of the file must be identical to the nodal condition table (nodecond.dbf

located in the modelname.dsNdataOdesign scenarioOds.mod folder). *ach item needs to be on

the same row of the file and separated by a comma.

• Nodal !ond#t#on Type

• G !oord#nate o the load

• E !oord#nate o the load

• H !oord#nate o the load

• G *al"e o the load

• E *al"e o the load

• H *al"e o the load

• Load !ase n"mber or the load. Remember3 only load !ase n"mbers #n thefle that mat!h the load !ase n"mber sele!ted #n the "ser #ntera!e aretranserred.

• Property Ident#f!at#on o the load. Th#s #s an ID n"mber ,h#!h po#nts toAnalys#sTypeaster.Load#n$.PropPropID2 ,h#!h enables the "ser to addan arb#trary n"mber o add#t#onal propert#es to th#s load. Normally th#s*al"e #s 7.

Note3 The res"lt or *al"e o the load #n the ASCII fle m"st be #n the same "n#ts as

the !"rrent odel n#ts. The *al"es ,#ll not be !on*erted ,hen #mported.

Import#n$ ASCII Nodal Cond#t#on Data #le3electing a file type of A"## $odal "ondition >ata %ile will import nodal2based loads and

apply them to the specified node. The file to import must have an extension of .nod to be

recogniEed.

Any type of nodal load supported can be defined in the A"## file. The format of this file

must be identical to the nodal condition table (nodecond.dbf located in the

modelname.dsNdataOdesignscenarioOds.mod folder).

Note3 The *al"e o the load #n the ASCII fle m"st be #n the same "n#ts as the!"rrent odel n#ts. The *al"es ,#ll not be !on*erted ,hen #mported.

Import#n$ ASCII )lement Cond#t#on Data #le3electing a file type of A"## *lement "ondition >ata %ile will import element2based loads

and apply them to the specified element. The file to import must have an extension of .ele to

be recogniEed.


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Any type of element load supported can be defined in the A"## file. The format of this file

must be identical to the element condition table (elemcond.dbf located in the

modelname.dsNdataOdesignscenarioOds.mod folder).

Note3

• The *al"e o the load #n the ASCII fle m"st be #n the same "n#ts as the!"rrent odel n#ts. The *al"es ,#ll not be !on*erted ,hen #mported.

• hen #mport#n$ the loads rom an ASCII fle+ add#t#onal #np"t may bere9"#red #n the model to "t#l#5e the loads. or e4ample3

o Certa#n types o loads+ s"!h as press"re stress analys#s2 and!on*e!t#on thermal analys#s2 "se a $lobal m"lt#pl#er to a!t#*ate theload. Be s"re that the $lobal m"lt#pl#er #s set on the Analys#sParameters s!reen.

o Don7%, such as plates

(which lack the rotational >7% about the axis normal to the element), a $odal Deight will

only effectively provide rotation resistance about the other two axes.

Apply Nodal e#$hts#f you have nodes selected, you can right2click in the display area and select the Add pull2out

menu. elect the %odal 4eig$t command. Cou can also access this load via the ribbon

command, .etu oads 4eig$t.

elect the appropriate radio button in the Mass Inut section to determine if the $odal

Deight input values are defined in units of force or mass (mass 1 weight4gravity). %or

nonlinear analyses, only mass units are permitted (the nits of force selection is grayed2out).


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#f the $odal Deight is e&ually effective in all translational directions, activate the /nifor+

check box and specify the magnitude of the mass in the 8 Direction field of the

Mass24eig$t section. Typically, a mass will be assumed to act e&ually in all directions for

the maBority of applications. #f the mass4weight is assumed to have different magnitudes

along the three translational directions, deactivate the /nifor+ check box and specify the

appropriate values in the 8 Direction, 9 Direction, and Direction fields in the

Mass24eig$t section. %or example, if a mass (like a car) is sitting on wheels on a ship deck,

you may want to assume that deck motion along the direction of travel does not effectively

accelerate the mass of the car in that direction (because the wheels rotate easily). #n such

cases, enter Eero or a reduced magnitude for that direction.

#f the $odal Deight is to be effective in rotational directions, specify the appropriate values in

the 8 Direction, 9 Direction, and Direction fields in the Mass Mo+ent of Inertia

section. +ere, with the exception of spherical obBects or regular cubes, the mass moment of

inertia will normally vary considerably about the three axes.

+ow the weight4mass and mass moment of inertia behave in the various linear analysis types,

for global or local coordinate systems, and when negative values are specified is summariEed

in the following table-

Analysis Type Mass :eig-t Mass Moment o%

+nertia

Stat#! Stress,#th L#near

ater#als

0lobalCoord#nates • #th $ra*#ty+

masses are!on*erted toor!es by #m # 4$ # + ,here # #s theG+ E+ and Hd#re!t#ons and $#s the $ra*#ty!onstant t#mesthe m"lt#pl#er.

• #th !entr#"$al

loads+ masses are!on*erted toor!es by # m# 4a#+ ,here # #s theG+ E+ and Hd#re!t#ons and a#s thea!!elerat#on r 40 2.

#th !entr#"$ala!!elerat#on+ #nert#as are

!on*erted to tor9"es by

T # I # 4 U # + ,here # #s theG+ E+ and H d#re!t#ons

and U #s the an$"lara!!elerat#on.

Lo!al

Coord#nates

ass beha*es as #

#np"t #s #n $lobal

#th !entr#"$al

a!!elerat#on+ #nert#as are


29/103


+nertia

!oord#nates+ not lo!al!oord#nates.

!on*erted to tor9"es by T # I # 4 U # + ,here # #s the

appropr#ate d#re!t#onand U #s the an$"lar

a!!elerat#on.

Ne$at#*eass or

e#$ht Inp"t

Ne$at#*e mass>,e#$ht and mass moment o #nert#a#np"t *al"es are !on*erted to pos#t#*e *al"es

d"r#n$ the sol"t#on. Thereore+ res"lts are #dent#!al

or pos#t#*e and ne$at#*e *al"es. A ,arn#n$messa$e appears #n the analys#s lo$ or ea!h

*al"e !on*erted.

L#nearNat"ral

re9"en!y

odal2

0lobalCoord#nates

asses ollo, $lobal!oord#nate system and

e6e!t the *#brat#on #n

the !orrespond#n$d#re!t#on.

Inert#as ollo, $lobal!oord#nate system and

e6e!t the *#brat#on #n


Lo!al

Coord#nates

asses ollo, lo!al

!oord#nate system ande6e!t the *#brat#on #n


Inert#as ollo, lo!al



Ne$at#*e

ass ore#$ht Inp"t

Ne$at#*e mass>,e#$ht and mass moment o #nert#a

#np"t *al"es are !on*erted to pos#t#*e *al"esd"r#n$ the sol"t#on. Thereore+ res"lts are #dent#!al

or pos#t#*e and ne$at#*e *al"es. A ,arn#n$

messa$e appears #n the analys#s lo$ or ea!h*al"e !on*erted.

L#near

Nat"ralre9"en!y

odal2 ,#th

LoadSt#6en#n$

0lobal

Coord#nates • Load st#6en#n$e6e!ts d"e to thel"mped mass arenot a!!o"ntedor.

• asses ollo,$lobal !oord#natesystem and e6e!tthe *#brat#on #nthe

!orrespond#n$

Inert#as ollo, $lobal


the !orrespond#n$

d#re!t#on.


30/103


+nertia

d#re!t#on.

Lo!al

Coord#nates

Lo!al !oord#nate

systems not s"pported.

Lo!al !oord#nate systems

not s"pported.

Ne$at#*e

ass or

e#$ht Inp"t

$egative mass4weight and mass moment of inertia input

values are interpreted as positive %7"* values of the

same magnitude, regardless of the 'ass4%orce Units

selection. $o warning messages are produced in the

analysis summary or log files. #n other words, if you

specify a mass of 2;99, the result will be the same as for a positive force of ;99. The resultant nodal load will differ

by a factor of g.

Reco++endation: To avoid confusion and potential

model setup errors, do not enter negative input values.

Cr#t#!al

B"!'l#n$Load

Nodal e#$hts are not s"pported or th#s analys#s type ne#ther

masses>,e#$hts nor mass moments o #nert#a2.

Trans#ent

Stress D#re!tInte$rat#on2

0lobal

Coord#nates

Inert#al e6e!ts ollo,

the $lobal !oord#natesystem.


!oord#nate system ande6e!t the mot#on #n the

!orrespond#n$ d#re!t#on.

Lo!alCoord#nates

Inert#al e6e!ts ollo,the lo!al !oord#nate

system.

Inert#as ollo, lo!al!oord#nate system and

e6e!t the mot#on #n the


Ne$at#*e

ass or

e#$ht Inp"t

Ne$at#*e mass>,e#$ht and mass moment o #nert#a

#np"t *al"es are !on*erted to pos#t#*e *al"es

d"r#n$ the sol"t#on. Thereore+ res"lts are #dent#!alor pos#t#*e and ne$at#*e *al"es. A ,arn#n$

messa$e appears #n the analys#s lo$ or ea!h*al"e !on*erted.

Nonl#near

Analyses

0lobal

Coord#nates

Inert#al e6e!ts ollo,

the $lobal !oord#nate

system.


!oord#nate system and

e6e!t the mot#on #n the



31/103


+nertia

Lo!alCoord#nates

Inert#al e6e!ts ollo,the lo!al !oord#nate

system.

Inert#as ollo, lo!al!oord#nate system and

e6e!t the mot#on #n the!orrespond#n$ d#re!t#on.

Ne$at#*e

ass ore#$ht Inp"t1

Ne$at#*e

masses>,e#$htsprod"!e rea!t#on or!es

#n the oppos#te d#re!t#on

relat#*e to pos#t#*e #np"t*al"es. or e4ample+ a

or!e #n the d#re!t#on o

the $ra*#ty *e!tor a!tson a pos#t#*e nodal

mass ,hen $ra*#ty #sappl#ed to the model.

or ne$at#*e *al"es+ theor!e ,#ll a!t #n the

oppos#te d#re!t#on rom

the $ra*#ty *e!tor.

Ne$at#*e mass moments

o #nert#a prod"!erea!t#on moments a!t#n$

#n the oppos#te d#re!t#on

relat#*e to pos#t#*e #np"t*al"es. or e4ample+ a

pos#t#*e #nert#a prod"!es

a tor9"e that opposesthe rotat#onal mot#on o

the mass. or a ne$at#*e*al"e+ the tor9"e a!ts #n

the same d#re!t#on+ass#st#n$ the rotat#onal

mot#on.

1 %ote: Dhile negative masses, weights, or mass moments of inertia have theoretical

significance, and their effects can be &uantified in a nonlinear analysis, there really are no

examples of this behavior in nature. Therefore, you will only need to use positive nodal

weights when modeling real2world phenomena.

Note3 See the !omments "nder the Application of Loads and Constraints at

Duplicate Vertices head#n$ on the Loads and Constra#nts pa$e or #normat#on

abo"t ho, nodal loads are appl#ed at d"pl#!ate *ert#!es.

Comments Re$ard#n$ L#near Dynam#!s Restart Analyses3%re&uency esponse, andom Iibration, esponse pectrum, Transient tress ('odal

uperposition), and >>A' analyses are all based on a prere&uisite modal analysis. The un2

scaled response of the structure (vibration mode shape results) are scaled according to thespecified excitation (ground motion) and other applicable loads. *ven though nodal weights

cannot be applied in these analysis types, their effects can be included in the initial modal

analysis. Therefore, nodal weights affect the restart analysis results, because the natural

fre&uency results on which they are based are affected by the nodal weights.

$ote that load stiffening effects due to gravity are not calculated for nodal weights in a

$atural %re&uency ('odal) with oad tiffening analysis. Therefore, you will have to apply a

nodal force in the direction of gravity in addition to each nodal weight to account for this

effect. e sure to run a $atural %re&uency ('odal) with oad tiffening analysis first, if you

want load stiffening effects to be represented in your restart analysis results.

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oments

A moment is a load that is applied to a node or surface. A moment can be applied about any

direction specified by a vector.

Apply omentsI yo" ha*e nodes or s"ra!es sele!ted+ yo" !an r#$ht&!l#!' #n the d#splay area+

sele!t Add and !l#!' 3odal Moment or Sur%ace Moment+ as appropr#ate. Eo"!an also apply moments *#a the r#bbon & sele!t a node or s"ra!e and !l#!' Setup

Loads Moment.

Note3 Eo" !an "se nodal moments only on plate and beam elements+ ,h#le yo"

!an "se s"ra!e moments only on plate+ br#!'+ and tetrahedron elements. Platesdo not s"pport nodal moments abo"t the a4#s normal to the a!e o the element.

pecify the magnitude of the moment that is to be applied to each selected obBect in the

Magnitude field and the direction of the moment in the Direction section. "lick the Fli$

%irection button ( ) to invert the sign of the applied moment, reversing its direction. The

data you enter for nodal moments applies to each obBect. %or example, if you select :9 nodes

and specify a :9 in2lb nodal moment about the K axis, you are applying :99 in2lbs (:9M:9) to

your model.

pecify the load case or load curve in which you want the moment placed in the oad

Case2oad Cur3e field. #f you want a moment to be applied in multiple load cases, you can

copy it to a new load set and change the oad Case2 oad Cur3e value.

T#p3 See the !omments "nder the Application of Loads and Constraints atDuplicate Vertices head#n$ on the Loads and Constra#nts pa$e or #normat#on

abo"t ho, nodal loads are appl#ed at d"pl#!ate *ert#!es.

Press"res or Tra!t#ons

Cou can apply pressure or traction loads to "A>2based, hand2built, or ?> 'esh ,

plate, membrane, thin composite, thick composite, brick, and tetrahedral elements. %or

nonlinear structural analyses, pressures or tractions can be applied to surfaces of pipe, ?>, ?>

kinematic, ?> hydrodynamic, shell, membrane, brick, tetrahedral, 8> kinematic, and 8>

hydrodynamic elements.

4$at does a ressure2traction load do5

• Appl#es an e*en d#str#b"t#on load or!e per "n#t area2 o*er the sele!tedarea.

• A press"re !an be appl#ed to the l#near and nonl#near str"!t"ral elementsthat are l#sted at the top o th#s pa$e. The press"re ,#ll be appl#ed normalto the a!es o br#!'+ tetrahedral+ plate+ th#n !ompos#te+ th#!' !ompos#te+shell+ membrane+ %D '#nemat#!+ and %D hydrodynam#! elements. It ,#ll be

appl#ed normal to the ed$es o D+ D '#nemat#!+ and D hydrodynam#!elements. It ,#ll be appl#ed as #nternal press"re to p#pe elements.

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• or l#near analyses+ a tra!t#on !an be appl#ed to plate+ br#!'+ andtetrahedral elements. A tra!t#on appl#es a press"re that #s or#ented #n aspe!#f! d#re!t#on.

• or nonl#near analyses+ a tra!t#on !an be appl#ed to all o the nonl#near

str"!t"ral elements that s"pport press"res+ e4!ept or p#pe elements. Thetra!t#on ,#ll be a press"re or#ented #n a spe!#f! d#re!t#on.

Note3 Lo!al !oord#nate systems are not s"pported or s"ra!e press"re or tra!t#on

loads. The d#re!t#on rad#o b"ttons and *e!tor !omponents are solely based onthe $lobal !oord#nate system.

Apply Press"res>Tra!t#ons#f you have surfaces selected, you can right2click in the display area and select the Add pull2

out menu and then choose the .urface Pressure27raction command. Cou can also access this

command via the ribbon (.etu oads Pressure). Cou can click the ribbon command

either before or after selecting the model surfaces where you want the load applied.

#f you are performing a nonlinear analysis or a transient stress (direct integration) analysis,

select the load curve that the pressure or traction will follow in the oad Cur3e field. !ress

the Cur3e button to define a load curve in the oad "urve *ditor , or use the .etu Model

.etu Para+eters dialog box.

For nonlinear anal*ses onl*:

• Spe!#y a *al"e other than 1 #n the Multiplier feld to ha*e an add#t#onalm"lt#pl#er appl#ed to th#s load.

• or the load to ma#nta#n the same relat#*e or#entat#on ,#th respe!t to themodel2 as #t deorms+ a!t#*ate the Follo0s Displacement !he!' bo4.

Note3 or CAD&based sol#d or s"ra!e models+ press"re and tra!t#on loads are

*#s"ally represented #n the )A )d#tor "s#n$ arro,s that #nd#!ate the loadd#re!t#on. or all other models+ VPV $lyphs are d#splayed at ea!h node alon$ the

loaded s"ra!es to #nd#!ate press"re or tra!t#on loads.

Press"resTo apply a normal pressure, select the Pressure button (this is the default). pecify the

magnitude of the pressure in the Magnitude field. "lick the Fli$ %irection button ( ) to

invert the sign of the applied load, reversing its direction.

%or ?>, and solid elements, a positive pressure is directed into the element and a negative

pressure is directed away from the element.

%or plate, thin composite, thick composite, and shell elements, a positive pressure points

away from the element normal point and towards the elements. A negative pressure points

towards the element normal point and away from the elements. The element normal point is

defined in the Orientation tab of the 6le+ent Definition dialog box.

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Tra!t#onsTo apply a traction load to any of the supported elements, select the 7raction button (it will

be grayed2out for non2supported elements). pecify the component of the traction in each of

the global directions in the 8 Magnitude, 9 Magnitude, and Magnitude fields.

Notes on 0eneral Shell )lements3 $onlinear &eneral .$ell elements take the thickness of the element into account for pressure

loading.

(The other planar elements that support hydrostatic pressure loads L plate, membrane, co2

rotational shell, and thin shell L consider the pressure to be applied at the midplane. The type

of shell element is set using the 6le+ent For+ulation selector within the Ad3anced tab of

the #le"ent %efinition dialog box.)


35/103

(b) As the elements stretch, the area of the top and bottom sides also stretch. Thus, the total

force due the same pressure on the top as on the bottom may be different. #n this example, the

top side stretches more than the bottom side, so the force in the model with the pressure on

the top is higher than the force in the model with the pressure on the bottom.

Remote or!es

T-e in%ormation in t-is section applies to linear and nonlinear structuralanalyses' Speci/cally; !emote Force loads are supported in t-e

%ollo0ing analysis types4

inear:

• Stat#! Stress ,#th L#near ater#al odels

• Nat"ral re9"en!y odal2 ,#th Load St#6en#n$

• Trans#ent Stress D#re!t Inte$rat#on2

• Cr#t#!al B"!'l#n$

%onlinear:

• e!han#!al )*ent S#m"lat#on )S2 ,#th Nonl#near ater#al odels

• Stat#! Stress ,#th Nonl#near ater#al odels

• )S R#'s Analys#s

hat does a Remote or!e doW

• S#m"lates the e6e!ts o a or!e appl#ed at a po#nt #n spa!e that #s not onthe model.

• Remote or!es are only appl#!able to model s"ra!es.

• The nodal rea!t#on or!es that ,o"ld o!!"r at the model d"e to the remoteor!e are !al!"lated+ and nodal or!es are appl#ed to all o the nodes alon$the sele!ted s"ra!e or s"ra!es.


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• Remote or!es d#6er rom Remote Loads and Constra#nts+ #n ,h#!ha"tomat#!ally&$enerated l#ne elements !onne!t the model to a po#nt #nspa!e+ and a s#n$le nodal load or !onstra#nt #s appl#ed at the remote po#nt .

Important3 hen a Remote or!e #s appl#ed to m"lt#ple s"ra!es+ the spe!#fed

load #s NOT d#str#b"ted o*er all o the sele!ted s"ra!es+ ,#th ea!h s"ra!ere!e#*#n$ only a port#on o the load ma$n#t"de. Rather+ the "ll spe!#fed or!e #s

d#str#b"ted o*er ea!h o the #nd#*#d"al sele!ted s"ra!es. or e4ample+ # a 77Nor!e #s appl#ed to three s"ra!es+ the total appl#ed load #s 877N 77N per

s"ra!e t#mes % s"ra!es2. I yo" need a s#n$le load ma$n#t"de at a po#nt #n spa!eto be d#str#b"ted o*er m"lt#ple s"ra!es+ "se the Remote Loads and Constra#nts

!ommand #nstead o the Remote or!e !ommand.

Apply a Remote or!e

1. Sele!t one or more s"ra!es ,here the remote or!e ,#ll a!t on the model.or e4ample+ !hoose the mo"nt#n$ s"ra!es or a motor bra!'et that #s not

#n!l"ded #n the model. Remote or!es !an be "sed to apply the e6e!ts othe motor and bra!'et ,e#$ht+ pl"s any operat#n$ loads+ at the sele!tedmo"nt#n$ s"ra!es.

. Cl#!' the Setup Loads !emote Force r#bbon !ommand. Or+ r#$ht&!l#!' #n the d#splay area and !hoose Add Sur%ace !emote Force romthe !onte4t men".

%. Spe!#y the or!e Magnitude. Cl#!' the Flip Direction b"tton 2 to #n*ertthe s#$n o the appl#ed load+ re*ers#n$ #ts d#re!t#on.

(. Spe!#y the lo!at#on o the remote po#nt by one o the ollo,#n$ t,omethods...

o Type the !oord#nates #n the X+ Y + and #np"t felds+ or

o Cl#!' the Point Selector b"tton and then p#!' a *erte4 on themodel. Th#s method ,or's # a !onstr"!t#on *erte4 has been addedat the remote or!e lo!at#on. It also #s "se"l # the des#red po#nt #s ata 'no,n o6set rom an e4#st#n$ model *erte4. In the latter !ase+ad/"st one or t,o o the !oord#nates to ree!t the lo!at#on o6setater !hoos#n$ the reeren!e *erte4.

-. Spe!#y the d#re!t#on o the load by one o the ollo,#n$ three methods...

o A!t#*ate an X+ Y + or rad#o b"tton to spe!#y a $lobal a4#s d#re!t#on.

o A!t#*ate the (ustom rad#o b"tton and enter the !omponents o a"n#t d#re!t#on *e!tor #n the X+ Y + and #np"t felds.

o Cl#!' the Vector Selector b"tton and then !l#!' t,o po#nts on themodel #n s"!!ess#on to #nd#!ate the des#red *e!tor d#re!t#on.

8. Spe!#y the Load (ase ) Load (ur*e n"mber. Opt#onally+ !l#!' the (ur*e b"tton to defne a load !"r*e or nonl#near analyses.

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. Cl#!' ", to apply the or!e and !lose the Remote or!e Ob/e!t d#alo$ bo4.

Remote Loads and Constra#nts

Dhat >o emote oads and "onstraints >oP

• Adds a nodal load or bo"ndary !ond#t#on to a po#nt #n spa!eF a po#nt not onthe model.

• The po#nt #n spa!e #s !onne!ted to sele!ted nodes on the model ,#th l#neelements.

• Eo" defne the propert#es o the l#ne elements as beam+ tr"ss+ or s#m#larl#ne elements.

• The remote load or bo"ndary !ond#t#on #s transm#tted thro"$h the l#neelements to the model.

• Remote Loads and Constra#nts d#6er rom Remote or!es+ #n ,h#!h thee6e!ts o a remote or!e are appl#ed d#re!tly to the model s"ra!e "s#n$a"tomat#!ally&!al!"lated nodal or!es no l#ne elements are !reated2.

ince the Re+ote oad command generates new geometry and a node at the point in space,

you can add any number of additional obBects at the new point.

Apply Remote Loads or Constra#nts

1. se any o the sele!t#on !ommands Selection Select2 to sele!t ,herethe remote load or !onstra#nt #s to be d#str#b"ted onto the model. ore4ample+ to apply a tor9"e to the end o a shat+ sele!t the *ert#!es ors"ra!e on the end o the shat. Re$ardless o ,hat #s sele!ted part+s"ra!e+ ed$e+ l#ne2+ the *ert#!es on the sele!t#on are "sed. ostappl#!at#ons re9"#re the remote load or !onstra#nt to be d#str#b"ted tothree or more *ert#!es not #n a stra#$ht l#ne.

. R#$ht&!l#!' and !hoose the (reate !emote Load < (onstraint !ommand. Th#s !ommand #s also a*a#lable *#a the r#bbon Setup Loads

!emote Load < (onstraint2.

%. se e#ther o the ollo,#n$ methods to spe!#y the lo!at#on o the remoteload or !onstra#nt.

o Type the X; Y; and !oord#nates o the des#red Load Location" Or+

o Sele!t one *erte4 or !onstr"!t#on *erte4 #n the d#splay area and!l#!' the =se Selected Point b"tton. The !oord#nates o thesele!ted *erte4 ,#ll be l#sted #n the G+ E+ and H felds.

(. The part+ s"ra!e+ ed$e+ or *ert#!es o*er ,h#!h the remote load or!onstra#nt #s to be d#str#b"ted are already l#sted by *#rt"e o start#n$ the

!ommand ,#th them sele!ted. o,e*er+ to !han$e the dest#nat#on or!reate a ne, remote load or !onstra#nt+ do one or both o the ollo,#n$3

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o Sele!t the ne, lo!at#on or lo!at#ons+ and !l#!' the Add b"tton.

o Sele!t one or more l#nes #n the Load Destination l#st and !l#!' the!emo*e b"tton.

-. Spe!#y the Part; Sur%ace; and Layer attr#b"tes or the l#ne elements that,#ll !onne!t the remote load to the model. 0enerally+ the dea"lt partn"mber #s a ne, pre*#o"sly "n"sed2 n"mber or the same n"mber aspre*#o"sly $enerated remote load elements.

8. Cl#!' the 5enerate Elements b"tton. The l#nes rom the remote loadlo!at#on to the model are !reated.

. Cl#!' the Add Load b"tton to see the l#st o nodal loads or bo"ndary!ond#t#ons that !an be added. Some o the a*a#lable opt#ons may not bes"#table depend#n$ on the analys#s type and the type o elements "sed orthe load elements.

J. I another remote load lo!at#on #s re9"#red+ repeat the abo*e steps start#n$,#th step %.

?. Cl#!' the (lose b"tton ,hen fn#shed apply#n$ all remote loads to allremote lo!at#ons.

T#p3 h#le the (reate !emote Load d#alo$ bo4 #s opened+ m"lt#ple loads orbo"ndary !ond#t#ons !an be added to the same node by "s#n$ the Add Load

b"tton more than on!e. Ater !los#n$ the d#alo$ bo4+ add#t#onal loads and

bo"ndary !ond#t#ons !an be added to the same node by sele!t#n$ the *erte4 at

the remote load lo!at#on Selection Select Vertices2+ r#$ht&!l#!'#n$+ and!hoos#n$ the appropr#ate entry "nder the Add y&o"t men".

Defne Remote Load>Constra#nt L#ne )lementsAfter the remote load or constraint line elements are created, use the browser (tree view) to

define the 6le+ent 7*e, 6le+ent Definition, and Material. Any line element type can be

chosen (beam, truss, gap, and so on), provided it suits the re&uirements of the analysis. +ere

are a few guidelines to keep in mind-

• oments !an be appl#ed as a remote load+ b"t they !an only betransm#tted thro"$h beam elements. Tr"ss elements+ $ap elements+ and

other l#ne element types that do not ha*e rotat#onal de$rees o reedom!annot transm#t moments and tor9"es. the /o#nts o these element typesare p#nned no translat#on+ rotat#on allo,ed2. See )etting $tarted:*ntroduction to Autodes+ $imulation FEA: Nodes and Elements oradd#t#onal #normat#on on transm#tt#n$ loads+ restra#nts+ and de$rees oreedom.2

• Ima$#ne the array o load elements as be#n$ s"pported by bo"ndary!ond#t#ons #nstead o !onne!ted to the model. The s"pport rea!t#ons atthese hypothet#!al bo"ndary !ond#t#ons are the loads that are transm#ttedto the model. The total o these s"pport rea!t#ons e9"als the appl#ed

loads+ b"t the d#str#b"t#on o the or!es and moments may be a6e!ted bythe st#6ness o the load elements.

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• St#6 beam elements a!ts l#'e a r#$#d str"!t"re atta!hed to the model+ sothe s"ra!e or nodes2 o the model ,here the remote load #s d#str#b"tedtend to 'eep the same shape b"t mo*e as a r#$#d s"ra!e. ea' beamelements and tr"ss elements transm#ts the load b"t do not !ompletelypre*ent deormat#on o the shape o the s"ra!e.

)4ample X se o Remote Loads and Remote Constra#nts%igures : and ? illustrates how to use remote loads to analyEe a shaft (made from brick

elements) that is part of a gear train. #n the %*A 'odel, the two boundary conditions at the

bearings prevent the shaft from rigid body translations in all directions. The bearing on the

left is held radially (Ty and TE) and axially (Tx, to contain thrust loads), and the mounting of

the bearing on the right constrains radial translation (Ty and TE) but allows axial movement

(floating bearing). Assume the bearings are spherical, so that they do not restrain rotation in

any direction.

#f the load at the pinion were to be modeled with a force, the shaft would still be free to rotateabout the axial direction. This would lead to an unstable model and potentially wrong results.

A remote boundary condition at the pinion tooth that restrains the model in the tangential

direction prevents axial rotation (x) and produces the reaction force needed to balance the

gear load.

Figure 1: Diagra+ of .$aft 4it$ &ears


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1. Remote Constra#nt atta!hed to s"ra!e o bear#n$ /o"rnal ,#th a no&translat#on !onstra#nt at !enter o bear#n$ T4+ Ty+ and T52.

. Remote Load atta!hed to $ear mo"nt#n$ s"ra!e ,#th or!e appl#ed at $eartooth lo!at#on.

%. Remote Constra#nt atta!hed to p#n#on mo"nt#n$ s"ra!e ,#th bo"ndary!ond#t#on #n tan$ent#al d#re!t#on Ty2.

(. Remote Constra#nt atta!hed to s"ra!e o bear#n$ /o"rnal ,#th a4#al andrad#al !onstra#nt bo"ndary !ond#t#ons Ty and T52.

Figure !: 6@ui3alent F6A Model /sing Re+ote oads

T#p3 I ,or'#n$ ,#th a CAD model+ the Mes- (AD Additions 2oint !ommand!an be "sed or the bear#n$s to !reate "n#*ersal&type /o#nts. The res"lt #s the

same $eometry as !reated by the remote load !ommand.

Temperat"res

Temperatures are also applicable to heat transfer analyses but are significantly different

within that context. %or more information, please refer to the following pages-

• In#t#al Temperat"re

• Controlled Temperat"re

A temperature can be applied to nodes, surfaces, or parts in a linear or nonlinear structural

analysis model and to nodes or surfaces in an electrostatic analysis model.

Dhat >oes a Temperature >oP

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• A s"ra!e temperat"re appl#es nodal temperat"res to ea!h node on thes"ra!e+ and a part temperat"re appl#es nodal temperat"res to ea!h node#n the part.

• In l#near and nonl#near str"!t"ral models+ temperat"res are "sed or

thermal stress analys#s. Temperat"res !a"se thermal e4pans#on o anymater#als ,#th non&5ero !oeY!#ents o thermal e4pans#on.

• The nodes to ,h#!h a temperat"re #s appl#ed are 'ept at the *al"espe!#fed #n the Magnitude feld. Th#s temperat"re #s only appl#ed to thesele!ted nodes and does not !ond"!t thro"$h the mater#al. A thermalanalys#s #s re9"#red to !al!"late heat !ond"!t#on or heat o, *#a!on*e!t#on or rad#at#on.2

• The stress !a"sed by the temperat"re #s !al!"lated rom the d#6eren!ebet,een the nodal temperat"re and the Stress Free !e%erenceTemperature+ ,h#!h #s sp

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