patran contact pairs & settings -...

Patran Contact Pairs & SettingsPart of MSC Nastran 3D Contact Video Series

Mica Parks

February 2015

Patran Contact Pair Settings

Related To Nastran Input

• Majority of this content is related to LBCs Body Pair

Geometric and Physical Contact Parameters.

– What do the various options write to BDF plus notion of the

physical behavior.

Contact InteractionPatran Settings & Toggles Map

IGLUE = ?

JGLUE = ? (NA unless IGLUE>0)

ICOORD = ?

3

ERROR = ?

BIAS = ?

SLIDE = ?

ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

• Default settings except Master-Slave search

ISEARCH (BCONPRG):

1. ERROR is based on element size or shell thickness.

2. BIAS=0.9 as shown.

3. IGLUE=0 or not written to BDF so contact is touch.

4. ISEARCH=1 setting search from Slave to Master.

• Default is ISEARCH=0, would not be written to BDF and not

what I suggest using.


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 0

JGLUE = 0 (NA unless IGLUE>0)

ICOORD = 0

1

2

3

NLOPRM NLDBG=… extra F06 output

4

• ICOORD=1 modifies slave node locations if bodies

within ERROR & BIAS distance criteria.

• Original intent for bolts in hole, tube in tube.

• Effective with both touch and glue.

• ICOORD settings (BCONPRG):

1. ERROR auto calculated & BIAS=0.9 as shown before.

2. IGLUE=0 or not written to BDF so contact is touch.

3. ICOORD=1 moves only the slave node in contact direction.


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 0


ICOORD = 1

1

2

3


1. ICOORD=2 moves master nodes in the in-plane or

tangential direction.

• ICOORD=1 not on active in this case.

2. SLIDE=# activated with ICOORD=2.


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 0


ICOORD = 2

1

2

ICOORD=2 physical representation


1. ICOORD=3 is a combination of ICOORD=1 & ICOORD=2.

2. SLIDE=# is shown but not written to BDF. This is an error

on Patran’s part and should be fixed in next version.

• Suggest using Patran ICOORD=2 to get SLIDE then manually

change to ICOORD=3


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 0


ICOORD = 3

1

2

SLIDE ?

• Patran incorrectly does not write SLIDE if

ICOORD=3. Due to incorrect documentation in 2013

QRG, PAT-23193. Correct documentation below:

• IGLUE > 0 settings (BCONPRG):

1. IGLUE=1 contact is glue and slave nodes projected/moved

onto master surface. Not moment carrying glue.

2. BIAS=0.0 is default with IGLUE<>0 but not reflected in

Patran.

• Only means to know this is look at QRG BCPARA.

3. ICOORD=2 and SLIDE=0.055 is left on for reference. It is

effective with glue but the focus of this slide.


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 1

JGLUE = 0

ICOORD = 2

1

2

• BCPARA shown is Patran default and can be problematic.

– BCPARA overwrites unset contact values.

– BCPARA 1st 0 indicates it is active for pre-load check and all subsequent

SUBCASES/STEPs

– NLGLUE=0 indicates permanent glue is active. But if any IGLUE=0 (touch) in model

or no initial glue is detected in the model then permanent glue isn’t activated.

3

3


1. IGLUE=2 contact is glue but slave nodes are NOT

moved/projected onto master patch/elements. Not moment

carrying glue.


Patran.



ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 2

JGLUE = 0

ICOORD = 0

1

2


1. IGLUE=4 contact is glue and moment is carried. Slave

nodes are NOT moved/projected onto master

patch/elements.


Patran.



ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 4

JGLUE = 0

ICOORD = 0

1

2


1. IGLUE=3 contact is glue and moment is carried. Slave

nodes are moved/projected onto master patch/elements.


Patran.



ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 3

JGLUE = 0

ICOORD = 0

1

2


– IGLUE=1 and IGLUE=3 can and do cause grounding!!

• They are intended for glueing meshes that are perfectly

aligned.

• If for some reason these settings are desirable turn on

ICOORD=1

– IGLUE=2 (no moment) and IGLUE=4 (include moment) are

better options.

• Activate with “Retain Gaps/Overlaps”


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 4

JGLUE = 0

ICOORD = 0

• JGLUE > 0 settings require IGLUE >0 (BCONPRG):

1. JGLUE=1 separation based on FNTOL with options

between force or stress based on IBSEP.

• Technically FNTOL is effective with touch, IGLUE/JGLUE is not

required. Next slide.

2. JGLUE=2 further granularity for separation between normal

and tangential stress


ISEARCH = 2

ISEARCH = 1

ISEARCH = 0

IGLUE = 1

JGLUE = 1, 2

ICOORD = 0

1

2JGLUE = 0

JGLUE = 1

JGLUE = 2

• Patran will give the false impression FNTOL is dependent glue; IGLUE>0 &

JGLUE>0. Not the case. PAT-23819


• Touch default FNTOL is outlined in BCPARA IBSEP

and based absolute value of the largest component

of residual force vector. Generally a good value

except with large concentrated force.

• Increasing FNTOL makes touch ‘sticky’. Not unlike

P/CGAP with large open stiffness. Use with caution!

• You can play games turning on IGLUE then JGLUE to change FNTOL then

uncheck IGLUE to get desired effect.


• In this case it may be best to explore the actual

location of the values, under Properties.

• Here you can change all the same settings the LBC

form but it isn’t as friendly.

• Force based breaking glue.

– IGLUE>0, JGLUE=1 then FNTOL

• Stress based breaking glue.

– IGLUE>0, JGLUE=2 then BGM, BGN,

BGSN and BGST

– This feature can be used for

delamination and crack initiation

– After breaking, standard touching

contact is activated if it comes into

contact again

163/24/2015

Patran Breaking Glue

contact normal tangential stress

• ISEARCH controls Master-Slave search order.

= 1 or Single Sided

• Most accurate and best option when problems arise.

=2 is Automatic

• Let Nastran determine Master-Slave based on element

density and thickness.

• Generally problematic unless set BCPARA THKOFF=1.

= 0 is Double Sided (Default)

• Okay shotgun approach but fails with changing density as

shown in last slide. 50% chance of getting good contact.

Contact InteractionN2S Who’s Master? Who’s Slave?

= 2

= 1

= 0

• It may be necessary to modify

Deformable Body Master-Slave setup.

• Plot Contours is a nice method to check

relationship. But modification must be

done on the LBCs form.

• Use Reverse Bodies to flip relationship.

• Remember:

– Slave = more nodes, finer mesh

– Master = less nodes, coarse mesh

*Patran 2014 arrow Master-Slave reverses.

183/24/2015

Patran Contact LBCs Modify – Master-Slave

= Master

= Slave *Patran 2013 shown

• How topology is conveyed to contact interaction.

COPTS(Slave)/M(Master) = A + 10*B + 1000*C

• Default shell thickness, (10*B) with B=1:

COPTS/M = 1011

• “Ignore Thickness” B=6:

COPTS/M = 1061

193/24/2015

Patran COPTs – Ignore Thickness

• Edge-Edge ignore thickness.

• Face-Face ignore thickness if FEM was created so

thickness was not accounted for.

203/24/2015

Patran COPTs – Ignore Thickness

– Initial model

– Bad! Default thickness causes

connection between top face. Will get

odd results.

– Good. Ignore thickness contact is at

element edges or centerline.

– Bad! Default thickness causes

connection between bottom face. Will get

odd results

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