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Subject: Re: [STRUC] MPCs on contacts with pilot node
Author: Krishna Raichur
Date: 2008-04-11 19:41:53

Brahmaji,

When you apply constraints directly on the area, you will *not* get reaction moments because the underlying solid elements only have translational DOF, no rotations. I am guessing your model also has solids, so if you want a moment reaction, you will need to tie those nodes to a pilot node with MPCs.

Regards,
Krishna

________________________________________
From: xansys-bounces_at_xansys.org [xansys-bounces_at_xansys.org] On Behalf Of brahmaji.vasantharao_at_rolls-royce.com [brahmaji.vasantharao_at_rolls-royce.com]
Sent: Friday, April 11, 2008 2:06 PM
To: xansys_at_xansys.org
Subject: FW: RE: [Xansys] [STRUC] MPCs on contacts with pilot node

>Below is a sample problem that shows the correct reaction moment for a
cylindrical pipe model. No need for any FSUM and SPOINT commands. >The input
builds three parallel models -- a Pipe16 model, a Solid185 model with MPC
contact elements, and another Solid185 model with MPC184 >rigid links. The
moment reaction from all three models is as expected.



>Regards,

>Krishna



Krishna,



I went through the sample code you emailed. You were able to obtain the
correct reaction moments, by creating another pilot node corresponding to
the constrained area and constraining it. I like your method, and it works.



But like I explained in my previous mails, when I went back into your solid
model and removed the pilot node corresponding to the constrained area and
applied my area constraints directly on the area, I did not get a reaction
moment. The displacements and stress were still there.



I think I understand the issue better now; it appears from your example and
the problem I was working on that one has to be aware of the fact that when
using MPCs on contacts with pilot node one may not get the correct reaction
moments if the model is constrained in the normal way of applying DA or D
commands directly on the areas and node components. The correct reactions
can be obtained by constraining the model by means of a pilot node
corresponding to the constrained area.



I want to thank you and everyone who has answered my question.



Regards,

Brahmaji



Rolls-Royce Energy Systems

PT Design - Mechanical Engineer

Mount Vernon, OH



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Posts possibly associated with message #92826AuthorDateScore
92794[STRUC] MPCs on contacts with pilot nodebrahmaji.vasantharao_at_rolls-royce.com2008/04/10 
92795Re: [STRUC] MPCs on contacts with pilot nodeCharles Bhaskaran2008/04/10 
92799Re: [STRUC] MPCs on contacts with pilot nodeKrishna Raichur 2008/04/10 
92800Re: [STRUC] MPCs on contacts with pilot nodebrahmaji.vasantharao_at_rolls-royce.com2008/04/10 
92806Re: [STRUC] MPCs on contacts with pilot nodeArne Löhn2008/04/11 
92807Re: [STRUC] MPCs on contacts with pilot nodeRiccardo Testi2008/04/11 
92818Re: [STRUC] MPCs on contacts with pilot nodeKrishna Raichur 2008/04/11 
92824Re: [STRUC] MPCs on contacts with pilot nodebrahmaji.vasantharao_at_rolls-royce.com2008/04/11 
92826Re: [STRUC] MPCs on contacts with pilot nodeKrishna Raichur 2008/04/11 
92827Re: [STRUC] MPCs on contacts with pilot nodeChristopher Wright2008/04/12