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Compressing ribbed cylinder- help requested

Compressing ribbed cylinder- help requested

Compressing ribbed cylinder- help requested

(OP)
Dear All,
I have a little experience with COSMOSWorks and have had good results in the past with simple models, but have come up against a problem which I now need to solve:

I'd like to induce a kink in a ribbed tube by compressing it between two small surfaces.

My technique was to draw the ribbed tube, then create two extruded bosses from remote planes, extruded up to the ribs to act as a Restraint and a Load. This gives a solid part that looks reasonable, here:
,


but when put through the simulation gives very strange results, perhaps because it acts as one solid body, image here:

Somehow the extruded bosses have moved 'inside' the ribs, perhaps like a potato through a slicer. This is very strange and not at all desired.

Is there a better way to model this kind of situation? I have looked for tutorials but have been unable to find any applicable.

If somebody could point me in the right direction or walk me through the concept I am missing (is there a better way than modelling the actual force blocks?) it would be very much appreciated.


best wishes,

Gwilym

Attached is the model I have been playing with, though of course I do not expect it to be done for me!

COSMOSWorks 2008 on SolidWorks 2008, Windows 7
Replies continue below

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RE: Compressing ribbed cylinder- help requested

Looks in the upper left corner of the display when you plot. What is the scaling factor for deformation set to? That is the usual culprit in a case like this.

Also, you are applying a force/pressure on one side and you have constrained the other side to be flat. This causes one of the "bars" to bend and the other to remain straight.

TOP
CSWP, BSSE
www.engtran.com  www.niswug.org
www.linkedin.com/in/engineeringtransport
Phenom IIx6 1100T = 8GB = FX1400 = XP64SP2 = SW2009SP3
"Node news is good news."

RE: Compressing ribbed cylinder- help requested

(OP)
Hello, thanks for your reply.
Deformation factor is 0.56.., does this shed light?

Your explanation goes some way towards explaining, thanks.
But I would expect the 'bars' to remain flat and parallel with the ribs buckled beneath, rather than poking through the ostensibly solid 'bars'.
Might you know why this is not the case? Or am I barking up the wrong tree?

best wishes,

Gwilym

RE: Compressing ribbed cylinder- help requested

Set the deformation to 1.

Only the bar with the displacement constraint should stay flat and level.

Use a forced displacement instead of a force if you want both to stay flat and parallel.

In Cosmos/M I would use the CPDOF command to constrain a component loaded with a force to stay flat and parallel. You don't have that capability in Simulation.  

TOP
CSWP, BSSE
www.engtran.com  www.niswug.org
www.linkedin.com/in/engineeringtransport
Phenom IIx6 1100T = 8GB = FX1400 = XP64SP2 = SW2009SP3
"Node news is good news."

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