Cyclic Symmetry, Pressure Loads on assembly

March 15, 2016, 12:36 am

≫ Next: Re: Cyclic Symmetry, Pressure Loads on assembly

≪ Previous: Re: Simulate, through thickness average stress also called membrane stress

$

0

0

Hi,

I am running Creo 3 Simulate, we are trying to determine the stress within the walls of a pressure vessel assembly from external pressure, but using cyclic symmetry to speed up the process.

The model runs ok and the analysis completes, but the result is always far beyond the material yield turning the model red, this happens even if the external pressure load is very low, say around 100psi, the material yield is 130ksi, the walls are more than capable of with standing this pressure, normal operating pressure would be 10kpsi.

Thanks

Geoff.

---

Re: Cyclic Symmetry, Pressure Loads on assembly

March 15, 2016, 1:06 am

≫ Next: Re: Cyclic Symmetry, Pressure Loads on assembly

≪ Previous: Cyclic Symmetry, Pressure Loads on assembly

$

0

0

Geoff, can you share your model so we can have a look at it?

Re: Cyclic Symmetry, Pressure Loads on assembly

March 15, 2016, 1:56 am

≫ Next: Re: Cyclic Symmetry, Pressure Loads on assembly

≪ Previous: Re: Cyclic Symmetry, Pressure Loads on assembly

$

0

0

Seems like a unit error... I see also that you have sharp reentrant corners, you may end up with non-converging high stresses in those locations. This is where the linearized stress query can be used with some norm, for dimensioning.

Re: Cyclic Symmetry, Pressure Loads on assembly

March 15, 2016, 2:07 am

≫ Next: Cluster/Distributed Computing für Creo Simulate?

≪ Previous: Re: Cyclic Symmetry, Pressure Loads on assembly

$

0

0

Might also be incorrect constraints; it looks as if there are deformations perpendicular to the symmetry planes near the sharp corners. And that long thin red artefact in the right top seems odd as well.

Cluster/Distributed Computing für Creo Simulate?

March 15, 2016, 3:39 am

≫ Next: Re: Need help regarding 3 point constraint system

≪ Previous: Re: Cyclic Symmetry, Pressure Loads on assembly

$

0

0

Hi!

Creo Simulate has a feature called distributed computing. Is this some parallel computing using e.g. MPI distributing a simulation load over multiple nodes? Is there any good setup-How-To? Is this feature always included or do we need an additional license (for each node)?

Any recommendations for setup or benchmarks for achievable speedup.

br Bernhard

Re: Need help regarding 3 point constraint system

March 17, 2016, 8:44 am

≫ Next: how to make animation video of various parts

≪ Previous: Cluster/Distributed Computing für Creo Simulate?

$

0

0

Thanks Jacob, Jonathan and Patrick.

I will incorporate all your suggestions into the analysis and check if I get the desired results for the quarterplate design.

I will post a reply as soon as I finish.

how to make animation video of various parts

March 17, 2016, 9:33 am

≫ Next: Re: how to make animation video of various parts

≪ Previous: Re: Need help regarding 3 point constraint system

$

0

0

How to make animation video of various parts in creo parametric 2.0

Re: how to make animation video of various parts

March 17, 2016, 12:35 pm

≫ Next: Re: how to make animation video of various parts

≪ Previous: how to make animation video of various parts

$

0

0

Are you talking about making animation videos from the Creo Simulation results?

---

Re: how to make animation video of various parts

March 17, 2016, 8:36 pm

≫ Next: Use a measure to calculate force in simulate

≪ Previous: Re: how to make animation video of various parts

$

0

0

Yes i want to know how  to make animation video in creo parametric 2.0

Use a measure to calculate force in simulate

March 18, 2016, 8:42 am

≫ Next: rototranslation wheel in Creo Mechanism

≪ Previous: Re: how to make animation video of various parts

$

0

0

Hello,

I want to conduct a drop test using simulate. I can calculate the energy on the component when it hits the floor using the formula mgh (mass x gravity x height). However, it's difficult to convert this to impact force. The impact force is given by energy divided by deflection. I need to get the deflection in order to apply force, but I need to apply force to get deflection.. Catch-22, mutually dependent condition.

I thought of a solution would be to create a measure for deflection, then use this deflection in a formulae to apply force.

Anyone know how to do this?

Below is the Load as function page in simulate where am trying to do this.

Cheers.

rototranslation wheel in Creo Mechanism

March 18, 2016, 9:23 am

≫ Next: Re: rototranslation wheel in Creo Mechanism

≪ Previous: Use a measure to calculate force in simulate

$

0

0

Hello,

I would like to turn the wheel on a plane, what kind of constraint I have to apply to wheel sufaces?

1 cam?

2 gear?

 

In my model applying cam constraint and servomotor, the wheel rotate but doesn't translate.

 

Re: rototranslation wheel in Creo Mechanism

March 18, 2016, 11:55 am

≫ Next: Re: Use a measure to calculate force in simulate

≪ Previous: rototranslation wheel in Creo Mechanism

$

0

0

You should use a cam and make sure you provide a friction coefficient. You may need to turn on gravity if it will provide the load between the wheel and the flat surface.

Re: Use a measure to calculate force in simulate

March 18, 2016, 2:36 pm

≫ Next: Re: Need help regarding 3 point constraint system

≪ Previous: Re: rototranslation wheel in Creo Mechanism

$

0

0

Hello,

 

You could use the Mechanism Dynamic Extension and perform the drop test in order to find the forces acting on your body when it hits the floor.

After that, you can export this loads to simulate and perform a simulation to see the deflections that it causes to your object.

Re: Need help regarding 3 point constraint system

March 18, 2016, 4:29 pm

≫ Next: Re: rototranslation wheel in Creo Mechanism

≪ Previous: Re: Use a measure to calculate force in simulate

$

0

0

Hello,

 

The rule for applying the three-point constraint is as follows:

 

• The points can be anywhere on the model surface, but are not allowed to be collinear.
• Fix the first point in all translational directions.
• Fix the second point in the two orthogonal directions relative to the axis through point 1 and point 2.
• Fix the third point normal to the surfaces through all points.

 

The main problem with this, is that it leads to singularities if your model is not in equilibrium. In other words, you have to apply other loads in order to have a resultant of 0 for forces and moments on the entire part.

 

The image shows you how to calculate an opposite "equal" force of 250 Mpa that you have to add to your model.

The video shows you how to review the total load in order to find the equilibrium, notice the approximate values to 0.

 

 

 

 

Note that this model does not have symmetry definitions, this is the final part and not a slice of it.

Re: rototranslation wheel in Creo Mechanism

March 18, 2016, 5:03 pm

≫ Next: Re: how to make animation video of various parts

≪ Previous: Re: Need help regarding 3 point constraint system

$

0

0

Are you anticipating simulation output or do you just want to show the action of the mechanism?

 

Just for illustration purposes, I would put features in place to treat it as a rack and pinion.

 

This means the wheel device has to be on a slider type constraint ad the wheel can be a generic gear connection between the wheel device and the wheel at a specific ratio.  Now you can rotate the wheel with a Servo motor and the device should move linearly along whatever guide path you set up.

 

You could opt for letting the plane move on rotation of the wheel in the same way if you have the connections set up for a rotational to linear motion gear connection.  There are ways to lock views onto the moving object to mimic an alternate ground element.

---

Re: how to make animation video of various parts

March 19, 2016, 5:00 am

≫ Next: Importing NASTRAN Results File (.xdb)

≪ Previous: Re: rototranslation wheel in Creo Mechanism

$

0

0

Let me clarify this again, I'm asking if you want to make a video with Creo Simulate not Creo Parametric.  If you want to use Creo Simulate, here's the instructions, and you start from the Simulation results window:

 

Importing NASTRAN Results File (.xdb)

March 19, 2016, 8:33 am

≫ Next: Problem from PTC Help Center

≪ Previous: Re: how to make animation video of various parts

$

0

0

Community,

 

Has anyone attempted to import .xbd files in to Creo Simulate and review the results?  The Help Center states you can import results.  Does anyone have a .xdb file they would like to share for training purposes?  Thanks in advance.

 

Problem from PTC Help Center

March 19, 2016, 8:03 pm

≫ Next: Re: Need help regarding 3 point constraint system

≪ Previous: Importing NASTRAN Results File (.xdb)

$

0

0

Hello,

 

I tried to perform an analysis of a problem from the PTC Help Center.

 

I get the same exact numbers of elements and equations. However, the result is QUITE DIFFERENT.

 

I checked all variables (units, measures...) and I cannot see my mistake. The image shows you the problem, the attached file is my analysis.

 

Can you help me to figure it out?

 

Thank you.

 

Re: Need help regarding 3 point constraint system

March 20, 2016, 12:54 am

≫ Next: Re: Need help regarding 3 point constraint system

≪ Previous: Problem from PTC Help Center

$

0

0

Hello,

 

looking at your animation brings up a question. Your symmetry surface in YZ-plane seems to be moving "out of plane". This would not be the case if symmetry truly exists, right? In your simulation that would mean the mirrored part should also move "out of plane" into the modelled part, which sound a bit odd to. In my opinion the symmetry surface in YZ-plane should move only along the Y-direction, otherwise symmetry is not existing.

 

Regards

Re: Need help regarding 3 point constraint system

March 20, 2016, 5:48 am

≫ Next: Re: Need help regarding 3 point constraint system

≪ Previous: Re: Need help regarding 3 point constraint system

$

0

0

Good point. That is because the moment is applied around a point. Depending on the choice of the point location, the deformations will look different.

 

If you model symmetry with help of constraints, these constraints may introduce reaction loads in your model. If you were to apply these exact same reaction loads in the model, you could then leave out the constraints, and you would end up with a similar model as in the movie. Adding up the reaction loads would also give a reaction moment equal in magnitude to the moment in the movie, but built up out of different loads. If one were to plot the reaction loads at the constraint locations, it would probably not look as neat as a total load at point.

But (I think) the idea here was not to show how to model symmetry with only loads, but rather how to put loads on a model without the need for constraints.

 

(Please note that only applying a 3-point constraint would also give non-symmetric results!)