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#1 Re: Code_Aster usage » How to increase the speed » 2020-10-29 11:02:51

Hello again
I was wondering if it was possible to set a variable time step, for example proportional to 1/V for the ramp, and then a constant one. The goal would be to reduce the simulation time.
Thanks a lot if you answer me again and have a nice day

#2 Re: Code_Aster usage » How to increase the speed » 2020-10-17 10:11:07

Hi,
Thanks for you time it is working fine. I can t share the flywheel mesh for confidentiality reason.
And I am not italien smile

#5 Re: Code_Aster usage » How to increase the speed » 2020-10-12 08:48:11

I don t understand how to print it sorry

#6 Re: Code_Aster usage » How to increase the speed » 2020-10-11 21:54:14

Hi,
Sorry for being so late.
Yes I had same formula as you do so that s nice.
It worked thanks but I am having two different files as the end (rmed) because I have two stage. Is it possible to have only one file ? I am exporting my files with paravis in csv but If I had them after one the same document I don t know if my datas are correct.

#7 Re: Code_Aster usage » How to increase the speed » 2020-10-10 18:28:34

Yes it is working fine thanks.
Just one last thing. Instead of having this increasement during the whole simulation I would like to have it only frew seconds. For exemple If I have a 5 seconds simulation I would like to have my increasement from 0 to 20 000 rpm the 2 first seconds and then stay at 20 000 rpm 3 seconds. I worked with formula as you did and so if I make it simple I will need to have
- sqrt(X*X+Y*Y)*cos(atan2(Y,X)+(Vradps/2)*INST*INST)-X    between 0 and 2 seconds
- sqrt(X*X+Y*Y)*cos(atan2(Y,X)+(Vradps*INST)-X                    between 2 and 5 seconds
Vradps is my speed in radian per seconds so 52rad/s.
I try to search how to have two different formula depending of the time but I didn t find how to do it.
Would you know the way ?

#8 Re: Code_Aster usage » How to increase the speed » 2020-10-09 14:25:29

Thanks a lot for your answers
Yes it is basicly what I want to do.
To explain you a bit better I am in intership and my goal is to simulate the expansion of a flywheel. Some experiments with the same flywheel at different speed were made and my aim is to be as close as possible from this results. But before working with this complex object I am simulating a simple cylinder with an hole, so a pipe, in two dimension.
It seems to work fine but I can t do a lot of revolution at high speed (my goal is 20 000 rpm) because I have convergence problem. So I need to have an extremely small timestep and I have problem with memory.
So to solve this problem and to be closer from the experiments I am trying to have a speed which goes from 0 to 20 000 rpm in few seconds and not directly 20 000 rpm during the whole simulation. As I didn t have the speed in my rotation formula I was trying to change an other parameter. I try with dtheta but as it wasn t a scalar anymore it wasn t recognized in the formula and it didn t work. So I don t really know what to do. I hope you will understand better my problem.
What you send me seems way better but I don t understand why cos(t) and how to define n(dt) in code aster. 
Thanks again for your help I really appreciate it.

#9 Re: Code_Aster usage » How to increase the speed » 2020-10-08 22:14:01

Ok thanks a lot I will try it. But to be closer for my experimental plots I think I will need to have an increasing speed anyway. Do you know how I should do it ?

#10 Re: Code_Aster usage » How to increase the speed » 2020-10-08 12:48:36

I tried to work with dtheta but I didn t achieve to do it, you will find attached my code with increasing dtheta. If you have any idea how to do it or if you want to tell my if my code is good for you I will highly appreciate it.
Thanks for advance and have a nice day

#11 Code_Aster usage » How to increase the speed » 2020-10-08 12:46:04

Clement M
Replies: 31

Hello,
I am working on code aster to analyse the expansion of a pipe in rotation in two dimension. I created a code which is working but I have some issue with convergence at high speed. I think it s because I am using a constant speed. So I am trying to increase it from 0 to max but I didn t achieve to do that for now. You will find attached my code aster code, gro_face is the the internal circle of my 2d pipe.