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  1. Hi, all right I tried to model the shell as a rigid body but I get a normal termination after one cycle, no apparent errors or warnings. Can you check the model attached? Thanks. 5_ww.hm
  2. yeah but in order to have the right pressure I should apply a gravity of 20000g's, and this would break any shell!
  3. All right, now the gas moves with the sphere but I still can't have useful informations about pressure field and VM stress. How do I get them? I need the pressure exerted on the lower face of the sphere due to the inertia of the gas. Tell me if my question is not clear.
  4. Hi, I'm still waiting for the simulation to end, but in the meantime I just made another model with a sphere instead of the cylinder. The sphere contains the gas and the objective is to accelerate it at high accelerations (just as the cylinder) and to gather informations about the pressure field generated because of the inertia of the gas within the sphere that pushes on the lower face. (It is the same concept of the cylinder). This time the simulation runs surprisingly fast but the problem is that, like you can see in the h3d attached, the gas modelled with sph doesn't move with te sphere as expected. What am I doing wrong? Also, how can I get the results that I need? Thanks for your help! 1.h3d 1_0000.rad 1_0001.rad
  5. Thank you! I will go through the webinar and I'll let you know about the results. Have a nice day!
  6. I thought it was unnecessary because I selected the nodes when I defined the BCs , but now I noticed the other field. I am now running again the simulation. Any other tips on how to reduce the computational cost? Thanks again, I appreciate your dedication. Have a nice day!
  7. Hi, ok thanks! I had the results but they are useless. I applied an acceleration of 20000g's but nothing moves. What am I doing wrong? I'm sorry for this questions but I need to bring out some reasonable result ASAP and it is my first approach with radioss. I will have the chance to follow altair's RADIOSS course in a month but I need something sooner. I'm attaching the results along with the new model file. I set a simulation time of 0.001 s because it was the only way to have a "reasonable" computation time (1.5days!!!). I think that now the model has the right measure units, but I can't understand why the computational cost is that high. Note that in the model file the simulation time is 0.0001 s because I updated it this morning , but the h3d file refers to the simulation with 0.001 s . Again, thanks for helping! 3_0001.rad 3_0000.rad 3.h3d
  8. Yes, actually I made a mistake with fabric datas. Thanks for your help. Now I have modified the model deleting the fabric and adding a cylindrical pipe as wall... I launched succesfully the simulation and now I'm waiting for the results. I'll let you know how it goes! I have another "off-topic" question : I need to apply a pressure which has a 3D gaussian distribution (so I need to apply an equation function of space variables x,y,z) ; I am almost sure that RADIOSS only handles equations variable in time. Is there a way to apply a pressure with that kind of distribution in space but constant in time? (just like optistruct equations) Thanks again for your help! Greetings.
  9. Hi, thank you for your reply. I fixed the issues with the penetrations and changed the type 1 to type 7. Still have 3 warnings about initial penetrations in each contact group but the penetration check doesn't find anything. This time, the run doesn't start anymore due to this warnings. You'll find the new model attached, please let me know I can I solve this problem. I already tried changing INACTI from 6 to 3, which should help to avoid initial penetrations, but it actually don't! Thanks again, and have a nice day! menoelementi_300_0000.rad menoelementi_300_0001.rad
  10. I'm sorry, I edited the last post with the correct files, it was my mistake. BTW , I updated the model but the ETAs still are nonsense. Please check the model and let me know what is the problem, in your opinion. Thanks so much for your help.
  11. You will find the new model attached. Any hint on how to solve the kinematic condition incompatibility showed by the warnings? In addition, I would appreciate a comment on the model... am I going in the right direction? base1_2_0001.rad base1_2_0000.rad
  12. Wow, thank you very much! It was very helpful! I will try to rebuild the model correctly. I was wondering ... I need to model the inertia of the plates and its effect on the gas compression. So if I model the lateral surface of the cylinder as a rigid wall, with the gas within that rigid wall, I still have to model the plates so that they interact with the gas due to their inertia. So if I model the plates as shells and I assign a material property to them so that they have a given mass, will they react with inertial effects if I impose an acceleration on the whole system? The reference frame is not an inertial frame, but it is moving with the plate which puts in motion the gas and the other plate. I hope I have been clear. Thanks again!
  13. ok thanks for your help! I'll try in the RADIOSS section.
  14. Hello guys, I need some advice: I need to simulate the behavior of a cylinder-shaped fluid mass contained between two plates ,within a hollow cylinder (like illustrated in the figure attached). In particular, I need output data about the pressure field within the fluid due to the application of a huge force/pressure on one plate so that the whole system accelerates within the hollow cylinder at tens of thousands of g's. The other plate reacts to the motion only with its inertia, so that after a transient phase there is a steady state condition in which the distance between the two plates is fixed, for given initial data. It's my first contact with radioss or with any explicit solvers so it's pretty hard to get what I need. I will also attach a first model (hm file) that I built in Hypermesh. It actually runs with radioss, but with nonsense ETA if compared to the simulations time. I also have some other question: -where can I find a list of the control cards which are supported by RADIOSS so that I can understand how they work? - how do I set a contact between an SPH and a 2D shell mesh? I used a type7 contact but I don't know if it is right. If anybody could help I would be very grateful. Thanks in advance! cylinder.bmp base.hm
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