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About bongirs

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  1. Hello, I have a plastic part subjected to heated air and I want to simulate the thermal expansion (no CFD required, just a simplified thermal expansion with temperature inputs is sufficient). I am using HyperMesh for pre and post processing and my solver is Abaqus. I have no idea how to do this, already tried the Joule heating solver, static solver, explicit solver, etc always get some errors which has no meaning intuitively. Can anybody tell me how to go ahead with this? If there is a tutorial or a pdf on this topic what would be very helpful.
  2. Your reply confuses me a little, so just want to confirm what I understood. You acknowledge that there is some issue with RADIOSS for different unit systems and are checking with QA/SD teams?
  3. George, I really didn't expect this kind of reply from you. Please see the .hm files I uploaded previously. I have already maintained consistency in geometry, mesh, material, boundary conditions, etc
  4. Hi Datta1234, Thank you for sharing your findings with me. I spent months trying to find out fault in my simulations when I realized this bug in RADIOSS. I don't understand why George is not replying. If anyone else is facing the same issue, then please post it here...
  5. I am still expecting some kind of reply... Do you get what I am saying George?
  6. Hello Duong and George, You are comparing the end value of IPS with the max value of SI model. It is linear elastic, so this is not a good comparison as they occur at different stages of the impact. Please see the excel I attached, the max stress values are provided in it. Clearly the IPS model has way too high stress. If you still cannot see the difference then I would recommend you to choose a Johnson Cook model with your choice of consistent parameters. You will find that the IPS model has like 3X plastic strain.
  7. Hello, I am running the same simulation in two different unit systems - inch-pound-second and mm-kg-ms. Please note that everything is consistent in unit conversion. I am observing tremendous stress/strain/deformation for the inch system compared to the mm system. Please note that the difference is by multiple magnitudes. What is wrong here? I have attached the .hm files as well as the excel file with details on units followed. As RADIOSS is a unit less solver, it should not matter what unit system we follow so long as it is consistent. mmkgs.hm ips.hm mmkgs.h3d ips.h3d mats.xlsx mmkgs.avi ips.avi
  8. Hi George, I got it in /TH/BRIC, so its strain energy density. I also wanted to ask you that I am not getting EPSD data in HyperView. I am using LAW2 and its supposed to give me strain rate for my elements. In thr contour plot it is listed, but the contour is all zero data. I cannot find any strain rate data in T file. So please tell me how to get the strain rate? I am using 3D tetra elements.
  9. Hello, I wanted to know whether the internal energy curve from T file is strain energy or strain energy density? Also, how do I get the contour plot for strain rate experienced by each element?
  10. Thank you George for your answer! So I understand that the initial velocity is set at t=0 to the selected nodes. The nodal velocities may change over the course of the simulation if the nodes face contact or if there are nodal forces. For imposed velocity, the velocity of selected nodes is maintained at specified value no matter what. So if they come in contact with another body, there will be increase in contact stress and even result in complete body motion to satisfy the imposed velocity. I was just wondering in which scenario could this be useful? I didn't quite understand the part about initial acceleration. What I understood from your reply is that if the simulation time is small then the acceleration would have negligible effect? The problem is that if for say drop test, the object is large. The nodes that come in contact will experience additional stress due to the acceleration of nodes that are still in air. I don't know how much effect that has though...
  11. Thanks George for the fantastic answer! Its really surprising to see that RADIOSS parameters in general are anti-user friendly. In case you have the ability to report to your UX team then please tell them in which era they are living? Just look at ANSYS or LS-Dyna, the documentation and user experience are superb. If I have a stress strain curve, I should be able to model that in any FEA software. I will check the recording and will let you know. I am really thankful to you for providing your useful insight and support from time to time., great job!
  12. Hello, I see that in BC Manager I can set initial velocity, imposed velocity, imposed acceleration but no initial acceleration. Why is this so? Also, what is the difference between initial and imposed velocity?
  13. Hi George! Thank you for your answer! I checked the law24 reference manual and there are so many parameters! Hardly any information about these parameters is given in the document. Can you please tell me how to model this law from the stress strain curve that I have? I also do not have access to the example you mentioned. Please just tell me which parameters I need to use for curve fitting and the meaning of these parameters.... My mesh is in 3D tetra, and the concrete is for drop testing an object on the concrete. Thanks again!
  14. I am trying to get a material model law for simulating a concrete block. The concrete stress strain curves are shown in the attached image, of which my need is for the 55MPa curve. Now, I am not choosing LAW36 because it deletes the element or brings the stress to zero after the element strain goes beyond the last point. So I am choosing LAW2 which allows me to keep straining the element and fixing the stress to the max value. But I want a law that allows me to let the stress reduce below the max value and keep constant thereafter so that the element keeps absorbing energy by continuing to strain. Please suggest a better law or how to modify law2 to achieve this?
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