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Andy

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Andy last won the day on April 23

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  1. Hi, Unfortunately, the ERROR ID : 760 is very generic and can be caused by many things. In your output file you have many warnings about empty surfaces. You might want to correct those warnings. It is possible that an empty surface is being used by an entity which then causes the error. You could load the import the model into HyperCrash and see what warnings and errors message you get. Also in HyperCrash there is a model checker you could run. If none of these items work, you could try removing one entity at a time until you find the one that causes the issue. For example, if you delete the honeycomb part does the error go away? Or delete all your contacts, etc... Thanks, Andy
  2. Hi, I reviewed your model and found the following issues, 1) Parts #10, and 11 need to have elements in them and thus should have a PART card image and a material and property assigned to them. 2) Their is an error with the /DT/AMS option. We recommend using /DT/AMS mostly for quasi-static cases only so I would remove in your model. Once I fixed these two issues the model will start to run. I noticed a few other issues looking at the model in HyperMesh. The connectors are all yellow which means they aren't realized. Unless you are interested in the studying the welds, I would suggest just merging the geometry and meshing it as one piece with node to node connections. If possible, I would convert the solid tube to hex brick elements because they are more accurate then the 1st order tetra you are using. Thanks, Andy
  3. Hi, Please review, https://altairuniversity.com/8889-some-principles-of-explicit-finite-element-analysis-by-paul-du-bois-and-altair-engineering-inc-videos/ video 1 ) starting at 13:45. Your specific question is addressed at 14:30. You could try a gradual reduction in the mesh size and see if that works and better. Thanks, Andy
  4. Hi, Sorry you cannot change /GRAV or accelerations via a restart. You will have to rerun the analysis from the beginning. Thanks, Andy
  5. Hi, The energy change you mention is when the phone impacts the floor. At the point of impact the kinetic energy decrease because the phone is not moving as it impacts and reverses direction. The internal energy increases as the elastic parts of the phone deform. After the point of impact, the phone reverses direction and bounces back up. The elastic internal energy is released and now goes back to being kinetic energy. Thanks, Andy
  6. Hi, To fix this problem, you can delete the Unsupported card in HyperMesh in the model browser, Cards, Unsupported, right click and select delete. I'm not sure why the /ALTDOCTAG is showing up as unsupported. It is a HyperMesh only card that Radioss does not need. Thanks, Andy
  7. When the structure is rotating at very high speeds, it is necessary to include the centrifugal force field acting on the structure to correctly account for the initial stresses in the structure due to rotation. Without those initial stresses, the rotor could expand as you described. There is an example in the Radioss help about this, RD-E: 5500 Fan Blade Rotation Initialization and Impact. Using /INIVEL/ROT/ with two engine files as in RD-E: 2300 Brake was an old method to define a rotational velocity about an axis before /INIVEL/AXIS existed in the Radioss stater. You can also define an initial velocity in the engine file using, /INIV/AXIS/. See example RD-E: 5500 Fan Blade Rotation Initialization and Impact for more details. Thanks, Andy
  8. Hi, I would recommend upgrading if possible. The latest version available is 2019.2. It might work to just use the new documentation with v14 but I am not really sure as I don't have a list of all the things that have changed for the user library since version 14. Thanks, Andy
  9. Hi, I would recommend updating to a newer version of Radioss. Version 14 is very old. The latest version is 2019.2. I have attached the Radioss 2019 usercode pdf documentation. I have also attached the usercode examples that are in the documentation. Thanks, Andy user_subroutine_example_2020.zip user_subroutine_radioss_2019.pdf
  10. Yes they both exist. Yes you need to declare F because every variable must be declared as recommended by FORTRAN. The deformation gradient variables are stored in the USERBUF data structure. However, they were not documented before but will be documented in the next version. I have attached newer documentation which includes the deformation gradient tensor stretch tensor and the rotation matrices from the global skew system to an element skew system. Engine Subroutine LUSERnn for Solid Elements.pdf
  11. Originally Radioss could only have 3 user material laws as described in User Material Laws 29, 30, 31. Later, additional user material laws (99 max) could be created as Extended Material Laws. The newer Extended material laws have newer features and thus I would recommend creating one of the extended material laws. Thanks, Andy
  12. Hi Wisawanart, Using one of the angle measure options in HyperView is probably the easiest to do. After you create the measure, you can then plot the angle. The rotation of the spring should also work but might be a more complex to setup. You would need to use a /PROP/TYPE13 and with zero stiffness. Note that the output of the spring will be in radians in the spring's local coordinate system as described in /PROP/TYPE13. Thanks, Andy
  13. Hi, Yes VisS is a damping coefficient on the interface stiffness which would effect the normal force. After reviewing your model, I am unable to find the source of the lost energy. Since the error only occurs with the contact model, there must be some part of the energy from the contact force that is not being tracked correctly. I'm not sure what you are simulating but if the results look reasonable to you then it is OK ignore the energy error. Thanks, Andy
  14. Hi, On your cluster you must have the HW desktop package installed and launch the Radioss simulation using the <install direct>/altair/scripts/radioss to automatically get the h3d file. If Radioss is launched directly using the executable then you must run hvtrans on the A001 files after the Radioss simulation is done. Running hvtrans could be after the job submission can be added to the submit script. This can be done using the command, altair/scripts/hvtrans -a *A001 *A001 -o model.h3d Thanks, Andy
  15. Hi, Thanks it doesn't seem to be the friction causing the issue. Can you run the model without damping and see how that changes the results? Also try setting in the model with FRIC=0 also set VISs = 1e-30 which will remove damping applied to the interface stiffness. Or if you can share the model, I can review it. Thanks, Andy
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