Jump to content

Andy

Moderators
  • Content Count

    75
  • Joined

  • Last visited

  • Days Won

    7

Andy last won the day on August 26

Andy had the most liked content!

About Andy

  • Rank
    Advanced User

Profile Information

  • Gender
    Male
  • Country
    United States
  • Are you University user?
    No

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. Hi, There was some incorrect information in the post you linked to. External Work includes the work from Imposed movement (displacement, velocity or acceleration), force (/CLOAD or /GRAV), and pressure. It also include the frictional energy from a /RWALL (when FRIC!=0.0) What loads are applied in your model? Do you have Friction defined in the contacts or rigid wall? Also plot, contact energy, internal energy, kinetic energy, and hourglass energy. Also plot DTE which is TTE - external Work. Thank, Andy
  2. This is NOT correct. External Work includes the work from Imposed movement (displacement, velocity or acceleration), force (/CLOAD or /GRAV), and pressure. It also include the frictional energy from a /RWALL (when FRIC!=0.0) If there are only an initial velocity, gravity and a rigid wall in the model then I would assume the high negative external work is caused by the friction on the rigid wall and maybe gravity. It is difficult to say without seeing the model. Thank, Andy
  3. Hi, k= interface stiffness g = contact gap thickness p= penetration into the contact gap Ln is the natural logarithm. We will improve the description in the theory manual. Yes this is dealing with normal penetrations. The contact energy output in Radioss also include the tangential frictional force but I don't have a formula for that calculation. The best way to see if the contact energy is due to penetration or friction is to make FRIC=0 so there is no friction and rerun the model. Thanks, Andy
  4. Hi, Using LAW42 would be recommended since it is a rubber material. Using Ismstr = 10 is recommended with hyperelastic material laws. As HyperMan shows, /PROP/SOLID, Isolid=14 with Ismstr = 10 works. Or you can use /PROP/SOLID, IHKT = 2 with Isolid = 24 (HEPH) and Ismstr = 10 which runs a little faster and also works. We have this statement in the comments of /PROP/SOLID but I realize it is easy to miss. Thanks, Andy
  5. Hi Ken, You need to define /TH/NODE and /TH/RWALL in your input model. These are defined in HyperMesh as Output block. You also need to define the frequency of output which is the engine option /TFILE which is in the control cards in HyperMesh. See the tutorial Step 8 in RD-T: 3500 Tensile Test Setup in the 2019.1 help. Thanks, Andy
  6. The issue with LAW2 is that it is linear elastic. For Non-linear elasticity, you can use one of the hyper-elastic materials like LAW42, LAW69, LAW92, or LAW94. Example "RD-E: 5600 Hyperelastic Material with Curve Input" shows more details about these materials. To viscous (rate) effects to the material you can use the viscous input in LAW42 or add /VISC/PRONY to the other materials. However, data for the viscous input is difficult to determine. So then maybe Hyperman's suggestion of Rayleigh damping /DAMP would be easier. Thanks, Andy
  7. My guess is there is some issue with your engine file filename_0001.rad. Maybe you don't have an end time defined and thus there is no endtime and it just runs one cycle? RUN/Cantilever_beam/1/ 0.3 Thanks, Andy
  8. Hi, If you are using 2019 and modeling the bolts with solid elements then you can use the option /PRELOAD. See the /PRELOAD reference guide and the User's guide, Explicit Structural Finite Element Analysis, Loads, Preload Unfortunately the /PRELOAD option, setup is not supported by HyperMesh but it is supported in HyperCrash 2019. If you are not modeling your bolts with solid elements but instead with springs, then you need to use the method you mentioned in your post. The SPR_PRE spring only has stiffness in 1 degree of freedom (tension / compression between the two nodes.) The SPR_BEAM spring has 6 degrees of freedom (DOF). Since SPR_PRE is in parallel with SPR_BEAM, you set for SPR_BEAM, k1=0 and Stif0=10000 N/m. Then for DOF k2-k6 in the SPR_BEAM you must calculate the correct stiffness for the other directions for your bolt. Thanks, Andy
  9. Hi, I would suggest using an /RBODY instead of an /RBE2 to connect the items. Then you can disable the /RBODY by specifying a Skew_ID which would reference a /SENSOR/INTER or /SENSOR/RWALL depending on how you are modeling the floor. RD-E: 1200 Jumping Bicycle shows an example of using /SENSOR/RWALL. Thanks, Andy
  10. Hi, Unfortunately, we don't have a theory manual for the TYPE24 interface. Most things are work the same as TYPE7 except for the contact stiffness and gap. The contact stiffness constant in TYPE24. The initial stiffness is calculated and used. Versus in TYPE7 the stiffness increases as the node penetrates in to the Gap. All the other details about TYPE24 are in the comments in the Reference Guide. Thanks, Andy
  11. I would suggest you try running without the MPI to make sure your model runs. Use the scripts that are included with HyperWorks and run without MPI by using -nt option. <install_dir>/altair/scripts/radioss -nt 8 micro1_0000.rad If this starts to run then you can try using the same script to run using the MPI. Are you running on one node or multiple nodes? For one node, <install_dir>/altair/scripts/radioss -np 8 -mpipath <path to mpirun> micro1_0000.rad Is there a reason why you are using Radioss 13? That is very old. Can you upgrade to a newer version?
  12. Hi, The problems is you have named your files with the *.dat extension but your script is looking for files with *.rad extension. It is typical to use *.rad for Radioss files so I would recommend you change the extension of your files to *.rad. I would also recommend you use a newer version of Radioss than 13 as this is very old.
  13. Hi, You will need to provide more details about the error message. Is there an error number? When does the error occur? Send text output from Radioss solver so we can see where it is happening. Thanks, Andy
  14. Hi, Is your engine file named micro1_0001.rad? What platform are you using Linux or Windows? If you want to use a GUI to start the job then you can use the HyperWork solver Run manager which can be started in Windows by picking the Radioss menu. On Linux you can use, <install dire>/altair/scripts/radioss -gui. For command prompt use, Linux <install_dir>/altair/scripts/radioss Windows <install_dir>/hwsolvers/scripts/radioss.bat If running on one machine to run the job it should be, <install_dir>/altair/scripts/radioss -np 8 micro1_0000.rad where -np # is the number of cores you want to use. Thanks, Andy
  15. Radioss will automatically calculate a stable time step so you don't need to enter any time step. You can change the time step scale factor if you want Radioss to use a lower time step than what it has calculated. By default Radioss uses a time step that is 0.9*maximum stable time step. Some problems require using a lower time step scale factor like 0.67 but you can use the default of 0.9 and see how it works. /DT 0.9 0 Thanks, Andy
×
×
  • Create New...