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    • Rahul Ponginan

      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 


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Showing most liked content since 05/26/17 in all areas

  1. 24 likes
    Hi, I am Simulating motion analysis of a mechanism in which the motion is transmitted from Gear Trains to Lead Screw to lever attached with Spring of high stiffness. I have given Contact between Gears , Lead Screw Mechanism. i have given simulation for few seconds but it is taking too much long time for analysis. Can anyone suggest me how to make simulation faster. thank you
  2. 3 likes
    PFA screenshot from Practical finite element analysis book.
  3. 3 likes
    Hi, You can try with the Advanced Query (Query>Advanced Query) option in HyperView, where you can extract the stress for each frequency and you can export the same. This option is available after you apply a contour plot to your model.
  4. 2 likes
    Two control cards are needed to run modal simulation in LS-Dyna: *CONTROL_IMPLICIT_GENERAL with IMFLAG=1 (tells Dyna it's an implicit simulation); and *CONTROL_IMPLICIT_EIGENVALUE with NEIG set to the number of modes you want extracted.
  5. 2 likes
    Actually I dont know anything about setting up contact interface. But the error message is so clearly to show us what to do
  6. 2 likes
    Hi Matthieu, Here is a macro for splitting 1D elements in 2 in one shot . I hope it will solve your problem and time *createmarkpanel elements 1 "select beams to split" #set elem_list [hm_getmark elements 1] set num [hm_marklength elements 1] hm_commandfilestate 0 hm_blockerrormessages 1 hm_blockmessages 1 *entityhighlighting 0 hwbrowsermanager view flush false eval *createarray $num [string repeat "2 " $num] *elementmarksplitwith1D 1 1 $num *entityhighlighting 1 hm_commandfilestate 1 hm_blockerrormessages 0 hm_blockmessages 0 hwbrowsermanager view flush true
  7. 2 likes
    Hi, Since its an edge to edge contact try defining the same with Type 11 contact which is used to define Edge to Edge or Line to Line Interface. Please try with the same and update.
  8. 2 likes
    Hi From hw13, use hwtk instead of hwt. Widgets of hwtk are nicer (vista ttk styles) set myWin [hwtk::toplevel .myWin -title "Create GUI"]
  9. 2 likes
    I have been able to solve this problem introducing a very thin thickness as you said, and results are good enough. Finally the problem were material properties which depended on temperature. Thanks for the offer. Pablo.
  10. 2 likes
    Hi, Negative Energy Error represents energy dissipated from the system and this can be from many sources including plastic deformation and Hourglass energy. Please check the hourglass energy of the model.Keep Isolid=24 and try running the simulation. If the components penetrate each other due to the loads applied the user need to define an interface/contact between them for achieving a realistic simulation. The master segment can be parts, elements, contact surface, node sets and similarly for slave the selection can be parts and node sets. Once these master slave sets are identified the algorithm will check these locations for potential penetration of a slave node through a master segment, and this check is done in every time step.
  11. 2 likes
    Hi, The steps looks fine. The damping is applied to the nodes specified in the node group, which is mandatory and you have assigned. If you want the damping in a specific direction you can assign it through the local skew. In engine /DAMP card provide the damping coefficient values. Please go through the files attached where Rayleigh Damping has been applied. SEAT_RAYLEIGH_0000.rad SEAT_RAYLEIGH_0001.rad
  12. 2 likes
    Hello guys, I think it would be helpful to have a step by step tutorial how to enable damping in Hypermesh. In the following lines I describe how I was trying to enable damping. ( It doesn't work for me atm) 1.assigned materials and properties to components, create a group of nodes in which the damping should occur 2. -in solver browser create->DAMP->DAMP -assign values for alpha and beta, assign the grnod_id -assign the skew_id (what differences will be caused when using the global coordinate system or a local system on the component? ) 3.enable ENG_DAMP control card, chose property which needs damping ( do I have to chose the property which was created in solver browser? ) Are these steps enough or do I need to do some more steps to get the right damping? Thank you
  13. 2 likes
    The settings file information is only a message, there is no need to do anything. The rest of the messages and errors are because HyperStudy cannot resolve many of the paths and dependencies on the server machine. Hand editing the xml is error prone and not recommended. On your local machine, please create an archive (File->Export Archive). This will create an *hstx archive file. This is an all-in-package, similar to a zip file. This package contains all the file dependencies internally and will automatically expand into proper paths on a different machine. The archive system is the proper way to maintain portability across machines. The archive file can be directly submitted to the hstbatch executable, please see the options in the help. Also, there is an error about the spreadsheet report, which requires excel to be installed. I'd guess that it is not installed on the server machine, so you should deactivate that report type.
  14. 2 likes
    the right procedure to obtain the scalar addition is derived results problem solved.
  15. 2 likes
    Hi Sonu, The API is *createmark nodes 1 "by sphere" x y z r inside 1 1 .1
  16. 2 likes
    Yes surface is not a named hypermesh entity. If you tagged the surf in catia. Maybe the tag will be imported into hm as metadata. Try searching it by: set md [hm_metadata findall] puts [join [lsearch -all -inline -glob $md "surfs $surfID *"] \n]
  17. 2 likes
    https://altair-2.wistia.com/medias/9v47veeusj Radioss file structure covers important engine parameter. https://altair-2.wistia.com/medias/0xlcd7hliu Type 7 contact https://altair-2.wistia.com/medias/e3f5yu02as Initial Velocity https://altair-2.wistia.com/medias/9dtedtjqjz Law 36 We requested you to download free Radioss Ebook which will address most of your queries. http://www.altairuniversity.com/free-ebooks-2/free-ebook-crash-analysis-with-radioss-a-study-guide/
  18. 2 likes
    In planar area having four side faces it is possible to get Rtrias with isomesh pattern. But if the area is not having four side faces and if it is having uneven geometrical lines then it is not possible to get isomesh pattern in simlab.With Body mesh control advanced mesh control setting option (Four sided face with Isomesh)you can get Rtrias pattern.See attached screenshot for body mesh control advanced option.(Surface mesh & Remesh does same with advanced setting) Regards Rahul R
  19. 1 like
    The process in FEKO is as follows: User performs simulation in frequency domain (need to ensure that the correct frequencies are simulated - determined by time signal in next step) User defines a time signal in POSTFEKO and then time domain results become available. User can display the time signal or the system's response to the time signal in the time domain. POSTFEKO does this by: Calculating the FFT of the time signal Multiplying the spectrum of the time signal with the spectrum of the model (calculated in the first step) Taking the IFFT of the result (after multiplication) to produce the time response of the system with the particular time signal Does that answer your question? Note that this topic seems to have diverged and is no longer about "Adaptive meshing". Please try to log new questions for new topics in the future (it makes it easier for other users to find and use the information in the future). I'm also guilty - I should not have added all the info about PO on this thread.
  20. 1 like
    Hi Alessandro, Thank you for notifying on this. User need to switch the global template (accessible in the panel area by pressing "g" on the keyboard) from standard format to long format for entities with Id's more than 8 digits. Please see the attached video file. model.swf
  21. 1 like
    Hi, For RADIOSS user profile please create BCs using BCs Manager from the Utility Menu. Else, in Solver Browser (View>Solver Browser) , right click > Create and select BCs.
  22. 1 like
    @ddwgw2017 You can use Equivalence panel (Shift + F3) the check connectivity. Use 3D page>> Detach>> ELements from elements
  23. 1 like
    Hi @wen li tang Wood is anisotropic in nature. You can use MAT2 or MAT8 or MAT9, MAT9ORT depending on type of element you use. MAT8, MAT9(ORT) are orthotropic which needs E, Nu, G values in three directions unlike MAT2.
  24. 1 like
    Hello, The easiest way that I can think of is for you to try the parameter sweep plugin. You'll find it under the "Macro library" in CADFEKO. How it would work is that you set your model up to work at a single frequency. The parameter sweep can then vary over frequency. This will result in a model that is meshed as specified for the specific simulation frequency only. Each permutation will result in a different model, which is then combined in POSTFEKO using another plugin. At the higher frequencies, you can start to look at different solver techniques as well. This might allow you to get away with much coarser meshing without compromising accuracy. My point here is that there's no silver bullet that will guarantee good results. SEP/FEM should work well lower down in your frequency range but have a look at RL-GO at higher frequencies. Also, FDTD might be an interesting one to try - it's usually one of the more expedient ways to get wideband data. Let me know if that helps!
  25. 1 like
    I would like to add something else that helped me to bypass the problem keeping zero as lower bound in the DESVARs. I set a constraint on the composite failure and this stops the solver to go for zero-thickness laminates to avoid failure. I hope this is helpful for other users. Regards, Alessandro
  26. 1 like
    Hi @boba_fett You can use either force or enforced displacement as load on stempel but make sure it is not constrained in the direction of motion.
  27. 1 like
    Hi Nachiket, If the initial penetration is too deep, then stability issues can occur. Ideally, any initial penetrations more than 30% of the initial gap should be fixed to avoid contact stability issues. A safeguard parameter to use is Fpenmax, to deactivate slave nodes that are initially too far penetrated. The node stiffness is deactivated if the Penetration ≥ Fpenmax*Gap. As a good practice use Fpenmax = 0.8 which means nodes will be deactivated if more than 80% into the gap.
  28. 1 like
    Hi, i created a window using toolkit,window created but automatically toolkit creates a close button in my UI.How can i avoid that kindly guide me to solve this issue kindly find the code which i mentioned below which i used to create a window using toolkit #********************************************************************** variable vars; set myWin [hwt::CreateWindow win \ -noGeometrySaving \ -minSize 200 50 \ -windowtitle "Create GUI " \ -post]; #********************************************************************** and kindly find the attachment which i mention issue as image thanks in advance suresh vijayan
  29. 1 like
    Hello bm kung It looks like you are almost there. If the model uses MoM (the default) with SEP for the dielectric (default), then you need to add waveguide ports. You would add a waveguide port on the dielectric face on both sides. If you then want to calculate the reflection coefficient, add a waveguide source on one of the ports (the other port will then only have a port on it and act as a sink / load). If you want to perform an S-parameter calculation, then you would not add the source, but rather add an S-parameter request for the ports. If you are using FEM (instead of MoM), then you need to add FEM Modal ports instead of waveguide ports. You will also add a FEM Modal source instead of a waveguide source. A good example to look at that shows both the MoM and FEM models is Example "A-12 Dielectric resonator antenna on finite ground" in the Example Guide.
  30. 1 like
    Hi Most of the times if you are not using calculate node and specifying an externally created node, this may cause problem some time. Make sure while creating rigids you create using calculate nodes and then select the node created automatically. Thanks
  31. 1 like
    Hi Perhaps your manipulation was wrong somewhere. In panel analysis>constraints>update, click to select constraints, modify parameters (dofs, load types,...) then click "update" > confirm what you want to update > click "update"
  32. 1 like
    When you like to merge component, do you mean geometrical entities? If yes, that's not need IMHO! Anyway you have to make the mesh. So do that with only ONE unit. The final mesh will be obtained from unit mesh with copy/translate/symmetry/paste,.... Before asking about BC, show us how you can make the mesh
  33. 1 like
    Hi Jason, Depending on the underlying solution technique, a volume mesh may be necessary. For FEM and FDTD, fields are calculated inside the mesh elements. However, when you use any of the other techniques (including MoM) then fields can be calculated at arbitrary positions in space. In other words, you only need to add an air box (or set the boundary conditions) when you use FEM or FDTD. FEKO is very good ad hybridising the different solver techniques, which allows a FEM region to transfer energy to a MoM environment and vice versa. The Examples Guide has two relevant examples that you can look at, namely: A-16 Periodic boundary conditions for array analysis A-17 Finite array with non-linear element spacing In both examples, you don't need to add an air box because the solution techniques doesn't require it. I hope that helps! Regards, Andries
  34. 1 like
    Do you forgot to delete the 2D elements after 3D meshing?
  35. 1 like
    Hi, Just use profile Optistruct to setup your analysis and run by Optistruct.
  36. 1 like
    Hi Eduard, Relieved the file. We will check this and will update you very soon.
  37. 1 like
    Answering my own question. I think in Hyperlaminate, there is an option to calculate the laminate properties using PCOMP definition. One has to click on available PCOMP cards to highlight/select & make it active. In the attached figure, the calculate button is greyed out because I had already used it to calc as can be seen on the right.
  38. 1 like
    Simlab mainly works based on defined local mesh controls. I feel this is robust for tetrahedral & tria meshing. Also approach for meshing is little different compared to Hypermesh. In HM for complex part we prefer to mesh complex region first, then we mesh other region. But in Simlab we define local mesh controls & mesh part in one go. For any 3D complex part consist of holes, fillets, cylinder which is covered by the local mesh control in Simlab. It is not ideal to compare 2d quad mesh with Hypermesh because both tools use a different mesh algorithm. So I would recommend you to explore Simlab for 3d tetra & tria meshing.
  39. 1 like
    Is there any last date to attempt for certification test??because i am busy with my college project now. so, i am planning for next week to write the test.
  40. 1 like
    I faced the same problem many years ago and I tried to solve it but could not really. I was working with regexp to look for pattern at the end of the name of parameters and this is quite easy to manage. The problem thought is then that you need to move all the elements that use H001 to use instead H and this can be cumbersome if you use the parameters in a lot of different things. I never thought of the solution proposed by the support (giving the value of H to H001), but this is in fact easier to achieve. The drawback is that you cannot delete H001 (still) so with many parameters and a lot of flux object, you end up with a mess. However, to make life easier and the system cleaner when you import a flux object, there should be a way of saying that if parameters have the same name and value they should be merged and not duplicated, imho.
  41. 1 like
    Hi, try this script: set Density1 5 set Density2 10 *deleteelementsmode 2 *createmarkpanel surfs 1 "Pick a surface:" if {[hm_marklength surfs 1]==1} { foreach LineId [join [hm_getsurfaceedges [hm_getmark surfs 1]]] {lappend LineList [list $LineId [hm_linelength $LineId]]} set LineList [lsort -increasing -real -index 1 $LineList] lassign [join $LineList] Line1 -> Line2 *setedgedensitylinkwithaspectratio -1 *elementorder 1 *defaultremeshsurf 1 [hm_getelementsize] 2 2 2 0 1 1 1 0 0 0 0 *createmark lines 1 $Line1 *change_edgedensities 1 1 $Density1 0 *createmark lines 1 $Line2 *change_edgedensities 1 1 $Density2 0 }
  42. 1 like
    Hi, Can you share the error message? Are you trying to open result file (.h3d) in HyperView or in any other clients?
  43. 1 like
    It's NOT so simple! Take a simple case of a beam in tension. If you increase the geometrical dimension as twice (x=2*x; y=2*y; z=2*z). The section will be increased 4 time! So if you increase your load twice, the stress of new model is only the half of initial ones! Have a look at : https://en.wikipedia.org/wiki/Similitude_(model)
  44. 1 like
    Hi @riham1994 Can you check whether boundary conditions are modeled properly? Constrain in all directions and check if this gives any good results.
  45. 1 like
    Hello, It is not necessary to switch the display off while working on purge command. Will you please redirect us to the video where you've seen that...!
  46. 1 like
    Hi Phil, There are other modelling errors also in the model. The material law (/MAT/LAW3) is incompatible and you have assigned solid property to shell elements. Please correct all these modelling errors in the model. I'm attaching a basic tutorial on RADIOSS, along with the model file for practice. Please go through it so that you will become familiar working with the RADIOSS solver. TENSILE_0000.rad Tutorial.pdf
  47. 1 like
    Hi Ramakiran, The easiest way to model joints in RADIOSS is to use a /PROP/TYPE8 spring. Provide high stiffness to all degrees of freedom those are fixed and zero stiffness in the direction which you want to be free.Unfortunately no webinars are available on this topic as of now, but a sample solver deck is attached for your reference. Rev_joint..zip
  48. 1 like
    Hi Zhang, It is possible to define an initial stress state by using option /INISTA. This option uses an OUTPUT file (Runname_0000.sty) describing the structure of the model for which a file Runname_nnnn.sty defines a stress state.The files Runname_0000.sty and Runname_nnnn.sty can be built in a first computation. It is also possible to enter the initial stress values element by element in the Runname_0000.rad file, by using options /INISHE and /INISH3 for shell elements.It is also possible to write with RADIOSS Engine state files Runname_nnnn.sta for shells. Such a file will contain the geometry of selected parts (nodes coordinates and element connectivity), plus cards /INISHE and /INISH3 defining the stress, strain, and so on, of the shells and 3-node shells belonging to these parts. Shared the same files in the example for your reference. TRUCK_EIG_0001.rad.zip TRUCK_EIG_0000.rad.zip Please find the video attached (.wrf format, plays in webex player) to know more on .sta files and results mapping. Results_Mapping.wrf
  49. 1 like
    i guess you should go for by attached 2-3 times for failed elements, then you simply do tetra re-mesh with 0.1(say) tet collapse criteria. For tetra i don't think you should worry much.
  50. 1 like
    Hi felipeds Check if there is any initial penetration in your model. Use Tool>> Penetration to check for penetrations and intersections. If there is no penetrations or the penetrations is no resolved, you can change Iacti= 6 in TYPE 7 interface card. Please let us know if this helped.