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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 04/22/17 in all areas

  1. 3 likes
    Hello Everyone Firstly thanks a lot Livil for all the help. Really grateful for it. Secondly, here is the file which Livil wrote, in case any one needs it in future. merged.tcl
  2. 3 likes
    work with only 1/4 Split surface of 2nd by 1st Make 2D mesh on 1st solid (yellow) => Make 3D tet mesh for 1st solid On interface, make 2D mesh on 2nd solid => Equivalence of nodes. Make the rest of 2D mesh of 2nd solid & equivalent of nodes: Finally fill 3D tet for 2nd solid and get the final result: Here's HM model: peca.hm HTH,
  3. 3 likes
    Hello everybody I made a new function for Hypermesh to copy mesh among sessions hmcp.zip <updated for HM2017> + <update installer.tcl to install in any folder> Please announce me if any error. - "Extract here" package hmcp.zip, copy the folder "hmcp" to anywhere you want to store. - Open hypermesh and run Installer.tcl file by enter menu File>Run >Tcl/Tk Script - start Hypermesh, it should shows an icon and provide some information like below: - You can copy elements selected in any current panel: - Once again, this topic is to introduce extensions for Hypermesh. I let updated version of hmdnd (drag and drop function) here tkdnd2.6.zip <updated installer.tcl so you can install it to any folder, just open hypermesh and File>Run>Tcl/tk script to run installer.tcl> related post: - And a package to help making your own toolbars: tbopts.zip <update installer.tcl so you can install it to any folder> related post
  4. 3 likes
    Hi Amar, The nodal time step equation is : sqrt (2m/k), where m is nodal mass and k is equivalent nodal stiffness. A scale factor will be also used to calculate the time step. Please go through https://altairuniversity.com/learning-library/considerations-about-time-step/ which is a webinar showing time step calculation in RADIOSS. RADIOSS will calculate nodal and elemental time steps of the model and will choose the highest of these to run. From Check Elems (F10) panel it is possible to determine the approximate minimum time step for explicit solvers based on element dimensions.
  5. 3 likes
    Yes, there is not direct but simple way It is like this *createmarkpanel elems 1 "Select elements:" hm_blockerrormessages 1 catch {*findloops elems 1 0} hm_blockerrormessages 0 if {[hm_entityinfo exist comps ^loops]} { #if you use hm14 or newers: *createmark elems 1 "by comp name" ^loops set FreeEdgeLoops [hm_findconnectedpatches elems 1] #if you use hm13 or olders: upgrade => version14 #just joke! try isolate only component ^loops, and gather its elems "by attached" }
  6. 3 likes
    You can find a lot of hm template example to summary data in folder ../altair/.../templates/summary those can summary cog, moi,... of comps or other entities if we loop through big data and use hm_getentity... to access data, use expr to calculate, or * commands, it is very slow but looping by template, it is very fast. example i have to check face-face angle of solid elems, tcl can do: foreach elemid $elemlist3d { set angle [p_calculateFaceFaceAngle $elemid] if {$angle>$criteria} {lappend failedlist $elemid} } => it's slow with plenty of solid elems now using template: set TplString { *elements(204,,,) //calculate angle... ... *if([#angle>#criteria]) *markfailed() *endif() *output() } #write it to a text file set fpt [open demo.tpl w] puts $fpt $TplString close $fpt #call template processor *usercheck demo.tpl demo.out 0 => so hm will loop through elems and calculate angle (very fast), tcl just calls template processor
  7. 3 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.
  8. 3 likes
    PFA screenshot from Practical finite element analysis book.
  9. 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.
  10. 3 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.
  11. 2 likes
    Hello Ray You could use the model browser to achieve this. Just go to model browser (you can access it through view->model browser) Once you are in the browser right click on the "Component"folder-> in the context menu select "empty". You will get a dialog which shows you all the empty components in your model. Just select them and hit delete.
  12. 2 likes
    Hi Ray, Enter panel F11-quick edit and click on the right button of "adjust/set density" and click on edge you want to review:
  13. 2 likes
  14. 2 likes
    Hello, You can do this using TCL. First open the command Window Go to View>>Command Window Then type the following code: *createmark elems 1 displayed hm_getaverageelemsize 1 This will give you the average element size. credits @tinh Thankyou
  15. 2 likes
    Hi, For an elasto-plastic material you can use /MAT/LAW2 or /MAT/LAW36. If the user is having a stress-strain curve use /MAT/LAW36. Create the function usinig curve editor (XYPlots>>Curve editor) and in the material card recall this function as shown below. Please note that the stress-strain curve should have post yield values. Also,the first point of yield stress functions (plastic strain vs stress) should have a plastic strain value of zero. As an example, If the yield value is 90, the curve starts with X Y 0 90 For rigid bodies always use /MAT/LAW1. /MAT/LAW13 is an obsolete card now. As in Dyna you can create a self/global contact in RADIOSS using the Type 7 contact. Select the master and slave as the same and a self contact between them will be established.
  16. 2 likes
    Hi, I have worked in FOAM Material using LAW 70 in one of my project. I tried validating LAW 70 for different scenarios. Attaching some sample validation case for reference. Hope it may help you. Thanks. Comp_20mm_0000.rad penetration_1DOF_0000.rad E_1100_0000.rad
  17. 2 likes
    Hi Zhaoying, For /MAT/LAW36 we provide post yield values in stress-strain curve, and the elastic portion of the material is defined by the Young modulus and Poisson’s ratio. By introducing strain rates we are controlling the change in strain (deformation) of a material with respect to time. Material plasticity curves can be given for up an arbitrary number of strain rates. Based on this strain rate the speed at which deformation of an object from its original shape occurs can be controlled.
  18. 2 likes
    Hello @Saeedbarzegari Please check the Examples Guide example A-8, which will demonstrate the different approaches in FEKO how to model a finite substrate and ground vs. an infinite substrate and ground. This approach applies to general MoM simulation, but also CMA. The effect of the infinite approach will be determined by the actual size of your ground plane and substrate. But it is straightforward to try both approaches and compare results.
  19. 2 likes
    Hi, Normally starting from a zero load we gradually ramp up the load until we achieve the desired total load. This gradual ramping up the load from a value close to zero is often a more robust approach for solving nonlinear problems. And we run the simulation for this total time over which we ramped the load. Please go through https://altairuniversity.com/learning-library/7-guidelines-to-apply-quasi-static-load-in-explicit-simulation/ which are the Guidelines to apply Quasi-static Load in Explicit Simulations.
  20. 2 likes
    You are welcome. Yes it is possible. To do it, one the project is solved: In data exchange, select export quantity and after select export spatial quantity and formula starting from different types of supports Flux open a window (see attached PPT file) With this method you need to do the same step for each region. In the new Flux version (2018), you can do it by selecting all the region in the same file. Best regards. Mesh_Export_From_Flux.pptx
  21. 2 likes
    Hello mustaphos, At this point you need to have a look at the CADFEKO API. Everything you need will be under "project". I would suggest that you have a look at chapter 7.1 (Scripting basics) and in particular the example in 7.1.1. I would then suggest that you work through example I-1 in the Example guide since it walks you through the process of creating a model in CADFEKO. Reading settings from the model is the same and it is also demonstrated.
  22. 2 likes
    hi from hm14 you can select nodes on edge in one click so just use hm_getbestcirclecenter to find cog of the nodes
  23. 2 likes
    Hi Ajay, Please go through these documents where you will get some relevant information. http://insider.altairhyperworks.com/scripts-of-the-month-jan-2016/ http://insider.altairhyperworks.com/transfer-path-analysis/
  24. 2 likes
    Your mesh looks good. But it's possible to do that better. In fact, in FEA world, we have to know where we have to ... stop to get something acceptable :-)
  25. 2 likes
    I think when you "allocate" 1500MB memory, Optistruct solvers understands that's the MAX limit of memory. So if your model is not so big the real used memory will be smaller that allocated value.
  26. 2 likes
    Hi, Please find the video attached which shows Airbag Simulation. Also, please go through https://www.youtube.com/watch?v=kCSRFss6GDE&list=PLQ7KUGFuVz4u5y3SvIEIU07427-gATaG6&index=5 which is a webinar showing creating monitored volume in RADIOSS. Hope this helps. Airbag_simulation_setup_.mp4
  27. 2 likes
    Hi, Adaptive mesh is employed in cases where the structure undergoes extreme deformation which results in mesh distortion and eventually terminates the job. Metal forming simulations, buckling and collapse are some application where the adaptive mesh is usually taken into account. In RADIOSS adaptive mesh is available for shell elements ( Tria and Quad). I have attached the keyword documents which is used to define the Adaptive Mesh in RADIOSS. admeshglobal.pdf admeshset.pdf admeshstatesh3n.pdf admeshstateshell.pdf
  28. 2 likes
    Hi, In SimLab 14.3, this option was moved to File --> preference--> system--> mouse settings
  29. 2 likes
    Hello Mahes, I tried recreating the property with user profile as Ansys and checked the command.tcl (which gets saved in the working directory or in Documents by default) to get an idea of what Ids are being used. Regards, LL
  30. 2 likes
    Hi BM Kung You can increase the number of characteristic modes to be calculated where you set up the problem in CADFEKO: I reran your model with 12 modes requested and then the first 6 modes were completely tracked across the frequency range from 2 to 5 GHz. (You could perhaps get the results you require by requesting fewer than that, i.e. selecting between 6 and 12 modes.)
  31. 2 likes
    Here is a modified model which works well and all modes are correctly tracked. I removed the foam and refined the mesh. I did not do a mesh convergence study, but rather over refined the mesh slightly, so you might be able to get the same results with a coarser mesh. You will see that 2 modes experience modal cross avoidance (at 2.24 GHz and 2.43GHz) where the 1 mode merges into the other mode - this is easiest seen and understood by looking at the modal current distribution and increasing the frequency through the cross avoidance point. Circularly_Polarized__U-Slot_Patch_Antenna-CM+.zip
  32. 2 likes
    Hi Nabil, I am having a look at this. Could you please also share the reference that you mentioned? One comment already is that there is no need to simulate the foam substrate (or at least not initially) - the permittivity is so close to vacuum that it will only have a nominal effect on the modes.
  33. 2 likes
    PFA screenshot for order change panel.
  34. 2 likes
    Why dont you create set after all updates? Somehow you should take the least effort of machine and man also Try arrange your work flow with fewer actions
  35. 2 likes
    Hi Sachin, Please make sure that your contour plot are "node based", it's a requirement for a "node path" curve. Otherwise "node path" and "nodal contour" options will not be there instead you can find "elemental contour" Switch on "averaging" (like in the example) from element based to node based results and check for the node path option. Also you can try with displacement results as they are always node based.
  36. 2 likes
    Hi Benoit, you can use the command hm_getdistance to do that
  37. 2 likes
    A finer mesh could resolve the problem (as suggested in the warning). Note that you can also set a custom mesh setting that is finer than the fine auto meshing option. I would also not recommend setting the curvature refinement settings all the way to the left (or right) - having these settings on the extreme could lead to extreme meshing conditions that you may not want in your model. I suspect the biggest problem is that you have 31 point from 6 to 9 GHz. This is a point every 100 MHz. In the comment above (Final remark) 21 frequencies were used over a 1 GHz bandwidth and it was indicated that this could be increased further to ensure good tracking. I would thus recommend that you increase the number of frequency points first and then consider a finer mesh (custom mesh setting based on wavelength). Without the model, I can't make any further suggestions.
  38. 2 likes
    Hi Pohan, The updated files has been sent to you. Meanwhile, also recommend you to upgrade to HyperWorks 2017 version, which you can download from http://www.altairuniversity.com/free-hyperworks-2017-student-edition/
  39. 2 likes
    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.
  40. 2 likes
    FEKO has greatly improved the mode tracking capabilities in the last few years and it is recommended that users use the latest version of FEKO. The tips below are still recommended for improved mode tracking. Characteristic mode analysis (CMA) is the numerical calculation of a weighted set of orthogonal current modes that are supported on a conducting surface. This how-to explains how the mode tracking is done in FEKO and why sometimes incomplete traces for modes are obtained in POSTFEKO. Introduction Characteristic modes are obtained by solving a particular weighted eigenvalue equation that is derived from the method of moments (MoM) impedance matrix. FEKO has a built-in solver that calculates these modes, with no need for post-processing by the user. The eigenvalues, modal significance, characteristic angles, currents, near fields and far fields can be visualised in POSTFEKO. However, inadequate setup of the model could result in inaccurate CMA results. Consider a dipole constructed with a cylinder (meshed into triangles). In CADFEKO, a characteristic mode configuration is requested and the standard configuration is deleted. The default number of modes to be calculated is kept at 6 as shown in the image. The frequency range is set from 2.5 to 3.5 GHz. In addition, the output of currents is requested so that we can view them during the post-processing phase. After FEKO is run, a Cartesian graph of the modal significance of the 6 modes are plotted in POSTFEKO. The graph is shown below. We see that only mode indices 1 and 2 are complete for the frequency range. POSTFEKO also shows warnings for traces 3 to 6. The reason for the incomplete traces for the other modes is as follows: When a frequency range is requested, mode numbers (rather indexes) are assigned according to their ranking at the lowest frequency. This initial ranking or sorting is based on the modal significance of the mode, that is, modes with a smaller eigenvalue will have a lower ranking. FEKO tracks the requested number of modes over the complete frequency range. If the user requested, for example, 6 modes, more modes are actually calculated to track every mode index over the whole frequency range. As the frequency changes, mode rankings will change. It could be that a mode that had a very low eigenvalue at the lowest frequency, and that was assigned a very low ranking, changes to a high eigenvalue at a higher frequency. FEKO will order the modes correctly at each frequency, but this ordering will be based on the mode rankings at the lowest frequency. Now since many more modes are to be calculated, these higher order modes often require a much finer mesh than the well known 1/10th of a wavelength for a MoM solution. If the mesh size is not sufficiently small for a particular mode, the mode cannot be represented accurately by the mesh and the mode tracking will fail. The mode tracking could fail at any frequency over the range. Consequently an incomplete curve could be obtained for a mode in POSTFEKO. If we look in the result palette in POSTFEKO in the Mode index dropdown, we see several modes listed, although we only requested 6 modes: This is also because a mode could not be tracked over the entire frequency range. For example a mode could have been assigned an index at the start frequency, but at a higher frequency this mode could not be tracked any more and was assigned a new index. It could even happen that the "new mode" is also untracked at a higher frequency, and again assigned a new index. The remedy is to use a finer mesh. The mesh size is adjusted using a 3 times smaller triangle edge length and the model is rerun. We see in the graph below all the modes are now tracked over the complete frequency range: In addition, if we expand the result palette again we now see only 6 modes listed: Final remarks The requested frequency range for this example was 21 frequencies from 2.5 to 3.5 GHz. In some cases, it could also be required to use finer sampling (more frequency samples) to obtain proper mode tracking. Continuous frequency sampling is not yet supported for CMA. feko_7p0p1_files.zip
  41. 2 likes
    Full ray tracing is the safest option and since ray tracing is not that time consuming, rather stick to it. This use to be a feature many years ago when computers were much slower. There are a few special cases where one of the other options can be used to improve the results, but no need to go into that here. Below is an illustrative example of what the different options mean and what the implications of the options are on results (in this case currents, but all field calculations are affected). PO ray tracing options available in FEKO The PO ray tracing options available are as follows: Full ray tracing - Slowest, rays are traced from each MoM element to each PO element. PO mesh normals can be mixed, with some pointing inward and some outward. Only illuminate from front - Rays will be traced only to the front of the PO mesh (implying that fields incident on the inside of PO triangles will not cause current flow). This will be faster than full ray tracing and is well suitable for closed bodies where all mesh normals point outward. Always illuminated - This is the fastest of all the ray tracing options. FEKO does not check for any shadowing and assumes that all PO triangles are illuminated by the source and MoM area. Example 1: Applying the ray tracing options to a dipole and triangular shaped box Consider the geometry below. A triangular shaped box is illuminated by a dipole antenna. The box is solved with the PO and the dipole is solved with the MoM. Figure 2: A triangular shaped box and dipole solved with the MoM/PO hybrid Now consider the results if, in turn, the three ray tracing options are applied to the model. We compare these to the MLFMM solution which can be taken as the reference. In all cases the current distribution is displayed over a magnitude range of -35 dB to -70 dB. Figure 3: Current distribution (with MLFMM as reference) for the different ray tracing options (a) MLFMM (b) always illuminated (c) only illuminated from front (d) full ray tracing We see that the cases "only illuminate from front" and "full ray tracing" yield identical results, but the "only illuminate from front" will be a more computationally efficient solution. For the case "always illuminated" we see that the incident field causes current flow on all the PO triangles, including those that are "shadowed" (i.e. not in direct line of sight) from the dipole. The MLFMM predicts some current flow on the back faces of the box, but the "always illuminated" case shows a much stronger current flow on the back compared to the MLFMM.
  42. 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"]
  43. 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
  44. 2 likes
    the right procedure to obtain the scalar addition is derived results problem solved.
  45. 2 likes
    Hi Sonu, The API is *createmark nodes 1 "by sphere" x y z r inside 1 1 .1
  46. 2 likes
    Hi Leox, I think you can use solid map for this. First at the end of the 1D elements put 2D elements with dia at the end of the wire and create Solid (hex) elements by using node path option. select beam nodes as node path. After that you can use sureface--> from Geometry option to create geometry in hypermesh.
  47. 2 likes
    When you have big diffence in element size, it's better to make several transition zones (geometru splitting). By this method, in stead of do 10mm=>2mm, you can do 10mm=>8mm=>5mm=>2mm.
  48. 2 likes
    Dear All, You can refer to attached document which contains Tutorials ( Model Files + Process PDF ) for 1. Hyper Mesh for FE Modelling 2. OptiStruct as solver for a. Analysis b. Optimization 3. Radioss as solver for NL Analysis Students can solve these tutorials & can ask their query on the forum itself. AOC_2017_Practise Models.zip
  49. 2 likes
    Hi, For /MAT/LAW2, if user sets Iflag = 1, user will need yield stress ( SIG_y) , Ultimate tensile engineering stress (UTS) and engineering strain ( EPS_UTS ) at necking point. With this new input, RADIOSS automatically calculates the equivalent value for a, b and n.
  50. 2 likes
    To select elements within a circle, Shift + Single click and release of the mouse displays the entity selection pop-up menu: From the entity selectionpop-up menu, choose one of the first six quick window selection modes: •Inside of circle selects the entities that are inside of a circle window.