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Found 9 results

  1. Hello, I have created a mesh file in HM and assigned material and properties to the elements. But when I export the same file, I am not able to see the properties or materials in LS dyna. May I know where am I going wrong? (I have used LS- dyna as profile) Thanks Bharat Hiranwale
  2. Hi all, I'm encountering a problem in a low-velocity impact simulation with a composite plate. As you can see from the image below, at the beginning of the analysis, the impactor literally penetrates the plate but without effective failing of any elements. I experience this problem when I try to simulate the delamination, ply by ply (in my case 16 ply), using very thin shell elements (the thickness of each ply is approximately 0,23 mm). Indeed, after studying the contact problem in LS-DYNA, I figured out that, when very thin shell elements are used, the plate drastically fail when the impactor approaches it. For this reason I had to reduce the SLSFAC from 0.1 to 0.001 in *CONTROL_CONTACT in order to have reasonable results, because the impactor of only 1,5 kg and with an initial velocity of 6,5 m/s destroyed the plate in the very first milliseconds of the simulation without this change. But now, solved one problem (however I'm not really sure about this, maybe someone can explain me better this contact stiffness problem), I have another one I'm using a MAT22 model for the composite and a MAT20 for the impactor (made of steel). To simulate the delamination I chose the *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE_TIEBREAK with 15 delamination model in between, penalty contact SOFT = 0 (justified by the fact each ply is identical) and OPTION = 8 for the failure criteria (I didn't know if PARAM = CCRIT for this option had to be used, so I left it blank). For the contact between impactor and the plate I chose *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE with SOFT = 2 (because of the different materials and meshes), FS=FD=0,5 and with the impactor being the master and all 16 plies being the slaves. Any suggestions to solve this problem? Thanks in advance for any response. impatto.bmp
  3. Hi, I have meshed a model in hypermesh and I exported it to Ls-dyna by using .k file. That worked all fine. But as I wanted to make some modifications in the mesh, I am not able to import the k file back into hyperworks. I tried saving for same versions of Ls-dyna from both the ends. It did not help. If I try to import the same file which I just exported from hypermesh, even that file is not being read. The message in the bottom says 'The file being opened for reading does not exist'. Screenshot attached. I have made sure that I am using the correct path of the file I want to open. But this ' file does not exist error' shows up for many cases, even when I try to check element quality or even when I open the hypermesh default screen. Screenshot attached. (2nd)What could be the problem?
  4. For LS-DYNA user profile inHypermesh, there is no "quad8" in "elem types". On exporting the mesh, elements are not exported and only the nodes are exported to the .k file. In "HYPERMESH" user profile, "quad8" is blank in 'elem types' and is not mapped to "SHELL" as it should be. Does it mean that Hypermesh doesn't support quad8 mesh?
  5. Hi I mesh my geometry with hypermesh and use LS-dyna as a FE solver. When I created tet10 mesh in hypermesh and looked at the element summary, it said " TETRA10 ELEMENTS NOT SUPPORTED in LS-DYNA template. These elements will not be exported." I would like to confirm that if I need to export tet4 mesh and convert them into tet10 in LS-prepost. Does anyone know about the problem? I would appreciate any help. Thanks, Jay
  6. Hi, I recently started to use Hyperview 2017.2 as a Postprocessor for LS-Dyna. Recently I'm facing the following issue: I wasn't able to activate *CONSTRAINED_NODAL_RIGID_BODY-components from a d3plot-file. Since I didn't find any information dealing with the topic in the hwhelp: Do you see any option to visualize these components in HM (add-ons, adapted Dyna output, switch settings)? Thanks in advance for your answer! Regards Christian
  7. Hi, I recently started to use Hypermesh 2017.2 as a Preprocessor for LS-Dyna. I'm already quite satisfied with the usability besides one exception: since we're using LSPrepost for the model creation as well, which is providing a clean and structured output regarding the keywords, Hypermesh doesn't: LSPrepost: *MAT_PIECEWISE_LINEAR_PLASTICITY_TITLE ALUMINUM PURE 99.45-O CONDITION $# mid ro e pr sigy etan fail tdel 12.71300E-6 68948 0.33 0.013362 0.0 0.2723 0.0 $# c p lcss lcsr vp lcf 0.0 0.0 3 0 0.0 0 $# eps1 eps2 eps3 eps4 eps5 eps6 eps7 eps8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 $# es1 es2 es3 es4 es5 es6 es7 es8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 HM: *MAT_PIECEWISE_LINEAR_PLASTICITY_TITLE ALUMINUM PURE 99.45-O CONDITION 12.7130E-06 68948.0 0.33 0.013362 0.0 0.2723 0.0 0.0 0.0 3 0 0.0 $$ HM Entries in Stress-Strain Curve = 8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 I also attached the original and HM output file to point out the difference. As far as I see, I'm not using very fancy keywords that HM should be able to process and which it's doing for the *DATABASE and *CONTROL keywords. Are there any setting options I missed? Or do I need an add-on to receive clean keyword output throughout the whole file? Thanks in advance for your support. Regards Christian HM_OUTPUT_OHT_qstatic_9_ALU_CNRB_1000_DT_5E-8.k OHT_qstatic_9_ALU_CNRB_1000_DT_5E-8.k
  8. Hello everyone, I am working on an FE model containing beams that have a square (or rectangular) cross-section. As a first example, I used a beam with a square cross-section. Each side measures 20e-2m. When I export my model in LS-DYNA format, I see that a *SECTION_BEAM keyword is created. I understand well the first parameters from secid to itt, but I can't understand how the j parameter is computed. Using Hypermesh for a square cross-section with a 20e-2m side, I have J=2.25310E-4m^4. However, when I try to find this value again using formulas from the wikipedia page (https://en.wikipedia.org/wiki/Torsion_constant), I can't find the exact same value. Depending on the used formula, I either find J = 2.25000E-4 m^4, J = 2.25600E-4 m^4 or J = 2.25333E-4 m^4. These values are close (especially the last one), but still they're not equal to the one given by Hypermesh. Right now, it might not be seen as a problem, but what if the values become too different if I use other cross-section values? That's why I need to understand what Hypermesh does. I have searched the Hypermesh documentation but I didn't find any information about how this value is computed. And I need it to understand this because I want to run comparisons between commercial solvers and personal codes. Does anyone have a hint about how to find this value? Thank you in advance, Corentin.
  9. Hi, I have a question concerning the Input of true stress vs effective strain curves in ls-dyna: I would like to insert several curves for different strain rates for MAT_24 using the table Option, because I dont know the Cowper-Symonds constants. These curves are from experiments and range from the yield point up to the ultimate tensile stress. The remainder is missing and that is why I have used the voce equation for it. Does it make sense to insert several Points using "Load xy Data" or just up to 8 Points? I plan on crushing a thin walled tube of AA6060. Greetings, Friendly
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