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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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Found 46 results

  1. Hi everyone, I have problem obtaining the TCL command of auto contact pair finding. My model contains 6 components, I use the Abaqus contact manager to automatically find contact pairs for me. Manually, I can successfully find contact pairs. Since I want to run this process automatically by TCL script, I do the process manually and check out the code added in the command.cmf file. Unfortunately, the code are very long, approximately 50000 lines. Also, the code are about nodes' data and surface set, which is not I am looking for. I am looking for the command that represents the buttons "auto", "components: all", "find", "create". I will show these buttons in the figures attached. By the way, the file: raw.hm is my model. Again, my goal is to get the TCL code for finding contact pairs. Please help me, thanks! raw.hm
  2. Hi everybody. I am designing a rapid attach system for the bucket of a skid steer loader (see picture below), taking inspiration from the commercial systems. In the second picture you can see how this system work: there a contact surface between the bucket and the tach. So there is a contact zone and of sure I should do a non-linear quasi static analysis; however since I would not do a non linear analysis I ask you if there is another way to get a solution. I've already done a non linear analysis but I can't validate the results since this kind of analysis should be quite instable. So I'd like to find another way (with linear analysis) just to compare the results. Thanks in advance for your help Best Regards Stefano
  3. Hello, I am doing a study inflating an airbag with a particular shape and there are a lot of contacts between surfaces, that I modeled with interface type 7. I have some troubles because there are some nodes that pass through master surfaces (even if the interface is activated) but then the contact is applied and the nodes can not pass through, creating high contact forces and reducing the time step. I wanted to use the control card DT/INT/DEL to delete the interface in those nodes, I fixed Tscale to 0.9 and Tmin to 1.0 e-4. When I run radioss, time step reduces up to 5e-5, some nodes are deleted but not those that passed through surfaces and have high contact forces. Any idea about how can I deactivate interfaces in nodes where the contact force is higher than a fixed value? Thank you
  4. Dear All, Could you help me to verify, is my simulation valid or not? I do not know because this is first time I use contact in hyperworks my material is steel, with mechanical properties : 1. E = 205000 MPa 2. Poisson Ratio = 0.29 3. Density = 7.85E-6 kg/mm3 4. Yield Strength = 490 MPa 5. UTS = 686 MPa The .hm files is in attachment. Thanks and Best regards, Iron_Man Contact_001.hm
  5. Hello, I have been having issues with a model containing contacts and friction. The model is relatively straight forward, a multiple mast model with wearpads and contacts between pad faces and adjacent mast sections. When the contact is set to property type slide N2S, the analysis demands around 47GB for In-Core Solution. However when the type is set to static friction coeff = 0.15, the in-core demand becomes 80GB. The model on my pc then typically fails because MUMPS demands significantly more RAM. I've tried adjusting the search distance and using a PCONT card to define friction with little impact on MUMPS demand. Any suggestions? I currently have one PARAM card... PARAM,EXPERTNL,CNTSTB
  6. How to define a contact between two surface of shell elements in Nastran profile? Which card image i should use? I created slave and master elements using contact surface collector . Am doing linear static and normal mode analysis.
  7. Hi, Due to contacts in my model I wanna let my optimization run nonlinear. So far the linear analysis and optimization works. To let the analysis and optimization run nonlinear I created a load collector with the card image NLPARM. Additionally I created a non-linear quasi-static loadstep. The nonlinear analysis gives me results where as the optimization does not give any result even though I can let the optimization run without any error. Here I'm uploading a very simplified model that is compatible to the HyperWorks student edition. The contacts are not implemented yet. But there should be contact between the green, the yellow and the blue component. Maybe someone can tell me by which criteria I have to decide if the contact partner is master or slave. I'd be glad to get any advice how I can set up a nonlinear optimization with contacts in Optistruct. My question is: which steps do I have to carry out to turn a linear into a nonlinear optimization. Unfortunately I couldn't find that much information about it. Felix P.S. The model shows a medical implant for connecting bones. Maybe someone is wondering what it is Impl-Mandible-Fib-4S-Uebergang_vernetzt_1_temp13_Federn.zip
  8. I am trying to simulate a quasi-static (NLSTAT) contact problem using Optistruct. I apply a constant displacement on a rigid cylinder which is set apart from a deformable body. The deformable body starts to deform from the beginning of the simulation without contact. As soon as there is contact, the simulation stops without an error message before the prescribed displacement is achieved. What possibly am I doing wrong? Can I use a composite (PCOMPP) as the deformable body in this case? I don`t remember exactly the message but I received an error saying that I could not use it. Also, as i understand from the manual, SLIDE is used for small sliding condition. What should I use if I have finite sliding? Thanks
  9. Please let me know the difference between NF-Resultant Normal Force and Resultant Force. Also what is difference between FX-X Total Force and FNX-Normal Force. I got this values from Radioss Interface output forces. Please let me your comments. Thanks and Regards, Yuvaraj
  10. Hi, I am trying to simulate contact for performing frontal crash analysis of a chassis having a tank. I have a tank which is wrapped by two brackets and supported by rubber. This bracket is welded to a chassis. I need to create contact for the following- 1) Between tank and bracket. 2) Between rubber and bracket. 3) Between rubber and tank. It is attached to chassis as follows- I know that I need to create Interface. Please tell me for each case which Type interface should be used and which should be selected as master and slave? Thank you, Datta
  11. Dear everyone, I have some problems about setting up contacts for two bodies with zero Gap at initial time. Type 7 was used, and two brick solid components were set for slave and master. An error message was received as follows: INTERFACE NUMBER. . . . . . . . . . . . . . 2 INTERFACE TYPE. . . . . . . . . . . . . . . 7 GAP MIN = 0.3000000000000 POSSIBLE IMPACT NUMBER: 77 (<= 1 *NSN) ** INITIAL PENETRATION = 0.3000000E+00 IMPOSSIBLE TO CALCULATE NEW COORDINATES OF SLAVE NODE 380483 ERROR ID : 612 ** ERROR IN INITIAL PENETRATION IN INTERFACE DESCRIPTION : -- INTERFACE ID : 2 -- INTERFACE TITLE : DiPao_WaLengZhi INACTI = 0 SLAVE NODE 380483 IS ON THE MASTER SURFACE ** INITIAL PENETRATION = 0.3000000E+00 IMPOSSIBLE TO CALCULATE NEW COORDINATES OF SLAVE NODE 377618 How to deal with this problem? Could anyone give some advice? Thank you!
  12. Hi all, I would like to model contact between 2 gears (like image in attached file). I took this illustration in a Altair document dealing with contact problems. But, the author do not mention how to implement this kind of contact in optistruct. Does anyone have any idea/advice on how to do this in optistruct? Thanks for your help. GAYE
  13. Hi I'm now working on BirdStrike Analysis using RADIOSS140. Like many paper on birdstrike analysis reports, I've done a reproduction of birdstrike experiment carried out by Wilbeck in 1977 [1]. The resultant pressure PH(*1) and PS(*2) meets with theoretical value very well. Except that,if you look at the pressure curve, there is a "ZERO Pressure" period just after the first contact. Taking closer look into the animation, the SPH bounce back just after the contact. Such blank period doesn't appear in the experiment result,or analysis results of other researchers report. [Question] : Is there a way to correct this ? Model setting is follows. -bird is using SPH. Material law is MLAW6 (Equation of State). -Using contact TYPE7. Istf = 1 StFac = 550 … recommended value by Altair Support Igap = 0 gapmin = h/2 (h = SPH radius) … recommended value by Altair Support I've varied the value of these parameters which didn't make any difference on "ZERO Pressure" period. ******************* *1 … PH: the peek pressure just after the contact(Hugoniot Pressure) *2 … PS: the constant pressure when bird deformation can be seen as constant flow.(Stagnation Point Pressure) [1]:J. Wilbeck,AFML-TR-77-134 1977 161121_Bird Strike experiment reproduction by RADIOSS.pdf
  14. I updated to Hyperworks Desktop 14.0.130 and the Contact Tool is not available in the "Tools" dropdown. It used to be grouped with the Pretension Manager and now it is missing. Where did it go?
  15. 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
  16. Hello, I'm trying to run a 3 point bend test. The supports doesn't matter, if possible i would like to make it rigid, but to avoid stress concentration in a point i need to model this contact between the support and the I beam. How can i do this, or find some tutorial more focused ? Thanks !
  17. Hello, 1. I try to simulate a high detailed model of a screw with OptiStruct. Currently the screw will be pretensioned with the pretension function and in the next LoadStep it will be rotated. Now in the following LoadSteps i want to add enforced displacements on the Contact Surface of the screw head. My main problem is the sequence with the enforced displacements. How can every single Loadstep use the results of the previous Loadstep (Stress, Displacement, Contact...)? For the pretension Loadstep i use the function STATSUB(PRETENS), but i dont know if the displacements will be freezed for the next Loadstep and i use CNTNLSUB to consider the contact. 2. The next poblem is, how can i enable/disable contacts between severally LoadSteps without using MODCHG (Older Version of OptiStruct than 14.210)? Thanks!
  18. Can any one Guide me for, Tutorial or Steps for: set up different type of contact condition between two solid and run in optistruct. (fix condition between surface pairs) post processing contact analysis result in Hyperview.
  19. Hello, everyone! I am a beginner for Hyperwork and using Optistruct to solve some problems. I have a question to define the contact between rule and cylinder just like in the picture. Because of the load in the middle both side of the rule will go up. How could i define this simple support contact in Optistruct? Thank you very much!
  20. Hi everyone, I'm trying to model a cylindrical section being held between a grip that tightens around it. When I look at each jaw however, I have a contact pressure concentration in one area and I can't seem to find out why. I'm using Optistruct V13 and I use the auto-contact tool to create the contacts between each component. I have checked for penetration between these components and there is none (there is between two other pieces but I do not look at these). I have quite a fine mesh as I'm looking at this specific area (mesh size 0.5mm). Does anyone know what I could do to get rid of this point? Could it be that these nodes are slightly irregular and 'sticking out' slightly from the component? Thank you for any help you may be able to give me!
  21. Hello, I would like to calculate a contact between a sphere and flat solid block, pressed together under certain load. I am interested in the contact stress and precise contact area (I would like to compare the results with the analytical solution of Hertzian contact theory). Is it feasible to get the desired results with a non-linear quasi static analysis in Optistruct or shall I do it with Radioss? Additionally, what is the best way to obtain the final nodes in contact or even to fix them together and perform an additional analysis? Thank you for you help, Matej
  22. hello, everyone ! can anyone share the related Gallery model file ? (optistruct 14.0 new feature)
  23. Dear all, I'd like to ask you for help regarding specific contact simulation. Please have a look at the sketch below (I know that this particular case can be easily calculated analytically ). There is a L-shape profile (on the right) which is screwed in to a flange on the left. There are two types of connection: Pin connection - pins transmit shearing load (red) Bolted joints which ensure flanges integrity (blue) There is also a contact plane marked in yellow. I have modeled pins explicitly with merged nodes between flanges as shown on the figure below. My question is how to model the contact between blue and dark yellow elements? Ideally it would be kind of no separation contact so both surfaces remain fixed but no shear load is transmitted. I want the pins to carry all shear load and I'm not interested in the bolts assessment. There is a nice presentation about optistruct contact settings - Optistruct Contacts.pdf And even contact type "NOSEP" is described but I can't find it in my v13. Could you please give me any advice? Thank you in advance.
  24. Hi there, Is it possible to define an initial contact between to surfaces in HyperCrash, while running RADIOSS, so that there isn't neither a gap nor an initial penetration? Thanks