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Found 13 results

  1. Hi, I am trying to solve a non-linear buckling analysis using Altair Hyperworks with Optistruct as a solver. I am unable to find the load step for it. Both non-linear static and linear buckling work. linear buckling won't accept NL static as input or as a STATSUB Preload. Is this option for non-linear buckling even available in this solver? or do I have to use any other solver. please advise. If there is any example available for this kind of analysis, that would be a lot of help. I couldn't find anything in the ebook "Non linear FEA using Optistruct".
  2. Hello! I am trying to do Free Shape Optimization of Large Displacement Non-linear Mooney/ODGEN material using EXPDYN and ultimately ELSM for equaivalent static load method as shown using OPTISTRUCT solver. I have setup model for EXPDYN using MAT1 and MATX42 with XSTEP in Sec with TA0=0.0 and DTA = 0.005 and TTERM = 0.05. I have contact surface defines by FRICTION with nu = 0 & 0.3(case-2). But i am getting error of INITIAL PENETRATION. I have seen earlier answers and removed penetration but still error is there. I have tried with TIE contacts as well.(.OUT and .rad file attached), but it is running for hours and no output is generated till. I want to know where i have made wrong. and If you could tell me how ELSM in OPTISTRUCT works? Could anyone please help me? Thanks in advanse...! RubberGasket_Opti_001.out RubberGasket_Opti_002.out RubberGasket_Opti_rad_s1_0000.rad RubberGasket_Opti_rad_s1_0001.rad
  3. Hello, I'd like to know if there's a way to conclude/cut-off an on-going iteration before it reaches the subcase termination time? I'm running a geometric non-linear explicit dynamic subcase. I want to base this iteration cut-off criteria once the rigid wall reaction force reaches a specific value...This should speed-up my topology optimization considerably... If not then, is there a way to define a constrain on the rigidwall reaction force ? I'm referring to the reaction force that we read from the "T01" file... Thanks !!
  4. Hello All, I am currently running a non linear simulation that requires around 25hrs of computing time on a 16 cores machine. It's got 300000 elements. Radioss adjust the timestep automatically and reduces to something around 4e-4s. I therefore need around 2500 time steps to converge. The problem I am trying to solve is something similar to a beam in bending ( I do need non-linear) and my requirement is to find the static deformed shape (not a dynamic case, it will converge to a steady result). I have tried explicit but timestep is 1e-9s and it would take 175days to converge... Are there any tricks/ideas that could be used to speed up the convergence? Thanks, NR
  5. Dear all, A pretension analysis is usually run before another non-linear analysis, as a first step of the same run. Is there a way to run a pretension analysis (until the end), and then use the results later in a another analysis. So instead of running one after another on the same run, run pretension, then create/run subcases which will reference the pretension results. Basically this becomes usuful if we want to change something in one subcase, then we won't have to run always the pretension step, but just use the results. I hope it makes sense and thank you in advance for your help and valuable time, Elias
  6. Dear Sirs, I'm trying to solve the pipe stress analysis according to the example ASME B 31.3 appendix S Fig.301.1, shown in below URL. LINK: ASME B31.3 pipe analysis example (page 21 & 22) I made the most of the pipe model except the pipe support at the node No.20. No.20 support is the constraint of vertical (Y-axis) movement of the pipe, so firstly I made the SPC with dof of "13456" aroud the pipe, but the analysis result showed unexpected movement. My SPC is fixing the vertical movement of "node on pipe surface", but I have to made is fixing vertical movement of all pipe elements passing through at the node 20. Therefore I have to made some constraint at the node No. 20 in global coordinates, not at the node on the pipe surface. Please refer to the attached .hm model. I assume this is non-linear analysis, but I have'nt done such analysis so I dont know what to do. I would appreciate any advice. Thank you in advance. Nonlinear.hm
  7. Hi all, I have some problems when doing tutorial example about non-linear problem by using optistruct. OS-1500: Nonlinear Implicit Analysis of Bending of a Plate I set up the problem according to the tutorial procedure. However, some error occurred when solving. *** ERROR # 4002 *** Running RADIOSS engine, 1 ERROR and 0 WARNINGs have been detected. They are listed below. ENGINE ERROR: ** ERROR : RADIOSS IMPLICIT STOPPED DUE TO SOLVER ERROR ** ISTOP=-4 NLGEOM subcase 1, engine finished The attachments are the model file and error message. Anyone can help how to solve this problem? Best Wishes Roy Geom_NonLinear.fem Geom_NonLinear.out Geom_NonLinear.hm
  8. Hello guys! I would like to find a possible method for simulating composites with non-linear material model. It's important for me to know the behavior of the material in the degradation phase, so after reaching the displacement in point A on the picture. I have to model the composite as shell, and have to use an implicit method. My question is that which solver with which property and material card combination is suitable for this analysis in Hyperworks? It is possible to use Optistruct to solve this matter? Thanks for your help in advance! Best regards, Tüki
  9. Hello Support team, I am using HyperMesh 14.0 and ANSYS workbench 17.0 (ANSYS Mechanical). I am performing a Explicit dynamic analysis on 2 bodies which are non-linear. I am using HyperMesh for meshing only and all other things (Material selection, Boundary conditions, Analysis set-up) are performed in ANSYS explicit dynamics model. However, my question is about element type selection. Could you please tell me which element type should select in this scenario? I used Solid185, but I didn't get any results with this. Would you suggest me any other ET Type? Also, if you have any document which would guide me through this process (Meshing > Set element type > Export to ANSYS), it would be great. Waiting for your kind response. Thanks & Regards, Vishal
  10. Dear All, can you please help me with, How to apply enforced displacement on shaft and fixed constraints on hub as shown in figure. i'm confused in load collectors, where to assign spc and where to assign spcd and in which collector. also want to know about search distance option what it means actually. is it a gap between contacting bodies? regards, Ganesh
  11. Hello, Since the contact surface is deformed in the current analyses, I would like to use tracking system to obtain the projection of the contact forces on the element surfaces. I could manage to use tracking system for displacement but I could not find a way to use for vectors of contact forces. the toggle A picture of the issue I mentioned, is attached to this message. The swicthed that is written "use tracking system" cannot be activated as shown in the second picture, Thank you for your help in advance.
  12. Hello, I am trying to run a topology optimization study on a model with non-linear geometry (large displacements). I am applying my loads by imposing a force via NLOAD1 Card Image. However, whenever I run the study, I receive the following error: ERROR # 4003: Abnormal termination in NLGEOM subcases. I have no idea what this error indicates, and I can not seem to find any other online resources to help me troubleshoot. The check screen output is shown below: Additionally, here is my NLOAD1 definition: And here is my Non-Linear subcase definition: Please let me know if you can help me identify the source of this error. Thanks in advance! Branden
  13. Hello, I use Radioss for a dynamic impact problem, but also for the moment to validate my model through a quasi-static analysis. A first component compresses a second component with an imposed velocity. The interface between them is of type 7. In dynamic explicit simulation the interface works fine but in the implicit simulation, I get a warning in interface : "NODE ... DE-ACTIVATED FROM INTERFACE". If I make an "initial penetration" (initial gap < gapmin entered into type 7 interface) I do not get this problem (however I get initial constraints I want to avoid). Would anyone know what the problem might be ? Hereunder a part of my engine.out file: -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- CYCLE TIME TIME-STEP ELEMENT ERROR I-ENERGY K-ENERGY T K-ENERGY R EXT-WORK MAS.ERR 0 0.000 0.2000E+05 SOLID 39426 0.0% 0.000 0.000 0.000 0.000 0.000 ANIMATION FILE: pression_statique_07A001 WRITTEN ***** WARNING : ELEMENT FORMULATION ISOLID= 0 IS NOT AVAILABLE FOR STIFFNESS MATRIX BUILDING, USING GENERIC ONE INSTEAD POSSIBLE CONVERGING ISSUE. ***** *--------- STIFFNESS MATRIX SETUP ---------* SYMBOLIC DIM : ND = 155532 NZ = 2897175 NB_MAX = 26 FINAL DIM : ND = 47480 NZ = 761383 NB_MAX = 26 --STIFFNESS MATRIX WILL BE REFORMED AFTER EACH 3 ITERATIONS-- * CONVERGED WITH 0 ITERATIONS, |du|/|u|,|r|/|r0|,|dE|/|E|= 0.1000E+01 0.0000E+00 0.1000E+01 WARNING INTERFACE 701 NODE 13703 DE-ACTIVATED FROM INTERFACE WARNING INTERFACE 701 NODE 13548 DE-ACTIVATED FROM INTERFACE WARNING INTERFACE 701 NODE 13693 DE-ACTIVATED FROM INTERFACE ANIMATION FILE: pression_statique_07A002 WRITTEN * IMPLICIT COMPUTATION TERMINATED WITH TOTAL NONLINEAR ITERATIONS: 0 * TOTAL NUM.OF MATRIX FACTORIZATION AND PCG ITERATION: 0 0 RESTART FILES: pression_statique_07_0001_[0001-0001].rst WRITTEN ------------- ** CPU USER TIME ** #PROC [K]SETUP [M]SETUP IMPL.SOLV IMPL.TOTAL 1 .4862E+02 .0000E+00 .0000E+00 .4930E+02 #PROC CONT.SORT CONT. F ELEMENT KIN.COND. INTEGR. I/O TASK0 ASSEMB. RESOL 1 .5591E-01 .6813E-02 .2678E+00 .2133E-01 .4654E-03 .5012E+00 .9117E-03 .1199E-01 .5030E+02 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Thank you a lot, Kinds regards, Alice
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