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Found 29 results

  1. Hello everyone, I want to do flexible riser simulation. riser pinned at two end (constrain at xyz translation, free xyx rotation) + upward force (top tension) define as load. The loadsteps in optistruct are: 1. Linear static: spc: defined load: defined 2. modal Analysis: spc: defined method (struct): defined statsub (preload): linear static I get an error during importing op2 file into acuconsole-eigenmode manager. The error only occur when there are two subcase (linear static + modal analysis). If i only do modal analysis without linear static, i can import the op2 file without any error. attached is the optistruct and acusolve file. riser top tensioned.hm riser.acs
  2. What is the difference between Frequency Response Analysis and Response Spectrum Analysis?
  3. Hi, All: May I ask how can I generate .op2 file in my OptiStruct analysis? Thank you very much for your help.
  4. Hi, Thanks a lot for your support and quick response. I am using Hypermesh with Ansys User Profile . Here I want to do the Static, Modal, Harmonic, Transient and Random Analysis. I want to give all the inputs in Hypermesh Itself. Please Guide me on this I have to give the inputs in Sinwave form. please provide me any link for tutorial. Thanks in advance for your valuable support.. Thanks, David
  5. Hi guys i performed a modal analysis in hypermesh but i'm not able to extract a table with all natural frequency and mode shape that i found. Is there any command that i need to apply in my imput file ? i uploaded my BFD file modal_added.bdf
  6. Hi, I have a HMSIW linearly polarized U-slot antenna (see attachment #1 and #2) tuned at 10 GHz (see attachment #3) and I would like to calculate a modal analysis. I am interesting in first 10 modes. The antenna should operates in fundamental mode which is TE 0.5;0. Based on the results calculated by FEKO (see attachment #4), the antenna operates in the 7th mode which is not correct, the 6th and the 8th modes are not calculated at all and the 9th mode is some kind of artefact. I think the modal analysis is not correctly calculated at all. Quick info about settings: start frequency: 3 GHz end frequency: 18 GHz frequency step: 50 MHz (301 frequency samples) number of modes to calculate: 100 model has infinite dielectric substrate (Arlon CuClad 217 with er = 2.17 and tan(alfa) is set to zero) and infinite ground plane mesh is finer than mesh size: Fine setting (length of the edge is 0.5) data storage precision: double precision What I am doing wrong? HMSIW linearly polarized antenna.cfx HMSIW linearly polarized antenna.pdf
  7. Hi all, How can I plot the eigenvectors of a mass-spring system? I have a system like this: constraint ----spring-----mass-----spring-----mass-----spring-----constraint A 2 degrees of freedom system, in a modal analysis will output 2 eigenvectors. I would like to see the vectors in the output file along with the eigenvalues (it is only for educational purposes). How can I do it?
  8. Hi, i have to carry out a modal frequency response analysis with optistruct. I need to study the acceleration FRF of 3 nodes on a panel (with an impulse force applied) in a range 50-5000 Hz. I create the EIGRL card with V1=0 and V2=6500, supposing to use the 30% more of the upper value needed for the FRF. My problem is that this process take a lot of time, i suppose because of the high number of mode to compute. Since my geometry doesn't change, but i have to change just the load, can i carry out the modal analysis, once for all, and then link the results obtained to the FRF analysis? In order to not calculate every time the mode and save time. Thanks for support.
  9. Hi, I did a modal analysis of a 2d plate. I generated a .pch file. Now if I open this file in notepad, I see three columns of data for every mode. Are these columns the x,y,z coordinates of the corresponding modeshape? I am asking this because I would like to plot the modeshape in MATLAB. I tried plotting it but I did not get a proper shape. At first I thought that every row corresponds to the coordinates of a node in the mesh. But later I observed that for every mode, the number of rows in the notepad file is different. This is what made me doubt about it. So what exactly does a pch file contain in the case of a modal analysis? It would be of great help if you can suggest me any other way to plot modeshapes in MATLAB using some result file from my analysis in Hyperworks. regards, Vachan
  10. Dear all: I have a model with plenty of elements (4,383,225) in OptiStruct for modal analysis. And I got the following error, would you please help on how to solve this problem? Thank you for your help. *** ERROR # 2005 *** WIN_IO: WriteFile failed. (112). **************** Too many error messages. Aborting run. Current limit is 10000. Use "MSGLMT" control card to change this value.
  11. How many modes does a single shell element - 4 noded (i.e. linear) have if a free free run is carried out?
  12. Hello, I am running modal analysis on a helicopter model that has both 2D and 3D elements. I created rigid links and applied mass at the middle node (to represent the lithium ion batteries) however I am not sure which card image to assign for the rigis links and the mass. I tried PMASS and got an error. When I take out the rigids and the masses, I can run the analysis without problem. Thank you in advance, Muge
  13. Hello all, I was trying to perform modal analysis in OptiStruct and the corresponding modes that I get, I feel, are in radian/sec and I wanted to switch those to Hz. Can anyone assist me with the same? Thank you! Regards, Aditya
  14. During modal analysis under pressure and fluid structure interaction i got below error *** ERROR # 2310 *** in the input data: MFLUID card must be used above the first SUBCASE. can anyone please help with this.
  15. Hi , I am working on modal analysis of rotor system in optistruct. I have queries regarding constraints. Pls find the following image which shows rotor assembly with bearing. I need to allow rotation free of rotor and shaft at bearing locations. How to give constraints at bearing locations ? Using RBE2 or any other options are there in Optistruct? Thanks Arul
  16. Dear users, I am running a modal analysis in Optistruct for a simple 2D plate in order to validate some Matlab scripts. I use CQUAD4 elements (PSHELL 2D property) in HM. Results from OS are consistent if I compare them with a 6-DOF per node element in Matlab. Now, I would like to compare the same case for membrane elements (2-DOF per node) but I am not able to find a way to model a membrane in HM. Any suggestion about a different element? Thank you Regards Fabio
  17. Messages for the job: *** ERROR # 5408 *** Aborting analysis because no structural modes have been computed in the modal dynamic subcase 1. *** PROGRAM STOPPED: FATAL ERROR(s) ENCOUNTERED. I am not understanding why this error is comming. Please help me.
  18. Hi, Can i get to now in which version do you plan to patch the following error : The SUBCASE ID in ATT1 field of DRESP1 does not refer to a modal FRF subcase. which occurs while performing modal analysis with the analysis type as "normal modes" and a optimization resaponse as "frequency" . I am facing the error in both HM 17 and 17.1!
  19. Is it possible to do operational Modal Analysis in optistruct?
  20. Hello, Modal analysis solve is taking huge time. My solve is running out of core. And it is taking lot of time. Please find below attached pic. Force_Motor_CD_CAE_31_Modal_T6.out
  21. Hi everyone, I am currently trying to perform a modal analysis of a component AFTER it has been loaded with a force. During the loading step, some parts of the component engage in SLIDE type contact. I use OPTISTRUCT. I currently plan to make two loadsteps for the analysis: 1.A non-linear quasistatic step during which I load my model and contacts are engaged 2.A normal modes analysis which should compute the modes for the deformed structure obtained after step1 Is this possible in Optistruct? Thanks in advance for any answer. Regards Matteo
  22. Dear all, I'm working on a project as the attached image shown: We want to increase the natural frequency of the blue plate by design reinforcing components attach to the plate. Therefore we set up a design space (green block). The objective is max mode 1 frequency of the whole model, and constraint is max 0.5 volume fraction of the design space. However as the second image shown: 1. Mostly only the element on the edge of the design space are left, and it's easy to understand they WON'T help to increase the plate natural frequency at all; 2. The mid elements circled in black are "floating", meaning they are not attached to the plate at all. Could anyone help to figure out what I may do wrong in the setup? Thank you, Peter Door_opt_Topo_Opt.hm
  23. Hello, I want to know how to do a normal modes analysis in RADIOSS not optistruct as i have modeled for crash with contacts and joints and couldnt find any cards for normal mode analysis. It will be great if some one helps me and thank you in advance.
  24. Hi All, How to output the results for Effective Mass Participation Factor in modal Analysis ? Is it sufficient to look for the first 6 to 10 modes or a couple of hundred Hz (say 500 Hz) ?
  25. HI all, i am performing modal analysis and i have spc and force in my model. I first create a modal analysis load step with a analysis type define as "normale modes" in which i specify the spc. I would like to know how to integrate force card in my modal analysis load step ? Thanks, GAYE
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