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Found 24 results

  1. 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
  2. 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.
  3. Hi everyone, I have been performing cyclic symmetric modal analysis using EIGRL card. I would like to have some results belongs to a certain Nodal Diameter.I am an Ansys user as well and it is possible to define harmonic indexes in order to have natural frequencies for various nodal diameters. How does it work in optistruct? How can I have natural frequencies at different Nodal diameters. Thank you Ugur
  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, 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.
  6. Hi, All: May I ask how can I generate .op2 file in my OptiStruct analysis? Thank you very much for your help.
  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 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
  9. 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
  10. 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
  11. 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.
  12. How many modes does a single shell element - 4 noded (i.e. linear) have if a free free run is carried out?
  13. 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.
  14. 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
  15. 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
  16. 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!
  17. Is it possible to do operational Modal Analysis in optistruct?
  18. 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
  19. 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
  20. 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.
  21. 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) ?
  22. 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
  23. Hello, First of all i want to explain what i did so far. I performed a frequency response modal Analysis to investigate the dynamic stiffness of my component in Hypermesh/Optistruct. I performed an Analysis with Optistruct and my results are the frequency-depended Displacement (s) and SPC-Force (F). Then i plotted the dynamic stiffness by calculating Cdyn=F/s. The results are exactly what i expected. After that i changed the structure of my component using Mesh Morphing and recalculated the dynamic stiffness of the changed component. This had a huge effect on the dynamic stiffness. I saved the morph-changes as shapes and created a shape design variable. I want to do a shape optimization to reduce (minimize) the dynamic stiffness. Now my questions: 1. Is it possible to do a shape-optimization to reduce the dynamic stiffness (reduce the quotient F/s) with optistruct? 2. When it is possible, can you give me a hint, how i have to proceed with the Responses, constraints and objectives for the optimization? Regards, Fatih Uysal
  24. Is it possible to calculate the Stiffness (N/m or N/mm) of the structure from any analysis??
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