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Found 33 results

  1. Hi , I am having following queries while trying Modal correlation option in Hyper view - NVH. 1. I am facing error while using transformation option in Hyper view - NVH - Modal correlation. Pls find the below image & help how to sort out. 2. How to use tolerance option in Node pairs menu. I could't able to get the values in the below table Regards, Arul
  2. Good afternoon! I was wondering whether there was some way to terminate a FEM modal port in a load matching the characteristic impedance?
  3. Hello, I am using Optistruct to numerically calculate some FRFs. I have test data to validate my numerical results. Measured test data is an FRF data in the form of Inertance (acceleration/force). I see that there is a big gap in frequency components' amplitudes between the measured data and numerically calculated data, though calculated and measured natural frequencies align very well. I have followed the modal frequency response tutorial and nowhere in the tutorial is it shown that we're specifically selecting the type of FRF we're wanting (e.g. inertance or mobility or receptance). GLOBAL_OUTPUT_REQUEST is used with DISPLACEMENT enabled and that makes me think that, what I am calculating in Optistruct is Receptance and not Inertance. I tried to request ACCELERATION instead of DISPLACEMENT, but ACCELERATION doesn't let me select the output node set which I used for DISPLACEMENT. How can I make sure in Optistruct that the numerical data I'm getting is inertance and not mobility (velocity/force) or receptance (displacement/force)? Best regards
  4. For Modal and Stiffness(torsional and bending) of ladder frame chassis, is there any significant difference in results when I use stick contact between frame and cross-members or when I use shell/rigid weld elements to connect cross-members and long members?
  5. Hi all, I'm working on a frequency optimization problem, where I want to minimize certain modes, maximize certain modes, and maintain a single mode within a certain range. Specifically: - reduce all modes under 10,000 Hz as much as possible - maintain a single longitudinal mode between 10,000-11,000 Hz (the 'working' mode) - maximize all modes above 11,000 Hz as much as possible Basically, the goal is to create high separation between the working mode and surrounding modes. There's a few key challenges here: 1) It's difficult to know how many modes exist under 10,000 Hz as the optimization runs. For example, ignoring rigid body modes, let's say there are 6 modes to begin. If I target the 6th mode to be reduced, it is sometimes eliminated entirely as the structure changes, which results in an error because the mode no longer exists, and the analysis stops. If I target the 5th mode instead, the 6th mode may not be as effectively reduced. Is there a way to perform a modal analysis in which the search decreases in frequency (i.e. it begins at 10,000 Hz and finds the first mode under)? This would solve this issue at least, as I could always target the first mode. Or are there other options? 2) Another problem is that it's difficult to maintain the working mode within the constraints. As soon as it goes below or above the range, the analysis again stops as there is no mode in the specified range. 3) A third problem is identifying the mode in 10-11 kHz as a longitudinal mode. Although it may begin as a longitudinal mode, that can quickly change to bending or torsional as the optimization runs. In the past, I've performed a harmonic analysis to excite this mode, and then try to maximize the displacement. This tends to point the optimization towards a longitudinal mode, since it resonates with the harmonic input force and creates larger displacements. However, I'm looking for a simpler method, if there is one. Does anyone have any ideas on how to formulate this problem for OptiStruct/HyperStudy? Much appreciated! albatrossor
  6. Is it possible to define the contact ( surface to surface , single surface contact) between components in vibration analysis ( Modal , FRF) in optistruct?
  7. Is it possible to do operational Modal Analysis in optistruct?
  8. Hi, Is it possible to do Modal analysis for rotor with shaft ( using 3D elements) using following example in optistruct?. or it is applicable for only 1D elements problem?? I have tried . But it is not working for 3D problems OS-1372: Rotor Dynamics of a Hollow Cylindrical Rotor
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