Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. ansysnewbee

    Genetic Algorithm Optimization

    hello Everyone, Iam having a problem with the GA and Direct Search toolbox of MATLAB. Iam not able to find how to specify lower and upper bounds of design variables. How does one specify that? In addition, if I want to specify equality and inequality constraints, how does one achieve it? Is it...
  2. ansysnewbee

    MP,DMPR

    Hi, I see that ANSYS has this new MPDMPR where damping can be specified for different materials.. With the full method in harmonic response analysis does MPDMPR formulate it according to the complex modulus approach? Thanks. -Emily Em.
  3. ansysnewbee

    genetic algorithm

    In the GA and Direct Search Toolbox of MATLAB, can the user specify the lower and upper bounds of the design variables? -Em
  4. ansysnewbee

    Damping, MP,DAMP, MP,DMPR

    Hello! With the introduction of ANSYS 8.1, there now seems to be two methods to represent material damping in a full harmonic response analysis (HROPT,FULL). They are: ---reference to exclusively the FULL method in the harmonic analysis-- a. MP,DAMP: Stiffness matrix multiplier representing...
  5. ansysnewbee

    Modes of Vibration: Excitation

    Oh..This post is getting very inetresting..and Iam learning a lot of new stuff!! Thank you very much Greg and Michael F Platten..It has answered a lot of questions. I would be interested to know how to process the data if the shaker is at a compound angle. Awaiting more discussion... -Em
  6. ansysnewbee

    Modes of Vibration: Excitation

    HI Greg, Thank you for your response.. this raises a few questions (sorry to bother you again!) Is there any mathematical explanation for this? Is there a name for such a behaviour? or any better explanation? or is it just a *common thing* in experimental modal analysis..I tried doing some...
  7. ansysnewbee

    Modes of Vibration: Excitation

    Hello All, Iam trying to get some modal results (nat freqs and damping constants) for a frame type structure. Iam using a shaker excitation (periodic) to excite my structure in the 0-500Hz freq range. The problem Iam suffering is that, when I excite the structure in say Z direction, I miss the...
  8. ansysnewbee

    Velocity-Mobilty FRF's

    Hi Greg, But Iam already working with Hz. during my harmonic analysis. Do I still need to convert to radians? Instead I thought it (variable 100) needs to be just sqrt(-1) Please advice me if Iam wrong. Emily.
  9. ansysnewbee

    Velocity-Mobilty FRF's

    Hello Everyone, Thanks for helping me with the Mobility FRF problem. Once I got my displacements from my ANSYS model, I created the following variables (working in Hz.) created variable 100 (-1*Pi) created variable 101 (100*freq) created variable 102 (101*disp) Variable 102 is mobility...
  10. ansysnewbee

    Plot Velocity-Mobility FRF

    BTW: My orginal post does carry the 3 magic letters.. FRF -Emily.
  11. ansysnewbee

    Plot Velocity-Mobility FRF

    Ok Drej, Iam sorry..didn't read your post properly. Yes, its ANSYS implementation was what I was after..Sorry if my post wasnt clear. So, what I did was(working in Hz.): created variable 100 (-1*Pi) created variable 101 (100*freq) created variable 102 (101*disp) Variable 102 is mobility...
  12. ansysnewbee

    Plot Velocity-Mobility FRF

    Again, everything you said is correct, but I dispute your 'fact' that velocities/accelerence cannot be obtained from a FE displacement result set. Look at this thread..I had posted the same question: http://www.eng-tips.com/viewthread.cfm?qid=115189&page=1 See, others do understand me...
  13. ansysnewbee

    Plot Velocity-Mobility FRF

    I strongly feel you are wrong. There are tons of papers where researchers have calculated the velocity from response obtained from a harmonic analysis. Velocity is simply {v}=j*omega*{u} where {u} is nodal displacement and {v} the nodal velocity. Emily
  14. ansysnewbee

    Velocity-Mobilty FRF's

    Hi Logesh, Thank you for your response. Yes, I need to create variables in time-history post processor and then plot the same. Meanwhile, I was reading a book, and it said: {v}=j*omega*{u} I dont see the 2*Pi .. Is that to convert rad/s to Hz? Thank you.. Sorry again, if the question was...
  15. ansysnewbee

    Velocity-Mobilty FRF's

    --Sorry, forgot to sign off Emily
  16. ansysnewbee

    Velocity-Mobilty FRF's

    Thanks everyone for the response..yes, srinivas, iam trying to do something like what you have described exp frf vs fe-frf's. Modal analysis of a simple frame. I have the computed displacements using ansys, so I now probably need to write a little code to multiply my displacements by...
  17. ansysnewbee

    Velocity-Mobilty FRF's

    Hello, Iam trying to get a mobility plot (velocity/frequency) from my ansys model. I ran a full harmonic analysis and I have the displacements. I would like to convert these displacements to velocities, to plot mobility FRF's. Could anyone tell me how to do it in ANSYS? Sorry if its a basic...
  18. ansysnewbee

    Plot Velocity-Mobility FRF

    Hello, Iam trying to get a mobility plot (velocity/frequency) from my ansys model. I ran a full harmonic analysis and I have the displacements. I would like to convert these displacements to velocities, to plot mobility FRF's. Could anyone tell me how to do it in ANSYS? Sorry if its a basic...

Part and Inventory Search

Back
Top