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  1. shellp70

    LQR Control And Voltage response

    Hello my friends!! I have used LQR control strategy to control a 3 layer sandwich beam with one piezoelectric patch . I have plotted voltage response applied to actuator for 3 different thicknesses. My voltage responses have almost same amplitude with different trends. Does anyone know why this...
  2. shellp70

    Damping Parameter and its unit

    Hi dear friends! I have recently learnt eigenvalue problems and I'm a beginner! I calculated the eigenvalue of a system and the result was EV=12+2i . I have figured out that "12" is frequency and its unit is " rad/s " and "2" is damping parameter but I don't know what its unit is! Can anyone...
  3. shellp70

    Piston theory for flutter

    Hi all!! Does anyone know about the Piston theory ?! I want to know what the " First Order Quasi Steady Piston Theory " means ?! Especially, What does " Quasi Steady " refer to ?!
  4. shellp70

    Comparing a three- layer Sandwich Panel with a one-layer one

    Actually, that wasn't my idea to design a AL/C-Epoxy/AL !! Having a composite course and its assignment, force me to that!! I derived the equation of motion of this beam ( Vibration analysis !!) and now I want to validate or my results with a one-layer AL beam!! How does it possible?!
  5. shellp70

    Comparing a three- layer Sandwich Panel with a one-layer one

    Hi dear friends, I have modeled and derived equations for a 3 layer sandwich panel ( upper & Lower layers are Aluminium and the core is Carbon/ Epoxy ). I want to validate my results with a one layer panel which is made up of Aluminium. Is it correct to replace Aluminium properties with...
  6. shellp70

    1D heat equation and BTCS code in Mathematica

    Hello everyone! I am trying to calculate the transient 1D heat equation in mathematica. I am trying to use BTCS method for solving it! I have finish my code, but it works only in t=0 and for the rests, it gives me an error ! Is anyone familiar with Mathematica software ? I need your help...
  7. shellp70

    Observability and controllability

    Hi guys! I am a beginner in Control field !! I have a system which is observable but not controllable! What does it mean ?! It means that I can not control my sytem with any of controlling method ?!
  8. shellp70

    a Problem In LQR controller

    In fact, I have a uniform beam with piezo actuator/sensor film and I want to control it based on LQR controller method. For gaining accurate results and convergence, I have to use at least 4 mode shapes in my numerical method. As a result, as I increase my mode shape in my code, the number of...
  9. shellp70

    a Problem In LQR controller

    Hi guys!! Does anyone know anything about LQR method? I have a problem in my code to gain a correct k-gains!!
  10. shellp70

    Plotting output result

    I want to plot the displacements vs. time!! I do not know how to plot it in NASTRAN !! I tried OUTPUT ( XYPLOT ), but it didn't work at all!! Does anyone know how to do that?![sad]
  11. shellp70

    Plotting output result

    I want to plot the displacements vs. time!! I do not know how to plot it in NASTRAN !! I tried OUTPUT ( XYPLOT ), but it didn't work at all!! Does anyone know how to do that?![sad]
  12. shellp70

    Change the output file format using OUTPUT (XYOUT)

    Dear everyone, I use OUTPUT (XYOUT) to plot the data. The format of output file is .plt . Does anyone know how I can change the output file format from .plt to something else ?! Thank you !![glasses]
  13. shellp70

    Change the output file format using OUTPUT (XYOUT)

    Dear everyone, I use OUTPUT (XYOUT) to plot the data. The format of output file is .plt . Does anyone know how I can change the output file format from .plt to something else ?! Thank you !![glasses]
  14. shellp70

    Model a beam using shell properties in PATRAN !!

    Thank you anyway dear almpunk !! [wink]
  15. shellp70

    Model a beam using shell properties in PATRAN !!

    I got it dear almpunk !! Thank you so much !! [glasses] You know what is going on !?! I want to model a SHELL as a beam and then use it in PATRAN to calculate FLUTTER analysis. I modeled the shell and validate the 10 first Natural Frequencies with another code in an other software. but when I...
  16. shellp70

    Model a beam using shell properties in PATRAN !!

    Thank you almpunk !!It was really useful. [glasses] Is it necessary to use MPC in my shell properties to make it a real beam ? For example some mode shapes[ i.e, torsional mode shapes] appear in shell properties which never happen in beam properties. I tried some MPCs, but I still had torsional...
  17. shellp70

    Model a beam using shell properties in PATRAN !!

    Hi everyone!! I want to model a beam structure using shell properties in PATRAN. I want to know if it is possible to do that. If yes, how could I do that???!! Please someone help me! Thank you in advance![glasses]
  18. shellp70

    Model a beam using shell properties in PATRAN !!

    Hi everyone!! I want to model a beam structure using shell properties in PATRAN. I want to know if it is possible to do that. If yes, how could I do that???!! Please someone help me! Thank you in advance![glasses]
  19. shellp70

    Model a beam using shell properties in PATRAN !!

    Hi everyone!! I want to model a beam structure using shell properties in PATRAN. I want to know if it is possible to do that. If yes, how could I do that???!! Please someone help me! Thank you in advance![glasses]

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