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  1. onemilimeter

    Can't view TUTORIAL...

    Try installing the Adobe RoboHelp.
  2. onemilimeter

    How to interprete the FRF phase and imaginary plots?

    Thanks electricpete for your detailed explanation. I really appreciate and, due to my poor background, I will need some time to go through your comments and digest them. I will come back soon... Thank you very much
  3. onemilimeter

    How to interprete the FRF phase and imaginary plots?

    Hi Dr Michael F Platten, Thanks for your recommendation. Fortunately the book you recommended is available in our library.
  4. onemilimeter

    How to interprete the FRF phase and imaginary plots?

    Thanks electricpete and GregLocock. Based on your comments, I tried to sketch the individual phase plots for Mode-1 and Mode-2 in Fig-3 (or modified as below). Let's say RED curve is the phase plot of Mode-1, BLUE curve is the phase plot of Mode-2, and GREEN is the effective phase plot. Please...
  5. onemilimeter

    Is "performing Impact Hammer test" an ART?

    Hi GregLocock, Thanks for your replies and suggestions, which are practical knowledge and very useful.
  6. onemilimeter

    PolyReference/PolyMAX and Agilent 35670A

    Hi GregLocock, Thanks for your reply. You mentioned that "... with such light symmetrical structure the mode shapes will rotate around and follow your accelerometer". I do not fully understand the underlined part. Would you please kindly advise? I will try to increase the frequency...
  7. onemilimeter

    How to interprete the FRF phase and imaginary plots?

    Hi GregLocock, Thanks for your reply. In your reply, you mentioned that "... where their magnitude lines cross, they are thus equal and opposite." Can I say that because of "... and opposite", the effective magnitude, as shown in Fig-1[a] drops or "trends" to zero? By the way, how does mode-3...
  8. onemilimeter

    Is "performing Impact Hammer test" an ART?

    Hi GregLocok, Thanks for your reply. I have some experimental results here: http://www.eng-tips.com/viewthread.cfm?qid=253310&page=1 I will be glad if you could comment and provide some advices to improve my coherence plots. Thank you very much
  9. onemilimeter

    PolyReference/PolyMAX and Agilent 35670A

    I have an Agilent 35670A. I carried out impact hammer tests and tried to find out the resonance frequencies of a simple structure (http://www.eng-tips.com/viewthread.cfm?qid=253310&page=1). Someone replied that "...no-one uses curve fits to the Nyquist plot any more for modal analysis (because...
  10. onemilimeter

    How to interprete the FRF phase and imaginary plots?

    The following information was extracted from this article: http://macl.caeds.eng.uml.edu/umlspace/oct03.pdf Kindly refer to Fig-1 and Fig-2. As stated in Fig-2: "...This is due to the fact that the magnitude of the FRF of mode 1 and mode 2 is equal at the anti-resonant frequency. But at this...
  11. onemilimeter

    Do with need a sound pressure level meter with a 'ball'?

    Oh I see... In my experimental, there is a blower around. So, I need the ball... Thanks.
  12. onemilimeter

    Do with need a sound pressure level meter with a 'ball'?

    When using sound pressure level meter, does it really matter to use it with the 'ball' or without the 'ball' as shown in figure below. Thank you very much
  13. onemilimeter

    Is it TRICKY to measure armature winding resistance?

    Hi BobM3, Thanks for your reply. I have no access to the brush/commutator assembly. There are two pair of leads out of the motor. One of them is for field winding, whilst another pair is for armature winding. I place the 4-wire probe across the armature winding and I find out the measurement is...
  14. onemilimeter

    Is it TRICKY to measure armature winding resistance?

    Has anyone such experience before?
  15. onemilimeter

    Which one is RESONANCE peak?

    Hi Dr MikeyP, Thanks for your advices. My background is electrical engineering and therefore I do not have much knowledge regarding modal analysis. I really hope that you will help and guide me to clear my doubts on impact hammer test. You mentioned that "... there are probably 5 modes"...
  16. onemilimeter

    Which one is RESONANCE peak?

    I carried out impact hammer test on a motor end cap as shown in Figure 1. The hammer has a built-in force sensor. Hammer hits were repeatedly applied at around 'X' location. The vibration response was measured by an accelerometer (blue). The output of the hammer force sensor and the output of...
  17. onemilimeter

    Is it TRICKY to measure armature winding resistance?

    I've a brushed DC shunt wound machine with the following specs: Rated Speed: 3000rpm Rated Power: 0.25kW Armature Voltage: 180V Armature Current (full load): 1.6A Field Voltage: 210V Field Current (full load): 0.2A I did some calculation as follows: w = n*2*pi/60 = 3000*2*pi/60 = 314.1593 rad/s...
  18. onemilimeter

    PM brushed DC motor without cogging torque?

    Hi DickDV, thanks again for your suggestion. Unfortunately, we have not purchased the DC machine yet. Due to limited budget, we wish to make sure that we will buy the right DC machine that will suit our application before we purchase. The "K" in my calculation is EMF constant, which is equal to...
  19. onemilimeter

    PM brushed DC motor without cogging torque?

    What does "base speed = 1750rpm" mean? Does it mean the speed at FULL LOAD (i.e. at Ia = 11A) is 1750rpm? I just received the torque-speed curve from Baldor, which shows that at FULL LOAD, the speed is around 1610rpm. Which one is correct?
  20. onemilimeter

    Is "performing Impact Hammer test" an ART?

    Hi, Jeyaselvan, the article is great. One of my problem might be the one explained in the article. Thank you very much

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