Vibratory System

Discussion in 'Hydrodynamics and Aerodynamics' started by gonzo, Jul 25, 2018.

  1. M&M Ovenden
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    M&M Ovenden Senior Member

    I'll hop back in when we get to Q factors.... lol.... it's been a very long time since I had to work any mechanical dynamics systems (School!).

    I agree it's hard to see posts that are wrong and not comment. It doesn't help anybody down the road. Its difficult to spot if it's not your area of expertise. My opinion is it's better to NOT make a comment unless you really truly are an expert on the subject. It's amazing how the true experts can usually explain a complex system for most to understand. This comes from the depth of the subject matter that allows them to offer it up with various schemas.

    Happy Friday,
    Mark
     
  2. MikeJohns
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    MikeJohns Senior Member

    Thanks Mark.
    Actually you had similar courses. There are a a lot of very similar concepts in systems analysis in your field.

    May all your poles remain in the left hand plane !
    Mike
     
  3. gonzo
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    gonzo Senior Member

    Your arguments are based on insults directed to me and have not provided any of the scientific background you claim to have. My reference to vibratory systems was in response to a poster saying that the waves could possibly excite the mooring system at its fundamental frequency. I would prefer to discuss this as adults. A chain may be modeled as a spring as I stated. I stand by my statement that gravity is a force and not energy. If it was energy, there would be a means to dissipate it, and therefore create a gravity engine. Can you explain how that is possible? Hopefully without resorting to vile language and using a scientific argument instead.
     
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  4. M&M Ovenden
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    M&M Ovenden Senior Member

    We all understand this to be "Gravitational potential energy"
    -Mark
     
  5. M&M Ovenden
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    M&M Ovenden Senior Member

    Like this right?

    Gravitational potential energy - Energy Education https://energyeducation.ca/encyclopedia/Gravitational_potential_energy

    Its not wrong to refer to gravitational forces (we all agree about that), but there is also such thing as gravitational potential energy.

    Murielle
     
  6. MikeJohns
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    MikeJohns Senior Member

    Gonzo, well it's very frustrating trying to explain to someone who stubbornly refuses to even look up basic physics concepts.
    Foundation concepts of physics ? As for more advanced concepts, it would take years before you could start to understand even why these equations can't usually even be solved in the time domain.

    Try reading a book on dynamic systems analysis . Or as I suggested an easier quicker route for you is to ask any other engineer on the forum.

    That was me Gonzo,
    then following my post you decided it was a vibratory system and I told you that wasn't actually correct.

    Distasteful as it may be to you, apparently we can only discuss this at the level of an academic and a pupil. How else?
    So once again;, it's a dual mass system, I tried to explain to you already. You need to understand that the horizontal force of a chain catenary is not a constant. I explained that the chain absorbs gravitational energy ( which by very definition has to be potential) that a spring stores strain energy ( also by definition potential). These are concepts you can search for yourself.

    Well for a start gravitational force is the force component of gravitational energy (and Gravity is acceleration not force) . You have been told that you need to learn the relationship between work force and energy before you can even start to understand even the very basics.

    I even went to the effort of finding you a school level physics tutorial that you have not apparently even watched. That's a really good start for the scientific background. If you can't absorb some basic physics, then what hope does anyone have of explaining complex dynamic systems?

    You find it insulting to be told you lack the learning required to understand why you are wrong. I would have thought that accepting that was your only graceful way out.
     
    Last edited: Jul 28, 2018
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  7. BlueBell
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    BlueBell "Whatever..."

    I think the oscillations are likely more harmonic in this case.
    Disturbance is a thoughtful nudge not a displaced potential moment.
    Gravity is stubborn, unforgiving and frankly, quite relentless over time.
    But Gonzo, you know better, no?
     
  8. Dolfiman
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    Dolfiman Senior Member

    This thread turns to be a remake of the historical vis viva controversy .... ;)
    It must be recognized that the teaching of mechanical concepts is often abrupt by the basic educational system , in school books. Mass, force, gravity, energy, potential of energy, movement quantity, ... as if these concepts were obvious, although it took centuries for the best of the best scientists to develop a coherence of it all, to put and agree on words to describe, and on equations to compute.
    I have always criticized educational system to not pay sufficient attention to tell the story in parallel to teach the concepts, probably that it is an economy of time for the professors but not for the students. And last but not least that can stimulate their interest in science which is a living story and not a marble monument.
    I recommend you this PowerPoint on "Historical aspects in the development of the concept of energy", 90 slides but it's worth :
    http://www.ak-energie.at/pdf/20140924_Energietag9_Pascolini.pdf
     
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  9. rwatson
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    rwatson Senior Member

    You make a great educational point. This is where maybe videos and multimedia can solve the expensive professors time, but still educate the student.

    The number of times I have seen comments like "Wow, I wish my teacher had explained it like this before " on serious Youtube videos, is quite large.
     
  10. gonzo
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    gonzo Senior Member

    Insults are not a scientific argument. It doesn't matter what or who I am. A theory or a fact should stand on its own. For example, potential energy is not gravitational, but is is energy added to a system against a force. The force may be gravity, but the energy is not generated by it. Further, wikipedia is not a reputable source; anyone can post in it.
     
  11. M&M Ovenden
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    M&M Ovenden Senior Member

    Really that's the problem with any open internet forum. The wikipedia pages I posted looked correct to me, but fell free to ignore them and look on the website you posted as reputable.

    Cheers,
    Mark
     
  12. gonzo
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    gonzo Senior Member

    I accept that as your opinion. However, you don't say if you agree or disagree with my statements and why.
     
  13. MikeJohns
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    MikeJohns Senior Member

    These insults you keep referring to? I'm sorry I'm sure you do find it insulting, but you are both wrong and stubborn.
    Apparently you have never studied advanced dynamics and have only met vibration and you have problems with some forms of energy. It's not a great start.
     
    Last edited: Jul 30, 2018
  14. MikeJohns
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    MikeJohns Senior Member

    But you have claimed that there is no such thing as Gravitational Energy ( by definition that is potential energy).

    It would at least be a small step if you could acknowledge that you now understand that.

    Do you still refuse to accept that Catenary action buffers shock loads when using a chain rode ? While you do understand that the elasticity of the nylon rode buffers shock loads with nylon rode.

    There are two forms of stored energy in those two systems, one is gravitational the other is strain. This is fundamental physics.
     
    Last edited: Jul 30, 2018

  15. M&M Ovenden
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    M&M Ovenden Senior Member

    Hi,
    Look, a few posts ago, and maybe on another thread you said there wasn't gravitational energy. I just pointed to a couple pages that describe gravitational POTENTIAL energy. Sure the other poster may not have put in the word potential, but it's sort of implied. It's really nothing to worry about and shouldn't be driving a conversation.

    I'm don't want to get drawn into debating the dynamic systems of anchoring, it's outside my area of expertise. Personally I wouldn't model a chain as a spring, as the stretch of the steel would be so small it would be negligible. A nylon rope road has lots of stretch , and sure that would be considered a spring. I like margin, so personally we have all 1/2" G4 chain and big anchors.

    I think I'm now done on this thread.
    Cheers,
    Mark
     
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