Vibratory System

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

  1. MikeJohns
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    MikeJohns Senior Member

    Well that's the very question I was asking you, there's nothing more than a single horizontal force input and the chain gets raised off the seabed. You say, contrary to reality, that's not possible since it violates your understanding of the laws of physics.

    It's also reasonable to think you might by now, have looked up Determining the Components of a Vector.

    I told you the vertical force is a component of the Tension vector of the Catenary at the attachment. And your response was "What do you mean by a Tension vector" !

    Now you are asking the same question again, where does the vertical force comes from. Yet that's the very question I'm asking YOU to think about.

    You could start by trying to comprehend the horizontal force acting on a body on an inclined plane that even Barry was trying to teach you. You'll find it in any school physics text book.
     
    Last edited: Aug 11, 2018
  2. Ad Hoc
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    Ad Hoc Naval Architect

    There are none. That is your own subjective interpretation of a technical debate.

    You are being asked to define or explain something you have said, as it is incorrect /misleading. Thus only you feel it is personal because only you can answer the disparity in your conflicting statements.
    Any engineer would not have problem with this...as there are no emotions in engineering, only facts. But it seems your 'facts' are at variance to that which is commonly accepted and understood by the wider engineering/scientific community. That's all.
     
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  3. gonzo
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    gonzo Senior Member

    The vector has a horizontal and a vertical component. However, are you saying it only has a horizontal component? I can't follow your argument. The weight of the chain and the anchor, plus the "hold" of the anchor have vertical components pointing down. The buoyancy of the boat has a vertical component pointing up. They cancel each other, like Newton's law postulates. You say that there is no vertical component, and that is what I claim is wrong.
     
  4. gonzo
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    gonzo Senior Member

    Once more you engage on a personal, emotional attack instead of discussing facts, while claiming there are no emotions in engineering. I asked a simple question: Do you claim there is no vibration system without damping? Also, I stated that every vibrating system is also an oscillating system; do you say that statement is wrong? Could you answer without emotional outbursts?
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    This thread has produced more bile than one of those caged Chinese bear farms !
     
  6. Ad Hoc
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    Ad Hoc Naval Architect

    You must be reading a totally different webpage___????

    Please explain where there is emotional content in the post above.

    If you, as an engineer, are unable to support your claims with evidence and known accetped facts, there is little i can do if you interpret this as an attack on you. Because it is not about you, it is about your claims nothing more nothing less. If you are unable to answer the question about your unsupported claims ~ your only retort will be to claim a personal attack. That is not an engineering reply! The basics of science and engineering is being able to support ones claims with facts and evidence. Thus there are no emtions only facts. Little of this so far.

    That was not what you said. You said this;

    And yes ....this statement is incorrect as noted on the other thread which you have yet to answer fully.
     
    Last edited: Aug 13, 2018
  7. BlueBell
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    BlueBell Ahhhhh...

    It comes from the vector.
    Just like the horizontal component.

    Is this a trick question or are you just dumbing things down a bit?
     
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  8. MikeJohns
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    MikeJohns Senior Member

    No, just that the vertical components you mention cancel out.

    But you are deviating a bit. In several posts you’ve clearly argued that a horizontal Applied Force can’t lift an object. That’s what we are currently discussing. I’ve asked you what force input does the work of lifting the chain considering there is only one applied force.

    You keep saying that you don’t understand where the vertical force component originates that does that work. But it’s no different to understanding how a horizontal force can push a body up an inclined plane.

    Maybe considering another model might help:

    Think of it as a tractor backing up to the wharf edge hooking the chain end to it’s tow hook, then driving forward until the catenary forms, then stopping. The horizontal pull of the tractor does all the work of lifting the chain, there is only one applied force and you can see that it's only horizontal.

    The increasing upward force from the ground through the wheels as the chain lifts is not an Applied Force, it’s a Reaction. If you start arguing about the inclusion of a pressure increase and partial flattening of the tires then you are just including unnecessary factors. Buoyancy is similar it’s a reaction similar to the tractors tires deforming.

    In the diagram below is every force directly relevant to modelling the ideal system in it’s equilibrium state. No other forces need to be added. We’ll ignore seabed friction for this case.

    It might help too if you comprehend the following:

    We can resolve the Tension vector at any point (Tangential) of the Chain. The Horizontal Force component of the tension vector is constant throughout the length. While the vertical force component isn’t constant, it ranges from a maximum at the top to zero at the touchdown point.
    Diagram for Gonzo.jpg
    [​IMG]
     
    Last edited: Aug 14, 2018
    latestarter likes this.
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