DNV Design Pressure

Discussion in 'Class Societies' started by vikramaditya91, Jul 3, 2015.

  1. Ad Hoc
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    Ad Hoc Naval Architect

    Alik

    I'm very well aware of those papers and many many more. I read them when a student all those years ago and many many more since and have them all on my shelf.

    Im also aware, more than most, how such research is used in Rules to provide correct solutions, being on LR's tech Comm reviewing and making recommendations where appropriate.
     
  2. Alik
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    Alik Senior Member

    Then, You should know how they define equivalent pressure. They define it from response, thus it might depend on material. And for composite materials, especially sandwiches, this approach is not accurate.
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    You must be reading a different paper to me then. Since they do not define an "equivalent pressure" anywhere in the paper. Only an equivalent length of beam.

    They note, correctly, using just a simple section modulus of the section may lead to failures. Which is correct, as it takes no account of shear.
     
  4. vikramaditya91
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    vikramaditya91 Junior Member

    Thanks for help, but one last question

    Thank you very much jehardiman, TANSL, Alik and Ad Hoc, for your invalauble advice. It would have been very difficult for us to go ahead with our design if not for your good guidance.

    We are designing a HSLC using DNV rules, and we are still amateurs. So any information is new to us. We plan to use the impact forces/loads and then use FEA to calculate the stress-concntrations, failures, etc.

    I have a few follow up questions if you do not mind answering,

    In this image you posted, Required Pressure vs Design Speed I am surprised to see that the slamming pressure does not increase with an increase in the velocity of the boat. We would be greatly obliged if you could provide the formulas used for plotting the graphs.
     
  5. Ad Hoc
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    Ad Hoc Naval Architect

    Unless you know how to use FEA correctly and what you are looking for, and if the vessel is below 50m, it may be a fruitless exercise and may cause more problems than you think. Good design detail practice is all you need. In LR's SSC rules there are some good general guidance examples if you are unsure.

    You need to read and understand Class rules, to know why.

    DNV here:

    DNV Slam Pressure.jpg

    and

    ABS here:

    ABS Slam pressure.jpg

    Good luck.
     
  6. vikramaditya91
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    vikramaditya91 Junior Member

    Thank you very much. Cheers. Arigato
     
  7. rxcomposite
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    rxcomposite Senior Member

    He is not Japanese. If I put my location/residence/area as Virgin Island, would that make me a virgin? :D:D:D
     
  8. vikramaditya91
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    vikramaditya91 Junior Member

    Haha. Maybe you are.
     
  9. BMcF
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    BMcF Senior Member

    I live on St. George's Island.

    I contend that makes me a saint. :)

    And yeah..Ad Hoc is one of those rare Japanese blokes with a very pronounced British accent. Or so I've heard. :D
     
  10. vikramaditya91
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    vikramaditya91 Junior Member

    Haha. True that. I see nothing about himself on 'Ad Hoc's profile. Is he Batman?
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    Nah...just a raggedy man! :p

    Prizes for correct ref, though :D
     

  12. rxcomposite
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    rxcomposite Senior Member

    That would be Alfred, the butler.
     

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