Re: [PSUBS-MAILIST] submarine kit-builder's society

[Wilfried Ellmer <info@concretesubmarine.com>]

To answer that question you need to look at "linearity" of the test results with models of different size. If linearity is high your model is "relative certain" if linearity is low your model is "quite uncertain".

Any model has its limits and should be taken as a "rough check if the concept works".

What really counts at the end is the 1:3 safety test of the finished boat.

As submarine builders we are much better off than other fields of engineering. For a highrise building like taipeh 101 the "real world test on earthquake safety" comes the day when your building is full of people and the results are uncertain. You have no way to shake the finished building with richter 8 to check for earthquake safety. - 

Small scale modelling and computer modelling is all you have until mother nature performs the real test.

The fine thing with a small sub is that you can test it in real world conditions at depth at low cost with no other risk than boat loss.

This makes design, building, and modelling uncertainty a "relative uncritical issue".

At the end you get what you get. You can test it to implement prudent safety factors. With safety test done and repeated in convenient time periods the hull is "reasonably safe in the tested range" - no matter how exact your modelling, or your math approch,  was in the first place.

Always be aware to take "FEA models" and "engineer opinions" as a replacement for real world safety testing.

Wil
concretesubmarine.com

2010/6/6 Jens Laland <laland@artematrix.org>

Wil

** You go to the junkyard and get a hydraulic cylinder,

** you put a model of your hull in there and test it.

What correlation would there be between the collapse pressure of a scale
model versus a full size hull in such a pressure test?

Best regards,
Jens Laland

************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
       removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************