Re: Deep dives and metal stress?
Posted by:
kurt
()
Date: January 09, 2002 01:17PM
Metal fatigue in steel normally requires thousands of cycles - even millions - to occur.
The exception is if there is 'plastic deformation'; bending the metal beyond the elastic limit to the point it is permanently deformed. Do this back and forth a few times and the metal will break - and be weakened with each cycle. Not much plastic deformation would happened to the main hull on a deep dive.
A thin walled vessel like a sub pressure hull collapses due to the wall instability under heavy load. Technically, it is a form of Euler beam buckling, which is an elastic phenomena.
However, localized spots may be subjected to unusual stress and undergo plastic deformation, so weak spots may be weakened by too many deep dives. By weak spots I mean a local joint, seal, valve, etc.
So the hull itself probably is not weakened with a deep dive, but some critical joint or valve etc may be.
(With regardss to the WTC on 9/11, metal does not soften with stress or pressure. It does soften and weaken with the heat of fire, but that is not an issue here for sub hulls).
The exception is if there is 'plastic deformation'; bending the metal beyond the elastic limit to the point it is permanently deformed. Do this back and forth a few times and the metal will break - and be weakened with each cycle. Not much plastic deformation would happened to the main hull on a deep dive.
A thin walled vessel like a sub pressure hull collapses due to the wall instability under heavy load. Technically, it is a form of Euler beam buckling, which is an elastic phenomena.
However, localized spots may be subjected to unusual stress and undergo plastic deformation, so weak spots may be weakened by too many deep dives. By weak spots I mean a local joint, seal, valve, etc.
So the hull itself probably is not weakened with a deep dive, but some critical joint or valve etc may be.
(With regardss to the WTC on 9/11, metal does not soften with stress or pressure. It does soften and weaken with the heat of fire, but that is not an issue here for sub hulls).
Subject | Written By | Posted |
---|---|---|
Deep dives and metal stress? | Leif... | 01/07/2002 04:49PM |
Re: Deep dives and metal stress? | Richard Carr | 01/08/2002 03:35PM |
Re: Deep dives and metal stress? | kurt | 01/09/2002 01:17PM |
Re: Deep dives and metal stress? - more than 280m | Cary | 01/17/2002 12:42PM |
Re: Deep dives and metal stress? | Ray | 01/10/2002 04:00AM |
Re: Deep dives and metal stress? | Leif... | 01/10/2002 01:16PM |
Re: Deep dives and metal stress? | Mike Holbrook | 01/13/2002 12:00AM |
Re: Deep dives and metal stress? | Tom | 01/13/2002 09:50AM |
Re: Deep dives and metal stress? | Leif... | 01/15/2002 11:17AM |
Re: Deep dives and metal stress? | Ed Dalder | 01/26/2002 07:30AM |
Old post on U-boat diving depths | SuperKraut | 01/31/2002 08:22PM |