NASA Scientific and Technical Aerospace Reports

In this report the implementation of the bending moment due to whipping and the hull plate dishing (due to the external
pressure load on the hull plate) in the SUS (Survivability after Underwater Shock) code is explained. The analytical
formulation of the dishing model is clarified. For both implemented items, example calculations are given. For comparison,
the dishing example was also calculated with DYNA3D.
Author
Bending Moments; Hulls (Structures); Pressure Distribution; Models; Ships; Underwater Explosions; Shock Waves; Plates
(Structural Members)
20040111198 Building and Construction Research TNO, Delft, Netherlands
Underwater Shock Analysis of Hull Variants for a Corvette Class Vessel
Hoogendoorn, J.; vanAanhold, J. E.; October 2003; 74 pp.; In English
Contract(s)/Grant(s): A00/KM/134/13714; TNO Proj. 006.38105
Report No.(s): Rept-2003-CMC-R039; TD-2003-0205; Copyright; Avail: Other Sources
Underwater shock analyses have been carried out for two hull variants for the S/L frigates successor. The hull variants
include a traditional corvette type hull form and one based on the Enlarged Ship Concept. Furthermore, the effects of adding
box and triangular girders for increasing the ultimate hull strength have been investigated. Whipping analyses show that the
ESC is more vulnerable to whipping and that addition of the box and triangular girders provide an increased resistance against
whipping. With box girders, some whipping conditions can even be survived when the bottom is lost. A finite element analysis
using a detailed model of a hull compartment shows that the hull plating between double bottom and triangular girders is lost
for a heavy shock condition due to the effects of the primary shock wave only. Gas bubble effects such as jetting, an effect
used by modern torpedoes to sink a ship, have not been considered in this study because to tools are available yet to analyze
such effects.
Author
Ships; Hulls (Structures); Shock Waves; Shock Resistance
20040111272 Building and Construction Research TNO, Delft, Netherlands
Hull/Superstructure as Mast and Sensor Foundation
vandenEikhoff, J.; 1 June 2004; 61 pp.; In English
Contract(s)/Grant(s): A03/KM/105/13885; TNO Proj. 6.38106
Report No.(s): TD-2003-0203; Rept-2003-CMC-R091; Copyright; Avail: Other Sources
The project aim is to acquire insight in the effects on the shock response of sensors and masts on the foundations. Analyses
are performed with our Simplified Interaction Tool on a simplified 3D hull model of a superstructure and hull. The model
consists of two sections of the steel hull with a superstructure. A steel and composite mast are considered. Foundations
investigated: A flexible without support and a stiff, supported on the strength deck. The hull behavior is almost equal for all
models and behaves like a standard B-pulse. The deck centers behave as the D-pulse for the composite and the C-pulse for
the steel mast model, with a higher amplification factor. The upper deck movements are influenced by the supporting
bulkheads. Longitudinal and transverse movement in the upper mast deck is almost location independent and cannot be
ignored. Vertical, longitudinal and transverse movements increase considerably if the mast is supported unsatisfactory. The
longitudinal movement of the steel mast is large because the support is inadequate and should be symmetric. Coincidence of
deck and mast structure natural frequency can lead to large deck displacements and must be avoided. Investigate fitting or
avoidance of multi-peak spectra.
Author (revised)
Ship Hulls; Shock Loads; Computerized Simulation
20040111425 NASA Langley Research Center, Hampton, VA, USA
Detection of Cracks at Welds in Steel Tubing Using Flux Focusing Electromagnetic Probe
Wincheski, Buzz; Fulton, Jim; Nath, Shridhar; Simpson, John; Namkung, Min; [1994]; 3 pp.; In English; No Copyright;
Avail: CASI; A01, Hardcopy
The inspection of weldments in critical pressure vessel joints is a major concern in the nuclear power industry. Corrosive
environments can speed the fatigue process and access to the critical area is often limited. Eddy current techniques have begun
to be used to help overcome these obstacles [1]. As direct contact and couplants are not required, remote areas can be inspected
by simply snaking an eddy current coil into the intake tube of the vessel. The drawback of the eddy current method has been
the high sensitivity to small changes in the conductivity and permeability of the test piece which are known to vary at
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