The present research investigates nonlinear barge motions through analyses
of coupled multi-degree-of-freedom (MDOF) deterministic and stochastic models.
Roll-Heave-Sway and other lower-ordered models are developed to predict the
nonlinear motions and analyze the stability of a class of ship-to-shore cargo barges.
The governing equations of motion contain coupled rigid body Roll-Heave-Sway
relations, hydrostatic and hydrodynamic terms. The rigid body relationships are a
part of the general six-degree-of-freedom model. Hydrostatic terms include effects of
the barge's sharp edge and of relative Roll-Heave states. Hydrodynamic terms are in
a "Morison" form. The characteristics of the excitation wave field are based on
linear wave theory.
Predictive capabilities of the Roll-Heave-Sway and the Roll-Heave models
are investigated. System parameters are calibrated to match experimental test results
using several regular wave test cases. Potential theory predictions provide initial
estimates of several key system parameters. With the identified system parameters,
numerical predictions obtained from time domain simulations of both models are
compared with experimental test results for a random wave case, and compared to
each other to investigate the coupling effects of sway on roll and heave motions.
Reliability against capsizing of a barge in random seas is investigated using
stochastic analysis techniques. With the Markov process assumption, the barge
response density to random waves is derived as a solution to the corresponding
Fokker-Planck equation. The path integral solution technique is employed to obtain
numerical solutions for the Roll-Heave and the Roll models. A quasi-2DOF model
is introduced to improve the accuracy of the 1DOF Roll model. The reliability of a
barge in a variety of sea conditions is analyzed as a first passage problem using the
quasi-2DOF model. Mean times to reach specified capsizing probabilities for a
barge operating in sea states 1 through 9 are obtained. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31491 |
| Date | 22 May 2002 |
| Creators | Nakhata, Tongchate |
| Contributors | Yim, Solomon C. S. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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