Date of Award

Fall 2007

Project Type

Thesis

Program or Major

Mechanical Engineering

Degree Name

Master of Science

First Advisor

Igor Tsukrov

Abstract

The North Atlantic right whale is under a great deal of public and private concern due to their endangered status and shrinking numbers. Of the 40 animals examined post-mortem (1970-2006), 21 deaths (52.5%) were caused by vessel-whale collision injuries, such as skull fractures. Several methods have been proposed to help reduce the number of fatalities. One such method is to place restrictions on ship speed within right whale critical habitats. However, no quantitative data exist regarding the effect of reduced vessel speed on the likelihood of fatality. The objective of this study is to develop a numerical model of the collision event to determine forces acting on the whale during impact. This will provide data on the mechanics of a ship-whale collision needed to form a basis for informed decisions regarding regulation of shipping traffic.

A representative three-dimensional finite element model of a whale has been developed using inputs from various sources. The mechanical properties of bone material and soft tissue were assigned based on experimental work and published data. The external geometry was created based on data available from necropsy findings. A simplified skeleton containing the major components was estimated based on the size of the external whale geometry. A surface model of a very large crude carrier was created as the representative hull model for the simulations. Since mandible fracture is assumed to be a fatal endpoint of collision, the relative positions of the whale and ship were chosen such that direct impact occurs on the mandible. Numerical simulations were performed for vessel approach speeds of 5, 8, 10, 12, and 15 knots. From the simulation results, the impact forces as a function of time and the overall collision dynamics can be determined. The resultant transient load curves can be applied to a detailed mandible model to predict what impact velocities result in mandible fracture.

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