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Research Papers: Structures and Safety Reliability

Global Responses of Struck Ships in Collision With Emphasis on Hydrodynamic Effects

[+] Author and Article Information
Huirong Jia

Centre for Ships and Ocean Structures,
Norwegian University of Science
and Technology,
Trondheim 7491, Norway

Torgeir Moan

Centre for Ships and Ocean Structures,
Department of Marine Technology,
Norwegian University of Science
and Technology,
Trondheim 7491, Norway

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received February 19, 2010; final manuscript received April 1, 2015; published online May 19, 2015. Assoc. Editor: Rene Huijsmans.

J. Offshore Mech. Arct. Eng 137(4), 041601 (Aug 01, 2015) (14 pages) Paper No: OMAE-10-1024; doi: 10.1115/1.4030343 History: Received February 19, 2010; Revised April 01, 2015; Online May 19, 2015

Hydrodynamic effects in ship collisions are usually considered by increased inertia force in the form of the equivalent added mass. It is necessary to reasonably estimate the equivalent added mass to calculate energy absorbed by ships in collisions. In this paper, motion equations in the horizontal plane for the struck rigid ship are first established considering hydrodynamic effects in the form of added mass, linear, and quadratic damping. The equivalent added mass are obtained in three ways and analyzed. It is shown that the equivalent added mass for the sway motion depends on not only the duration of collision impact, impact force, but also the collision position, while the equivalent added mass for the yaw motion could be assumed to be independent of the collision position. In addition, a simple formula is proposed to relate the equivalent added mass for part of the vessel to that of the whole vessel, provided that the underwater area of the transverse section is known. As a consequence, it is possible to estimate rigid hull girder responses based on the simplified methodology, which could be used in design and probabilistic collision analyses. In the end, the hull girder responses are estimated considering both a flexible and rigid vessel. Comparisons are made between rigid and flexible hull girder responses.

Copyright © 2015 by ASME
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Figures

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Fig. 3

The equivalent added mass for the sway motion with rectangular impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 4

The equivalent added mass for the yaw motion with rectangular impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 9

The equivalent added mass for sway against the duration of collision with impact through the gravity center: (a) method 1, (b) method 2, and (c) method 3

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Fig. 10

The equivalent added mass for the yaw motion against the duration of collision impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 2

The curve of the underwater area of the transverse section for the tanker

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Fig. 19

Flexible hull girder responses at impact section for sine impact (xc = 66 m, td = 2 s)

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Fig. 5

The equivalent added mass for the sway motion with sine impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 6

The equivalent added mass for the yaw motion with sine impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 7

The equivalent added mass by different methods against the collision position (sine impact, td = 0.2 s): (a) Aeq2 and (b) Aeq6

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Fig. 8

The equivalent added mass from different impact forces against the collision position (td = 0.2 s): (a) Aeq2 and (b) Aeq6

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Fig. 12

Rigid ship motions for rectangular impact (xc = 66 m, td = 3 s): (a) acceleration, (b) velocity, and (c) displacement

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Fig. 13

Rigid hull girder responses at impact section (xc = 66 m): (a) Sine impact (td = 6 s), (b) Half-triangular impact (td = 6 s), and (c) Rectangular impact (td = 3 s)

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Fig. 14

Maxima of hull girder moment for sine impact force (xc = 66 m, td = 6 s)

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Fig. 15

The critical bending moment against the collision position for sine impact (td = 6 s)

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Fig. 16

Error in the approximate critical bending moment with sine impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 17

Error in the approximate critical bending moment with rectangular impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 18

Error in the approximate critical bending moment with half-triangular impact: (a) method 1, (b) method 2, and (c) method 3

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Fig. 11

Rigid ship motions for sine impact (xc = 66 m, td = 6 s): (a) acceleration, (b) velocity, and (c) displacement

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Fig. 20

Comparison of rigid and flexible hull girder responses for sine impact (xc = 66): (a) td = 0.2 s and (b) td = 5 s

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Fig. 21

Comparison of rigid and flexible hull girder responses for half-triangular impact (xc = 66): (a) td = 0.2 s and (b) td = 5 s

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Fig. 22

The critical bending moment for sine impact: (a) td = 0.2 s and (b) td = 5 s

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Fig. 23

The critical bending moment for triangular impact: (a) td = 0.2 s and (b) td = 5 s

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Fig. 24

The critical bending moment for half-triangular impact: (a) td = 0.2 s and (b) td = 5 s

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Fig. 25

The critical bending moment for rectangular impact: (a) td = 0.2 s and (b) td = 5 s

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Fig. 26

The dynamic magnification factor against the collision duration

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