Structural Response of Free – Fall Lifeboats During Emergencies
Andrya Sara Roy1, Sheeja Janardhanan2, E.M.S. Nair3
1Andrya Sara Roy, Department of Civil Engineering, SCMS School of Engineering and Technology, Karukutty (Kerala), India.
2Sheeja Janardhanan, Department of Mechanical Engineering, SCMS School of Engineering and Technology, Karukutty (Kerala), India.
3E.M.S. Nair, Department of Mechanical Engineering, SCMS School of Engineering and Technology, Karukutty (Kerala), India.
Manuscript received on 20 May 2019 | Revised Manuscript received on 06 June 2019 | Manuscript Published on 15 June 2019 | PP: 211-216 | Volume-8 Issue-1S2 May 2019 | Retrieval Number: A00490581S219/2019©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC-BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: A lifeboat is a small floating structure released from ships during an emergency for the rescue of people onboard. This task is accomplished by dropping the structure from a predetermined height (drop height) and inclination (fall angle). The structure is now a freely falling body under the influence of gravity with the bow pointed down. The beginning of the lifeboat’s trajectory includes an initial flight in air followed by its diving in water and then emerging out of water under the buoyancy effects. During sudden impact on the surface of water, large slamming loads act on the structure, especially at the bow. Slamming is of great concern as it results in severe structural damage of the bow as well as its supporting frames and scantlings. The study of slamming involves an interaction between the structural components of the lifeboat and the fluid load on the hull. Bow impact is a salient feature since high accelerations are exerted upon the lifeboat when it first hits the water surface during its water entry phase. In the present study an approach for the design of a typical life boat is presented. Fluid pressure on the bow has been estimated using a computational fluid dynamics (CFD) approach coupled with a six degree of freedom (6DOF) solver. A user defined function (UDF) has been written in C language and has been complied within the solver for accomplishing the body motions. Geometric modeling and meshing have been carried out using ANSYS ICEM CFD and FLUENT has been used as the solver. The impact peak pressure has been applied at the bow and a 3D structural analysis has been performed initially at the bow region of the bare hull without scantlings and later with scantlings. The results seem to provide guidance for the design modifications in terms of scantling dimensions.
Keywords: Lifeboat, Slamming, Bow Impact, Buoyancy, Scantlings, Hull.
Scope of the Article: Solid and Structural Mechanics