Redesign and shock analysis of HALIFAX class frigate gas turbine uptake structure

The gas turbine exhaust uptakes in the HALIFAX class frigates of the Canadian Navy have experienced thermally-induced fatigue cracking since soon after the commissioning of these ships. The uptake structure is heavily stiffened in order to meet shock resistance requirements. Unfortunately, the result has been that thermal expansion of the uptake shell is constrained, thus every flash-up and shut-down of a gas turbine results in a fatigue cycle of its uptake with extremely high stresses. Among the methods proposed to address the problem is the structural redesign of the uptakes within the constraints of the original mounting arrangements. Any such redesign would be required to reduce thermal stresses while still meeting the shock resistance requirements. This work presents the redesign of the uptakes such that they continue to meet shock requirements while incorporating design aspects, developed in the literature, which are anticipated to reduce thermal stresses. The original intention was to use the modal-based design response spectrum method to assess shock resistance. However, due to excessive stresses in the original model and in all subsequent modifications using this method, the less-rigorous base acceleration method was primarily used.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Summers, Simon A. (Simon Andrew)

Advisor dc:contributor.advisor

• Tomasz Wierzbicki.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/44923

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/44923