UPDATED APPROACH TO SHOCK FAILURE ASSESSMENT OF SHIPBOARD EQUIPMENT
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Authors
Didoszak, Jarema M.
Subjects
fluid structure interaction
underwater explosions
ship shock
ship survivability
mechanical shock
equipment fragility
pseudo velocity
failure criteria
peak velocity
change in displacement
shock severity
functional failure
damage boundary
underwater explosions
ship shock
ship survivability
mechanical shock
equipment fragility
pseudo velocity
failure criteria
peak velocity
change in displacement
shock severity
functional failure
damage boundary
Advisors
Gordis, Joshua H.
Kwon, Young W.
Papoulias, Fotis A.
Scandrett, Clyde L.
Shin, Young S.
Date of Issue
2019-12
Date
Dec-19
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
Naval vessels are subjected to underwater explosions that impart a mechanical shock onto the ship structure, its subsystems, equipment and crew. This violent shock loading, although not in direct contact with the ship hull, seeks to cause significant damage and even failure of critical components, potentially rendering vital systems inoperable. To ensure deployment of robust systems, shock hardening of surface ships is established in part through shock qualification of mission-essential shipboard equipment. Current shock qualification methods predominantly rely on demonstration of satisfactory performance under prescribed physical testing schedules using standardized shock test machines. A pass/fail rating is assigned based on post-test operational evaluation and visual inspection of structural elements, not from measured response values. An updated shock failure assessment approach is found through numerical experimentation of standard shock platform models, full ship simulations and reduced order equipment models approximating various shock testing scenarios. Introduction of a simple functional failure representation provides a definite means by which to assess the response severity and time at failure. Threshold values for the peak velocity response and change in displacement are thusly established and proposed as deterministic shock failure criteria in order to reduce uncertainty in the shock qualification of shipboard equipment.
Type
Thesis
Description
Includes supplementary material. For those interested in obtaining the supplemental documents for review, please contact the NPS Dudley Knox Library.
Series/Report No
Department
Mechanical and Aerospace Engineering (MAE)
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NPS Report Number
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.