FINITE ELEMENT BASED SPECTRAL METHODS FOR FATIGUE DAMAGE ASSESSMENT OF SHIP STRUCTURES

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Authors
  1. Stredulinsky, D.C.
  2. Orisamolu, I.R.
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN)
Abstract
The prediction of fatigue crack initiation or crack growth in a structure can be accomplished most accurately if the time history of loads is known and can be used to predict the time history of the structural response. In the case of ship structures the load history is usually only known in terms of the time spent at combinations of different ship speeds and headings in various sea environments. The sea environment may only be known in terms of a wave frequency spectrum which in combination with a given ship speed and heading can be used to derive a frequency spectrum of the local structural response (stress, strain or stress intensity factor) at a location or region of the ship. The resulting response spectra can then be applied in a fatigue damage assessment based on either spectral crack initiation or crack propagation analysis methods. This paper outlines a method for calculation of the frequency spectrum of the structural response based on the use of regular wave hull pressure loads and rigid body accelerations provided by PRECAL (a linear frequency domain hydrodynamics code based on 3D potential flow) and a top down quasi-static structural analysis procedure implemented in the VAST suite of finite element codes. The finite element quasi-static analyses are conducted for unit pressure loads on each hydrodynamic mesh facet and for unit rigid body acceleration load cases. TRUNCATED
Keywords
Structural damage;Structural response;Spectral fatigue analysis;Computer programs (PRECAL)
Date of publication
01 Jun 1997
Number of Pages
12
DSTKIM No
98-00036
CANDIS No
506549
Format(s):
Hardcopy;Document Image stored on Optical Disk

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