ssc-367 - Ship Structure Committee

3.
FATIGUE DESIGN AND ANALYSIS PARAMETERS
One approach to assess the variables,parameters and assumptionson
fatigue is to separate the design from analysis. Fatigue design
parametersdo affectthe fatigueperformanceand they can be revised
during the design process to optimize the structure.
Fatigue analysis parameters and assumptions affect the computed
fatigue life of the structure. The analyses approach selected
should be compatible with the structure configuration and its
fatigue sensitivity. Both fatigue design and analyses parameters
are summarized on Figure 3-1 and discussed in the following
sections.
3.1
REVIEW OF FATIGUE DESIGN PARAMETERS
All of the parameters affecting fatigue performance of a marine
structure and its components can be grouped into three categories
based on both function and chronological order. The three groups
are:
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●
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Design parameters
Fabrication and post-fabricationparameters
In-Serviceparameters
The parameters in these three groups actually dictate crack
initiation,crack propagation to a critical size and exceedance of
cracked weldment residual strength. While these parameters are
assessed and incorporated into a design program to qualitatively
enhance fatigue performance,quantitativeanalyses are necessaryto
verify that the structure’s components have satisfactory fatigue
lives. Fatigue analysis parameters and analysis sequence are
discussed in Sections 3.2 and 3.3, respectively.
3-1
.,