ssc-367 - Ship Structure Committee

3*1*1 Desiqn Parameters
There are numerousparametersthat can be incorporatedinto a design
to enhance fatigue performance, These parameters are grouped into
four general categories:
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Global configuration
Component characteristicsand structural details
Material selection
Fabrication procedures and specifications
The effect of these parameters
discussed as follows.
are summarized on Figure 3-2 and
Global Configuration
The overall configuration of every marine structure, mobile or
stationary, should be reviewed to ensure that the applied
environmental forces will be minimized. Trade-offs are often
necessary to ensure that the extreme environment and operating
environmentloadingsare both as low as possible (althoughit may be
that neither is minimized) to ensure overall optimum performance.
Planned redundancy is extremely beneficial to fatigue performance
because alternativeload paths are providedto accommodatea fatigue
failure. Such redundanciesprevent catastrophicfailures, and also
provide ample time for repair of local failures.
Component Characteristicand Structural Details
Wherever possible,acomponent’s arrangementand stiffnessshouldbe
similar to that of adjacent components to ensure a relatively
uniform load distribution. Nominal stresses at a given detail will
be amplified because of the geometry of the detail. The ratio of
the peak or hot spot stress to the nominal stress, known as the
stress concentration factor (SCF), is affected by many variables,
including component member load paths, interface plate thicknesses
3-2