ssc-367 - Ship Structure Committee

D.7.2 Analysis for Wind-Induced Cross-flow Vortex Shedding
Using procedures discussed in Section D.4 a flare structure bracing
members are analyzed for crossflow oscillationsproduced by vortex
shedding. The analysis is performed using a Lotus spreadsheet. The
general procedure is as follows:
(a)
Member and environmental parameters are input.
(b) Critical velocity, peak amplitudes of oscillation and
corresponding stress amplitudes are computed.
(c) The time (in hours) of crossflow oscillation required to cause
fatigue failure is computed.
Analysis Description
The following is a detailed description of the spread sheet input and
calculation.
(a) Spread Sheet Terminology
Columns are labeled alphabetically while rows are labeled
numerically. A “cell” is identified by referring to a specific
row and column.
(b) General Parameters
The following are parameters common to all members analyzed as
given at the top of the spread sheet.
CELL C5: DAMPING RATIO = E
CELL C6: AIR MASS DENSITY = ~
0-20