HELP - mode shape equations
HELP - mode shape equations
(OP)
I am desparately trying to analyze a free spanning pipeline that may be subjected to vortex induced vibrations. DNV RP F105 requires calculation of the effective mass. This requires knowledge of the "assumed mode shape satisfying the boundary conditions". We are working out of a temporary office and I don't have any reference materials here. Can anyone help? The pipe span is about 143 ft long, the pipe is 8.625" OD x 0.500" WT.





RE: HELP - mode shape equations
if the ends are stationary then you just have the modes of a plucked string,
i=1,2,3...
f=i/(2*L)*(T0/m)^.5
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: HELP - mode shape equations
f = 1/(2L) * [(T+π2EI/L2)/m]½
RE: HELP - mode shape equations
f=SVo/D
where Vo is the airflow velocity in fps, D is pipe diameter in feet, S is the Strovhal Number, approximately .2 for a reasonably smooth surface.