Page 179 - Pipelines and Risers
P. 179
152 Chapter 10
where:
- The hotspot stress spectrum
Between displacement and stress range there is the following linear relation:
a 'z(x t) (x)
Ao(x,t) = -ED- = -EDCZ, (c)*
ax "4 dX
The stress spectrum for a specific point along the beam, is therefore given by:
The hotspot stress spectrum is given by:
S-(f.X) = (SCF)*S,(fJ)
where:
SCF is the stress concentration factor.
The resulting hotspot stress response spectrum will be numerically integrated to obtain the
necessary moments m, that are used for cdculating the fatigue damage.
m, = /;f"S,,$,,(f.x)df for n=O, 1,2 ""
The zero crossing rate and bandwidth are determined by:
10.4 Comparisons of Frequency Domain and Time Domain
Approaches
A computer program called "FATIGUE" has been developed. Time-domain program consists
of two parts;
- part one solves the differential equation of motion,
