4.1.1 Where
calculations indicate that the limits for torsional vibration within
the range of working speeds are exceeded, measurements, using an appropriate
technique, may be taken from the machinery installation for the purpose
of approval of torsional vibration characteristics, or determining
the need for restricted speed ranges and the confirmation of their
limits.
4.1.2 Where
differences between calculated and measured levels of stress, torque
or angular amplitude arise, the stress limits are to be applied to
the stresses measured on the completed installation.
4.1.3 The method
of measurement is to be appropriate to the machinery components and
the parameters which are of concern. Where shaft stresses have been
estimated from angular amplitude measurements, and are found to be
close to limits as defined in Pt 13, Ch 1, 3.2 Limiting stress in propulsion shafting,
strain gauge techniques may be required. When measurements are required,
detailed proposals are to be submitted.