This study is concerned with the vortex-induced vibrations of a flexible ca
ntilever in a fluid flow. Our cantilever comprises a leaf spring encased wi
thin a rubber flexible cylinder, restricting the vibrations of the body in
a water channel flow to principally transverse motion. It is found that the
transverse amplitude response of the cantilever has a marked similarity wi
th transverse vibrations of an elastically mounted rigid cylinder, in that
there is a clear initial branch extending to high amplitudes, with a jump t
o a lower branch response, as normalized velocity is increased. The continu
ous initial branch suggests that a distinct upper branch does not exist for
the cantilever, as is found for a rigid cylinder under similar conditions
of low mass and damping. Good agreement is found between the response ampli
tude and frequency for two "identical" cantilevers, one set up by Pesce and
Fujarra, where strain is measured to infer the body dynamics, and the othe
r arrangement by Flemming and Williamson, where the tip motion is measured
using optical techniques. An interesting large-amplitude response mode is f
ound at higher normalized velocities (U* > 12) outside the principal synchr
onization regime (typically U* = 4-8), which is observed for an increasing
velocity, or may be triggered by manual streamwise disturbances of the body
. This vibration mode is due to a coupled streamwise-transverse motion, whe
re the streamwise amplitude becomes non-negligible, and may be related to a
further vibration mode at high normalized speed, found for a vibrating piv
oted rod, by Kitagawa et al. (1999). (C) 2001 Academic Press.