To suppress cable vibrations' active stiffness control, which changes
the tension as a positive use of parametric excitation, is studied. An
optimal algorithm is obtained from energy analysis and verified by ex
periment on a scale model. Numerical investigation is then made on the
control of a combined system of cable and single-degree-of-freedom st
ructure; the degree-of-freedom of the latter is along the cable axis.
It is found by numerical simulation that instability occurs when the m
ass ratio of cable to structure is large, or when the frequency ratio
of structure to cable is close to 2.0.