Study on stability of cable-anchored underwater platform by parametric excitation

Aiming at the stability of the heaving–pitching coupling motion of the cable-anchored underwater platform in the nonlinear flow field, considering the change of its initial equilibrium position under the flow field, a coupled heaving–pitching motion equation is established; the transition curve of stability at frequency ratios of 0, 0.5, and 1 was obtained by using the virtual mass method and deformation parameter method. According to the Floquet theory, the stability characteristics under weak parameter excitation are studied. The stability and instability regions were identified and verified by time history response. The results show that the range of the stability region can be changed by adjusting the damping of the system. With the increase of damping, the range of stability gradually increases. Therefore, it is possible to take measures such as adding the helical damping side plate, changing the cross-sectional shape of the platform floating body, and increasing the cross-sectional diameter to suppress the heaving displacement and pitching range of the cable-anchored underwater platform.