Pitch stability characteristics of fully balanced hoist vertical shiplift under hydraulic dynamic leveling

ZHANG Yang1,2, SHI Duan-wei1,2, XIAO Tong2, CHENG Xiong-hao2, ZHOU Ji2
(1.Key Laboratory of Ministry of Education of Hydraulic Machinery Transients, Wuhan University, Wuhan 430072,
China; 2.School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China)

Abstract: Aiming at the problem of pitch stability of the fully balanced hoist vertical shiplift under hydraulic dynamic leveling, the pitch stability of ship chamber, the calculation of wire rope critical distance of suspension points, the stability characteristics of each subsystem and the rapidity of response were studied. An analytical method for pitch stability characteristics analysis of ship chamber coupling system was presented. The mechanicalhydraulicstructuralfluid coupling dynamics model was established by coupling the shallow water sloshing subsystem, the hydraulic leveling subsystem, the main hoist mechanical subsystem and the ship chamber subsystem. The variable step RungeKutta method was used to solve the system displacement response.The results indicate that the wire rope critical distance of suspension points calculated by the presented method is close to the result obtained by the Lyapunov motion stability criterion (the error is less than 4%).Furthermore, the most vulnerable to instability is the shallow water sloshing subsystem, the speed of response adjusted to steady statefrom fast to slow is hydraulic leveling subsystem, ship chamber structural subsystem, main hoist mechanical subsystem and shallow water sloshing subsystem.
Key words: fully balanced hoist vertical shiplift; pitch stability; hydraulic dynamic leveling; critical distance of suspension points; Runge-Kutta method；mechanical-hydraulic-structural-fluid (MHSF)coupling model