Vibration Characteristics Analysis Of Marine Pump Based On Flexible Multi-body Dynamics

Marine pump is one of the important auxiliary machinery, which can ensure thenormal sailing of ships and meet the needs of the mariners and passengers. The vibrationprediction for the pump is an essential step in the designing and manufacturing of marinepump. It will affect the safety of the marine shipping and reduce the concealment of thewarships when the amplitude of vibration is too large. In order to improve the vibrationperformance and reduce the vibration and noise of marine pumps, the analysis of vibrationcharacteristic is necessary. Taking the marine two stage centrifugal pump as the researchobject, dynamics modeling, dynamics simulation, the vibration characteristic analysis andvibration modal test are researched deeply.The stiffness and damping of marine pump parts connection have a great influence onthe vibration of pump. First of all, the theoretic analysis on the behaviors of marine pumpjoints is presented. The combining site is equivalent to spring-damper elements, startingfrom the most basic vibration equation, the expression of the stiffness and damping at ajoint of a single plain is derived, the equivalent dynamics model of the pump is established.The equations are derived that can describe the rigid and flexible combination of twosubstructures, and join the joint behaviors parameters into the the equation. Based on thetheory of flexible multi-body dynamics, the impeller blade is scattered by assumed modalmethod, get the coupling deformation of blade. Large range of motion of marine pumps keyparts, the deformation of component itself and coupling deformation are considered at thesame time, derived flexible multi-body dynamic equations of pump shaft components byusing Lagrange equations. Finally the static characteristic and dynamic characteristic of thepump are acquired through the coupling solution to the kinematic variables and flexibledeformation variables.The3-D entity model of the pump shaft components is established. The modalanalysis and flexible processing are carried out on the key parts of pump by using the finiteelement software, and export related modal neutral file(MNF). The flexible multi-bodydynamic model of pump shaft components is established in multi-body dynamic analysissoftware by importing the MNF. Adding input channel and output channel, through thedynamic simulation and forced vibration analysis of the flexible multi-body dynamicmodel, the dynamic response and the modal parameters of the pump are acquired. Design aproject of modal test experiment of pump to get the natural frequency, damping ratio and modal stiffness. Through comparison of the experimental data and simulation data, thecorrectness and effectiveness of flexible multi-body dynamic model is verified, this laid afoundation for optimization design of the marine pump and reduction of vibration andnoise.