Vibratory Power Flow Analysis of a Gear‐Housing‐Foundation Coupled System

Abstract

The marine gearbox is usually installed on a vibration isolation system in order to reduce oscillation transmitted to the ship foundation. However, researches on vibration transmission in the gear-housing system and isolation system are currently independent. With the increasing requirement of lower vibration, a coupled model needs to be built to control the vibration propagation from a view of the whole system. Considering the mesh transmission error excitation of a gear pair, a flexible gearhousing-foundation coupled impedance model is constructed in this paper, and the vibratory power flow of the whole system is calculated. Power transmissions between three different gearbox installation configurations, that is, rigid installation, singlestage isolation, and double-stage isolation, are compared. Taking the single-stage isolation configuration as an example, parameter influences on the vibration of the foundation are studied. Results show that double-stage isolation can achieve lower vibration than single-stage isolation; decrease in bearing stiffness or Young's modulus of isolator will yield better vibration isolation performance; housing damping and isolator damping are beneficial to vibration reduction.

Numerical Noise Transfer Analysis of a Flexible Supported Gearbox Based on Impedance Model and Noise Transfer Function

“…en, each subsystem is modeled separately. Finally, the coupled impedance model of the gear system is established by impedance synthesis method [3]. e excitation included in the model is the gear transmission error excitation.…”

“…e gear pair is modeled as a massspring-damper element with six degree of freedom (DOF). e dynamic equation of gear subsystem is as follows [3]:…”

“…where x GP is the displacement vector of gear nodes, M GP is the mass matrix of gears, C GP � c GP VV T is the mesh damping matrix, c GP is the mesh damping, K GP (t) � k GP VV T is the time-varying mesh stiffness matrix, k GP (t) is the normal mesh stiffness, f GP is the reaction load vector of shaft to gear, and e GP is the comprehensive mesh error vector. Equation (1) can be approximated into a frequency domain form [3]:…”

“…e shape of the isolator is a cylinder with a diameter of 40 mm and a length of 40 mm. e modulus of elasticity is 1 × 10 7 Pa, density is 1000 kg/m 3 , Poisson's ratio is 0.49, and loss factor is 0.1. e isolator is modeled as continuous Timoshenko beam element [3]. e dynamic transfer matrix is obtained by the wave equation, which can then be converted into an impedance matrix.…”

“…He then built a BE model to predict the radiation noise under this load. Ren et al [3] proposed a gear-housingfoundation coupled impedance model, which can realize the fast vibration simulation of flexible supported gear system considering the coupling relationship between transmission system, housing, and isolation system. In order to obtain the dynamic parameters of bearing, Lin et al [4] identified the bearing stiffness and damping parameters through experimental modal analysis and least square method and built a coupled FE model of the gear-shaft-bearing-housing system to study the vibration and noise of gearbox.…”