Dynamics modeling and impact resistance study of the marine gas turbine isolation system

The isolation system, which protects the gas turbine by isolating the impact from the ship's hull when the ship is impacted, consists of a steel frame and isolation elements. A rate-dependent generalized Prandtl-Ishlinskii model is proposed and the mechanical models of the isolation elements are developed, which are verified by impact tests and found to have a maximum error of 3.05 % in relative displacement and 9.75 % in acceleration. The steel frame is discretized into multiple Timoshenko beam cells, and a stiffness matrix establishment method for spatial rigid-flexible coupling unit is proposed to establish the dynamics model of the isolation system. The maximum error in the natural frequency of the steel frame is found to be 8.44 % by comparing with the simulation results, and the maximum error in the natural frequency of the steel frame-gas turbine system is found to be −10.62 %. The impact dynamics calculations are completed based on the pseudo-force method, and the influence of the isolation elements arrangement on the isolation performance is analyzed in conjunction with the energy transfer between modes. The isolation system has the highest energy share for the 7th, 8th, and 11th order modes, and it does affect the energy share of each order mode when changing the number, position, and spacing of the isolation elements.