| The warship will inevitably face the threat of attack from anti-ship weapons during its service period.As the main power unit of warship,the gearbox must not only have good working performance,but also show strong resistance to shock.In the past,when analyzing the shock dynamic response characteristics of a gearbox,the gear tooth properties were usually not considered,and the influence of the strength of the gear teeth and the meshing coupling of the gear pair on the system were ignored.Actually,the impact resistance of the gear pair which is the contact transition area of the gear transmission system,directly determines whether the equipment can run.In this paper,a series of researches are carried out on the anti-shock characteristics of marine gear transmissions system in the context of underwater explosions,taking the gear teeth meshing coupling effect into account.Firstly,the inherent properties of gear pair are studied according to the dynamics of gear system,and the formation mechanism of time-varying meshing stiffness of gear pair is studied from the actual motion process.The accuracy of time-varying meshing stiffness is verified by comparing the calculation results of the potential energy method and the finite element method.It is found that the time-varying meshing stiffness is mainly affected by the disk stiffness and the tooth stiffness,so it is necessary to take the tooth influence into account when calculating the shock resistance of the gear system.Based on the vibration analysis model of the gear system,a transient shock dynamic analysis model of the gear pair is established.Secondly,on the basis of the transient impact dynamics analysis model of the gear pair,the gear teeth are simplified.A numerical simplified model of shock dynamics of the gear-rotor system including the gear pair and drive shaft is established,in which the gear teeth are replaced by springs.The feasibility and advantages of the simplified model are verified from both structural natural frequency and structural impact response.The research shows that the simplified model can reflect the transmission characteristics of the impact load in the gear-rotor system,and excludes the influence of the mesh size of the gear teeth,so the calculation efficiency is higher and less computing resources are occupied.Then,by designing a simplified gearbox model and carrying out a drop impact experiment,the accuracy of the time-domain analysis method is verified.Based on the numerical simplified model of shock dynamics of the gear-rotor system,the time-domain analysis method is used to study the impact response characteristics of the gear transmission system including the coupling effect of gear tooth mesh in three directions of vertical,horizontal and vertical,and the relationship between the impact load of different peaks and different pulse width combinations and the maximum stress response of the upper case,in order to analyze the structural impact response law and find the weak part of the structure,which provides a reference for the optimal design of the structure against impact.Finally,based on the acoustic-solid coupling theory,the elastic system coupling theory and the above research results,an integrated numerical calculation model of the flow field-hull-equipment coupled is established to simulate the real ship equipment impact environment.This section explores the impact response characteristics of the gear transmission system when the coupling effect between the equipment and the hull is taken into account,quantitatively analyzes the influence of shock factor,explosive distance,and charge weight on the maximum impact force between the gear teeth,and then assesses the strength of the gear teeth.The difference between the equivalent time-domain non-integration calculation results and the integration calculation results is compared and analyzed to provide guidance for subsequent equipment shock analysis. |
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