Dynamic Characteristic Analysis Of Gear System With Broken Teeth

Gear transmission system has many advantages,such as stable transmission,strong bearing capacity and accurate transmission ratio.It is widely used in marine ships,aerospace,wind power generation,engineering machinery and other fields.Because of its low transmission stage,low power loss,low noise and high reliability,the parallel gear system is often used as a combined power transmission component of naval ships,which has complex excitation such as high load bearing,eccentric load impact,axial transient impact of clutch,etc.,and the gear meshing coupling and the dynamic coupling effect coexist,will inevitably induce the gear failure,the acceleration gear failure.Broken teeth,as a common failure form of heavy-duty transmission,are easy to cause safety accidents,bring serious economic losses and even have bad social effects.Therefore,the study on dynamic characteristics of gear system with broken teeth is of great theoretical significance and engineering application value for the safety and reliability of gear system.In this paper,a time-varying meshing stiffness calculation method is proposed for the gear system of marine parallel running gear,based on the changing rules of meshing stiffness under different broken teeth faults,a multi-degree-of-freedom bending-torsion-shaft coupling dynamic model was established to study the dynamic characteristics of the gear system under broken teeth.The main research contents are as follows:(1)Improving the calculation method of the length of the contact line of the helical gear pair,solving the length of the time-varying contact line of the helical gear pair,and combining the calculation criterion of the ISO stiffness,putting forward a new method of the time-varying meshing stiffness of the helical gear pair,then the influence of gear geometric parameters on time-varying meshing stiffness is studied by using the control variable method.(2)In this paper,the fault model of tooth breaking of marine helical gear pair is established,and the analytical expressions of contact line length and time-varying meshing stiffness of helical gear pair under the condition of arbitrary tooth breaking fault are derived,the influence of different length and angle of tooth breaking on time-varying meshing stiffness;(3)Considering the factors such as meshing stiffness,meshing damping,bearing supporting stiffness and damping,transmission error and tooth side clearance,the lumped mass dynamic model of bending-torsion-shaft coupling of marine gear transmission system is established Runge-Kutta method based on adaptive variable step size is used to solve the problem of gear System dynamics differential equation,and the dynamic response characteristics of gear system under normal condition and broken teeth are studied Then the influence of different fault types and sizes on the dynamic response characteristics of the gear system is studied;(4)The Time History Diagram,phase diagram,Poincaré section diagram and FFT spectrum diagram of the marine gear System dynamics are solved by dimensionless processing of the differential equation group,then,the influence of different breaking degree and rotating speed on the bifurcation characteristics of marine gear system is studied and the stability of the system is judged.