Thermal Mechanical Coupling And Residual Life Analysis Of Wind Turbine High Speed Shaft Brake

Wind power high-speed shaft brake is a key component that directly affects the continuous output of electric energy,and it is an important guarantee for the safe and reliable operation of wind turbines.The interaction of fluid,friction,heat transfer and other physical fields involved in the braking process is an important topic to study the brake.The thermoelastic instability can be randomly combined into different research centers according to the structure,material,working condition and other conditions.The thermomechanical coupling and life prediction are the most important methods to characterize the performance of the brake.Based on ABAQUS finite element software and heat transfer theory,the thermal mechanical coupling model of2.5MW wind power high-speed shaft brake is established.The braking process of the brake under emergency and normal parking conditions is simulated by using complete thermal mechanical coupling method.The temperature field distribution characteristics of the brake in different dimensions are studied,and the variation characteristics are highly similar to the thermal stress field,And the life of the instability area is estimated,which provides a profound theoretical basis for further promoting the development and application of the brake.The main research work is as follows:(1)This paper introduces the selection and implementation of wind power high-speed shaft brake,summarizes the research status of brake at home and abroad in the aspects of thermal damage,heat transfer,thermal elastohydrodynamic,thermal fatigue,friction vibration suppression,etc.,leads to the research content of this paper is mainly thermal mechanical coupling analysis and residual life prediction,and further introduces the friction,contact,heat transfer,thermal stress,finite element method and other related theories It lays a foundation for the following simulation work.(2)Using ABAQUS and 3D drawing software,the brake structure is established and simplified,and the mesh is refined.On this basis,the finite element calculation model is established through the unsteady heat transfer theory.Then,given the brake material characteristics,size,operating conditions and other conditions,the braking torque and convective heat transfer coefficient are calculated to determine the two most important nonlinear parameters in the braking process.Finally,the load,speed,contact and other boundary conditions are added to input the influencing factors of the braking and parking process orderly.After checking,the dynamic simulation of the wind power high-speed shaft brake is completed.(3)Through the comparison and observation of the distribution of temperature field and stress field under the two working conditions,many similarities and differences between the brake disc and the friction plate in the two characteristics are obtained.Firstly,depending on the strength difference of heat conduction,heat transfer and heat generation in the friction contact process,the temperature distribution of the disk surface and the instantaneous temperature rise curve of the nodes in the circumferential path were observed.It was found that the high temperature transition trend of the rib disk surface to the inter rib disk surface was obvious at the initial braking stage,which was from water drop shape to irregular shape,and the temperature of different nodes in the radial path changed with time The temperature rise of the disk surface is similar to that of the previous experiments.The temperature field distribution of the friction plate is mainly attributed to the different contact coverage order of the brake disc.With the further decrease of the rotating speed,the change characteristics of the high temperature zone in the disc contact zone move from the flaky and willow leaf shape to the elliptical shape at the end of the period.The distribution and variation of thermal stress field is similar to that of temperature field,showing a high degree of coupling,which also shows the consistency of thermal mechanical coupling.The difference is that there are some differences in the stage and amplitude of temperature rise under the two conditions,but generally speaking,they are caused by the input of heat flow and the intensity of convective heat transfer rate.(4)By introducing the formation mechanism of fatigue crack,the prediction range of service life is derived.According to the simulation results,the possible damaged parts of the brake are accurately located.It is judged that the failure part is the theoretical friction radius of the brake disc under normal parking conditions.The residual service life of the brake is predicted according to Manson coffin method.It also shows that under the premise of protecting the stable operation of the unit,the braking life should also be considered,and the braking time should be appropriately increased to avoid the brake failure caused by multiple emergency stops,resulting in unnecessary losses of the wind turbine.