Study Of The Effect Of Surface Micro-Texturing On The Frictional And Wear Characteristics Of Wind Turbine Spindle Disc Brakes

The wind turbine spindle mechanical brake system is one of the most important systems in wind turbine equipment and plays an important role in the safe operation,normal shutdown maintenance and emergency brake maintenance of wind turbines.Based on the frictional wear of wind turbine spindle brakes,this paper investigates the frictional wear characteristics and micro-weaving wear reduction mechanism of C17200 and 34 CrNiMo6 brake materials,and numerically simulates the wear of pin-disc frictional subsets and the thermo-mechanical coupling process of wind turbine brakes in combination with experiments.The distribution and variation rules of contact compressive stress,contact friction and wear depth during the pindisc wear process,and the distribution and variation rules of temperature and thermal stress of the smooth surface and micro-weave surface brake discs are analysed,which provide some theoretical basis for the material selection,failure mechanism and structural optimisation design of wind turbine brakes.The main research contents and conclusions are as follows:(1)The current development status and future development trend of the energy and wind power industry is mainly explained,the structure and working principle of the wind turbine spindle brake system is introduced,the main problems and failure mechanisms of the current wind turbine brake system are analysed,and the current research status of friction and wear and thermo-mechanical coupling,numerical simulation of friction and wear,and weaving treatment of brake discs for wind turbine brakes is systematically summarised at home and abroad,leading to the research content of this paper,which mainly focuses on the friction and wear characteristics of wind turbine brakes and thermo-mechanical coupling analysis,laying the foundation for the subsequent research.(2)The friction and wear characteristics of C17200 pin and 34 CrNiMo6 disc under different speeds and loads were investigated using pin-disc friction and wear reduction mechanisms of microweaving.The minimum average friction coefficient under different working conditions was found to be greater than 0.5,showing excellent braking performance and wear resistance compared with other brake friction sub-materials.The average friction coefficients and wear amounts of smooth disc surfaces and disc surfaces with different microfabrication parameters under the same working conditions were compared and analysed.It was concluded that the microfabrication structure can reduce the wear rate,accelerate heat conduction and heat dissipation,and the friction coefficients are all greater than 0.4,which meets the braking requirements.(3)Based on the ARCHARD wear theory,a three-dimensional pin-disc plane/plane wear theory model was established,taking into account the surface roughness and uneven contact pressure distribution factors,and written as the UMESHMOTION subroutine using the FORTRAN language.The maximum error between the simulation results of the proposed pindisk wear theoretical model and the experimental results is less than 5%.The proposed pin-disk wear model is applied to meet the actual wear condition and has high accuracy,which is of certain reference significance for later related research.(4)Based on the transient heat transfer theory and the micro-woven pin-disc wear reduction law test,a simplified three-dimensional model of the smooth surface and microwoven surface brake disc structure is established.Based on the three-dimensional transient heat conduction differential equation and the fixed solution conditions,material parameters,boundary conditions and operating conditions are determined for the direct thermo-mechanical coupling numerical simulation of the wind turbine brakes with smooth and microwoven discs respectively.It was found that the temperature of the brake discs of the two types of discs fluctuates in a "sawtooth" pattern with braking time at different nodes in the friction radius area,with the temperature rising first and then falling,and that the temperature of the two types of discs has a greater influence on the thermal stress.The maximum temperature and maximum thermal stress of the rectangular slotted disc is less than that of the smooth disc,and the temperature and stress of the brake pad are greater than that of the brake disc in contact with it.The micro-weave structure can be used in the brake disc structure of wind turbines to achieve the effect of heat dissipation and heat conduction,reduce the influence of temperature on the stress of the brake disc and prolong the service life of the brake.