| The mechanical brake of wind turbine is an important equipment to ensure safe operation.However,when the brake runs after a period of time,pollutants will adhere to the surface of friction pairs,which will decrease the friction coefficient,aggravate wear,thereby weakening the mechanical braking performance,and even cause serious safety accidents.Therefore,to ensure the safe operation of wind turbine,it is significant to study the influence of pollutants on the mechanical braking performance.This paper mainly does the following work.(1)The brake friction pairs of served wind turbine are investigated.The composition of pollutants on the surface of-friction pairs is measured by energy spectrum analysis,and it is found to be composed of oil and third body.The particle size and shape of the third body is measured by SEM.By studying the brake structure and its operating conditions,the source of the third body and oil is analyzed,and the adhesion of oil to the third body under high-velocity rotation and high-frequency vibration conditions is studied.The wear morphology of the brake disc's surface is analyzed by 3D optical profiler and the wear mechanism of the third body to the brake disc is studied.(2)The third body friction and wear tests is carried out by selecting appropriate friction pairs and tester to further study the friction and wear mechanism of the third body.A method for selecting test velocity is proposed,that is to control the velocity and sampling frequency to make the friction pairs always in the same relative position,then measure the test data.This method can reduce the interference of machining error and setting error to the output data of the test.The experimental results show that the fluctuation of friction coefficient measured using this method is decreased and the distribution is more centralized.(3)Targeted at the test condition of high velocity and high-frequency vibration,the third body and deteriorated oil mixed pollutants is adhered to the surface of friction pairs for experiment By changing the test velocity and force,the influence of the third body on the friction and on the wear properties of friction pairs is studied.The results show that the third body weakens the friction coefficient of the friction pairs and aggravates its wear.The fluctuation of friction coefficient increases with the increase of velocity and decreases with the increase of pressure.And the third body will greatly weaken the static friction coefficient.In this paper,wear of friction pairs is studied and the composition and source of pollutants on the surface of friction pairs is analyzed,which can provide evidence for the design,check and maintenance of mechanical brakes.The wear rule obtained from the third body wear test provide evidence for improving the braking capacity and prolonging the service life of the friction pairs. |
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