| The brake is one core component of the wind brake system,which has great effects on the safety of wind turbines directly.The dynamic process involves multiple physical fields,which can reveal the friction mechanism in the braking process.At the same time,the brake disc is subjected to cyclic alternating heat stress during braking,so the brake disc is damaged by fatigue.Based on the results of thermal-structure coupling,it is of great significance to study the fatigue crack life of disc brake disc.This paper studies the disc brake of 1.5 MW wind turbine,a large three-dimensional finite element model of main shaft brake of wind turbine is built based on the finite element software ansys,The distribution of temperature field and stress field of wind force in emergency brake is simulated using the method of heat and structural sequence coupling.Just as well,the expansion of crack propagation of wind mechanism was studied,Based on the results of it the residual life of the moving disk was analyzed.The main researches are listed as follows:(1)The domestic and foreign research situations of the thermo-mechanical are summarized.The theories related to thermo-mechanical coupling analysis involved in the process of wind power,such as Thermo-mechanical method,friction theory,calculation of the stress intensity factor of semi-elliptic crack.(2)The finite element model of the brake has been established using the finite element software ansys.The boundary conditions of disk brake of wind turbine,structural parameters and material parameters have been determined,the wind turbine disc brake braking torque has been calculated.On the basis of this,the distribution of temperature field and stress field of wind turbine brake under emergency brake is simulated.The results show that the temperature distribution of the brake disc is uneven,and the surface temperature of the brake disc and the friction disc is the highest,the stress distribution on the brake disc is not uniform.(3)Based on the distribution of the brake disc temperature field and the stress field in the emergency brake,the failure mechanism of the brake disc is analyzed and the area of the crack is determined.To simulate the wind braking disc under high temperature and low temperature stress intensity factor of the different circumstances,establish the mechanism of wind dynamic stress intensity factor of crack and the relationship between the crack length.The initial crack length of the disc brake is considered to be random distribution,and the extended life of crack propagation of wind mechanism under different initial cracks is analyzed.Studies show that if the wind braking disk disk initial crack exists in the process of braking,the thermal stress of the brake disc is cycle,disk of initial crack expanding,continuously reduce the service life of brake disc with the propagation of the crack,so strictly control the wind braking disc of the initial crack Have a very important role for its life. |
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