| The full-size fatigue load test of wind turbine rotor blades is an important means to test the reliability of wind turbine rotor blades.At present,the empirical method is usually used to determine the loading scheme during the test.However,due to the development of large wind turbine rotor blades,the efficiency of this method is very low,and a group of loading schemes meeting the requirements of bending moment distribution can only be obtained after many test loads.In order to solve this problem and improve the efficiency of blade fatigue load test,this paper studies three aspects: quick calculation of test bending moment,optimal design of fatigue loading scheme and development of engineering application software.In this paper,based on Euler beam theory,the fan blade is equivalent to a cantilever beam with variable section,and the discrete model of the blade is established.The transfer equation and transfer matrix of the blade are derived by using the transfer matrix method,and the characteristic equation of the system is obtained by taking into the boundary conditions of the cantilever beam.First,based on the Euler beam theory,according to the structural characteristics of the blade,it is equivalent to a section of variable cross-section cantilever beam,and the discretization model of the blade is established.The transfer equation and transfer matrix of the blade are derived by using the transfer matrix method,and the characteristic equation of the system is obtained by substituting the boundary conditions of the cantilever beam.A dynamic model of the blade single point resonance fatigue loading system was established,and the mathematical model of the system was derived using the Lagrange equation.A program was developed using MATLAB to solve the natural frequency of blades and the bending moment distribution and deflection curve of blades under harmonic excitation.By comparing the results with the finite element solution,it was verified that the theoretical solution has a high solution accuracy.The loading scheme of fan blade fatigue load test is optimized by using modern optimization algorithm.Combining the advantages and disadvantages of genetic algorithm and particle swarm optimization algorithm,a hybrid particle swarm optimization algorithm was designed to optimize the problem.Among them,the crossover probability and mutation probability of the adaptive genetic algorithm are updated adaptively with the fitness value.The initial value of the inertial weight coefficient of the adaptive particle swarm optimization algorithm is selected adaptively with the fitness value of the global optimal solution obtained by the genetic algorithm,and the inertial weight value is updated with a linear decline strategy.Takin g 78 m blade as an example,the optimization calculation of the brandishing direction test scheme is carried out.The results show that the algorithm has the ability of fast convergence,and the bending moment error can be controlled within 10%.Using C# and MATLAB mixed programming method to compile engineering application software.The MATLAB program of blade bending moment calculation and optimization design of loading scheme is encapsulated into a dynamic link library.dll file that can be called by C#.Use C# to write software interface,related data processing.Through the development of the industrial software,the MATLAB program can be run without MATLAB platform,which brings great convenience for engineering applications. |
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