Study On Magnetic Memory Detection Technology For Early Damage Of In-serve Wind Turbine Tower

As the main load-bearing component,wind turbine tower is easy to produce stress concentration in the local deformation area of the surface working in long-term service in complex environments.Stress concentration will cause early damage to the material.Early damage is one of the important factors that threaten the safe operation of the tower.Its further deterioration will reduce the service life of the wind turbine and seriously cause a tower collapse accident.To this end,using magnetic memory detection technology in the test,building early damage detection system of a tower,and designning tower test simulation components.Based on simulation analysis of different working conditions,carrying out magnetic damage detection of tower's early damage by loading test,and discussing the influence of different factors in the detection of the tower on the magnetic memory signal.The main work and results of this article are as follows:(1)Designing the magnetic memory detection system according to the metal magnetic memory detection principle,including the design of the magnetic memory signal acquisition circuit and the compilation of the host computer acquisition interface.High-sensitivity magnetoresistive sensors are used to detect magnetic field changes and find stress concentration areas.Incremental encoder is used to achieve the signal's acquisition of early damage position,and finally based on LABVIEW interface realizing the functions including intuitive magnetic memory signal waveform's display,analysis and storage.(2)Component design is based on the similar principle.On the premise of ensuring geometric similarity,material similarity and load similarity,wind turbine tower component is systematically analyzed by reducing the size and simplifying the load,and manually precut grooves and flat bottom hole to simulate stress concentration.The design of the model test piece is more beneficial to improve the reliability and accuracy of magnetic memory signal analysis under tower tower simulation test,by replacing the limitations brought about by the original plate test block research.(3)Using the finite element analysis to perform simulation analysis of the stress distribution of the tower components under different working conditions,completing the multi-channel loading test platform,and carring out the magnetic memory detection experiment of the early damage of the tower components.The control variable method are used in the test,involving the influence of magnetic memory signals under different load effects,detection orientation,detection angle and damage type,finally obtaining the change law of the early damaged magnetic memory signal of the tower and analyzing the corresponding relationship of the signal characteristics of early damage under different factor changes.The test analysis show that the peak-to-peak value of the synthetic magnetic field strength and the rate of change of the synthetic magnetic field strength can characterize the signal characteristics of the fan tower under load.The reasonable detection angle,detection orientation,and signal characteristics corresponding to the two types of damages of grooves and bottom holes are also given.Finally providing guidance for the early damage detection of the in-service wind turbine tower in the test analysis,and the effectiveness of the magnetic memory detection technology applied to the local stress concentration detection of the tower is verified.