风机塔筒早期应力集中状态检测方法研究

Research on Application of Acoustic Emission Technology in On-line Monitoring of Wind Turbine Tower

风力发电机组由于所处工作环境恶劣,运行时所承受载荷状态十分复杂,易引起塔筒局部的应力集中,引发结构的早期损伤。因此,为实现对局部应力集中的全面且早期的诊断和分析,本文通过有限元模拟方法对风机塔筒所受应力集中区域进行分析,根据仿真分析结果,在建立等效风机塔筒模型基础上,模拟实际风电塔筒在不同风况下受载状态,同时利用声发射技术对塔筒模型应力集中状态进行检测。实验结果表明:应力随塔筒高度的减小呈递增趋势,且缺口处应力随载荷的增加逐渐增大。声发射方法可以对风电塔筒应力集中点进行有效标定,随着应力集中程度增加,声发射信号振铃次数、幅度和能量均呈现明显下降趋势,在100kHz以上部分的频率范围内,声发射信号幅值不断增加,且主频带从180kHz移动至250kHz附近。

Due to the harsh working environment of wind turbines and the complex load state,it is very easy to cause local stress concentration in the tower during the operation,which leads to early damage to the structure.Therefore,in order to achieve a comprehensive and early diagnosis and analysis of the local stress concentration,this paper analyzes the stress concentration area of the wind turbine tower by means of finite element method,and simulates the actual wind turbine tower under different wind conditions on the basis of establishing an equivalent wind turbine tower model.The experimental results show that:the stress magnitude tends to increase with the decrease of tower height,and the stress at the notch gradually increases with the increase of load.And the acoustic emission method can effectively calibrate the stress concentration point of wind turbine tower,with the increase of stress concentration,the number of ringing,amplitude and energy of acoustic emission signal display a significant decreasing trend.In the frequency range above 100 kHz,the amplitude of the acoustic emission signal increases,and the main frequency band moves from 180 kHz to 250 kHz.