兆瓦级风机机架焊缝疲劳分析

在风力发电机机架的焊缝疲劳分析时,目前应用最广的方法为表面外推热点应力法.表面外推热点应力法直接应用热点应力作为疲劳应力控制参量,板厚尺寸和载荷模式效应通常按经验修正公式考虑,焊趾缺口效应在热点应力S-N曲线中统计考虑.以某兆瓦级风机焊接机架为例,首先建立机架的有限元分析模型,计算得到热点的应力,其次通过将载荷历程与其进行通道合并,并运用雨流计数法计算得到等效疲劳应力,最后结合焊缝的S-N曲线进行焊缝的疲劳强度评定及寿命预测.

Weld Fatigue Analysis of Mainframe of MW-class Wind Turbine

The surface hot spot stress extrapolation method is most widely used in doing weld fatigue analysis of mainframe of wind turbines.The hot spot stress is directly used as the stress control parameters in this method,the size of thickness and the effect of loading mode are usually considered by empirical correction formula and the effect of weld toe notch is only considered in S-N curve of the hot spot stress.Taking a welded mainframe of some MW-class wind turbine for example,firstly,this paper builds the FEA model of mainframe,gets the hot spot stress,then combines the channel with load history,and by the rain flow counting method,obtains the equivalent fatigue stress,finally it evaluates the fatigue strength and predicts the life of the weld seam based on S-N curve.