基于表面外推法的结构热点应力计算方法研究

Research on the Calculation Method of Structural Hot Spot Stress Based on Surface Extrapolation Method

为获得准确的结构热点应力,确保风电机组部件疲劳寿命的可靠性,建立不同网格尺寸、单元类型的有限元模型,研究了网格精度、单元类型、外推方法对焊接接头结构热点应力计算结果的影响。结果表明:结构热点应力随着网格尺寸细化呈现出先增大后减小的趋势,在网格尺寸为0.33t(t为板厚)时达到峰值。四面体单元模型的计算结果保守且受网格尺寸的影响更为显著,并且对网格精度有较高要求。不同网格精度的四面体模型运用两种外推法计算结果最大相差13.56%;六面体单元模型运用两种外推法计算结果相差均在10%以内。随着网格细化两种外推法的计算结果逐渐接近;当网格尺寸细化到0.2t时,六面体单元模型的结构热点应力仅相差1.87%。

To obtain accurate structural hot spot stress and ensure the reliability of fatigue life of wind turbine components,finite element models of wind turbines are established with different grid dimensions and element types on fixtures,the effects of grid dimension,element types,and extrapolation methods on the calculation results of hot spot stress in welded joint structures are studied.The results show that the structural hot spot stress shows a trend of first increasing and then decreasing with the refinement of the grid dimension,reaching its peak at a grid dimension of 0.33t.The calculation results of the tetrahedral element model are conservative and more significantly influenced by the grid dimension,and have high requirements for grid dimension.The maximum difference in calculation results between two extrapolation methods for tetrahedral models with different grid dimensions is 13.56%.The difference in the calculation results of the hexahedral element model using two extrapolation methods is within 10%.As the mesh refinement approaches,the calculation results of the two extrapolation methods gradually approach.When the grid dimension is refined to 0.2t,the structural hot spot stress of the hexahedral element model only differs by 1.87%.