复合材料风电叶片预埋螺栓套连接的轴向刚度分析

Stiffness analysis of embedded bushing with stud bolt connection in wind turbine blades

预埋方式的螺栓连接是大型风力机叶片根部连接和分段式叶片连接的主要形式之一。螺栓连接刚度的准确计算是保证风电叶片静态和疲劳载荷安全设计的重要因素。基于分段式叶片中的预埋螺栓套连接结构,假设被连接件内的轴向应力满足锥形分布,推导了其轴向刚度的解析方程;采用有限元数值方法确定了锥形半角;研究了螺栓直径、夹持长度以及螺栓套厚度对被连接件刚度的影响,通过对比被连接件刚度的解析解与数值解,验证了预埋螺栓套刚度解析表达式的精度。结果表明:预埋螺栓套连接的锥形半角取值范围为15°~18°;被连接件的刚度随着螺栓直径、螺栓套厚度的增大而增大,随着夹持长度的增大而逐渐减小。

Embedded bushing with stud bolt connection is a major method for root connection and segment joint of large wind turbine blades.Accurate computation of clamped member stiffness is a key issue to ensure the safety design of static and fatigue loads of wind turbine blades.Based on the embedded bushing with stud bolt connection used in a real sectional blade,assuming frustum distribution of the stress field of the hollow cone clamped embedded bushing members,the analytical expression of axial member stiffness could be derived.The finite element method was implemented to determine the suitable conical half-angle.The effects of the bolt diameter,the thickness of the bushing,and the grip length on the axial member stiffness were further studied.By comparing the analytic and numerical solutions,the accuracy of the theoretical expression of axial member stiffness was verified.Member stiffness increases with the diameter of the bolt and the thickness of the embedded bushing but reduces gradually with grip length.The results indicated that the preferable conical half-angle for embedded bushing with stud bolt connection is between 15°and 18°.