摘要
将叶片视为变截面悬梁,离散成任意段,每一段满足各向异性双向弯扭耦合振动微分方程,其解表作为两端节点10个自由度的函数,相邻段在同一截面内的节点位移由连续性条件联系,由此建立起求解叶片双向弯曲与扭转响应的传递函数,然后根据边界条件,得到一组仅含10个未知数的齐次方程,其非零解即是叶片各阶固有频率。相对有限元等其他数值方法,这种传递函数的解变量少,算法设计容易,求解速度快,精度高。基于该算法对一种大型叶片叶根段结构铺层优化后的频率特性进行了分析,结果显示,新设计方案不仅叶片重量显著降低,而且叶片刚度和频率特性完全满足使用要求。
A wind turbine blade is considered as a cantilever beam with variable sections,which can be divided to arbitrary segments. Each satisfies the governing differential equations of biaxial bending coupled with torsional variations. The material properties involved can be anisotropic. Solutions to them are represented as functions of 10 free degrees at both end nodes. Nodal displacements of the same cross-section from two adjacent segments are connected by the continuity conditions,resulting in a transfer function correlating the nodal freedoms at one cross-section with those at any other. Finally,a group of homogeneous equations that contain only ten unknown variables is established by applying the boundary conditions at the fixed and the free tip ends of the blade. A nontrivial solution condition results in the frequency equation to be solved. Compared with finite element and other numerical methods,this transfer function method has several advantages such as fewer variable,easier to implement into a computer program,more quickly to obtain a solution and higher accuracy achievable with the same cost in time and computer sources. The method is then applied to evaluate frequencies of a large blade with optimized laminate structure. The result shows that not only the weight of the blade after optimization can be significantly reduced,but also its stiffness and frequency characteristics can meet the operating requirements.
出处
《玻璃钢／复合材料》
CAS
CSCD
北大核心
2015年第12期28-34,共7页
Fiber Reinforced Plastics/Composites
基金
国家自然科学基金(11272238
11472192)
教育部博士点基金(20120072110036)
关键词
复合材料
风机叶片
固有频率
传递函数
结构优化
composite material
wind turbine blade
natural frequency
transfer function
structural optimization
