Research Initiation: Design Methodology for Advanced Composite Rotary-Wing Structures

这项研究的目的是改进目前先进的复合材料旋翼结构的设计和分析方法。研究成果包括：(1)非均质各向异性梁的改进结构理论，以及(2)荷载形状关键应用的优化设计方法。通过将现有的一维各向异性梁理论扩展到考虑非均匀和横向剪切的影响，发展了精化梁理论。该理论是Timoshenko梁理论的推广，它使用由圣维南弹性解优化技术确定的一组扩展的剪切修正系数来确定柔性叶片的初始形状，使其重量最小化，校核应力和稳定性边界，并且设计变量包括叶片几何和材料定义。这些设计方法将对未来旋翼结构的设计产生影响。复合材料的使用将更加智能，叶片的形状可能会因此而改变。叶片推进效率的重大改进是可能的，这将为下一代飞机节省大量燃料。

The objectives of this research are to improve the design and analysis methods currently used for advanced composite rotary- wing structures. The outcome of the research involves the development of: (1) a refined structural theory for nonhomogeneous anisotropic beams, and (2) an optimum design methodology for loaded- shape-critical applications. The refined beam theory is developed by extending existing one-dimensional anisotropic beam theories to include the effects of nonhomogeneity and transverse shear. This theory, which is an extension of Timoshenko's beam theory, uses an extended set of shear correction factors that are determined by Saint-Venant's elasticity solutions optimization techniques to determine the initial shape of a flexible blade weight is minimized, the stresses and stability boundaries are checked, and the design variables include the blade geometry and material definition. These design methods will impact the future design of rotary-wing structures. Composite materials will be used more intelligently and blade shapes may changes as a result. Major improvements in blade propulsive efficiency are possible, which would result in substantial fuel savings for the next generation of aircraft.