Structural dynamics and smart helicopter rotor blades

近年来，申请人研究计划的一个主要重点是开发高保真直升机智能旋翼叶片的数学模型。这样的模型将被用来研究减弱与直升机旋翼叶片操作有关的不良动态响应的可能性。在这项研究计划的前一阶段，已经开发了智能刀片的连续模型。该模型代表了一种薄壁、闭合截面的有源复合梁，它结合了压电纤维作为致动器，在结构上集成到碳纤维复合材料中，形成宏观纤维复合材料(MFC)。这一建议有两个目标：1)现有的智能旋翼叶片模型没有考虑现代直升机旋翼叶片可能存在的初始扭转的影响。根据目前的提议，这一能力将纳入现有的数学模型。此外，在各种地面和航天结构中使用开口薄壁自适应梁的想法也是一个新的概念，例如由自适应薄壁开口截面组成的带有支柱的转子叶片。在下一阶段，还将建立确定开口薄壁主动MFC梁的截面刚度的控制方程。2)研究智能MFC旋翼叶片对舰载直升机叶片滑行现象(BSP)的控制效果是本方案的第二个目标。BSP是指在舰载直升机旋翼低转速时，特别是在高风致气动载荷和公海船舶甲板剧烈运动的共同作用下，叶片可能发生的大弹性变形。因此，叶片可能会与直升机的机身或尾梁接触，造成机身严重损坏，包括机组人员和舰船甲板人员的安全。

A major focus of the applicant's research program in the recent years has been the development of a mathematical model for a helicopter smart rotor blade with a high degree of fidelity. Such a model will be used to investigate the possibility of attenuating undesirable dynamic responses associated with operation of helicopter rotor blades. A continuous model of a smart blade has already been developed in the previous phase of this research program. The model represents a thin wall, closed-section, active composite beam that incorporates piezoelectric fibres as actuators that are integrated structurally into a carbon fibre composite to form Macro Fibre Composites (MFC). This proposal has two objectives: 1) the existing model of smart rotor blades does not take into account the effect of initial twist that could be present in modern helicopter rotor blades. This capability will be integrated into the existing mathematical model under the current proposal. Moreover, the idea of using open cross-section thin-wall adaptive beams in various terrestrial and aerospace structures, e.g., rotor blades with spars consisting of adaptive thin-wall open sections, is also being proposed as a novel concept. In the next phase the governing equations to determine the cross-sectional stiffnesses of open-section, thin wall, active MFC beams will also be developed. 2) Investigation of the effectiveness of smart MFC rotor blades to control Blade Sailing Phenomenon (BSP) in ship-board helicopters is the second objective of this proposal. BSP refers to large elastic deformation of blades that can occur at low rpms of rotors on shipboard helicopters, especially under the combined effect of high wind-induced aerodynamic loads and severe ship deck motion at high seas. As the result, the blades can come into contact with the fuselage or tailboom of the helicopter causing substantial airframe damage and comprising the safety of flight crew and the ship deck personnel.