Attenuation of Vibrations in Aircraft Landing Gears due to Impact Loads Using Magnetorheological Dampers

飞机在着陆时会受到冲击载荷的作用。冲击载荷的强度取决于进场速度、着陆条件、操纵面展开、跑道粗糙度等。由此产生的振动会影响乘客舒适度和结构完整性。本研究的目的是探讨磁流变阻尼器对起落架系统减振性能的影响。飞机起落架中减震器的基本功能是吸收着陆时飞机机体框架的冲击动能。目前使用的是油-气动减震器系统，其本质上是具有形成流体弹簧和阻尼器的气体和油的减震器。它们具有延伸穿过流体流动孔口的计量销，这可以改变孔口面积。通过使计量销成形，支柱载荷被调节为在动态载荷下相当恒定。如果阻尼可以根据载荷和进场要求而变化，例如对于不同的飞机重量或着陆时不同的下沉率，则将是理想的。 在着陆期间，飞机机翼仍然通过升力承载大部分飞机重量。目标是优化升力的逐渐减小，使得飞机在垂直方向上经历恒定的减速。这又减少了结构部件中的振动应力。 上述研究的科学方法是（i）系统运动方程的解析解，该系统本质上是具有时变质量和阻尼特性的系统，（ii）包括磁流变流体阻尼器的起落架动力学的数值模拟，以及（iii）遵循硬件在环方法的MR阻尼器组件的实验研究。 新奇和预期的意义，在更好的车辆设计的工作：磁流变液阻尼器改变其阻尼性能非常迅速的应用适当的电流的MR流体。通过引入蓄能器和阀，可以在MR阻尼器中实现刚度的变化。该技术已非常成功地应用于车辆悬架，以半主动方式控制振动。预计在飞机结构中也可以实现类似的减振。 HQP培训将成为本研究的一部分。磁流变液阻尼器在车辆悬架的半主动控制乘坐振动已被发现是成功的。三个博士学生们正在研究配备MR阻尼器的系统的不同方面。拟再培养2名博士。学生在拟议项目的过程中

Aircrafts are subject to impact loads during landing. The intensity of the impact loads depends on the approach velocity, landing conditions, control surface deployment, runway roughness etc. The resulting vibrations can affect passenger comfort and structural integrity. The objectives of the proposed research are to study the performance of the landing gear system in reducing vibrations by incorporating magnetorheological fluid dampers. The basic function of the shock absorber in aircraft landing gears is to absorb the impact kinetic energy of the aircraft body frame during landing. Oleo-pneumatic shock absorber system, which are essentially shock absorbers with gas and oil forming a fluid spring and damper, are currently used. They have a metering pin extending through the fluid flow orifice, which can vary the orifice area. By shaping the metering pin the strut load is adjusted to be fairly constant under dynamic loading. It would be ideal if the damping could be varied according to the load and approach requirements such as for different weight of the aircraft or different sink rate at the time of touchdown. During landing, the aircraft wings still carry the bulk of the aircraft weight with the lift force. The objective is to optimize the progressive reduction in the lift such that the aircraft experiences a constant deceleration in the vertical direction. This in turn reduces the vibratory stresses in the structural components. The scientific approaches for the above studies are (i) Analytical solutions to the equations of motion of the system which is essentially one with time varying mass and damping properties, (ii) numerical simulation of the landing gear dynamics including the magnetorheological fluid dampers, and (iii) experimental studies on the MR damper component following a Hardware-in-the-loop approach. Novelty and expected significance of the work in better vehicle design: Magnetorheological fluid dampers change their damping property very quickly by the application of appropriate current to the MR fluid. Variation in stiffness can be achieved in the MR damper by introducing an accumulator and a valve. The technology has been very successfully applied in vehicle suspensions to control vibrations in a semi-active fashion. It is expected that similar vibration reduction can be achieved in aircraft structures also. HQP training will form a part of this research. MR fluid dampers in vehicle suspensions for semi-active control of ride vibrations have been found to be successful. Three Ph.D. students are working on different aspects of systems equipped with MR dampers. It is proposed to train 2 more Ph.D. students in the course of the proposed project