Synthesis and Optimization of Mechanical Networks with Inerters in Landing Gear for Improved Landing Performance and Vibration Control at Touchdown Considering Airframe Flexibility

Abstract

The landing impact case results in the development of significant loads and accelerations within the airframe. Accurate knowledge of the landing loads is not only necessary for the stress analysis and design of the airframe, but also for designing strategies to mitigate the vibratory loads and improve the ride quality. Perceived passenger comfort is dependent both on the magnitude of the acceleration experienced by the passengers and on the frequency content of the vibrations. Using a flexible airframe model of a 150-passenger regional jet with cantilevered landing gear in a tricycle configuration, this study optimizes various single-port (two-terminal) passive mechanical networks that consist of an arrangement of springs, dampers, and inerters to minimize passenger discomfort and peak forces applied to the aircraft. The performance of the mechanical networks is compared to a baseline oleopneumatic shock absorber. First, the importance of including airframe flexibility effects was demonstrated as the peak landing gear loads, the loading regime, and the frequency response of the structure were altered when compared to the equivalent rigid model. Next, eight candidate layouts were optimized, then the observations from this exercise were used to synthesize a mechanical network with a desired frequency response. All considered mechanical networks demonstrated the ability to control the frequency content of the input loading, thus resulting in a reduction in accelerations and an improvement in all comfort parameters used in this study over the oleo-pneumatic baseline.This research was financially supported in part by the Natural Sciences and Engineering Research Council of Canada both by the Canada Graduate Scholarship-Master's and Discovery Grants. In addition, entrance scholarships to the Mechanical and Aerospace Engineering department, and Teaching Assistantships helped fund my research.