Experimental and Computational Evaluation of Particle Impact Dampers in Multi-Mode Passive Vibration Control of eVTOL Support Arms

Electric vertical takeoff and landing aircraft (eVTOL) have swiftly risen to prominence since the early 2000's due to their potential to serve as a sustainable and scalable improvement in urban air mobility. In edgewise forward flight, these aircraft can experience significant time-varying aerodynamic loads due to being variable RPM vehicles. Their fuselage, booms and auxiliary lifting surfaces are often very lightly damped, lightweight and highly stiff. Thus, multiple bending and torsional modes of vibration can be excited and result in unacceptably high stress levels. Particle impact dampers (PIDs) are an attractive vibration mitigation strategy as they can target more than one mode of vibration. The potential use of a PID to target a bending mode of vibration is experimentally and numerically studied within this work. Experimental forced response analysis shows a 53% attenuation in amplitude of vibrations at the cost of a 5% mass penalty. A reduced order model was developed in order to allow users to parametrically study the damper performance as a function of a variety of inputs. Initial numerical simulations of this reduced-order model show behavior observed in the experimental arrangement. Model parameters are set to match laboratory values, and agreement is found with experimental results.This publication, in tandem with the work presented at the Vertical Flight Society's 80^th Annual Forum, by the same authors, sheds light on the potential multi-mode damping capacities of these devices.