Evaluation of vibration reduction devices for helicopter ride quality improvement

Abstract

This work presents the use of a modern helicopter simulation environment for the evaluation of the combined performance of several systems for helicopter ride quality assessment. The proposed framework can handle increasingly detailed aeroservoelastic helicopter models while providing great flexibility and versatility in modeling human biodynamic models for vibration evaluation as well as models of the vibration attenuation devices. A numerical model representative of a medium weight helicopter is used to demonstrate the approach. Lumped parameter models of seat-cushion and human biodynamics are dynamically coupled to the helicopter model to provide a more realistic estimate of the actual vibratory level experienced by the occupants. Two performance indicators are formulated, based on the acceleration of the seat locations and using the ISO-2631 standard: i) qualitative criteria and related vibration dose values of the individuals seated at prescribed locations of a fully occupied helicopter, and ii) an overall rating of the occupants inside the cabin, considering the most and least comfortable seating distributions as the number of occupants changes. To demonstrate the proposed method, three configurations of helicopter-specific passive vibration absorbers are considered.