Vibration Mitigation Analysis of a Seahawk Helicopter Seat Suspension Concept
Technical Report,01 Oct 2017,30 Apr 2019
711th Human Performance Wing Wright-Patterson AFB United States
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Recent surveys aboard rotary-wing aircraft strongly suggest that aircrew are being exposed to operational vibration associated with the potential for health risk. The objective of this study was to evaluate the effectiveness of a seat suspension concept to mitigate vertical operational vibration and minimize health risk. A Seahawk seat fitted with a magnetorheological active damper system was mounted onto the Six-Degree-of-Freedom Motion Simulator SIXMODE located at the Air Force Research Laboratory AFRL. Nine military volunteers were exposed to multi-axis flight vibration recreated in the SIXMODE. Seat system configurations included LOCKED no damper, UNLOCKED ON damper with variable viscosity, and UNLOCKED OFF damper with constant viscosity. Triaxial accelerations collected at the seat interfaces and subject anatomical sites were used to estimate rms spectra. The ISO 2631-1 1997 and MIL-STD 1472 were used as guidelines for health risk assessment. The UNLOCKED ON and OFF configurations showed similar results significant reductions in the vertical acceleration peak associated with the blade passage frequency 17 Hz and in the overall vertical acceleration 1-80 Hz P0.05, specifically at the seatoccupant interfaces, as compared to the LOCKED configuration. The weighted seat pan vibration total values VTVs were substantially reduced in the vertical direction and the allowable daily exposures for minimal health risk was increased with the UNLOCKED configurations. Suspension seats can mitigate rotary-wing aircrew health risk. The specific effectiveness of variable viscosity dampers may depend on the vehicle vibration characteristics and the ability to tune the damper with respect to frequency. Additional improvement to aircrew performance may also require consideration of seat interface postural influences.
- Human Factors Engineering and Man Machine Systems