Semi-Active Magnetorheological Helicopter Crew Seat Suspension for Vibration Isolation

This study explores the use of magnetorheological dampers in a semi-active seat suspension system for helicopter crew seats to enhance occupant comfort. Key concepts in designing a magnetorheological seat suspension system to isolate the occupant from rotorcraft vibration are identified. Using these design concepts, a magnetorheological damper is designed, fabricated, and retrofitted into a tactical SH-60 Seahawk crew seat. This magnetorheological damper is implemented in series with the existing fixed load energy absorbers such that the crashworthiness capability of the seat is not impaired. Semi-active control is implemented and performance is evaluated both analytically and experimentally. Experimental test results have shown that this system reduced the dominant rotor-induced vertical vibration (4 per rev) transmitted to a 50th percentile male aviator by 76%, which is a 61-70% improvement over the unmodified SH-60 crew seat depending upon whether a soft seat cushion is used. Furthermore, these experimental tests also show that this system significantly reduces vertically induced seat rocking that occurs as a result of an offset center of gravity in the crew seat design.

[1]  Doyoung Jeon,et al.  Semiactive Vibration Control of a Smart Seat with an MR Fluid Damper Considering its Time Delay , 2002 .

[2]  Stanley P. Desjardins,et al.  The Evolution of Energy Absorption Systems for Crashworthy Helicopter Seats , 2003 .

[3]  P M Bongers,et al.  Back pain and exposure to whole body vibration in helicopter pilots. , 1990, Ergonomics.

[4]  Norman M. Wereley,et al.  Effective design strategy for a magneto-rheological damper using a nonlinear flow model , 2005, SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[5]  Dean Karnopp,et al.  Vibration Control Using Semi-Active Force Generators , 1974 .

[6]  Seung-Bok Choi,et al.  A Semi-Active Suspension Using ER Fluids for a Commercial Vehicle Seat , 1998 .

[7]  Mark Geiger,et al.  Whole Body Vibration Exposure for MH-60S Pilots , 2005 .

[8]  Norman A Merritt.  AIRCRAFT CRASH SURVIVAL DESIGN GUIDE. , 1989 .

[9]  Subhash Rakheja,et al.  EVALUATION OF VIBRATION AND SHOCK ATTENUATION PERFORMANCE OF A SUSPENSION SEAT WITH A SEMI-ACTIVE MAGNETORHEOLOGICAL FLUID DAMPER , 2002 .

[10]  Norman M. Wereley,et al.  Self-Powered Magnetorheological Dampers , 2009 .

[11]  Seung-bok Choi,et al.  Vibration Control of a MR Seat Damper for Commercial Vehicles , 2000 .

[12]  Yang Zhou,et al.  Development and analysis of a variable stiffness damper using an MR bladder , 2009 .

[13]  Norman M. Wereley,et al.  Dimorphic magnetorheological fluids: exploiting partial substitution of microspheres by nanowires , 2008 .

[14]  Norman M. Wereley,et al.  Biodynamic response mitigation to shock loads using magnetorheological helicopter crew seat suspensions , 2005 .

[15]  N. Wereley,et al.  Nondimensional analysis of semi-active electrorheological and magnetorheological dampers using approximate parallel plate models , 1998 .

[16]  William G. Bousman,et al.  Putting the Aero Back into Aeroelasticity , 1999 .