This research focuses on the use of magnetorheological (MR) dampers for enhanced occupant protection during harsh vertical landings as well as isolation of the occupant from cockpit vibrations. The capabilities of the current state-of-the-art in helicopter crew seat energy absorption systems are highly limited because they cannot be optimally adapted to each individual crash scenario. In addition they present needlessly high-risk of damage by not reducing the load transmitted to the occupant through a collision. Furthermore, current rotorcraft seats offer no way of separating the occupant from dangerous cockpit vibrations. The aim of this study was to examine and demonstrate the feasibility and advantages of an MR-based suspension for rotorcraft seats…
Contents
Chapter 1: Introduction
1.1 Research Objective & Organization of the Dissertation
1.2 Rotorcraft Seat Suspension Design
1.2.1 Crashworthy Seat Suspension Design
1.2.2 Whole-Body Vibration
1.3 Semi-Active Magnetorheological Seat Suspensions
1.3.1 Magnetorheological Fluid Dampers
1.3.2 Dynamic Behavior of Systems Utilizing MR Dampers
1.3.3 Semi-Active Control
1.3.4 Prior Work with ER & MR Seat Suspensions
1.4 Mathematical Modeling
1.4.1 Lumped Parameter Biodynamic Model for Crash Simulations
1.4.2 SDOF Model for Vibration Simulations
1.5 Fundamental Contributions of the Present Research
1.5.1 Adaptive Crashworthiness
1.5.2 Vibration Isolation Combined with Crashworthiness
Chapter 2: Investigation of MR Dampers for Enhanced Crashworthiness and
Vibration Isolation of Helicopter Crew Seats
2.1 MR Seat Suspension Design Principles
2.2 Case 1: Designing MR Dampers Solely for Vibration Isolation
2.3 Case 2: Designing MREAs for Adaptive Occupant Protection
2.4 Case 3: Dual-Goal MREA Design
2.5 Summary and Conclusions
Chapter 3: Control of MREAs for Enhanced Crashworthiness
3.1 Load Limiting or VLEA Control
3.1.1 Analytical Results
3.1.2 Effect of MR Damper Time Response
3.2 Notched-Profile or VPEA Control
3.2.1 Analytical Results
3.2.1 Effect of MR Damper Time Response
3.3 Crash Load Adaptive (CLA) Control
3.3.1 Analytical Results
3.3.2 Effect of MR Damper Time Response
3.4 Summary and Conclusions
Chapter 4: Semi-Active Magnetorheological Helicopter Crew Seat Suspension for Vibration Isolation
4.1 Integration into the Unarmored SH-60 Seahawk Crew Seat
4.2 MR Damper Characterization
4.3 Semi-Active Control
4.4 Experimental Setup
4.5 Experimental Results and Discussion
4.6 Summary and Conclusions
Chapter 5: Summary, Conclusions, & Recommendations for Future Work138
5.1 Original Contributions
5.1.1 Investigation of MR Dampers for Enhanced Crashworthiness and Vibration Isolation of Helicopter Crew Seats
5.1.2 Control of MREAS for Adaptive Crashworthiness
5.1.3 Semi-Active Magnetorheological Helicopter Crew Seat Suspension for
Vibration Isolation
5.2 Future Work
5.2.1 MREA Design
5.2.2 MREA Control Experimentation & Refinement
5.2.3 Refinement of MR Seat Suspension for Vibration Isolation….
Source: University of Maryland
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