Type of Document	Master's Thesis
Author	Liam, Christopher Charles
Author's Email Address	cliam@vt.edu
URN	etd-05162011-104944
Title	Testing and Modeling of Shock Mitigating Seats for High Speed Craft
Degree	Master of Science
Department	Mechanical Engineering
Advisory Committee	Advisor Name Title Ahmadian, Mehdi Committee Chair Inman, Daniel J. Committee Member Taheri, Saied Committee Member
Keywords	high speed craft shock mitigating seats
Date of Defense	2011-05-06
Availability	unrestricted
Abstract This study conducted a series of tests on a shock mitigating seat designed for high speed craft using various input excitations to better understand the relationship between various seat and operational conditions, and the response of the seat. A seat model of the test seat is used for a parametric study of various spring, damping and operational configurations. A seat shake rig is implemented to simulate motions of multiple high-speed craft as well as various defined inputs. At each test input the occupant weight and suspension preload is varied and the response is analyzed to find changes in acceleration, which is representative of the changes in force and displacement. By representing the seat as a based-excitation two-degree-of-freedom system, we develop the equations of motion and model them in Simulink to analyze the effects of various spring rates and damping coefficients. Based on the results it is found that an increase in occupant mass results in a decrease in observed acceleration. Increasing suspension preload is found to be detrimental to the mitigating abilities of the seat, changing the dynamics to those similar of a rigid-mounted seat. An analysis of the defined inputs resulted in confirming various seat characteristics. The analysis of the Simulink model revealed that increasing the spring rate results in an increase in acceleration. An increase in damping coefficient resulted in an increase in acceleration and ride harshness.
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