Modares Mechanical Engineering

Modares Mechanical Engineering

Experimental Investigation of Pilot Whole-Body Vibrations in Helicopters Using Nonlinear Dynamic Modeling of Polyurethane Seat Cushion

Document Type : Original Article

Authors
seyed mohammad Kamali 1
Ali nouri 1
Heshmat allah mohammad Khanlo 1
Hadi Saouri 2
1 Department of Aerospace Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, Iran
2 Faculty of Engineering, Department of Mechanical Engineering, Kharazmi University, Tehran, Iran
10.48311/mme.2026.119007.82968
Abstract
Exposure to helicopter vibrations during flight and maneuvers can lead to long-term physical strain on pilots, particularly in the low-frequency range (0–20 Hz). While seat suspensions provide some vibration isolation, the seat cushion plays a critical role in overall ride comfort. This study presents an integrated computational and experimental investigation of nonlinear polyether polyurethane seat cushions and their effect on helicopter pilot comfort. Ride comfort is initially analyzed using a 4-DOF biodynamic model and subsequently extended to a 5-DOF model to explicitly include seat cushion dynamics. Experimental measurements of both linear and nonlinear stiffness and damping properties are conducted through modal analysis tests, providing data for model validation. Results demonstrate that considering nonlinear cushion behavior significantly improves predictions of transmissibility, mechanical impedance, and apparent mass, showing strong agreement with experimental observations. The findings highlight the importance of accurate nonlinear modeling for the design of seat cushions that enhance vibration isolation and improve overall pilot ride comfort
Keywords
Cushion
ride comfort
Whole body vibration
Transmissibility
Nonlinear Damping and Stiffness
Subjects
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Modares Mechanical Engineering
Volume 26, Issue 9
September 2026
Pages 743-755