Amirkabir University of Technology AUT Journal of Mechanical Engineering 2588-2937 9 4 2025 10 01 Investigating the Effect of Seat Suspension System and Cushion on the Dynamic Behavior of the 214 Helicopter Pilot's Body 431 446 5797 10.22060/ajme.2025.23838.6161 EN Seyed Mohammad Kamali Department of Aerospace Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, Iran Ali Nouri Department of Aerospace Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, Iran Heshmatallah Mohammad Khanlo Department of Aerospace Engineering, Shahid Sattari Aeronautical University of Science and Technology, Tehran, Iran Hadi Sabouri Department of Mechanical Engineering, Faculty of Engineering, Kharazmi University, Tehran, Iran Journal Article 2025 01 29 In this study, the influence of the stiffness and damping characteristics of the pilot seat cushion in the Bell 214 helicopter is investigated as two critical factors in reducing the transmission of vibrations to the pilot’s body. Since the dominant vibrations in the Bell 214 occur at low frequencies, typically between 2 and 15 Hz, the seat suspension system is not effective in this range, and the seat cushion plays a more significant role in vibration isolation. First, the biodynamic response of the human body is validated by comparing the results with existing experimental and analytical data related to helicopter vibration exposure. Then, the biodynamic equations of motion are analyzed using a four-degree-of-freedom seated human model under various configurations, with and without suspension and seat cushioning. Finally, the frequency domain response is examined through three-dimensional plots to evaluate the effect of different cushion stiffness and damping values. The results indicate that selecting optimal mechanical properties for the cushion can significantly enhance pilot comfort and play an effective role in reducing vibration-induced physical injuries. https://ajme.aut.ac.ir/article_5797_df3e443c67329afb0580bf4bf1e2d4ea.pdf