Effective seat-to-head transmissibility under combined-axis vibration and multiple postures

摘要

Effective seat-to-head transmissibility (ESTHT) is introduced in this work to objectively evaluate human biodynamical response in a six-degree-of-freedom input/output vibration environment. In ESTHT the complex transmissibility matrix is transformed to simple forms that can be easily interpreted. In this study, human responses were compared using ESTHT under different seated postures, including an upright seated posture with no backrest, a backrest-supported sitting posture, a backrest-supported sitting posture with forearms resting on armrest supports, and a backrest-supported sitting posture in which participants used the armrest supports and rotated their heads to the side. Twelve healthy males participated in the study and were tested under random-vibration files of 0.5-12 Hz with different magnitudes. The results showed the capability of ESTHT to identify the frequency spectrum at which the motion is magnified. The study also revealed that ESTHT was able to detect differences in human response due to different postures and vibration directions.