Energy Absorption of Seated Body Exposed to Single and Three-Axis Whole Body Vibration

Abstract

The absorbed power characteristics of seated body exposed to whole-body vibration along the individual and combined fore-aft (x), lateral (y) and vertical (z) axes are investigated through measurements of body-seat interactions at the two driving-points formed by the body and the seat-pan, and upper body and the seat backrest. The experiments involved two levels of back support (no back support and vertical backrest) and two levels of broad-band vibration with nearly constant acceleration power spectral density in the 0.5-20 Hz frequency range applied along the individual x-, y-and z-axis (0.25 and 0.4 m/s 2 rms acceleration), and along the three-axis (0.23 and 0.4 m/s 2 rms acceleration along each axis). The biodynamic responses, measured at the seat-pan and the backrest are applied to characterize the total seated body's energy transfer along each axis. Furthermore, an alternative frequency response function method H v is employed to capture the coupling in the seated body responses to uncorrelated multi-axis vibration. The total vibration absorbed power responses to simultaneous x, y and z -axis vibration are subsequently derived as the summation of vibration absorbed power along the individual axis within each one-third frequency band. The mean responses measured at the seat-pan suggest strong effects of the back support, and the direction and magnitude of vibration. The total vibration power absorbed by the seated body is further estimated under a multi-axis vibration environment of four different work vehicles. The results suggest that total average power absorbed under reported vehicular vibration varies with the effective acceleration in a nearly quadratic manner.

Gender and anthropometric effects on whole-body vibration power absorption of the seated body

“…A few studies have shown a nearly quadratic relationship between the VPA and the excitation magnitude. 18,20 Mansfield and Griffin 16 have thus normalized the absorbed power spectrum with the acceleration power spectral density. The studies have also shown definite effects of body mass and sitting posture on the absorbed power responses.…”

Dynamics of a group of quasi-zero stiffness vibration isolators with slightly different parameters

“…Another example of harmful influence of vibration is heavy-duty vehicles: the driver suffers from high vibration and shocks, and hence it is required to use a seat suspension system with high vibration isolating properties. 4,5 Also vibration can be caused by household appliances, for example by a washing machine. 6 For noise and vibration protection, different methods can be applied: adding weight to the equipment, application of vibration isolator, installation of dynamic damper, etc.…”

An analysis of the impact of agricultural tractor seat cushion materials to the level of exposure to vibration

“…Numerous studies show that prolonged exposure to high-level vibrations can lead to low back injuries, digestive system illnesses and cardiovascular problems. [2][3][4][5][6] The harmful impact of vibrations is especially evident in older models of the tractors which are not equipped with appropriate suspension system for shock and vibration absorption. These tractors have good performances during the farming work, but they are not comfortable in terms of vibrations, i.e.…”

“…Numerous studies show that prolonged exposure to high-level vibrations can lead to low back injuries, digestive system illnesses and cardiovascular problems. 2–6…”