This document describes the range of idealized values of the apparent mass modulus and phase applicable to seated individuals with and without a back support subjected to x-, y- and zâ€‘axis sinusoidal or broad-band random vibration and to standing individuals subjected to zâ€‘axis sinusoidal or broad-band random vibration under specific experimental conditions. Additionally, this document describes the range of idealized values of seat-to-head transmissibility modulus and phase applicable to seated individuals without a back support subjected to zâ€‘axis sinusoidal or broad-band random vibration.
The ranges of idealized values defined in this document are considered to be valid for subjects on a rigid seat (or standing on a rigid platform for z-axis only), with feet supported and vibrated. The range of idealized seat-to-head transmissibility values is considered to be applicable also to the condition with the feet hanging freely. For seated individuals subjected to sinusoidal or broad-band random vibration, the apparent mass values are defined over the frequency range of 0,5 Hz to 10 Hz for the xâ€‘axis and yâ€‘axis, and over the frequency range of 0,5 Hz to 20 Hz for the zâ€‘axis. The frequency and amplitude characteristics of the vibration fall within the range for which most vibration exposure is likely to predominate while driving vehicles such as agricultural tractors, earth-moving machinery and fork-lift trucks. Application to automobiles is not covered by this document in view of the lack of a meaningful database for conditions involving posture and vibration excitation levels most likely associated with car driving.
The upper and lower values of modulus and phase defined at each frequency for each of the biodynamic response functions considered represent the range of most probable or idealized values. The middle values represent overall weighted means of the human data and define the target values for general applications. Such applications can involve the development of mechanical analogues for laboratory seat testing, or of functions to correct for the human interface when representing the body as a rigid mass, or the development of analytical human body models to be used for whole-body vibration exposure estimations or for seat and cushion design optimization.