Multi-Axis Sinusoidal Whole-Body Vibrations: Part II — Relationship between Vibration Total Value and Discomfort Varies between Vibration Axes

Abstract

The influence of vibration duration and the amount of rest between successive vibrations was addressed in Part I of this study. The relationship between discomfort and Vibration Total Value for different axes of vibration is assessed in Part ll. Ten subjects were exposed to repeated single axis, planar, and 6 degree of freedom multi-axial vibrations. We observed statistically significant differences in discomfort between the different axes of vibration for similar ranges of Vibration Total Values. In particular. we observed that discomfort reports for vibrations in the Z axis and XY plane were less than discomfort reports associated with XZ plane and 6 df vibrations when the same range of Vibration Total Values were compared. Furthermore, single axis vertical vibrations were typically associated with less discomfort than multi-axis vibrations when similar ranges of Vibration Total Values were compared. This finding infers that the frequency weighting scheme presented in ISO 2631-1 does not achieve inter-axis equivalence and indicates that a more comprehensive study of multi-axis vibration is required to suggest changes to the ISO 2631-1 weighting factors.

Combined Effects of Long-Term Sitting and Whole-Body Vibration on Discomfort Onset for Vehicle Occupants

“…Factors affecting the discomfort could include the physical shape of the seat, the fit of the seat to the occupant, the materials which the seat is made from (which will dictate its stiffness), the thermal environment to which the occupant is exposed, exposure to wholebody vibration and/or mechanical shocks, opportunity for changing postures (thus changing the muscle groups which are supporting the body weight), and the length of time the occupant has been sitting in the seat (e.g. [8,9]). …”

Reducing whole-body vibration through field vibration tested heavy equipment seat retrofitting

“…Three randomized trials of each combination of seat and profile were conducted using eight male and eight female inexperienced operators as well as four male experienced operators from a participating steel making company. Assessment variables included operator reported normalized (to the operator's mean response) comfort which was verbally reported by subjects following each vibration exposure according to methods reported in Dickey et al [18]. The other assessment variables were 6-DOF Vibration Total Value (VTV) Weighted Comfort which was assessed using a 6-DOF seat pad transducer according to ISO 2631-1 standards [3] and Seat Effective Amplitude Transmissibility (SEAT) [19] using the seat pad transducer and a second 6-DOF transducer fixed to the robotic platform.…”

Comfort Based Seat Selection to Minimize 6 DOF Wholebody Vibration in Integrated Steel Manufacturing Mobile Machinery

“…All subjects provided informed consent and all laboratory procedures were approved by the Research Ethics Board at the University of Guelph. Assessment variables included operator reported normalized (to the operator's mean response) comfort (ORC) which was verbally reported by subjects following each vibration exposure according to methods reported in Dickey et al 2 The other assessment variable was 6 DOF VTV Weighted Comfort (VTVC) which was assessed using a 6-DOF seat pad transducer according to ISO 2631-1 standards.…”