Abstract:
One of the main passenger transportations in Sri
Lanka is the bus. Most of these busses used for the passenger
transportation do not have proper vibration dampers and
passengers who travel in them are subjected to severe vibration
levels as most of the time they are travelling standing up rather
than sitting down on comfortable seats. Sever vibration levels
produced by the engines of the busses and the poor road
conditions in Sri Lanka are directly transfer to the passengers
due to poor vibration damping of the busses. This paper
discusses the vibration levels that the passengers travelling in
Sri Lankan busses encounter by using accelerometers and the
mechanical modelling of the passenger whole body vibrations.
A new model is put forward to account for the nonlinear
effects. Also the paper compares the passenger vibration levels
with the international standards for safer passenger vibration
levels (ISO2631). First part of the paper discusses the power
spectral densities of the vibrations generated in the busses and
also transferring from the road on to different locations of the
busses where the passengers are normally travelling. Also the
paper further discusses improved lumped parameter based
mechanical dynamics model for standing up travelers
subjected these vibrations, catering for the nonlinear effects by
using additional viscous springs and dampers. Final part of the
paper discusses the effectiveness of the use of commonly
available elastic soles, elastic insert pads or elastic slippers foot
ware to reduce the harmful vibrational effects of frequent
travelers.
