Controlling and Reducing Hazard Exposure to Hand Power Tools Vibration

Abstract

This paper investigates the combination of hand arm response and the vibration of hand
power tools. The model of the hand power tools used in this paper to analyse cumulative
sequences from the excitation during the operation is the jack hammer. The user subjected to
many diseases during operation of the 'jack hammer such as (sever pain, numbness, pins,
needles, loss of sense, and touch, loss of grip strength and painful wrist) .These diseases
caused from the successive high amplitudes of vibration transferred from the jack hammer to
the hand arm of the user. Results are presented to study the relationship between the
excitation and the response of the system with the aid of Ansys program to give the
indications of Eigen values and Eigen vectors deformation, to predict the behavior of handarm
vibration,
to
control
the
risks
from
the
vibration
of
the
tool.
This
indicates
that
the
high amplitudes
of
the
jack
hammer
can
be
minimized
by
adding
the
dynamic
vibration
absorber which
is
a
simply-spring
mass
system
to
the
original
mass
system to
make
the
system
to
two degree
of
freedom
system
and
the
entire
system
will
have
two
Eigen
values
one
above
the excitation
and
the
other
under
the
excitation
and
this
leads
to
eliminate
the
higher
response and
will
have
very
small
amplitude
instead
of
very
large
amplitude
to
protect
the
users
from the
risks
of
hand
arm
vibration
during
the
operation