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 hand-arm 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.