Wave propagation in human tissue from transient high frequency vibrations

Abstract

Hand-arm vibration injury from the daily exposure of vibrating hand-held machine is one of the common health injuries and causes severe nerve cell damage to the person operating the machine for a long time. The major health problems caused by daily use of vibrating tools causes signs and symptoms like peripheral vascular and peripheral neural disorders of the fingers and hands. These disorder symptoms include numbness, pain, and blanching of the fingers. ISO 5349 claims that the vibrating machines with frequencies in the range of 8-1250 Hz must be regulated. However, vibrations with frequencies higher than 1250 Hz from machines like an impact wrench or dental drills can also damage nerve cells and blood vessels. The objective of this thesis is to study wave propagation in human tissue from transient high frequency vibration of machines tools. The software LS-DYNA is used for performing the simulation and analyze the results. The 2D cross-section finite element model is created for the simulation to see the wave propagation into the finger tissue. The following analysis of simulation results shows that the different load cases from the hand-held vibrating machines affect the skin. However, the change in bulk modulus and decay constant does not make much difference. The intermediate skin layer has more impact caused by the hand-held vibrating machines.