ABSTRACT
In this paper the dynamic behavior of a cylindrical bar with longitudinal crack as a
new case of crack geometry is investigated. The bar is bounded and excited in way
which permits only torsional vibration of the bar. This work is based on crack induced
by the manufacturing processes not due to applied load. The dynamic analysis of the
cracked bar is based on the investigation of the measured transient response in time
and frequency domains beside its modal parameters. Experiments are carried out in
two different specimens of the bar providing that their mechanical properties and
dimension are kept identical. The first specimen of the bar is uncracked while the
second one has a longitudinal crack along its whole length. The bar is excited with its
first torsional mode and the measured signals are analyzed using (FFT) analysis. A
finite element model has been made using ANSYS software to simulate the
uncracked bar. Modal, transient and harmonic analysis are made to validate the
experimental work. The finite element prediction of the dynamic response and the
fundamental natural frequency were in good agreement with the experimental
results. This work suggests a simple method for crack detection in beams.