Abstract: During the last decades a great variety of methods have been
proposed for damage detection by using the dynamic structure characteristics,
however, most of them require modal data of the structure for the healthy state
as a reference. In this paper the applicability of the mode shape curvature
squares determined from only the damaged state of the structure for damage
detection in a beam structure is studied. To establish the method, two
aluminium beams containing different-size mill-cut damage at different
locations are tested by using the experimentally measured modal data. The
experimental modal frequencies and the corresponding mode shapes are obtained
by using a scanning laser vibrometer with a PZT actuator. From the mode shapes,
mode shape curvatures are obtained by using a central difference approximation.
With the example of the beams with free-free and clamped boundary conditions,
it is shown that the mode shape curvature squares can be used to detect damage
in the structures. Further, the extent of a mill-cut damage is identified via
modal frequencies by using a mixed numerical-experimental technique. The method
is based on the minimization of the discrepancy between the numerically
calculated and experimentally measured frequencies.
