HOLOGRAPHIC ASSESSMENT OF SURFACE CRACK DEPTHS IN RECTANGULAR BARS

It is shown that a partially-clamped, nondefective bar under an end lo ad is characterized by a linear relationship between two normalized pa rameters which are related to the fringe order and the fringe location . That this linearity is perturbed due to the presence of a surface cr ack subsequently forms the basis for unambiguous detection of normal a nd inclined transverse cracks on the bar. This paper also demonstrates that the defective bar may be modeled as a partially-clamped stepped bar whose cross-sectional change is related to the geometry and depth of the crack. Furthermore, with the present method of analysis, the ch ange in the fringe pattern with optical arrangement during constructin g and reconstructing the hologram is easily taken care of.