Obtained Fringe Patterns Research Articles

Fourier-based digital laser photography: a monitoring system for stone damage

A digital double-exposure speckle system is developed for in situ measurements of in-plane displacements or deformations. A fast Fourier transform algorithm with an inexpensive computer is applied to obtain fringe patterns of Young's type: some applications of the method to stone samples under mechanical stresses, for determining the extent of movements in the vicinity of pre-deteriorated areas, like cracks, are reported.

Stress and Failure Analysis of a Pin-Loaded Composite Plate: An Experimental Study

A graphite/epoxy quasi-isotropic composite plate was loaded through an aluminum pin. High-sensitivity moire interferometry was used to obtain fringe patterns of in-plane displacement components near the pin-plate contact surface. Stresses around and near the contact surface were determined from the experimentally obtained displacements using a localized hybrid approach which consisted of introducing the displacements around a local region of interest into a finite element analysis. X-ray radiography and optical microscopy were employed in a failure analysis of the plate. Stress distributions on the near contact interface were obtained. Local damage was also documented successfully. A simple failure prediction based on classical laminate theory gave good agreement with the observed location of damage. Valuable local aspects fric tional phenomena were documented.