Residual Stresses Determination near FSW Joints by Combining the Hole Drilling Method and Reflection Hologram Interferometry

The results of residual stress characterization near friction stir welded (FSW) butt joint of aluminum plates are reported. The experimental analysis employs two-side measurements of local deformation response on small hole drilling by reflection hologram interferometry. The approach developed is based on the unequivocally solution of the properly posed inverse problem thus deriving both membrane and bending residual stress components. Residual stress components of high level are derived inside the tool shoulder borders on both specimen faces.

Post-Process of Density Streaks Image of Flow Field in Supersonic Jet Device Captured by Laser Dual Hologram Interferometry

Wind tunnel test can not simulate effectively the flow field of fuze electrical machinery at flight test conditions. In order to deeply research the structure of flow field and measure the flow field density out of fuze electrical machinery, the laser dual hologram interferometry was applied and the streaks photos were obtained clearly. To recognize the contours of density field, identification is needed to deal with interference streaks, and the density of local streaks is calculated with interference principle. The hologram interferometry photos of density field were pro-processed in the thesis, for the problem of photos that the left part was much brighter than the right, the method of multiple threshold was used to binary image. It can be seen that the method gives consistent results to a certain extent of human perception and gives ideal results to find uniform regions in the image plane. Then the binary image is thinned by pixels searching algorithm according to the lines to get coordinates of the pixels of each streak and to lay the foundation for extracting density field from density interference streak in future research.