Residual stress measurement in composites using slitting method and digital image correlation technique

Using the digital image correlation (DIC) technique, the displacements and released elastic strains due to the sectioning in the successive slitting method were calculated. Proper speckle pattern was created at the back surface of a cross-ply composite specimen. A high resolution camera captured images of the deformed surface before and after each slitting phase. Unlike the strain gages which were able to record the released strains merely in specific points, the new technique has the potential to acquire the strains or displacements over the entire surface. Utilizing the full-field characteristic of this technique and assuming several virtual strain gages, the obtained strains of the new technique were compared with the results of the previous technique which relied on installed strain gages. Finally, it was illustrated that in spite of the lower measurement precision of the DIC technique, the obtained strains and calculated residual stresses of the DIC technique and strain gage have good agreement with each other.

کلیدواژه ها:

digital image correlation ، residual stress measurement ، slitting method ، laminated composites