Digital Speckle Correlation Method And Its Application In Experimental Mechanics

Based on the variational and image recognition principle, this dissertation gives new theoretical description in detail for digital speckle correlation method (DCM). Two new methods are then derived from the previous correlation iterative method. One is the correlation analysis method (CAM), the other is the correlation search method (CSM), each of them is corresponding to the generalized and simplified form of CIM respectively. Through analysis and synthesis of deformation model, both great simplification of correlation procedure and direct full field measurement of object deformation are achieved. On the other hand, the simplist CSM provides an easy and effective tool for rigid body deformation (rotation and displacement) and large strain field measurement. The correlation function, sensitivity, reliablity etc. of DCM are also analyzed systematically. As a result, the optimized correlation function is given, and ways of further improving the measuring sensitivity and reliablity are pointed out.In the later part of this dissertation, two types of application in mechanics are carried out. The first is in macro-mechanics, which consists of measuring fluid flow (laminar flow and vortex), out-of-plane deformation (combined with shadow speckle metrology) and large deformation field of forging object, all the results are satisfactory. The second application is in micromechanics. In this experiment, deformation field of photographs ( general and cracked ) from Scanning Electronic Microscope with high magnification are measured quantitatively. These results prove the viablity of DCM applied to micromechanics, and the problem of quantitatively measuring deformation field of micromechanics is promisingly solved.