Application of Electronic Speckle Pattern Interferometry (ESPI) to the hole drilling method of determining residual stress

The hole drilling method is a well established technique of determining residual stresses in engineering materials. The method involves drilling a small blind hole through the center of a stain gage rosette installed on the specimen to be inspected. Residual stresses can be determined from the strain detected as the stresses are redistributed around the hole. The method is semi-destructive in that the hole is very small and can be blended out in most cases.;Several researchers have proposed the use of coherent optical techniques such as holography and moire interferometry to determine residual stresses instead of strain gages. This thesis proposes the use of Electronic Speckle Pattern Interferometry (ESPI) to measure such stresses. This thesis contains a measurement demonstration, which when coupled with the theory, provides the foundation for the advanced research required to make the system practical in the field.