ABSTRACT--The in-plane method and the out-of-plane method are used to analyze blind-hole residual stress as measured by optical interferometry. The in-plane method, which constructs a relation between the in-plane displacement field and the residual stress released from blind-hole drilling, is applicable when the sensitivity vector of the interferometer used in the measuring system is parallel to the object surface. Three in-plane displacements obtained from one interference pattern are sufficient to determine the residual stress. The out-of-plane method, which establishes a new relation between the out-of-plane displacement field and the released residual stress, is suggested when the sensitivity vector is perpendicular to the object surface. Two relative out-of-plane displacements extracted from one interference pattern are sufficient to determine the residual stress. With the adoption of these two methods, interpolating calculation is not needed to determine the fringe order of each data point, since the selections of the required data points are flexible using these two methods. Two experiments, one for the in-plane method and the other for the out-of-plane method, were carried out to illustrate the applicability and usefulness of these two methods.The displacement field due to the residual stress released from blind-hole drilling can be divided into an in-plane displacement field and an out-of-plane displacement field. Makino and Nelson 1 and 2 Nelson et al. first constructed the relation between the in-plane displacement field and the released residual stress. Three in-plane displacements, each determined by taking the difference of the fringe orders of two diametrically opposite points, and obtained from one holographic interference fringe pattern, are needed to recover the residual stress. Two methods that established the relation between the out-of-plane displacement field and the released residual stress were later proposed by Lin, Hsieh, and Hu. 3 The first cancels the in-plane displacement field by adding the fringe orders of two diametrically opposite points. Three relative out-of-plane displacements deduced from an interference fringe pattern are required to determine the residual stress. In the second method, the sensitivity vector is set normal to the detected surface, and two relative out-of-plane Original manuscript submitted: June 25, 1999. Final manuscript received: September 7, 1999 displacements measured from an interference fringe pattern are sufficient to determine the stress. Although experimental results obtained by all the researchers mentioned above fitted well with their respective theoretical data, interpolation was employed to pull out the fringe orders of some data points in order to perform accurate measurements.A general form that constructed the relation between the displacement field and the relieved residual stress was proposed by Lin, Hsieh, and Lee. 4 Three relative displacements, each determined by taking the difference of the fringe orders of two points lying on the same ...
