NEW METHODS FOR THE ALIGNMENT OF INSTRUMENTATION FOR RESIDUAL-STRESS MEASUREMENTS BY MEANS OF NEUTRON-DIFFRACTION

Adequate alignment of instrumentation and specimens is imperative for the successful performance of residual-stress measurements by means of neutron diffraction. This paper presents a number of alignment method s that enable the user to align reproducibly a stress-measurement setu p and a specimen positioned therein. Most of these methods employ the position and the direction of the incident neutron beam as their prima ry source of geometric reference. A mathematical description for each of the proposed alignment steps is given, which makes the alignment qu antitative and enables quantitative assessment of the alignment qualit y after each alignment step. Examples from actual practice show that t he alignment quality that can be achieved using these methods is bette r than 0.05 mm for translations and better than 0.05-degrees for rotat ions.