Imperfection measurement of cylinders using automated scanning with a laser displacement meter

Abstract Geometric imperfections, commonly in the form of depressions at the circumferential welds, are present in most metal silo structures and can greatly reduce the structure's buckling strength. These imperfections sure close to axisymmetric in form. This paper describes the measurement system which was developed for an experimental study of this phenomena. Computer controlled steppennotors for both Hie circumferential and longitudinal travel of the measurement carriage provided a precise and repeatable traverse of the specimen. A laser displacement meter, which is capable of high speed, non‐contact measurement and has a resolution of 0.5 microns, was controlled synchronously with the steppennotors to provide a very accurate three‐dimensional measurement system. Both the initial geometrically imperfect shape and the progressive growth of deformations during loading were accurately measured.