Whole field out-of-plane displacement measurement on curved surface using a single camera in buckling experiment

The variation of modality of a specimen plays an important role in a buckling experiment. However, it is not easy to obtain a whole field measurement by most traditional manners in some particular experimental condition. In this paper, we develop a simple method for out-of-plane displacement measurement on a curved surface using one camera. An algorithm based on LDC (Line Detection using Contours) is used to detect corners. The out-of-plane displacement is then determined by a geometrical method on the captured images. And by using multiple scales method, the problem of the variable prospective shrink rate on a curved surface is simplified. Experiments of buckling specimens with curved surface demonstrate that this method is simple, accurate and suitable for measurement of out-of-plane displacement in the limited experimental conditions.