3D shape and strain measurement of a thin-walled elastic cylinder using fringe projection profilometry

This paper describes an optical measurement system that is capable of simultaneously measuring a three-dimensional shape and circumferential train in a thin-walled cylinder. We used the fringe projection technique to obtain a three-dimensional shape and out-of-plane displacements, which were then associated with out-of-plane strain. Although 360 deg profilometry is not new, we propose an experimental setup that requires only one camera and one projector, since two mirrors are located at 120 deg with respect to the y-z plane of the reference system to obtain three distinct, complementary views of the sample studied. A sequence of images of the fringe pattern was captured and processed using the phase-shifting method, while the out-of-plane data were determined by comparing the specimen before and after deformation. A latex tube filled with liquid was used to perform mechanical testing. The cylinder was subjected to internal hydrostatic pressure that caused deformation. Experimental results were compared with analytical solutions, and the results show that out-of-plane strains can be accurately measured using the proposed method.