A dynamic moiré method for deformation measurement of curved surfaces

A simple method is proposed for obtaining moiré patterns, and information is given on the deformation of curved surfaces. The experimental arrangement is based on the projection-moiré principle and consists of a projector and a camera. A transparent object, e.g., a shell with line gratings, is projected onto the focal plane of this projector and superposed there with a reference grating which describes the undeformed state of the curved surface in the form of a transparent picture. Moiré patterns are obtained by simultaneously superposing the projected line grating in the shell's deformed state and the reference grating. They present a general picture of the behavior of the object during loading, such as during impact if the patterns are recorded with a high-speed camera.