In-plane vibration detection using sampling moiré method

Various methods have been proposed to measure vibration frequency. However, mechanical systems are not efficient as they have to be attached to the object of interest. So, the measurements are not precise when a new mass is introduced to the vibration surface. Besides, obtaining the power and phase distribution on the whole surface of the vibrating object is not possible through using accelerometers or other mechanical vibrometers. Out-of-plane vibration detection was previously proposed by one of the authors, using one pitch phase analysis method. In this paper, a novel accurate in-plane vibration detection technique by using sampling moiré method is proposed. This paper is the first published report on the in-plane vibration distribution of an industrial scale size object. Since noncontact deformation distribution of a deformed body is possible using sampling moiré method, in this study sampling moiré method is applied to vibration analysis of a tuning fork using a high-speed camera. This paper shortly describes the principle of in-plane vibration detection method and compares the experimental in-plane frequency results with those obtained by an accurate laser displacement meter. Moreover, for the first time, power and phase distribution graphs of the whole surface of the tuning fork, in two different frequency modes, are obtained. This technology will be useful for vibration investigation in any movable object on an industrial scale.