Modal analysis of beam-like structures using multipoint dynamic testing vision system based on composite fringe pattern

Abstract

A multipoint dynamic testing vision-based system for beam-like structures based on composite fringe pattern (CFP) was proposed. The CFP was decorated on the surface of a beam as a sensor, whose image sequences were captured by a camera for dynamic identification. The CFP consists of two cosine fringe patterns. The fringes on both sides of the CFP are used to locate the measuring positions and the middle one is used to measure the spatial displacement of structures. The key advantage of the proposed method is that it can measure multipoint vibration information along the length direction of the beam at one measurement without point-by-point scanning. Experiments on two different beams were carried out, and the results show that the method can get multipoint vibration information and the modal shapes of the beam. Therefore, the vision and CFP-based measurement method is suitable for vibration monitoring and modal analysis of beam-like structures.