Modal shape analysis using thermal imaging

Abstract

In recent years, advances in aeronautical engineering field include, among others, the development of increasingly lightweight and flexible materials, allowing better performance of systems in applications such as Unmanned Aerial Vehicles, photographic model airplanes, light weight aircraft etc. This progress, however, can cause difficulties in design and various types of tests, such as those performed in modal analysis, since the instrumentation weight and shape can influence the behavior of very light and aerodynamic structures. This paper proposes a new technique to perform modal analysis in simple structures, eliminating the use of accelerometers, which must be numerous in this type of analysis and have significant weight; the whole structure can be analyzed at the same time, and this is an advantage in comparison with other techniques as vibrometer laser, that analyses one point at a time. The technique in question makes use of infrared imaging, detecting, through the heat, the structure deformation, allowing the trace of its modal shape. For this, a theoretical analysis and a thermomechanical modeling of a known structure are performed, with subsequent test to be validated, and finally the conclusions and suggestions for future work are presented.