Strain-based experimental modal analysis: New concepts and practical aspects

Resumo

The most common and established way of performing experimental modal analysis is to use acceleration based transducers that lead to the calculation of the displacement mode shapes. However, the use of strain measurements for experimental modal analysis has recently gained a lot of popularity. Not only there are applications where the use of strain measurements makes for a more attractive and interesting option, such as structural health monitoring methods, but there are also applications where sensor size and placement might be critical and therefore strain sensors are the most eligible candidate. This work has as the main focus of research the use of strain sensors for experimental modal analysis. In this sense, experimental methodologies and improvements on the current ways of carrying out strain modal analysis are presented, paying particular attention to the relationship between strain and displacement modes. This study of the strain displacement relationship led to the development of a scaling methodology for strain modes and is used to demonstrate the presence of reciprocity under certain conditions. To validate the proposed methodologies, beam and plate structures will be analyzed and experimental results will be shown.