Strain-Based Experimental Modal Analysis: Advances in Theory and Practice

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 use in experimental modal analysis has gained a lot of popularity in the last couple of years. 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 thesis 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. Overall, there are many experimental cases presented in this work, with the main objective of not only validating the theoretical aspects presented in the thesis, but also to provide guidance through the many steps and difficulties associated with experimental strain modal analysis.1 Introduction 2 Classical Modal Analysis 3 Strain-Based Modal Analysis 4 Sensors and Instrumentation 5 Modal Strain on Multiple Directions 6 Strain Modes and Mode Curvature on Beams 7 Strain Modes and Curvature Relations on Plates 8 Conclusions and Discussion Bibliography Appendix A – The Use of Modal Parameters for Structural Health Monitoringstatus: publishe