Laboratory for Dynamics of Machines and Structures 
Identification of modal parameters using continuous wavelet transform

Diploma thesis, LADISK, Faculty of Mech Eng, Univ of Ljubljana & Pipistrel d.o.o., March 2009

www.fs.uni-lj.si
Abstract
The work presents an experimental modal analyis of damped multi-degree-of-freedom mechanical system using continuous wavelet transform. An approximation of wavelet transform of impulse response function is indicated, which serves as a basis for extraction of modal parameters (eigen frequencies, damping ratios and mode shapes). Presented approach is applied to real mechanical systems, such as steel beam and horizontal tail of ultralight motorcraft. With presented measurement procedure in three-dimensional space it is possible to reconstruct systems mode shapes. The use of contionuous wavelet transform enables the reconstruction of higher mode shapes which, due to their short-term presence, remain unrecognised by classical methods (i.e. frequency response function).