Simulation and validation of ODS measurements made using a Continuous SLDV method on a beam excited by a pseudo random signal

Abstract

Continuous-Scanning LDV (CSLDV) methods are now available as alternative approaches to the conventional Stepping mode for Operational Deflection Shape (ODS) measurements. CSLDV techniques were initially used with sinusoidal excitation of the tested structure but later these techniques have been extended for use with impact excitation where the LDV time history could be also used to extract modal parameters by post-processing the data using modal analysis software. The latest extension of CSLDV is the use of a pseudo random signal to excite the tested structure for this work, a cantilever steel beam was used. Analytical models of the structure, the LDV output signal and excitation waveform were produced to simulate several responses which could be studied to identify the relationship between three fundamental parameters: (i) LDV scan rate, (ii) sampling frequency and (iii) frequency resolution of the pseudo random signal. This paper produces a theoretical background of the study presenting simulations and validations of both LDV output time signals and ODSs, respectively. ©2010 Society for Experimental Mechanics Inc.