The Measurement of a Nonlinear Resonant Decay Using Continuous-Scan Laser Doppler Vibrometry

The nonlinear resonant decay of a structure offers much insight into the frequency-amplitude behavior of a structure's dynamic response. The spatial deformation during this decay is especially important since nonlinear responses can cause unexpected stress concentrations necessitating full-field measurements for comparison with a model. In this context, full-field measurement techniques, such as continuous scan laser Doppler vibrometry (CSLDV) and high speed three dimensional digital image correlation (3D-DIC) provide tools to obtain the full-field dynamic response experimentally. While CSLDV has been used to measure the steady state response of linear and nonlinear structures as well as transient responses of linear structures, it is unclear whether the approach can be successful for transient nonlinear measurements where the frequency of the dynamic response is amplitude dependent. In this investigation, the capabilities of CSLDV will be utilized to measure the nonlinear resonant decay of a clamped-clamped flat beam. The response measured using CSLDV will then be compared with the decay response measured with 3D-DIC to validate the CSLDV method and to understand the advantages and disadvantages of each.