Hybrid stress analysis of vibrating plates using holographic interferometry and finite elements

The work reported herein is concerned with an investigation of the potential of mating time-average holography and static-finite-element analysis (a ‘hybrid’ stress-analysis technique) in solving dynamic problems. The model studied is a vibrating thin rectangular cantilever plate. Realtime holography was used to locate natural vibrating modes of the plate. Experimental data were smoothed to remove scatter using a spline-like procedure in one or two dimensions, as applicable. Two methods of smoothing the experimental displacement data used in the hybrid procedure were considered. The first involved preprocessing (smoothing) the data before they were incorporated into the numerical model, while the second involved smoothing the data as part of the solution process. In both instances the amount of smoothing was specified by the user. The first and fourth vibrational modes were investigated. The results were compared to a NASTRAN dynamic solution and to a Ritz method series solution with very good results.