On the estimation of frequency response functions, dynamic rotational degrees of freedom and strain maps from different full field optical techniques

Different optical techniques are nowadays at disposal for advanced tests on lightweight structures, each with its own advantages, drawbacks and preferred usage domains, in order to obtain highly spatially defined vi- bration patterns for many applications in vibration engineering and product development. This work aims at benchmarking the potentials of three completely different technologies, but on a common target and test rig. SLDV, dynamic ESPI and hi-speed DIC are here challenged in a unique test on the estimation of FRFs from a thin plate, which exhibits broad band dynamics and high modal density in the common frequency domain on which the techniques can find an operative intersection. Full field measurement technologies can not estimate only spatially detailed displacement fields, but can exploit the accuracy and spatial consistency of the results by means of differentiation operators to obtain rotational degrees of freedom and superficial strain distributions. Approaching the task with the aid of superior quality dynamic displacement fields, this work implements proper differentiation operators and signal processing techniques to calculate full field FRFs, ro- tational dofs maps and dynamic strains from the three different full field technologies. Both extracted results can be used as advanced benchmarks for numerical models, advanced finite element formulation and fatigue analysis, as well as experimental and hybrid models in sub-structuring frameworks.