Full field experimental modelling in spectral approaches to fatigue predictions

none1noExperimental techniques based on optical dynamic measurements with high spatial definition proved to be able to model dynamic strain maps on the surface of components by means of corresponding strain frequency response functions. By means of a constitutive model, dynamic stress FRFs can be modelled directly from receptance estimations, avoiding the costly & time-consuming steps of building and tuning a numerical dynamic model of a flexible component or a structure in real life conditions. Once dynamic stress FRFs are obtained, spectral fatigue approaches can predict the life of a component in different excitation conditions. In this paper high quality receptance maps from three different full field technologies (SLDV, Hi-Speed DIC and dynamic ESPI), estimated on a thin plate as light-weight structure with broad band dynamics and high modal density in a unique comparative set-up, are used to obtain the dynamic stress FRFs. Different spectral shapings of the excitation can be used to enhance the comparison in the framework of the spectral approaches for fatigue life calculations. The fatigue life predictions from the three optical measuring techniques are compared and discussed in detail, highlighting benefits and drawbacks of a direct experimental approach to failure & risk assessment in structural dynamics.Chair della sessione dedicata a: Full Field Measurements for Advanced Structural Dynamics Corresponding Organizer: Dr. Alessandro Zanarini University of Bologna, Italy & Vienna University of Technology, Austria, Email: a.zanarini@unibo.it The improvements in the electronics of modern cameras have raised the attention on image based technologies also for the precise measurement of complex vibration patterns for dynamic analyses in a broad extent beyond traditional Holography and scanning techniques. The advancements of digital cameras has brought Speckle Interferometry techniques to a renewed interest. Besides, the production of hi-speed digital cameras has recently raised DIC technique as another competitive technology in the full field domain; the SLDV, thanks to its ability to scan discrete locations over the surface, can also be considered close to the full field technologies, even if not full field native. Other techniques might address the same topic, as distributed sensors like Fiber Bragg gratings. Present dynamic testing and analysis approaches, based on traditional transducers, do not take full advantage of the growing full field measurements, while full field techniques have proved to be increasingly effective in complex dynamic analysis. This symposium aims at exploring the procedures & algorithms in structural dynamics and the feasibility of new specific approaches for full field measurements, Experimental Modal Analysis & Identification, dynamic strains and advanced model updating.mixedAlessandro ZanariniAlessandro Zanarin