Experimental 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.
Full field experimental modelling in spectral approaches to fatigue predictions
ZANARINI, ALESSANDRO
2015
Abstract
Experimental 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
