1,722,599 research outputs found
Local diagnoses in modal analysis through additional poles
No full textThe main scope of this article is to show how certain additional poles of a structural system, other than the classical ones, can be measured and considered within the area of structural dynamics such as for example damage detection and model updating; such poles can enrich the intrinsic modal database of the system and even be used to analyze the structure in a local sense. Such poles can be extracted by using certain response-based frequency response functions (R-FRFs) which do not require the measurement of exciting forces. Therefore, the objective of the present article is multiple because (i) the potential of certain FRFs is illustrated in the realm of structural dynamics along with the possibility to (ii) increase a privileged data-base (poles) through which (iii) local analyses of a structure can be carried out. Numerical simulations test the theoretical findings and show the ability of such additional poles to carry out local diagnoses on structural systems generally through a higher sensitivity than that of classical poles
Bibliografia in Giuseppe Veltri e Evelien Chayes, Oltre le mura del ghetto: accademie, scetticismo e tolleranza nella Venezia barocca.
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Vibration of Complex Euler-Bernoulli and Timoshenko-Ehrenfest Beams Through Affine GPSFs
No full textVibrations of thin and thick beams containing internal complexities are analyzed through generalized bases made of global piecewise-smooth functions (GPSFs). Such functional bases allow us to globally analyze multiple domains as if these latter were only one, such that a unified formulation can be used for different mechanical systems. Such bases were initially introduced to model a specific part of stress and displacement components through the thickness of multi-layered plates; subsequent extensions were introduced in the literature to allow the modeling of thin-walled beams and plates. However, in these latter cases, certain analytical difficulties were experienced when inner boundary conditions needed to be englobed into the GPSFs; in this work, such mentioned difficulties are successfully overcome through certain affine transformations which allow the analyses of vibrating complex beam systems through a straightforward analytical procedure. The complex mechanical components under investigation are Euler and/or Timoshenko models containing inner complexities (stepped beams, concentrated mass or stiffness, internal constraints, etc.). The ability of the models herein analyzed is shown through the comparison of the resulting solutions to exact counterparts, if existing, or to finite elements solutions
Bibliografia in G. Veltri, Sapienza Alienata. La Filosofia ebraica tra mito, scienza e scetticismo
No full textTraduzione di alcuni capitoli in Sapienza Alienata. La Filosofia ebraica tra mito, scienza e scetticismo
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Detecting damage through the processing of dynamic shapes measured by a PSD-triangular laser sensor
No full textAbstractThere exist several studies in the literature which have shown the potentiality offered by certain vibration-based techniques aimed at detecting damage in structural systems. In all these existing techniques noise (distributed and/or outliers) plays a significant role and can make the difference between a successful or an unsuccessful application. In spite of such a mentioned remarkable influence, the studies aimed at investigating the influence of noise on the success of the techniques are not as rich in experimental details as they are in numerical simulations. In this work an extensive set of experiments aimed at evaluating the feasibility of certain diagnosing techniques is provided. This work should also be considered as the experimental validation of certain analytical and numerical simulations carried out in the past [Gentile, A., Messina, A., 2003. On the continuous wavelet transforms applied to discrete vibrational data for detecting open cracks in damaged beams. International Journal of Solids and Structures 40, 295–315; Messina, A., 2004. Detecting damage in beams through digital differentiator filters and continuous wavelet transforms. Journal of Sound and Vibration 272, 385–412] within the frame of real measurements based on a particular laser technology; in addition, the mentioned validating experiments illustrate certain peculiarities not shown in the past, and, finally, valuable benchmarks are provided for testing future diagnosing techniques in numerical simulations. The experimental set-up consists of both commercial and electronic circuits appropriately designed and realized, whose significance, in the measuring system is accurately described in order to increase the signal/noise ratio of the dynamical measurements
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