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Analytical formulation and finite element modelling of beams with arbitrary active constrained layer damping treatments
No full textFinite element modelling of beams with arbitrary active constrained layer damping treatments
Full text linkThis paper concerns arbitrary active constrained layer damping (ACLD) treatments
applied to beams. In order to suppress vibration, hybrid active-passive treatments
composed of piezoelectric and viscoelastic layers are mounted on the substrate beam
structure. These treatments combine the high capacity of passive viscoelastic materials
to dissipate vibrational energy at high frequencies with the active capacity of
piezoelectric materials at low frequencies. The aim of this research is the development
of a generic analytical formulation that can describe these hybrid couplings in
an accurate and consistent way. The analytical formulation considers a partial layerwise
theory, with an arbitrary number of layers, both viscoelastic and piezoelectric,
attached to both surfaces of the beam. A fully coupled electro-mechanical theory for
modelling the piezoelectric layers is considered. The equations of motion, electric
charge equilibrium and boundary conditions are presented. A one-dimensional finite
element (FE) model is developed, with the nodal degrees of freedom being the axial
and transverse displacements and the rotation of the centreline of the host beam, the
rotations of the individual layers and the electric potentials of each piezoelectric layer.
The damping behavior of the viscoelastic layers is modeled by the complex modulus
approach. Three frequency response functions were measured experimentally and
evaluated numerically: acceleration per unit force, acceleration per unit voltage into
the piezoelectric actuator and induced voltage per unit force. The numerical results
are presented and compared with experimental results to validate the FE model
Arbitrary active constrained layer damping treatments on beams: analytical formulation and finite element modelling
No full textThis paper concerns the analytical formulation and finite element modelling of arbitrary active constrained layer damping (ACLD) treatments applied to beams. A partial layerwise theory is utilized to define the displacement field of beams with an arbitrary number of elastic, viscoelastic and piezoelectric layers attached to both surfaces, and a fully coupled electro-mechanical theory is considered for modelling the behavior of the piezoelectric layers. The damping of the viscoelastic layers is modelled by the complex modulus approach. The weak forms of the analytical formulation, governing the motion and electric charge equilibrium, are presented. Based on the weak forms, a one-dimensional finite element (FE) model is developed, with the nodal mechanical degrees of freedom being the axial displacement, transverse displacement and the rotation of the mid-plane of the host beam and the rotations of the individual layers, and the electrical elemental degrees of freedom being the electrical potential difference of each piezoelectric layer. Frequency response functions were measured experimentally and evaluated numerically for a freely suspended aluminium beam with an ACLD patch. In order to validate the FE model the results are presented and discussed
Vibration based structural health monitoring and the modal strain energy damage index algorithm applied to a composite T-beam
Full text linkA Finite Element based numerical model for a vibration based damage identification method for a 2.5D composite structure is discussed in this chapter. The linear dynamic response of an intact and a locally delaminated 16-layer unidirectional carbon fibre PEKK reinforced T-beam is analysed. A commercially available Finite Element package is employed for the numerical model. The aim of the model is to perform parametric studies. This virtual modelling replaces extensive experimental testing. The parametric study is preceded by an experimental verification of the numerical model. Subsequently, the capabilities of detection and localization of a delamination is analysed by varying the size and location of delamination, as well as the number of data points employed. The Modal Strain Energy Damage Index Algorithm is applied using the bending and torsion modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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