354 research outputs found
Modelling of Damaged Laminated and Sandwich Shell Structures by means of Higher-order Shear Deformation Theories
No full textThe main aim of the current research is the development of a mathematical formulation for the modelling of damage in laminated and sandwich composite shells. For this purpose, the damage of some areas of the structures can be seen as concentrated decays of the mechanical properties of the elastic constituents. In general, several kinds of damage can affect the mechanical behavior of a generic laminated structure, such as microcracking, debonding, fiber ruptures, and transverse matrix cracking, as specified in [1].
Without investigating the causes of the damage, the current approach suggests to introduce peculiar functions that multiply directly the mechanical properties of the elastic media, expressed in terms of engineering constants. To this aim, the Gaussian function and an ellipse shaped law are used to model a quick variation of the mechanical properties within the whole structural domain. By setting properly the parameters that characterize these distributions, it is possible to control the intensity of the deterioration and the width of the damaged areas, as well as the point of applications.
The present approach is employed to characterize the damage in some doubly-curved shells characterized by different radii of curvature. The difficulties related to the description of these curved surfaces are overcome by means of an analytical formulation based on differential geometry [2]. As far as the mechanical properties are concerned, several constituents are considered and combined.
The theoretical framework is based on a formulation that allows to develop easily different kinematic models and expansions in a unified manner. Thus, several Higher-order Shear Deformation Theories, which can include also the zig-zag effect, are employed. In fact, it has been proven that peculiar mechanical configurations require an enriched structural model, since lower-order theories could be inadequate to capture the effective mechanical behavior.
Finally, a numerical technique able to solve the strong form of the governing equations is used. For this purpose, the partial derivatives that appear in the fundamental system are directly approximated through the Generalized Differential Quadrature method due to its accuracy [3].
References
[1] Tornabene, F., Fantuzzi, N., Bacciocchi, M., “Linear Static Behavior of Damaged Laminated Composite Plates and Shells”, Materials, 10, 811, 1-52 (2017).
[2] Tornabene, F., Fantuzzi, N., Bacciocchi, M., and E. Viola, Laminated Composite Doubly-Curved Shell Structures. Differential Geometry. Higher-order Structural Theories, Esculapio, Bologna (2016).
[3] Tornabene, F., Fantuzzi, N., Ubertini, F., Viola, E., “Strong Formulation Finite Element Method Based on Differential Quadrature: A Survey”, Applied Mechanics Reviews, 67, 020801-1-55
La thématique de la lutte et l’ἀγὼν θεῖος dans 4 Maccabées
No full textThis article argues for the importance of a linguistic analysis of biblical texts and proposes such an analysis in relation to the language of 4 Maccabees and the metaphors its author uses to describe the battle between the pious Jews and the king Antiochus IV, who wants to forcefully convert them. The expressions taken from the war lexicon are analysed in the light of the relationship between Hellenistic Judaism and the cultivated Greek language. Although these textual instances provide a detailed framework for the construction of the Greek enemy by the Jews, they nevertheless clearly show the high level of acculturation they had acquired in relation to the colonial language
Modelling of Damaged Laminated and Sandwich Shell Structures by means of Higher-order Shear Deformation Theories
No full textThe main aim of the current research is the development of a mathematical formulation for the modelling of damage in laminated and sandwich composite shells. For this purpose, the damage of some areas of the structures can be seen as concentrated decays of the mechanical properties of the elastic constituents. In general, several kinds of damage can affect the mechanical behavior of a generic laminated structure, such as microcracking, debonding, fiber ruptures, and transverse matrix cracking, as specified in [1].
Without investigating the causes of the damage, the current approach suggests to introduce peculiar functions that multiply directly the mechanical properties of the elastic media, expressed in terms of engineering constants. To this aim, the Gaussian function and an ellipse shaped law are used to model a quick variation of the mechanical properties within the whole structural domain. By setting properly the parameters that characterize these distributions, it is possible to control the intensity of the deterioration and the width of the damaged areas, as well as the point of applications.
The present approach is employed to characterize the damage in some doubly-curved shells characterized by different radii of curvature. The difficulties related to the description of these curved surfaces are overcome by means of an analytical formulation based on differential geometry [2]. As far as the mechanical properties are concerned, several constituents are considered and combined.
The theoretical framework is based on a formulation that allows to develop easily different kinematic models and expansions in a unified manner. Thus, several Higher-order Shear Deformation Theories, which can include also the zig-zag effect, are employed. In fact, it has been proven that peculiar mechanical configurations require an enriched structural model, since lower-order theories could be inadequate to capture the effective mechanical behavior.
Finally, a numerical technique able to solve the strong form of the governing equations is used. For this purpose, the partial derivatives that appear in the fundamental system are directly approximated through the Generalized Differential Quadrature method due to its accuracy [3].
References
[1] Tornabene, F., Fantuzzi, N., Bacciocchi, M., “Linear Static Behavior of Damaged Laminated Composite Plates and Shells”, Materials, 10, 811, 1-52 (2017).
[2] Tornabene, F., Fantuzzi, N., Bacciocchi, M., and E. Viola, Laminated Composite Doubly-Curved Shell Structures. Differential Geometry. Higher-order Structural Theories, Esculapio, Bologna (2016).
[3] Tornabene, F., Fantuzzi, N., Ubertini, F., Viola, E., “Strong Formulation Finite Element Method Based on Differential Quadrature: A Survey”, Applied Mechanics Reviews, 67, 020801-1-55
Filogeneomica comparata tra Primati e Scandentia: il mappaggio delle sonde cromosomiche umane su Tupaia minor (Scandentia)
No full text
The stress intensity near a stiffener disclosed by photoelasticity
No full textCan the thickness of a thin inclusion (in a matrix material) be made so small (though retaining sufficient stiffness and matrix adhesion) to generate ‘in practice’ a stress state in agreement with the analytical (square-root singular) solution for a rigid line inclusion (so-called ‘stiffener’) embedded in a linear elastic plate? Can this inhomogeneous stress state be generated for tensile loading parallel to the stiffener? We provide a direct and positive answer to these questions, by showing how to produce elastic materials containing thin inclusions and by providing photoelastic investigation of these structures. The experiments fully validate the stress state calculated for an elastic plate containing a rigid (finite-length) line inclusion, until a distance from the inclusion tip on the order of its thickness, corresponding to a stress concentration up to seven
Michele Bigoni Selected as the Recipient of the 2016 Margit F. and Hanns Martin Schoenfeld Scholarship Award
No full textMichele Bigoni holds a PhD in Accounting and Finance from the University of Ferrara, Italy. He has been recently appointed as a Senior Lecturer in Accounting at the Kent Business School, University of Kent
Literary and Dramatic Aspects of LXX Esther
No full textRecent studies on the Greek book of Esther have taken up the challenge of defining and analyzing the literary composition of the various forms of the text, including the so called additions, which characterize the Greek versions as compared to the Hebrew. As Cavalier (2012) remarks, these efforts have strongly enhanced our understanding of the complex textual history of the book and can shed light on the question of the original language of the additions. This paper focuses on the dramatization of the text, which appears in the LXX form as compared to the MT and L, through the frequent use of direct speeches. This feature improves the literary quality of the text and highlights the main theological contents. The paper aims to analyse the feature of direct speeches in the LXX version and to determine
their possible context of performance: the dramatic insights that can be traced in this version could in fact be perceived as aids and indications to the reading in public representations
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