1,720,963 research outputs found
A numerical implementation of the Coupled Criterion of Finite Fracture Mechanics for elastic interfaces
No full textA new numerical procedure for predicting interface failures between solids is developed. The procedure is based on the Linear Elastic-(Perfectly) Brittle Interface Model (LEBIM) combined with the Coupled Criterion of the Finite Fracture Mechanics (CCFFM). Although in the present investigation this procedure is implemented in a 2D BEM code, a general pseudocode is devised allowing its implementation in any BEM or FEM code. The pull-push shear test is used as a benchmark problem, where the fracture mode II is dominant. Nevertheless, the present procedure can tackle a debond growth occurring under any fracture mode mixity. The pull-push problem is chosen since it allows us to check the obtained numerical results against an available analytical solution based on a beam model. Additionally, the numerical results are compared with some experimental data from literature. Furthermore, an inverse analysis is applied to obtain the interface strength and fracture parameters that the model needs
Interface crack model using finite fracture mechanics applied to the double pull-push shear test
No full textAn analytical procedure predicting a debond (interface crack) onset and growth in an adhesive joint between two beams or plates is developed and applied to a specific configuration often used in reinforcement tests in civil engineering. The procedure is based on Timoshenko beam theory and Linear Elastic-(Perfectly) Brittle Interface Model (LEBIM) combined with the Coupled Criterion of the Finite Fracture Mechanics (CC-FFM) for mixed-mode fracture. First, a sixth order differential equation in the shear stresses along the adhesive layer is deduced and solved, leading to closed form expressions for both shear and normal stresses in the adhesive. Then, the critical value of the applied load necessary to produce debonding is predicted by coupling a stress and an energy condition based on: (i) the stress distribution produced in the interface before the debond onset and (ii) the energy released during the debonding process along the interface. Although the developed procedure can be applied to several types of joints with different geometries, materials and loads (e.g., double lap joint tests including adherents made of steel or composites), herein it is applied to the double pull-push shear test where the debond onset and growth between a Carbon Fibre Reinforced Polymer (CFRP) laminate and a concrete block occurs. For such a case, the debond is produced under predominant fracture mode II; nevertheless, it is shown that relevant normal (peeling) stresses associated to mode I may appear as well. A comparison of the present solution with a previous one by the shear-lag model is provided as well
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
Single-Domain Cohesive-Zone-Model Formulation and Implementation using the Symmetric Galerkin Boundary Element Method
No full textA new symmetric boundary integral formulation
for embedded cohesive cracks growing in the interior
of homogeneous linear elastic isotropic media is
developed and implemented in a numerical code. The
use of an exponential cohesive law for 2D and the special
treatment about the way in which the law is included
in the Symmetric Galerkin Boundary Element
Method (SGBEM) allow us to develop a simple and efficient
formulation that includes a Cohesive Zone Model
(CZM). This formulation is only dependent on one variable
in the cohesive zone (relative displacement). The
corresponding constitutive cohesive equations present a
softening branch which induce to the problem a potential
instability. The development and implementation
of a suitable solution algorithm capable of following
the growth of the cohesive zone and subsequent crack
growth becomes an important issue. An arc-length control
combined with a Newton-Raphson algorithm for iterative
solution of nonlinear equations is developed.The
Boundary Element Method is very attractive for modeling
cohesive crack problems as all nonlinearities are located
along the boundaries (including the crack boundaries)
of linear elastic domains. A Galerkin approximation scheme, applied to a suitable symmetric integral
formulation, ensures an easy treatment of cracks in homogeneous
media and excellent convergence behavior of
the numerical solution. Numerical results for the wedge
split test are presented and compared with experimental
results available in the literature
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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