1,720,984 research outputs found
Parametric investigation on the tensile response of GFRP elements through a discrete lattice modeling approach
No full textFiber Reinforced Polymers (FRP) are a relatively new construction material. Their attractive features, such as lightness and durability, are currently paving an attractive way for structural engineering applications. However, since their mechanical properties are strongly influenced by the arrangement of the fibers (which is dictated by the production process), more research is still needed to fully characterize the material and to predict its behavior under different multi-axial actions. In this regard, the goal of the present manuscript is to shed light on these aspects by means of numerical analyses according to a lattice modeling approach proposed in (Fascetti et al., 2016) for FRP materials and herein modified to better capture the uniaxial alignment of pultruded elements. Novelty of the work and main contribution to the field is the definition of a numerical procedure for the saturation of the computational domain with different pointsets (i.e. a regular and a random one) in order to increase the accuracy of the method. The proposed approach is validated for tensile loadings, both in terms of mechanical properties and failure modes, through a parametric investigation carried out to simulate the results of the experimental campaign reported in Quadrino et al. (2018) which employed small-scale specimens directly extracted from pultruded glass fiber reinforced polymers (GFRP) beams
A critical review of numerical methods for the simulation of pultruded fiber-reinforced structural elements
No full textPultruded Fiber-Reinforced Polymers (FRP) are innovative structural elements that are experiencing a steady increase in use for different structural applications. Due to their appealing properties that set them apart from traditional construction materials, such as magnetic transparency and excellent strength-to-weight ratio, numerous experimental and numerical studies have been performed in the last decades to assess their performance as structural components. The description of the micro- and macro-scale mechanical features of FRP elements requires multiple levels of information to be accurately characterized to predict their strength, and as a result, researchers have developed computational models with varying levels of complexity to parametrize their response and investigate design parameters through numerical simulations. This paper presents a critical review of the current state-of-the-art in numerical modeling of structural fiber-reinforced polymeric elements for the prediction of their mechanical behavior under serviceability and failure limit state conditions, with particular attention devoted to pultruded Glass Fiber Reinforced Polymers (GFRP), and their use as load-bearing structural elements. The most commonly adopted numerical methods for the solution of this set of problems range from classical Finite Element Method (FEM) approaches to eXtended Finite Element Method (XFEM), Virtual Crack Closure Technique (VCCT), Cohesive Zone Modeling (CZM), Multiscale Reduced Order Modeling (ROM), as well as Random Lattice Modeling (RLM) techniques recently developed by the co-authors. Each one of these methods has its own distinctive features and brings specific challenges and capabilities that will be presented and discussed in detail in the manuscript. This paper, therefore, aims at illustrating the reliability of existing numerical models for the simulation of FRP structural elements and draw conclusions and recommendations for future research, discussing 160 references from the available literature
Lattice discrete modeling of concrete under compressive loading: Multiscale experimental approach for parameter determination
No full textLattice Discrete Particle Models (LDPM) effectively relate concrete heterogeneity, in terms of coarse aggregate-paste structure, to damage patterns and load-displacement response. Interest in this type of model is enhanced by its abilities to overcome issues that plague traditional methods, such as mesh dependence and needs fo renergy regularization. Herein, an experimental procedure is developed to identify the mechanical parameters defined at the concrete mesoscale. The bounding surface of the LDPM is modified to accept the mesoscale parameters as inputs. Based on the parameter values, identified through the multiscale experimental campaign, macroscopic response to compressive load is simulated. Accuracy of theapproach is demonstrated through comparisons with experimental result
A Lattice Model to study FRP elements
No full textA lattice model is proposed to study the mechanics of pultruded FRP elements. Special attention is devoted to the modeling of crack propagation on the web-flange junction of a pultruded GFRP profile which is subject to a localized pullout force. The proposed numerical model discretizes the beam into rigid blocks interconnected by 1D elements. The work presents: 1) the adopted strategy for the model formulation; 2) the definition of mesoscale constitutive laws and their scaling to preserve correct energy dissipation; 3) a multiscale experimental investigation devoted to the identification of the mesoscale properties of the 1D lattice elements; 4) concluding remarks and directions for future research
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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