1,720,984 research outputs found
Finite element implementation of the aortic double-dispersion fibre model and development of a predictive damage model
No full textWith the development of next-generation cardiovascular prosthesis, the requirement for more advanced simulations for predicting the mechanical response of biological tissue has arisen. Finite-element analysis represents a powerful tool capable of simulating complex behaviours within this framework. The present work proposes the computational implementation of an advanced constitutive model for the fibre-reinforced tissue making up the aortic wall. The formulation available in literature is numerically implemented within the FE software Abaqus© through specific user subroutines, and model predictions are compared with the already available single-dispersion-model results. The influence of each dispersion parameter on the macroscopic behaviour is analysed and discussed. Finally, the model is extended by a damage regime based on strain invariants, which is capable of considering the influence of patient ageing on the mechanical response failure strain. The user subroutines are here provided in the Appendix for applications
Combined RVE-Cohesive elements approach to the multi-scale modelling of FDM 3D-printed components
Full text linkMechanical strength of 3D-printed components dramatically depends on printing process parameters. These can be usually set over a relatively wide range, in combinations that determine the microstructure morphology and the resulting mechanical behaviour. The present investigation focuses on the relationship between revealed structure and resulting mechanical properties of FDM-printed ABS specimens. The peculiar structures, examined at the meso- and microscale, are modelled by a finite-element Representative Volume Element (RVE) approach, in conjunction with cohesive elements to reproduce the sealing efficiency between fused filaments. The simulation of the tensile response up to failure falls within the 95% of confidence with experiments. Also, homogenized response of RVE determines spatial material constants useful for the effective numerical simulations of functional components, and intra- and inter-layer damage mechanisms are distinguished providing hints for the structural optimization
Effetti di training sul riconoscimento di forme incomplete. Un esperimento con soggetti in età prescolare.
No full textSlip strength of COR-TEN and Zn-coated steel preloaded bolted joints
Full text linkKnowledge of the effective slip strength is a crucial safety issue when a bolted connection is designed to work by
friction. Even if technical standards indicate the necessary tightening torque to obtain the desired preload,
experimental relationship between bolt torque and preload is required in many cases where surface and bolt
conditions are uncertain. In this work, the torque–preload relationship and the effective slip factors of bolted
joints operating under non-standard surface conditions, namely COR-TEN and Zn-coated plates, are determined
experimentally, and compared with standard as-rolled data. Results indicate that the requirements of design
standards are not always conservative, making experimental characterization of the joint necessary
Analysis and modelling of damage mechanism in FDM 3D-printed lattice structure under compression loading
No full textFused filament fabrication (FFF), commercially known as fused deposition modelling (FDM), is a widespread 3D printing process that builds up components by depositing a continuous filament of material, typically a thermoplastic, along a determined path. The mechanical performance of such parts is promising, even if strongly influenced by the deposition process. In this work, the mechanical behaviour of a specific lattice structure printed in acrylonitrile butadiene styrene (ABS) is studied and a model of lattice behaviour up to the damage regime is developed, with emphasis on the resulting anisotropy. The investigation starts with the analysis of the anisotropy of simple prismatic samples printed with various filament orientations. Deformation and damage of the lattice structure under compressive loading is observed at the meso- and micro-scales. An anisotropic model is then developed within the ABAQUS (c) environment to reproduce the elasto-plastic behaviour, incorporating onset and evolution of inter- and intra-layer damage. Good agreement is observed between the modelled and experimental response
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
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