Search results for "Scale model"
showing 10 items of 64 documents
On the improvement of monumental structure safety: a case study
2006
The present paper deals with the problem of the preservation of the monumental patrimony and discusses a practical application. The analysis methodology based on modern dynamic identification techniques was used for a monumental church in the historic area of Catania (Italy). The dynamic response of the church was measured in terms of accelerations, by means of vibration tests in situ. The numerical analyses highlighted the vulnerability of the drum dome system. Hence interest focused on this part of the building. A reduced scale model of the above system was built to be subjected to dynamic tests on a shaking table at the ENEA laboratory at Casaccia (Rome). Different kinds of reversible de…
Multiscale modeling of polycrystalline materials: A boundary element approach to material degradation and fracture
2015
Abstract In this work, a two-scale approach to degradation and failure in polycrystalline materials is proposed. The formulation involves the engineering component level (macro-scale) and the material grain level (micro-scale). The macro-continuum is modeled using a three-dimensional boundary element formulation in which the presence of damage is formulated through an initial stress approach to account for the local softening in the neighborhood of points experiencing degradation at the micro-scale. The microscopic degradation is explicitly modeled by associating Representative Volume Elements (RVEs) to relevant points of the macro continuum, for representing the polycrystalline microstruct…
Supramolecular self-assembly on the B-Si(111)-(√3x√3) R30° surface: From single molecules to multicomponent networks
2017
Abstract Understanding the physical and chemical processes in which local interactions lead to ordered structures is of particular relevance to the realization of supramolecular architectures on surfaces. While spectacular patterns have been demonstrated on metal surfaces, there have been fewer studies of the spontaneous organization of supramolecular networks on semiconductor surfaces, where the formation of covalent bonds between organics and adatoms usually hamper the diffusion of molecules and their subsequent interactions with each other. However, the saturation of the dangling bonds at a semiconductor surface is known to make them inert and offers a unique way for the engineering of m…
Modelling Polycrystalline Materials: An Overview of Three-Dimensional Grain-Scale Mechanical Models
2014
International audience; A survey of recent contributions on three-dimensional grain-scale mechanical modelling of polycrystalline materials is given in this work. The analysis of material micro-structures requires the generation of reliable micro-morphologies and affordable computational meshes as well as the description of the mechanical behavior of the elementary constituents and their interactions. The polycrystalline microstructure is characterized by the topology, morphology and crystallographic orientations of the individual grains and by the grain interfaces and microstructural defects, within the bulk grains and at the inter-granular interfaces. Their analysis has been until recentl…
Wall collision and drug-carrier detachment in dry powder inhalers: Using DEM to devise a sub-scale model for CFD calculations
2018
Abstract In this work, the Discrete Element Method (DEM) is used to simulate the dispersion process of Active Pharmaceutical Ingredients (API) after a wall collision in dry powders inhaler used for lung delivery. Any fluid dynamic effects are neglected in this analysis at the moment. A three-dimensional model is implemented with one carrier particle (diameter 100 μm) and 882 drug particles (diameter 5 μm). The effect of the impact velocity (varied between 1 and 20 m s−1), angle of impact (between 5° and 90°) and the carrier rotation (±100,000 rad s−1) are investigated for both elastic and sticky walls. The dispersion process shows a preferential area of drug detachment located in the southe…
An Early Stage Researcher's Primer on Systems Medicine Terminology
2021
Background: Systems Medicine is a novel approach to medicine, that is, an interdisciplinary field that considers the human body as a system, composed of multiple parts and of complex relationships at multiple levels, and further integrated into an environment. Exploring Systems Medicine implies understanding and combining concepts coming from diametral different fields, including medicine, biology, statistics, modeling and simulation, and data science. Such heterogeneity leads to semantic issues, which may slow down implementation and fruitful interaction between these highly diverse fields. Methods: In this review, we collect and explain more than100 terms related to Systems Medicine. Thes…
Comparison of the accumulation of fibre breaks occurring in a unidirectional carbon/epoxy composite identified in a multi-scale micro-mechanical mode…
2010
National audience; A model to predict fibre break accumulation that takes into account all physical phenomena at the origin of the fibre break (i.e. the random nature, stress transfer due to breaks, fibre debonding and viscosity of the matrix) shows clearly that the failure of a unidirectional composite structure results in the formation of random fibre breaks which at higher loads coalesce into clusters of broken fibres. The object of the study is to experimentally confirm this scenario. Many techniques exist to detect the failure of carbon fibre composites, however none of them offer a resolution that allows this goal to be achieved in a non-destructive manner and in three dimensions. Hig…
Effect of the Time Dependent Loading of Type IV Cylinders using a Multiscale Model
2019
International audience; The current requirements for composite cylinders are still based on an arbitrary approach derived from the behaviour of metal structures, that the designed burst pressure should be at least 2.5 times the maximum in-service pressure [1]. This could lead to an over-designed composite cylinder for which the weight saving would be less than optimum. Moreover, predicting the lifetime of composite cylinders is a challenging task due to their anisotropic characteristics. A federal research institute in Germany (BAM) has proposed a minimum load-cycle requirement that mitigates this issue by using a Monte-Carlo analysis of the burst test results [2-3]. To enrich this study, m…
Analyse multiéchelle d'un composite textile = Multiscale analysis of a textile composite
2009
National audience; On propose dans cette étude de comprendre le comportement mécanique d'un composite textile. Pour ce faire, l'étude se scinde en deux parties distinctes. Dans cet article, nous présentons la modélisation multiéchelle qui fait suite à une étude expérimentale. Son objectif est double : comprendre la nature du comportement macroscopique observé et expliquer l'origine des endommagements susceptibles d'apparaître. L'étude expérimentale du matériau fait l'objet d'un premier article.
A hierarchical model for novel schemes of electrodialysis desalination
2019
Abstract A new hierarchical model for the electrodialysis (ED) process is presented. The model has been implemented into gPROMs Modelbuilder (PSE), allowing the development of a distributed-parameters simulation tool that combines the effectiveness of a semi-empirical modelling approach to the flexibility of a layered arrangement of modelling scales. Thanks to its structure, the tool makes possible the simulation of many different and complex layouts, requiring only membrane properties as input parameters (e.g. membrane resistance or salt and water permeability). The model has been validated against original experimental data obtained from a lab scale ED test rig. Simulation results concern…