Multi-scale characterization and modelling of damage evolution in nuclear Gilsocarbon graphite

2015 ◽  
Vol 1809 ◽  
pp. 1-6 ◽  
Author(s):  
Dong Liu ◽  
Peter Heard ◽  
Branko Šavija ◽  
Gillian Smith ◽  
Erik Schlangen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
Numerical Models ◽  
Ion Beam ◽  
Microstructural Characterization ◽  
Scale Model ◽  
Small Scale ◽  
Length Scale ◽  
Multi Scale ◽  
Scale Characterization

ABSTRACTIn the present work, the microstructure and mechanical properties of Gilsocarbon graphite have been characterized over a range of length-scales. Optical imaging, combined with 3D X-ray computed tomography and 3D high-resolution tomography based on focus ion beam milling has been adopted for microstructural characterization. A range of small-scale mechanical testing approaches are applied including an in situ micro-cantilever technique based in a Dualbeam workstation. It was found that pores ranging in size from nanometers to tens of micrometers in diameter are present which modify the deformation and fracture characteristics of the material. This multi-scale mechanical testing approach revealed the significant change of mechanical properties, for example flexural strength, of this graphite over the length-scale from a micrometer to tens of centimeters. Such differences emphasize why input parameters to numerical models have to be undertaken at the appropriate length-scale to allow predictions of the deformation, fracture and the stochastic features of the strength of the graphite with the required confidence. Finally, the results from a multi-scale model demonstrated that these data derived from the micro-scale tests can be extrapolated, with high confidence, to large components with realistic dimensions.

scholarly journals Artificial generation of representative single Li-ion electrode particle architectures from microscopy data

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Orkun Furat ◽  
Lukas Petrich ◽  
Donal P. Finegan ◽  
David Diercks ◽  
Francois Usseglio-Viretta ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Electron Backscatter Diffraction ◽  
Ion Beam ◽  
Lithium Ion ◽  
Scale Model ◽  
Multi Scale ◽  
Physics Modeling ◽  
Microscopy Data ◽  
Microscopy Techniques ◽  
Backscatter Diffraction

AbstractAccurately capturing the architecture of single lithium-ion electrode particles is necessary for understanding their performance limitations and degradation mechanisms through multi-physics modeling. Information is drawn from multimodal microscopy techniques to artificially generate LiNi0.5Mn0.3Co0.2O2 particles with full sub-particle grain detail. Statistical representations of particle architectures are derived from X-ray nano-computed tomography data supporting an ‘outer shell’ model, and sub-particle grain representations are derived from focused-ion beam electron backscatter diffraction data supporting a ‘grain’ model. A random field model used to characterize and generate the outer shells, and a random tessellation model used to characterize and generate grain architectures, are combined to form a multi-scale model for the generation of virtual electrode particles with full-grain detail. This work demonstrates the possibility of generating representative single electrode particle architectures for modeling and characterization that can guide synthesis approaches of particle architectures with enhanced performance.

scholarly journals Design of a Small-Scale Experimental Model of the International Space Station Crew Quarters for a PIV Flow Field Study

2019 ◽  
Vol 111 ◽  
pp. 01045
Author(s):  
Matei-Razvan Georgescu ◽  
Ilinca Nastase ◽  
Amina Meslem ◽  
Mihnea Sandu ◽  
Florin Bode
Keyword(s):  
International Space Station ◽  
Numerical Models ◽  
Space Station ◽  
Scale Model ◽  
Microgravity Environment ◽  
Small Scale ◽  
Piv Measurements ◽  
International Space ◽  
The Subject ◽  
Small Scale Model

An attempt at improving the ventilation solution for the crew quarters aboard the International Space Station requires a thorough understanding of the flow dynamics in a microgravity environment. An experimental study is required in order to validate the numerical models. As part of this process, a small-scale model was proposed for a detailed study of the velocity field. PIV measurements in water offer high quality results and were chosen for the subject. Following certain similitude criteria, an equivalence can be found between the results of these measurements and the real ventilation scenario. This paper describes the development process of this small-scale model as well as its performance in the initial test runs. Details regarding the advantages and weaknesses of this first model are the core of the paper, with the intention of aiding researchers in their design of similar models. The conclusion presents future steps and proposed improvements to the model.

Multi-scale model updating for the mechanical properties of cross-laminated timber

2016 ◽  
Vol 177 ◽  
pp. 83-90 ◽  
Author(s):  
E.I. Saavedra Flores ◽  
R.M. Ajaj ◽  
I. Dayyani ◽  
Y. Chandra ◽  
R. Das
Keyword(s):  
Mechanical Properties ◽  
Model Updating ◽  
Scale Model ◽  
Cross Laminated Timber ◽  
Multi Scale

scholarly journals Multi-Scale Structural and Tensile Mechanical Response of Annulus Fibrosus to Osmotic Loading

2012 ◽  
Author(s):  
Woojin M. Han ◽  
Nandan L. Nerurkar ◽  
Lachlan J. Smith ◽  
Nathan T. Jacobs ◽  
Robert L. Mauck ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intervertebral Disc ◽  
Mechanical Testing ◽  
Biochemical Composition ◽  
Annulus Fibrosus ◽  
Mechanical Response ◽  
Tissue Level ◽  
Multi Scale ◽  
Osmotic Loading

The annulus fibrosus (AF) is a multi-lamellar fibrocartilagenous ring in the intervertebral disc. The variation of biochemical composition from the outer to the inner AF is largely responsible for the heterogeneous mechanical properties. In vitro tissue-level studies require mechanical testing in aqueous buffers to avoid tissue dehydration. The varying glycosaminoglycan (GAG) contents from outer to inner AF suggest that the response to high and low PBS osmolarity may also be different with radial position. Previous studies in tendon and ligament have been conflicting: soaking tendon fascicles in PBS decreased tensile modulus1 and treating ligament in buffer had no effect on modulus.2

scholarly journals Decomposition technique for contributions to groundwater heads from inside and outside of an arbitrary boundary: Application to Guantao County, North China Plain

2019 ◽  
Author(s):  
Ning Li ◽  
Wolfgang Kinzelbach ◽  
Haitao Li ◽  
Wenpeng Li ◽  
Fei Chen
Keyword(s):  
Boundary Conditions ◽  
Numerical Models ◽  
Soil Column ◽  
Scale Model ◽  
Small Scale ◽  
Decomposition Technique ◽  
Arbitrary Boundary ◽  
Groundwater Head ◽  
Administrative Unit ◽  
Small Models

Abstract. To assess the efficiency of groundwater management of an administrative unit, we propose to decompose the groundwater head changes within an administrative unit into inside and outside contributions by using numerical models. Guantao County of Hebei Province, China, serves as an example to demonstrate the decomposition technique. The groundwater flow model of Guantao was constructed using observed heads as prescribed head boundary conditions. The model was coupled with Hydrus 1D, to calculate the groundwater recharge distribution in time reflecting the delay and damping effects of the soil column on seepage at the surface. The model was calibrated by adjusting parameters such as hydraulic conductivities, recharge infiltration ratios and specific yields. The calibrated parameters are then used in a large model with a boundary at large distance from Guantao administrative boundary to determine the groundwater head changes due to inside drivers. The differences of the two models on the Guantao boundary serve as the specified head values on the boundary for a small scale model, which is used to calculate the groundwater head imposed by outside drivers. To eliminate inconsistencies caused by the different types of boundary conditions of large and small models, the groundwater head changes due to inside drivers must be updated. The results indicate that the groundwater head changes in the centre and south of Guantao County are influenced equally by both inside and outside contributions, while in the north outside contributions have the stronger impact. The sensitivity analysis shows that the groundwater head changes and their decomposition are much more sensitive to infiltration ratios than to the aquifer parameters. The parameters within Guantao have a certain influence on the net groundwater head changes while the parameters outside of Guantao have only an influence on the decomposition.

scholarly journals A multi-scale flow model for blood regulation in a realistic vascular system

2020 ◽  
Author(s):  
Ulin Nuha Abdul Qohar ◽  
Antonella Zanna Munthe-Kaas ◽  
Jan Martin Nordbotten ◽  
Erik Andreas Hanson
Keyword(s):  
Blood Flow ◽  
Blood Circulation ◽  
Numerical Models ◽  
Scale Model ◽  
Fluid Exchange ◽  
Desktop Computer ◽  
Multi Scale ◽  
Proposed Model ◽  
Porous Media Model ◽  
Capillary Bed

Abstract In the last decade, numerical models have been an increasingly important tool in medical science both for the fundamental understanding of the physiology of the human body as well as for diagnostics and personalized medicine. In this paper, a multi-scale model is developed for blood flow and regulation in a full vascular structure of an organ. We couple a 1D vascular graph model to represent blood flow in larger vessels and a porous media model to describe flow in smaller vessels and capillary bed. The vascular model is based on Poiseuille’s law, with pressure correction by elasticity and pressure drop estimation at vessels junctions. The porous capillary bed is modeled as a two compartments domain (arterial and venal) and Darcy’s law. The fluid exchange between the arterial and venal capillary bed compartments is defined as blood perfusion. The numerical experiments show that the proposed model for blood circulation: 1) is closely dependent on the structure and parameters of both the vascular vessels and of the capillary bed, and 2) it provides a realistic blood circulation in the organ. The advantage of the proposed model is that it is complex enough to capture the underlying physiology reliably, yet highly flexible as it offers the possibility of incorporating various local effects. Furthermore, the numerical implementation of the model is straightforward and allows for simulations on a regular desktop computer.

scholarly journals Formulation and Stability Analysis of a Multi-Scale Modeling Approach for Simulation of Elastic Wave Propagation

2021 ◽  
pp. 2141010
Author(s):  
Siddhesh Raorane ◽  
Tadeusz Uhl ◽  
Pawel Packo
Keyword(s):  
Wave Propagation ◽  
Stability Analysis ◽  
Elastic Wave ◽  
Numerical Models ◽  
Practical Interest ◽  
Elastic Wave Propagation ◽  
Scale Model ◽  
Perfect Agreement ◽  
Multi Scale ◽  
Analytical Formulae

In this work, we report on the formulation and detailed stability analysis of a dynamic multi-scale scheme involving two different local computational strategies for modeling of elastic wave propagation. The coupled model involves the Local Interaction Simulation Approach and Cellular Automata for Elastodynamics, however the presented analysis approach is general and applies to other numerical techniques. This scheme is capable of coupling two numerical models with possibly dissimilar spatial discretization lengths and material properties, hence it is appealing for a multi-scale and/or multi-resolution analysis. The method developed in this paper employs an interface force–displacement coupling to yield the multi-scale model equations. It is shown that the governing equations contain a self-coupling term that affects the stability of the system, as it contributes to additional stiffness at the interface. Stability analysis is presented in terms of rotations of two vectors in [Formula: see text] space, where each vector represents individual model’s stability. Three model configurations of practical interest were investigated, analytical formulae derived and used to analyze stability. These analytical formulae were compared against results from numerical simulations and perfect agreement was observed.

Multi-scale characterization of the effect of saturated steam on the macroscale properties and surface changes of moso bamboo

2021 ◽  
Vol 11 (5) ◽  
pp. 740-748
Author(s):  
Tiancheng Yuan ◽  
Jie Liu ◽  
Shouheng Hu ◽  
Xinzhou Wang ◽  
Xianmiao Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Great Influence ◽  
Modulus Of Rupture ◽  
Saturated Steam ◽  
Vascular Bundles ◽  
Multi Scale ◽  
Light Yellow ◽  
Scale Characterization

Bamboo is a woody material that has become a key substitute for wood resources in many fields. This study is aimed to analyze the effects of saturated steam (140, 160, 180 °C) on physical, crystallinity, chemical composition, mechanical properties as well as microstructures at different periods (4, 6, 8, 10 min). Expectedly, a reduction of hemicellulose and cellulose and increment of relative content of lignin in bamboo when temperature above 160 °C was positive to reduce the equilibrium moisture content (EMC). Thus, the hygroscopicity improved and the parenchyma cells and vascular bundles were shrunk slightly. Both temperature and time positively affected the crystallinity of bamboo samples in comparison with the control. Heat treatment parameters affect the mechanical properties of bamboo. When the treatment was carried out at 140 °C, the modulus of rupture (MOR) and modulus of elastic (MOE) increased in comparison to no treatment; Furthermore, The MOR and MOE decreased by 40% and 19% compared with that of the untreated bamboo at 180 °C for 10 min. The temperature and time had a great influence on a*, b*, and L* of the bamboo. The results showed that during the heat treatment, the bamboo color changed from light yellow to dark red-brown, and the overall color changed evenly. Among them, a* increased firstly and then decreased, indicating that the treated bamboo was reddish, while b* and L* mainly showed a downward trend. The ΔE value positively corresponded to heat treatment severity.

scholarly journals CEOHYDRAULIC INVESTIGATIONS OF RUBBLE MOUND BREAKWATERS

1988 ◽  
Vol 1 (21) ◽  
pp. 166 ◽  
Author(s):  
W. Burger ◽  
H. Oumeraci ◽  
H.W. Partenscky
Keyword(s):  
Pore Pressure ◽  
Scale Effects ◽  
Numerical Models ◽  
Model Tests ◽  
Physical Models ◽  
Core Material ◽  
Scale Model ◽  
Small Scale ◽  
Rubble Mound ◽  
Rubble Mound Breakwaters

Due to the increase of ship sizes in recent decades a number of harbours and terminals have been built in deeper waters. Accordingly, the structures which have to provide protection against wave action become higher, too. In most cases, these protective structures are of the rubble mound type. Under such conditions the flow induced by waves within the breakwater and the related geotechnical behaviour of the rubble mound fill become more significant fcr the overall stability and should be considered in the design. In addition, it is known that the scales usually adopted in hydraulic models (1:30 to 1:60) for investigating the stability of large rubble mound breakwaters generally lead to scale effects with respect to the flow field inside the breakwater. This means that small-scale model tests are not appropriate for investigating the internal flow patterns or for evaluating the pore pressure field induced by the incident waves in,the core material. because of the uncontrolled conditions in the prototype, and since the actual permeability of the prototype rubble mound fill cannot be predicted (segregation, settlement, variation in grading, etc.), the use of large-scale physical models seems to be the most promising method for basic investigations of this kind. Moreover, the results of such largescale model tests may be used to validate the usual smaller scale models and to calibrate numerical models. Therefore, it is one of the objectives of our research programme on rubble mound breakwaters, which started in 1987, to concentrate on the evaluation of the wave-induced flow and pore pressure distribution within the breakwater.

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