scholarly journals STATISTICAL ANALYSIS OF THE LOCAL STRUT THICKNESS OF OPEN CELL FOAMS

2013 ◽  
Vol 32 (1) ◽  
pp. 1 ◽  
Author(s):  
André Liebscher ◽  
Claudia Redenbach
Keyword(s):  
Euclidean Distance ◽  
Interconnected Network ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Open Cell ◽  
Strut Thickness ◽  
Thickness Profile ◽  
Open Cell Foams ◽  
Polynomial Models ◽  
Sectional Shape

Open cell foams are formed by an interconnected network of struts whose thickness varies locally. These variations were shown to have an impact on the elastic and thermal properties of the foam. In this paper we quantify the local strut thickness by means of micro computed tomography (µCT) imaging. We introduce a skeletonization based topological decomposition of the foam structure into its vertices and struts. This allows to estimate the thickness of individual strut segments by the Euclidean distance transform, where an appropriate correction for struts with nonspherical cross-sectional shape is applied. Conflating these estimates based on the strut lengths results in a strut thickness profile for the entire foam. Polynomial models for the strut thickness profile are investigated by means of a regression analysis.

Thermal and Fluid Transport in Micro-Open-Cell Metal Foams: Effect of Node Size

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Xiaohu Yang ◽  
Yang Li ◽  
Lianying Zhang ◽  
Liwen Jin ◽  
Wenju Hu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Chemical Engineering ◽  
Fluid Transport ◽  
Metal Foams ◽  
Cross Sectional ◽  
Open Cell ◽  
Conjugated Heat Transfer ◽  
Sectional Shape ◽  
Node Size

Open-cell metal foams exhibit distinctive advantages in fluid control and heat transfer enhancement in thermal and chemical engineering. The thermofluidic transport characteristics at pore scale such as topological microstructure and morphological appearance significantly affect fluid flow and conjugated heat transfer in open-cell metal foams, important for practically designed applications. The present study employed an idealized tetrakaidecahedron unit cell (UC) model to numerically investigate the transport properties and conjugated heat transfer in highly porous open-cell metal foams (porosity—0.95). The effects of foam ligaments and nodes (size and cross-sectional shape) on thermal conduction, fluid flow, and conjugated heat transfer were particularly studied. Good agreement was found between the present predictions and the results in open literature. The effective thermal conductivity was found to decrease with increasing node-size-to-ligament ratio, while the permeability and volume-averaged Nusselt number were increased. This indicated that the effects of node size and shape upon thermofluidic transport need to be considered for open-cell metal foams having high porosities.

Influence of Morphology on Flow Law Characteristics in Open-Cell Foams: An Overview of Usual Approaches and Correlations

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Prashant Kumar ◽  
Frédéric Topin
Keyword(s):  
High Performance ◽  
Pore Space ◽  
Cross Sectional ◽  
Open Cell ◽  
Industrial Systems ◽  
Wide Range ◽  
Open Cell Foam ◽  
Successful Design ◽  
Open Cell Foams ◽  
Flow Law

Foam structures have been a subject of intensive research since the last decade. The pore space in open-cell foam is interconnected, forming perforated channels of varying cross-sectional areas where fluid can flow. Knowledge of pressure drop induced by these foam matrices is essential for successful design and operation of high-performance industrial systems. In this context, analytical correlations were derived for the determination of Darcian permeability (KD) and Forchheimer inertia coefficient (CFor) in open-cell foams of different strut shapes. It has been shown that the flow law characteristics are strongly dependent on strut shape, strut characteristic dimension, and length. The applicability of new correlations was examined by comparing and validating the numerical and experimental flow law characteristics data against the predicted ones. An excellent agreement has been observed for the foam structures of different materials and variable texture in a wide range of porosity and Reynolds number.

scholarly journals APPROPRIATE MODELS FOR SIMULATING OPEN-POROUS MATERIALS

2017 ◽  
Vol 36 (2) ◽  
pp. 107 ◽  
Author(s):  
Tomasz Wejrzanowski ◽  
Samih Haj Ibrahim ◽  
Jakub Skibinski ◽  
Karol Cwieka ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Porous Materials ◽  
Pore Size ◽  
Open Porosity ◽  
Diameter Distribution ◽  
Cell Diameter ◽  
Micro Computed Tomography ◽  
Open Cell ◽  
Geometrical Features ◽  
Open Cell Foams ◽  
Number Of Faces

In the present paper two representative models applied for modeling of two types of porous materials - open-cell foams and open-porosity tapes - are addressed. Algorithms presented here base on Laguerre-Voronoi tessellations (open-cell foams) and the sphere representation (open-porosity tapes) and enable creating the desired porosity and pore size distribution. The geometrical features of the models, such as: porosity, mean pore size, cell diameter distribution and number of faces per cell were compared with those obtained by 3D micro-computed tomography and good agreement was obtained.

On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

1990 ◽  
Vol 48 (3) ◽  
pp. 566-567
Author(s):  
J.-F. Revol ◽  
Y. Van Daele ◽  
F. Gaill
Keyword(s):  
Contrast Imaging ◽  
Animal Kingdom ◽  
Bright Field ◽  
Field Mode ◽  
Cross Sectional ◽  
Ultrathin Sections ◽  
The Cross ◽  
Sectional Shape ◽  
Valonia Ventricosa ◽  
C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

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