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1 – 10 of over 5000
Article
Publication date: 1 March 2006

Shutian Liu and Yongcun Zhang

In this paper, a homogenization‐based multi‐scale method for predicting the effective thermal conductivity of porous materials with radiation is presented, which considers…

Abstract

In this paper, a homogenization‐based multi‐scale method for predicting the effective thermal conductivity of porous materials with radiation is presented, which considers the effect of geometry and distribution of pores. Using homogenization method to solve the pure conductive problem of porous materials with periodic structure, the effective thermal conductivity without considering radiation is predicted, and a temperature field in a local domain of a unit cell is obtained. This temperature field is taken as the good approximation of the real temperature distribution, and the radiative thermal conductivity is obtained. The effect of the microstructure, the distribution and geometry of pores on heat transfer of porous materials is discussed. It is concluded that the dimension of the pores is an important influence factor on the thermal transfer property of porous materials if radiation is considered. Increasing the pore’s dimension enhances the contribution of radiation to the heat transfer property of porous materials. For porous materials with cylindrical and spherical pores, the radiative thermal conductivity is proportional to pore’s diameter.

Details

Multidiscipline Modeling in Materials and Structures, vol. 2 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 17 August 2021

Mingkang Zhang, Yongqiang Yang, Meizhen Xu, Jie Chen and Di Wang

The purpose of this study is focused on the mechanical properties of multi-materials porous structures manufactured by selective laser melting (SLM).

Abstract

Purpose

The purpose of this study is focused on the mechanical properties of multi-materials porous structures manufactured by selective laser melting (SLM).

Design/methodology/approach

The Diamond structure was designed by the triply periodic minimal surface function in MATLAB, and multi-materials porous structures were manufactured by SLM. Compression tests were applied to analyze the anisotropy of mechanical properties of multi-materials porous structures.

Findings

Compression results show that the multi-materials porous structure has a strong anisotropy behavior. When the compression force direction is parallel to the material arrangement, multi-materials porous structure was compressed in a layer-by-layer way, which is the traditional deformation of the gradient structure. However, when the compression force direction is perpendicular to the material arrangement, the compression curves show a near-periodic saw-tooth waveform characteristic, and this kind of structure was compressed consistently. It is demonstrated that the combination with high strength brittle material and low strength plastic material improves compression mode, and plastic material plays a role in buffering fracture.

Originality/value

This research provides a new method for the design and manufacturing of multi-materials porous structures and an approach to change the compression behavior of the porous structure.

Details

Rapid Prototyping Journal, vol. 27 no. 9
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 12 May 2021

P.S. Liu and X.M. Ma

The purpose of this paper is to provide a summarization and review of the present author's main investigations on failure modes of reticular metal foams under different…

Abstract

Purpose

The purpose of this paper is to provide a summarization and review of the present author's main investigations on failure modes of reticular metal foams under different loadings in engineering applications.

Design/methodology/approach

With the octahedral structure model proposed by the present authors themselves, the fundamentally mechanical relations have been systematically studied for reticular metal foams with open cells in their previous works. On this basis, such model theory is continually used to investigate the failure mode of this kind of porous materials under compression, bending, torsion and shearing, which are common loading forms in engineering applications.

Findings

The pore-strut of metal foams under different compressive loadings will fail in the tensile breaking mode when it is brittle. While it is ductile, it will tend to the shearing failure mode when the shearing strength is half or nearly half of the tensile strength for the corresponding dense material and to the tensile breaking mode when the shearing strength is higher than half of the tensile strength to a certain value. The failure modes of such porous materials under bending, torsional and shearing loads are also similarly related to their material species.

Originality/value

This paper presents a distinctive method to conveniently analyze and estimate the failure mode of metal foams under different loadings in engineering applications.

Details

Multidiscipline Modeling in Materials and Structures, vol. 17 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 6 August 2018

Yi Liu, Hao Wang, Yongfeng Liu, Meng Shi and Duolong Di

The purpose of this paper is to focus on the selection of the optimum porous material modified with poly-dopamine coating for peptides enrichment. The adsorption behaviors…

Abstract

Purpose

The purpose of this paper is to focus on the selection of the optimum porous material modified with poly-dopamine coating for peptides enrichment. The adsorption behaviors for peptides and the antioxidant capacity of peptides fraction purified by the porous materials were investigated.

Design/methodology/approach

The optimum porous material with the highest adsorption capacity for peptides was selected for surface modification. The surface modified porous material was characterized by SEM, nitrogen adsorption-desorption isotherm and color change.

Findings

The results showed that the porous material was successfully modified with poly-dopamine coating. Adsorption capacity for peptides of the modified porous material was enhanced compared to the original porous material. Antioxidant capacity of peptides fraction enriched by the modified porous material was much higher than that enriched by the original porous material, indicating that the introduction of poly-dopamine coating was inclined to enrich peptides with certain amino acid residues.

Research limitations/implications

The structures of peptides are a bit not clear, which is the subject of future investigation.

Practical implications

This contribution provides a method to design and prepare porous materials with poly-dopamine coating to separate and enrich peptides or peptides fraction with high antioxidant capacity.

Originality/value

It showed that polarity, surface area, pore diameter and interactions were contributed to high adsorption capacity. The peptides fraction purified by the modified porous material showed excellent antioxidant capacity through results of reduction of DPPH radical, because of the enrichment of the peptides with certain amino acids residues which were considered to enhance radical scavenging capacity. This paper provides new insights into designing and preparing porous materials with poly-dopamine coating to enrich peptides fraction with high antioxidant capacity.

Details

Pigment & Resin Technology, vol. 47 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 29 April 2022

Mojtaba Fadaei, Mohsen Izadi, Ehsanolah Assareh and Ali Ershadi

This study aims to evaluate the melting process of the phase-change RT-35 material in a shell and tube heat exchanger saturated with a porous medium. Titanium porous media…

Abstract

Purpose

This study aims to evaluate the melting process of the phase-change RT-35 material in a shell and tube heat exchanger saturated with a porous medium. Titanium porous media with isotropic and inhomogeneous structures are studied. The considered tubes in the shell and tube exchanger are made of copper with specific thicknesses. The phase-change material has a non-Newtonian behavior and follows the endorsed Carreau–Yasuda Model.

Design/methodology/approach

The enthalpy–porosity method is used for modeling of the melting process. The governing equations were transferred to their dimensionless forms. Finally, the equations are solved by applying the Galerkin finite element method.

Findings

The findings for different values of the relative permeability (K*) and permeability deviation angle (λ) are represented in the forms of charts, streamlines and constant temperature contours. The considerable effects of the relative permeability (K*) and deviation angle (λ) on the flow line patterns of the melting phase-change material are some of the significant achievements of this works.

Originality/value

This study was conducted using data from relevant research articles provided by reputable academic sources. The data included in this manuscript have not been published previously and are not under consideration by any other journal.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 12
Type: Research Article
ISSN: 0961-5539

Keywords

Open Access
Article
Publication date: 24 October 2018

Samuel Evans, Eric Jones, Peter Fox and Chris Sutcliffe

This paper aims to introduce a novel method for the analysis of open cell porous components fabricated by laser-based powder bed metal additive manufacturing (AM) for the…

Abstract

Purpose

This paper aims to introduce a novel method for the analysis of open cell porous components fabricated by laser-based powder bed metal additive manufacturing (AM) for the purpose of quality control. This method uses photogrammetric analysis, the extraction of geometric information from an image through the use of algorithms. By applying this technique to porous AM components, a rapid, low-cost inspection of geometric properties such as material thickness and pore size is achieved. Such measurements take on greater importance, as the production of porous additive manufactured orthopaedic devices increases in number, causing other, slower and more expensive methods of analysis to become impractical.

Design/methodology/approach

Here the development of the photogrammetric method is discussed and compared to standard techniques including scanning electron microscopy, micro computed tomography scanning and the recently developed focus variation (FV) imaging. The system is also validated against test graticules and simple wire geometries of known size, prior to the more complex orthopaedic structures.

Findings

The photogrammetric method shows an ability to analyse the variability in build fidelity of AM porous structures for use in inspection purposes to compare component properties. While measured values for material thickness and pore size differed from those of other techniques, the new photogrammetric technique demonstrated a low deviation when repeating measurements, and was able to analyse components at a much faster rate and lower cost than the competing systems, with less requirement for specific expertise or training.

Originality/value

The advantages demonstrated by the image-based technique described indicate the system to be suitable for implementation as a means of in-line process control for quality and inspection applications, particularly for high-volume production where existing methods would be impractical.

Details

Rapid Prototyping Journal, vol. 24 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 18 January 2022

Yanhong Yan, Chengwen Yang, Yanfei Zhou, Wenbin Dong, Pengjuan Yan and Zhining Jia

Previously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters…

Abstract

Purpose

Previously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters by tensile strength and perform tribological tests with optimal combination of parameters.

Design/methodology/approach

In this paper, porous polyimide (PI) materials were fabricated using vacuum hot molding technology. The orthogonal experiment was designed to test the mechanical properties of porous PI materials with the process parameters and the content of pore-forming agent as the changing factors. The porous PI oil-bearing materials were obtained by vacuum immersion, and tribological test were carried out.

Findings

The results showed that porous PI oil-bearing materials are suitable for low-speed and low-load conditions. The actual value of the friction coefficient basically match with the theoretical value of the regression analysis, and the errors of the friction coefficient are within 10% and 3%, respectively, which proves that the method used in the study is feasible for the friction coefficient prediction.

Originality/value

In this paper, we have produced a new porous oil-bearing material with good tribological properties. This study can effectively predict the friction coefficient of PI porous material.

Details

Industrial Lubrication and Tribology, vol. 74 no. 2
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 18 November 2021

Jyoti Pandey, Mohd. Zahid Ansari and Afzal Husain

Porous media can provide excellent performance in thermal energy transport applications. This study aims to optimise the square porous slabs (placed in the middle of the…

Abstract

Purpose

Porous media can provide excellent performance in thermal energy transport applications. This study aims to optimise the square porous slabs (placed in the middle of the channel) parameters to enhance the cooling performance of the jet-impingement microchannel heat sink.

Design/methodology/approach

Three levels of each design parameters, i.e. porous slab side, porous slab height, type of material, permeability and quadratic drag factor, are studied; and an L27 orthogonal array is adopted to generate the design points in the specified design space. Optimum designs of the porous media slabs are achieved to minimise the maximum-wall temperature, thermal resistance and pressure drop and maximise the average heat transfer coefficient and figure of merit (FOM).

Findings

Results exhibited that the porous media material and permeability are the most, whereas drag factor is the least significant factors with respect to the overall performance of the heat sink. The optimum value of FOM for the proposed hybrid heat sink model belongs to the set of design variables, i.e. 0.4 mm slab side, 0.6 mm slab height, 5 × 10−11 m2 permeability, 0.21 drag factor and copper as substrate material.

Originality/value

This study proposes a novel design and a hybrid approach to investigate and optimise the hydrothermal performance of jet impingements on porous slabs inserted in the microchannels.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 8
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 5 February 2018

Gino Cortellessa, Fausto Arpino, Simona Di Fraia and Mauro Scungio

In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for…

Abstract

Purpose

In this work, a new two-phase version of the finite element-based Artificial Compressibility (AC) Characteristic-Based Split (CBS) algorithm is developed and applied for the first time to heat and mass transfer phenomena in porous media with associated phase change. The purpose of this study is to provide an alternative for the theoretical analysis and numerical simulation of multiphase transport phenomena in porous media. Traditionally, the more complex Separate Flow Model was used in which the vapour and liquid phases were considered as distinct fluids and mathematically described by the conservation laws for each phase separately, resulting in a large number of governing equations.

Design/methodology/approach

Even though the adopted mathematical model presents analogies with the conventional multicomponent mixture flow model, it is characterized by a considerable reduction in the number of the differential equations for the primary variables. The fixed-grid numerical formulation can be applied to the resolution of general problems that may simultaneously include a superheated vapour region, a two-phase zone and a sub-cooled liquid region in a single physical domain with irregular and moving phase interfaces in between. The local thermal non-equilibrium model is introduced to consider the heat exchange between fluid and solid within the porous matrix.

Findings

The numerical model is verified considering the transport phenomena in a homogenous and isotropic porous medium in which water is injected from one side and heated from the other side, where it leaves the computational domain in a superheated vapour state. Dominant forces are represented by capillary interactions and two-phase heat conduction. The obtained results have been compared with the numerical data available in the scientific literature.

Social implications

The present algorithm provides a powerful routine tool for the numerical modelling of complex two-phase transport processes in porous media.

Originality/value

For the first time, the stabilized AC-CBS scheme is applied to the resolution of compressible viscous flow transport in porous materials with associated phase change. A properly stabilized matrix inversion-free procedure employs an adaptive local time step that allows acceleration of the solution process even in the presence of large source terms and low diffusion coefficients values (near the phase change point).

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 28 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 1 March 1995

D.R.J. Owen, S.Y. Zhao and J.G. Loughran

A finite element solution to the rolling of two‐phase materials ispresented and applied to the rolling of prepared sugar cane. The generalizedBiot theory is extended and…

Abstract

A finite element solution to the rolling of two‐phase materials is presented and applied to the rolling of prepared sugar cane. The generalized Biot theory is extended and modified to suit the present problem and the velocity of the solid skeleton and the pore pressure are taken as the primary unknowns. The finite element approach is applied to the governing equations for spatial discretization, followed by time domain discretization by standard difference methods. A constitutive relation evaluated from a finite element simulation of experiments performed on a constrained compression test cell is employed. The computational model of the rolling of prepared cane with two rolls is presented. The material parameters of prepared cane are described and their variation during the rolling process are derived and discussed. Numerical results are presented to illustrate the performance and capability of the model and solution procedures.

Details

Engineering Computations, vol. 12 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of over 5000