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Article
Publication date: 30 June 2020

Kaili Yao, Dongyang Chu, Ting Li, Zhanli Liu, Bao-Hua Guo, Jun Xu and Zhuo Zhuang

The purpose of this paper is to calculate the Hugoniot relations of polyurea; also to investigate the atomic-scale energy change, the related chain conformation evolution…

Abstract

Purpose

The purpose of this paper is to calculate the Hugoniot relations of polyurea; also to investigate the atomic-scale energy change, the related chain conformation evolution and the hydrogen bond dissociation of polyurea under high-speed shock.

Design/methodology/approach

The atomic-scale simulations are achieved by molecular dynamics (MD). Both non-equilibrium MD and multi-scale shock technique are used to simulate the high-speed shock. The energy dissipation is theoretically derived by the thermodynamic and the Hugoniot relations. The distributions of bond length, angle and dihedral angle are used to characterize the chain conformation evolution. The hydrogen bonds are determined by a geometrical criterion.

Findings

The Hugoniot relations calculated are in good agreement with the experimental data. It is found that under the same impact pressure, polyurea with lower hard segment content has higher energy dissipation during the shock-release process. The primary energy dissipation way is the heat dissipation caused by the increase of kinetic energy. Unlike tensile simulation, the molecular potential increment is mainly divided into the increments of the bond energy, angle energy and dihedral angle energy under shock loading and is mostly stored in the soft segments. The hydrogen bond potential increment only accounts for about 1% of the internal energy increment under high-speed shock.

Originality/value

The simulation results are meaningful for understanding and evaluating the energy dissipation mechanism of polyurea under shock loading, and could provide a reference for material design.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 4 October 2022

Limin Wei, Fei Zhou, Shuo Wang, Weixun Hao, Yong Liu and Jingchuan Zhu

The purpose of this study is to propose extended potentials and investigate the applicability of extended Finnis–Sinclair (FS) potential to Cr with the unit cell structure…

Abstract

Purpose

The purpose of this study is to propose extended potentials and investigate the applicability of extended Finnis–Sinclair (FS) potential to Cr with the unit cell structure of body-centered cubic (BCC Cr).

Design/methodology/approach

The parameters of each potential are determined by fitting the elastic constants, cohesive energy and mono-vacancy formation energy. Furthermore, the ability of the extended FS potential to describe the crystal defect properties is tested. Finally, the applicability of reproducing the thermal properties of Cr is discussed.

Findings

The internal relationship between physical properties and potential function is revealed. The mathematical relationship between physical properties and potential function is derived in detail. The extended FS potential performs well in reproducing physical properties of BCC Cr, such as elastic constants, cohesive energy, surface energy and the properties of vacancy et al. Moreover, good agreement is obtained with the experimental data for predicting the melting point, specific heat and coefficient of thermal expansion.

Originality/value

In this study, new extended potentials are proposed. The extended FS potential is able to reproduce the physical and thermal properties of BCC Cr. Therefore, the new extended potential can be used to describe the crystal defect properties of BCC Cr.

Details

Multidiscipline Modeling in Materials and Structures, vol. 18 no. 6
Type: Research Article
ISSN: 1573-6105

Keywords

Content available
Article
Publication date: 4 June 2021

Francisco M. Andrade Pires and Chenfeng Li

144

Abstract

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Article
Publication date: 3 July 2017

Domenico Borzacchiello, Jose Vicente Aguado and Francisco Chinesta

The purpose of this paper is to present a reduced order computational strategy for a multi-physics simulation involving a fluid flow, electromagnetism and heat transfer in…

Abstract

Purpose

The purpose of this paper is to present a reduced order computational strategy for a multi-physics simulation involving a fluid flow, electromagnetism and heat transfer in a hot-wall chemical vapour deposition reactor. The main goal is to produce a multi-parametric solution for fast exploration of the design space to perform numerical prototyping and process optimisation.

Design/methodology/approach

Different reduced order techniques are applied. In particular, proper generalized decomposition is used to solve the parameterised heat transfer equation in a five-dimensional space.

Findings

The solution of the state problem is provided in a compact separated-variable format allowing a fast evaluation of the process-specific quantities of interest that are involved in the optimisation algorithm. This is completely decoupled from the solution of the underlying state problem. Therefore, once the whole parameterised solution is known, the evaluation of the objective function is done on-the-fly.

Originality/value

Reduced order modelling is applied to solve a multi-parametric multi-physics problem and generate a fast estimator needed for preliminary process optimisation. Different order reduction techniques are combined to treat the flow, heat transfer and electromagnetism problems in the framework of separated-variable representations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 27 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 8 June 2015

Dinesh Kumar, Veena Verma, Keya Dharamvir and H S Bhatti

– The purpose of this paper is to study elastic properties of III-V nitride nanotubes (NNTs) using second generation (REBO) potential.

Abstract

Purpose

The purpose of this paper is to study elastic properties of III-V nitride nanotubes (NNTs) using second generation (REBO) potential.

Design/methodology/approach

In the present research paper elastic properties of BN, AlN and GaN nanotubes have been investigated, using the second generation REBO potential by Brenner and co-workers, which is a bond order potential earlier used for carbon nanostructures successfully. In the present calculation, the same form of potential is used with adjusted parameters for h-BN, h-AlN and h-GaN. In all these cases the authors have considered graphite like network and strongly polar nature of these atoms so electrostatic forces are expected to play an important role in determining elastic properties of these nanotubes. The authors generate the coordinates of nanotubes of different chirality’s and size. Each and every structure thus generated is allowed to relax till the authors obtain minima of energy. The authors then apply the requisite compressions, elongations and twists to the structures and compute the elastic moduli. Young’s Modulus, Shear Modulus and Poisson’s ratio for single-walled armchair and zigzag tubes of different chirality’s and size have been calculated. The computational results show the variation of Young’s Modulus, Poisson’s ratio and Shear Modulus for these NNTs with nanotube diameter. The results have been compared with available data, experimental as well as theoretical.

Findings

The authors have calculated bond length, cohesive energy/bond, Strain energy, Young’s Modulus, Shear Modulus and Poisson’s ratio.

Originality/value

To the best of the knowledge this work is the first attempt to study elastic properties of III-V NNTs using second generation REBO potential

Details

Multidiscipline Modeling in Materials and Structures, vol. 11 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 18 August 2022

Zhufeng Yue, Ming Li, Lei Li and Zude Zhou

This paper aims to propose a new concept of product manufacturing mode which takes physical manufacturing theory as the basic starting point. In this work, the authors…

44

Abstract

Purpose

This paper aims to propose a new concept of product manufacturing mode which takes physical manufacturing theory as the basic starting point. In this work, the authors intend to systematically define the basic connotation and extension of physical manufacturing, and sort out the typical characteristics of physical manufacturing, in order to propose the general concept of physical manufacturing.

Design/methodology/approach

How to study the combination of physics, mathematics, mechanics and other disciplines with the manufacturing disciplines, and how to elevate modern manufacturing science to a new height, has always been a problem for scientists in the field of manufacturing and engineering construction people to deeply think about. Therefore, on the basis of tracing the development of physics and combining the attributes and functions of manufacturing, the authors propose the basic concept of physical manufacturing. On this basis, the authors further clarify the connotation and extension, theoretical basis and technical system of physical manufacturing, reveal the basic problem domain of research and construct the theoretical foundation of physical manufacturing research, which are of great theoretical value and practical significance to adjust and optimize the manufacturing industry structure, improve the quality of manufacturing industry development and promote the green development of manufacturing industry.

Findings

The research on the basic theory and technical system of physical manufacturing will therefore broaden the way of thinking and make a better understanding of manufacturing science and technology, which will promote the development of manufacturing industry to some extent.

Originality/value

On the basis of continuous improvement of the basic theory and conceptual system of physical manufacturing, the physical manufacturing technology will become more and more perfect; physical manufacturing system and intelligent manufacturing system will become the mainstream of next-generation manufacturing system.

Details

Multidiscipline Modeling in Materials and Structures, vol. 18 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

Article
Publication date: 8 July 2019

Łukasz Łach, Dmytro Svyetlichnyy and Robert Straka

A fundamental principle of materials engineering is that the microstructure of a material controls the properties. The phase transformation is an important phenomenon that…

141

Abstract

Purpose

A fundamental principle of materials engineering is that the microstructure of a material controls the properties. The phase transformation is an important phenomenon that determines the final microstructure. Recently, many analytical and numerical methods were used for modeling of phase transformation, but some limitations can be seen in relation to the choice of the shape of growing grains, introduction of varying grain growth rate and modeling of diffusion phenomena. There are also only few comprehensive studies that combine the final microstructure with the actual conditions of its formation. Therefore, the objective of the work is a development of a new hybrid model based on lattice Boltzmann method (LBM) and cellular automata (CA) for modeling of the diffusional phase transformations. The model has a modular structure and simulates three basic phenomena: carbon diffusion, heat flow and phase transformation. The purpose of this study is to develop a model of heat flow with consideration of enthalpy of transformation as one of the most important parts of the proposed new hybrid model. This is one of the stages in the development of the complex model, and the obtained results will be used in a combined solution of heat flow and carbon diffusion during the modeling of diffusion phase transformations.

Design/methodology/approach

Different values of overheating/overcooling affect different values in the enthalpy of transformation and thus the rate of transformation. CA and LBM are used in the hybrid model in part related to heat flow. LBM is used for modeling of heat flow, while CA is used for modeling of the microstructure evolution during the phase transformation.

Findings

The use of LBM and CA in one numerical solution creates completely new possibilities for modeling of phase transformations. CA and LBM in comparison with commonly used approaches significantly simplify interface and interaction between different parts of the model, which operates in a common domain. The CA can be used practically for all possible processes that consist of nucleation and grains growth. The advantages of the LBM method can be well used for the simulation of heat flow during the transformation, which is confirmed by numerical results.

Practical implications

The developed heat flow model will be combined with the carbon diffusion model at the next stage of work, and the new complex hybrid model at the final stage will provide new solutions in numerical simulation of phase transformations and will allow comprehensive modeling of the diffusional phase transformations in many processes. Heating, annealing and cooling can be considered.

Originality/value

The paper presents the developed model of heat flow (temperature module), which is one of the main parts of the new hybrid model devoted to modeling of phase transformation. The model takes into account the enthalpy of transformation, and the connection with the model of microstructure evolution was obtained.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

Keywords

Article
Publication date: 2 February 2015

M. Grujicic, V. Chenna, R. Yavari, R. Galgalikar, J.S. Snipes and S. Ramaswami

To make wind energy (one of the alternative-energy production technologies) economical, wind-turbines (convertors of wind energy into electrical energy) are required to…

Abstract

Purpose

To make wind energy (one of the alternative-energy production technologies) economical, wind-turbines (convertors of wind energy into electrical energy) are required to operate, with only regular maintenance, for at least 20 years. However, some key wind-turbine components (especially the gear-box) often require significant repair or replacement after only three to five years in service. This causes an increase in both the wind-energy cost and the cost of ownership of the wind turbine. The paper aims to discuss these issues.

Design/methodology/approach

To overcome this problem, root causes of the gear-box premature failure are currently being investigated using mainly laboratory and field-test experimental approaches. As demonstrated in many industrial sectors (e.g. automotive, aerospace, etc.) advanced computational engineering methods and tools cannot only complement these experimental approaches but also provide additional insight into the problem at hand (and do so with a substantially shorter turn-around time). The present work demonstrates the use of a multi-length-scale computational approach which couples large-scale wind/rotor interactions with a gear-box dynamic response, enabling accurate determination of kinematics and kinetics within the gear-box bearings (the components most often responsible for the gear-box premature failure) and ultimately the structural response (including damage and failure) of the roller-bearing components (e.g. inner raceways).

Findings

It has been demonstrated that through the application of this approach, one can predict the expected life of the most failure-prone horizontal axis wind turbine gear-box bearing elements.

Originality/value

To the authors’ knowledge, the present work is the first multi-length-scale study of bearing failure in wind-turbines.

Details

International Journal of Structural Integrity, vol. 6 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 24 May 2022

Yaojie Zheng, Sun Huili, Luchun Yan, Xiaolu Pang, Alex A. Volinsky and Kewei Gao

High-strength martensitic steels having strong hydrogen embrittlement (HE) susceptibility and the metal carbide (MC) nanoprecipitates of microalloying elements such as Nb…

Abstract

Purpose

High-strength martensitic steels having strong hydrogen embrittlement (HE) susceptibility and the metal carbide (MC) nanoprecipitates of microalloying elements such as Nb, V, Ti and Mo in the steel matrix can effectively improve the HE resistance of steels. This paper aims to review the effect of MC nanoprecipitates on the HE resistance of high-strength martensitic steels.

Design/methodology/approach

In this paper, the effects of MC nanoprecipitates on the HE resistance of high-strength martensitic steels are systematically described in terms of the types of MC nanoprecipitates, the influencing factors, along with numerical simulations.

Findings

The MC nanoprecipitates, which are fine and semicoherent with the matrix, effectively improve the HE resistance of steel through the hydrogen trapping effects and microstructure optimization, but its effect on the HE resistance of steel is controlled by its size, number and distribution state.

Originality/value

This paper summarizes the effects and mechanisms of MC nanoprecipitates on HE performance of high-strength martensitic steel and provides the theoretical basis for corrosion engineers to design high-strength martensitic steels with excellent HE resistance and improve production processes.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 3 May 2016

Marjan Refaat and Mohammad Reza Moslemi

Nanowires, nanostructures with the diameter of the order of a nanometer, have recently attracted as gas sensors because of their interesting properties such as high…

Abstract

Purpose

Nanowires, nanostructures with the diameter of the order of a nanometer, have recently attracted as gas sensors because of their interesting properties such as high sensitivity, fast response and high selectivity and stability. Among the different types of gas sensors, metallic nanowires used in high frequency applications because of their long mean free path that make the conduction ballistic.

Design/methodology/approach

This paper presents the results of simulations to find the effects of adsorbing some molecules by silver Ag nanowires. The mechanisms of the simulated gas sensor are implemented in the Atomistix Toolkit 13.2 (ATK 13.2).

Findings

The simulation results show high sensitivity of silver nanowires in adjacent with water and ethane. The resistance of the simulated nanowire increased to about 3.65 kΩ for ethane and 4.95 kΩ for water molecules. This result shows that the sensitivity of a silver nanowire is about triple for the case of adsorbing water in comparison to the adsorption of ethane molecules.

Originality/value

This paper presents a simulation study on silver nanowires and compares their sensitivities in adjacent with water and ethane molecules.

Details

Microelectronics International, vol. 33 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

1 – 10 of 41