Mingjian Li, Ping Yang^*, Pengyang Zhao

CMES-Computer Modeling in Engineering & Sciences, Vol.140, No.2, pp. 2019-2034, 2024, DOI:10.32604/cmes.2024.048334 - 20 May 2024

Abstract The experimental results in previous studies have indicated that during the ductile fracture of pure metals, vacancies aggregate and form voids at grain boundaries. However, the physical mechanism underlying this phenomenon remains not fully understood. This study derives the equilibrium distribution of vacancies analytically by following thermodynamics and the micromechanics of crystal defects. This derivation suggests that vacancies cluster in regions under hydrostatic compression to minimize the elastic strain energy. Subsequently, a finite element model is developed for examining more general scenarios of interaction between vacancies and grain boundaries. This model is first verified and More >

Sheng Qian¹, Qi Tong^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.3, pp. 1-1, 2023, DOI:10.32604/icces.2023.010116

Abstract Applications such as aircrafts and electronic devices require the noise and vibration reduction without much extra burden, such as extra damping systems. High damping metallic materials that exhibit the ability to dissipate mechanical energy are potential candidates in these application via directly being part of the functional components, such as the frame materials. The energy damping in polycrystalline metals depends on the activities of defects such as dislocation and grain boundary. However, operating defects has the opposite effect on strength and damping capacity. In the quest for high damping metals, maintaining the level of strength More >

Yangyang Hao, Yue Liu^*, Guorui Cao^*

Journal of Renewable Materials, Vol.10, No.12, pp. 3505-3519, 2022, DOI:10.32604/jrm.2022.023122 - 14 July 2022

Abstract Aiming to reduce the defects of perovskite film and improve carrier transport, an organic small molecule, benzo [d]isothiazol-3(2H)-one 1,1-dioxide (OBS), is introduced as an additive in the solution-processing of perovskite and prepare uniform perovskite films with a continuous distribution of OBS at grain boundaries. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy are conducted to reveal the interactions of hydrogen bonding and coordination bonding between OBS and perovskite. Various characterizations (including X-ray diffraction, UV-vis spectroscopy, electrochemical impedance spectroscopy, etc.) are conducted to uncover the effect of OBS on device performance. Consequently, high efficiency of 23.26% More > Graphic Abstract

Yaochan Zhu^{1, 2, *}, Hua Qiu¹, Håkan Hallberg³

CMC-Computers, Materials & Continua, Vol.62, No.3, pp. 1289-1302, 2020, DOI:10.32604/cmc.2020.06281

Abstract Based on multiphase field conception and integrated with the idea of vectorvalued phase field, a phase field model for typical allotropic transformation of solid solution is proposed. The model takes the non-uniform distribution of grain boundaries of parent phase and crystal orientation into account in proper way, as being illustrated by the simulation of austenite to ferrite transformation in low carbon steel. It is found that the misorientation dependent grain boundary mobility shows strong influence on the formation of ferrite morphology comparing with the weak effect exerted by misorientation dependent grain boundary energy. The evolution More >

Qin Siwei, Shen SP

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.2, pp. 53-54, 2011, DOI:10.3970/icces.2011.019.053

Abstract Among many multiscale methods ,we choose the quasicontinuum method to understand the mechanical response at the nanocrystalline of grain boundaries(GBs) under tension. The energetic and mechanical strength of 6 i?"<110> symmetric tilt GBs are investigated in nanocrystalline Cu and Ni. We focus on discussing the interaction of the structural units of symmetric tilt GB for the initial deformation mode and the strength of model. At the basis of the previous, We study the nanocrystalline Cu/a-Al2O3 interface and analyze the relationship during the grains orientations, GB energy and interface. Special emphasis is placed on the crystal slip More >

M.A.Arafin¹, J.A.Szpunar²

CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 125-140, 2009, DOI:10.3970/cmc.2009.014.125

Abstract A novel microstructure, texture and grain boundary character based model has been proposed to simulate the intergranular crack propagation behavior in textured polycrystalline materials. The model utilizes the Voronoi algorithm and Monte Carlo simulations to construct the microstructure with desired grain shape factor, takes the texture description of the materials to assign the orientations of the grains, evaluates the grain boundary character based on the misorientation angle - axis calculated from the orientations of the neighboring grains, and takes into account the inclination of grain boundaries with respect to the external stress direction. Markov Chain More >

K. Jayabal, A. Arockiarajan, S.M. Sivakumar¹

CMES-Computer Modeling in Engineering & Sciences, Vol.27, No.1&2, pp. 111-124, 2008, DOI:10.3970/cmes.2008.027.111

Abstract A three dimensional micromechanically motivated model is proposed here based on firm thermodynamics principles to capture the nonlinear dissipative effects in the polycrystal ferroelectrics. The constraint imposed by the surrounding grains on a subgrain at its boundary during domain switching is modeled by a suitable modification of the switching threshold in a subgrain. The effect of this modification in the dissipation threshold is studied in the polycrystal behavior after due correlation of the subgrain behavior with the single crystal experimental results found in literature. Taking into consideration, all the domain switching possibilities, the volume fractions More >

B.B. Karki¹, R. Kumar¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.1, pp. 35-42, 2007, DOI:10.3970/icces.2007.003.035

Abstract We report important preliminary results from atomistic simulations of grain boundaries in minerals. The recently developed parallel PCMD (polycrystal molec-ular dynamics) program was used to perform structural optimization. In particular, we have simulated the {310}/[001] symmetric tilt grain boundary of MgO as a function of pressure. The simulation cell containing about 55,000 atoms was used. Visualization of the atomic position-time series data show that the structure changes dramatically on compression from a simple open-structure at zero pressure to a highly dense structure containing high coordination state and a screw-like dislocation at high pressure, consistent with More >

K. Nishimura¹, N. Miyazaki²

CMES-Computer Modeling in Engineering & Sciences, Vol.2, No.2, pp. 143-154, 2001, DOI:10.3970/cmes.2001.002.143

Abstract In this paper, we present a classical molecular dynamics algorithm and its implementation on Cray C90 and Fujitsu VPP700. The characters of this algorithm consist in a grid based on the block division of the atomic system and a neighbor list based on the use of a short range potential. The computer program is used for large scale simulations on a Cray C90 and a 32-node VPP700, and measurements of computational performance are reported. Then, we examine the interaction between a crack propagating and a tilt grain boundary under uniaxial tension using this computer program.… More >