• 제목/요약/키워드: Computational mechanics

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A framework for geometrically non-linear gradient extended crystal plasticity coupled to heat conduction and damage

  • Ekh, Magnus;Bargmann, Swantje
    • Multiscale and Multiphysics Mechanics
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    • 제1권2호
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    • pp.171-188
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    • 2016

  • Gradient enhanced theories of crystal plasticity enjoy great research interest. The focus of this work is on thermodynamically consistent modeling of grain size dependent hardening effects. In this contribution, we develop a model framework for damage coupled to gradient enhanced crystal thermoplasticity. The damage initiation is directly linked to the accumulated plastic slip. The theoretical setting is that of finite strains. Numerical results on single-crystalline metal showing the development of damage conclude the paper.

  • https://doi.org/10.12989/mmm.2016.1.2.171 인용

Application of Computational Mineralogy to Studies of Hydroxyls in Clay Minerals (전산광물학을 이용한 점토광물 내의 수산기 연구 가능성)

  • Chae, Jin-Ung;Kwon, Kideok D.
    • Journal of the Mineralogical Society of Korea
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    • 제27권4호
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    • pp.271-281
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    • 2014

  • The physicochemical properties of clay minerals have been investigated at the atomistic to nano scale. The microscopic studies are often challenging to perform by using experimental approaches alone. In particular, hydroxyl groups of octahedral sheets in 2:1 clay minerals have been hypothesized to impact the sorption process of metal cations; however, X-ray based techniques alone, a common tool for mineral structure examination, cannot properly test the hypothesis. The current study has examined whether computational mineralogy techniques can be applied to examine the hydroxyl structures of clay minerals. Based on quantum-mechanics and molecular-mechanics computational methods, geometry optimizations were carried out for representative dioctahedral and trioctahedral phyllosilicate minerals. Both methods well reproduced the experimental lattice parameters; however, for structural distortion occurring in the tetrahedral or octahedral sheets, molecular mechanics showed significant deviations from experimental data. The orientation angle of the hydroxyl with respect to (001) basal plane is determined by the balance of repulsion between the hydroxyl proton and Si cations of tetrahedral sites; the quantum-mechanics method predicted $25-26^{\circ}$ for the angle, whereas the angle predicted by the molecular-mechanics method was much higher by $10^{\circ}$ (i.e., $35^{\circ}$). These results demonstrate that computational mineralogy techniques are a reliable tool for clay mineral studies and can be used to further elucidate the roles of hydroxyls in metal sorption process.

  • https://doi.org/10.9727/jmsk.2014.27.4.271 인용 PDF KSCI

Homogenization based continuum damage mechanics model for monotonic and cyclic damage evolution in 3D composites

  • Jain, Jayesh R.;Ghosh, Somnath
    • Interaction and multiscale mechanics
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    • 제1권2호
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    • pp.279-301
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    • 2008

  • This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

  • https://doi.org/10.12989/imm.2008.1.2.279 인용