• Title, Summary, Keyword: brittle solids

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Natural Element Analysis on Micro-cracking Behavior of Brittle Solids (취성 재료의 마이크로 크랙킹 거동에 관한 자연요소해석)

  • Kang, Sung-Soo
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.6
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    • pp.724-730
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    • 2006
  • Fracture behavior of brittle solids is closely related to microcracking. A meso-scale analysis method using the natural element method is proposed for the analysis of brittle microcracking solids. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The meso-analysis method is applied to the simulation of the microcracking behaviors of brittle solids subjected to tensile macrostress. The method is also applied to the analysis of the propagation of a macrocrack accompanied by the coalescence with microcracks formed near the macrocrack-tip.

Analysis of Microcracking Behaviors of Solids under Multiple-Loading Conditions (다양한 하중 상태에서의 마이크로 크랙킹 거동 해석)

  • Kang, Sung-Soo;Kim, Hong-Gun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.2
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    • pp.23-29
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    • 2007
  • Fracture behavior of brittle solids such as rocks, ceramics and concrete is closely related to microcracking. A meso-scale analysis method using the natural element method is proposed for the analysis of material damage of brittle microcracking solids. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The proposed meso analysis method is applied to the simulation of the microcracking behaviors of brittle solids subjected to uniaxial and biaxial macrostress. The obtained results are in good agreement with the results by computational damage mechanics model. The validity of the proposed method has been demonstrated by these numerical examples.

Dynamic fracture instability in brittle materials: Insights from DEM simulations

  • Kou, Miaomiao;Han, Dongchen;Xiao, Congcong;Wang, Yunteng
    • Structural Engineering and Mechanics
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    • v.71 no.1
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    • pp.65-75
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    • 2019
  • In this article, the dynamic fracture instability characteristics, including dynamic crack propagation and crack branching, in PMMA brittle solids under dynamic loading are investigated using the discrete element method (DEM) simulations. The microscopic parameters in DEM are first calibrated using the comparison with the previous experimental results not only in the field of qualitative analysis, but also in the field of quantitative analysis. The calibrating process illustrates that the selected microscopic parameters in DEM are suitable to effectively and accurately simulate dynamic fracture process in PMMA brittle solids subjected to dynamic loads. The typical dynamic fracture behaviors of solids under dynamic loading are then reproduced by DEM. Compared with the previous experimental and numerical results, the present numerical results are in good agreement with the existing ones not only in the field of qualitative analysis, but also in the field of quantitative analysis. Furthermore, effects of dynamic loading magnitude, offset distance of the initial crack and initial crack length on dynamic fracture behaviors are numerically discussed.

Reliability evaluation of brittle structures under thermal shocks (열충격이 작용하는 취성구조의 신뢰성 평가)

  • 이치우;장건익;김종태
    • Journal of Ocean Engineering and Technology
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    • v.12 no.1
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    • pp.58-64
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    • 1998
  • An analysis method for the reliability of ceramic structures subjected to thermal shocks is presented. Flaws with the size of given probability distribution function are assumed to be distributed at random with a certain density per unit volume in the structures. Criterions for crack instability are derived for brittle solids under general thermal stresses. A probabilistic failure model is presented to study the probability of crack instability for brittle solids containing cracks with uncertain size. The reliabilities of brittle structures are evaluated based on the weakest-link hypothesis, which states that a structure fails when the cracks in any differential volume become unstable. A numerical example is given to demonstrate the application of the proposed method.

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Lateral Crack in Abrasive Wear of Brittle Solids (취성소재 연삭마멸에서의 측면균열에 관한 연구)

  • 안유민;박상신;최상현
    • Tribology and Lubricants
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    • v.15 no.1
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    • pp.46-51
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    • 1999
  • An analytical model about lateral crack occurring in abrasive wear of brittle solids is developed. Stress field around the lateral crack and stress intensity factor at the crack tip are analytically modeled. Abrasive wear by abrasive particle is experimentally studied. In soda-lime glass, it is observed that chipping by lateral crack occurs and produces the greatest material removal when normal load applied by the abrasive particle is about 1.5∼3.0 N. The prediction of lateral crack length from the model is compared with the experimentally measured length in soda-lime glass.

Reliability Evaluation of Ceramic Structures Under Thermal Shocks (열충격이 작용하는 세라믹구조의 신뢰성 평가)

  • 김종태;심확섭;장건익;이치우;이환우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.954-958
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    • 1996
  • An analysis method for the reliability of ceramic structures subjected to thermal shocks is presented, Flaws with the size of given probability distribution function are assumed to be distributed at random with a certain density per unit volume in the structures. Criterions for crack instability are derived for brittle solids under general thermal stresses. A probabilistic failure model is presented to study the probability of crack instability for blittle solids containing cracks with uncertain crack size. The reliabilities of brittle structures are evaluated based on the weakest-link hypothesis, which states that a structure fails when the cracks in any differential volume become unstable. A numerical example is given to demonstrate the application of the proposed method.

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Natural Element Analysis on Macro Elastic Moduli for Materials with Micro-cracks (마이크로 크랙을 포함한 재료의 매크로 탄성 정수에 관한 자연요소해석)

  • Kang, Sung-Soo
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.6
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    • pp.716-723
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    • 2006
  • A meso-scale analysis method using the natural element method is proposed for the analysis of material damage of brittle microcracking solids. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the micorcracks. The macro elastic moduli of isotropic solids containing a number of randomly distributed microcracks are calculated considering the effect of microcrack closure to demonstrate the validity of the proposed method.

An Evaluation of the Effect of Micro-cracks on Macro Elastic Moduli (매크로 탄성 계수에 미치는 마이크로 크랙의 영향 평가)

  • Kang, Sung-Soo;Kim, Hong-Gun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.5
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    • pp.97-103
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    • 2006
  • A meso-scale analysis method using the natural element method, which is a kind of meshless method, is proposed for the analysis of material damage of brittle microcracking solids such as ceramic materials, concrete and rocks. The microcracking is assumed to occur along Voronoi edges in the Voronoi diagram generated using the nodal points as the generators. The mechanical effect of microcracks is considered by controlling the material constants in the neighborhood of the microcracks. The macro elastic moduli of anisotropic as well as isotropic solids containing a number of randomly distributed microcracks are calculated in order to demonstrate the validity of the proposed method.

Elasto-Plastic Dynamic Analysis of Solids by Using SPH without Tensile Instability (인장 불안정이 제거된 SPH을 이용한 고체의 동적 탄소성해석)

  • Lee, Kyoung Soo;Shin, Sang Shup;Park, Taehyo
    • Journal of The Korean Society of Civil Engineers
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    • v.31 no.2A
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    • pp.71-77
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    • 2011
  • In this paper elasto-plastic dynamic behavior of solid is analyzed by using smoothed particle hydrodynamics (SPH) without tensile instability which caused by a clustering of SPH particles. In solid body computations, the instability may corrupt physical behavior by numerical fragmentation which, in some cases of elastic or brittle solids, is so severe that the dynamics of the system is completely wrong. The instability removed by using an artificial stress which introduces negligible errors in long-wavelength modes. Applications to several test problems show that the artificial stress works effectively. These problems include the collision of rubber cylinders, fracture and crack of plate.

Plasticity of Amorphous Alloys: 1. Homogeneous Deformation (비정질 합금의 소성 1: 균일변형)

  • Park, Kyoung-Won;Lee, Chang-Myeon;Lee, Jae-Chul
    • Korean Journal of Metals and Materials
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    • v.47 no.11
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    • pp.759-772
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    • 2009
  • Amorphous alloys, in addition to being promising materials for a variety of practical applications, provide an excellent test bed for evaluating our understanding of the underlying physics on deformation in amorphous solids. Like many amorphous materials, amorphous alloys can exhibit either homogeneous or inhomogeneous deformation depending on the stress level. The mode of deformation has a strong influence on whether the material behavior is classified as ductile or brittle. It was observed that the characteristics of these deformations are largely dependent on the atomic-scale structures of the alloys and determine the amount of the plastic deformation prior to failure. In this study, the structural features that control the homogeneous deformation of amorphous alloys are outlined on the basis on experiments and molecular dynamics simulations.