• Title/Summary/Keyword: crack density

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Analysis of ITO on Polymer Substrate by External Bending Force

  • Han, Jin-Woo;Kim, Young-Hwan;Kim, Jong-Hwan;Hwang, Jeoung-Yeon;Seo, Dae-Shik
    • Transactions on Electrical and Electronic Materials
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    • v.6 no.4
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    • pp.149-153
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    • 2005
  • In this paper, we investigated the island density-dependent stress distribution of indium-tin-oxide (ITO) film on polycarbonate substrate by external bending force. We used e-beam and RF­sputter for SiON, ITO sputtering. It was found that there are influence of island density on the substrate and decreasing crack density as goes to the minimum density. From the result that crack density was increasing at maximum island density, it is evident that more stress is imposed on same island position as island density.

A Study on Fatigue Crack Propagation Behavior in Random Short-Fiber SMC Composites (비규칙 단섬유강화 SMC 복합재료의 피로균열 전파거동에 관한 연구)

  • Kim, Jae-Dong;Koh, Sung-Wi
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.26 no.2
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    • pp.204-212
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    • 1990
  • The SMC composite, now being considered in certain structural applications, is anticipated to experience repeated loading during service. Thus, understanding of the fatigue behavior is essential in proper use of the composite material. In this paper, using the SMC composite composed of E-glass chopped strand and unsaturated polyester resin three point bending fatigue tests are carried out to investigate the fatigue crack propagating behavior under various cyclic stresses and fatigue damage of various microcrack forms. The following results are obtained from this study; 1) Most of the total fatigue life of the SMC composite is consumed at the initial extension or the growth of the macroscopic crack. 2) A Paris' type power-law relationship between the crack propagation rate and stress intensity factor range is obtained, and the value of material constant m is much higher (m=9~11)than that of other metals. 3) In case of high cyclic stress the fatigue damage show high microcrack density and short crack length, but in case of low cyclic stress does it vice versa. 4) Fatigue damage is characterized by microcrack density, crack length and distribution of crack orientation.

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Simulation Analysis on the Property of Crack Propagation and Growth at High Tension Steel Plate (고장력 강판에서의 크랙 전파 및 성장특성에 대한 시뮬레이션 해석)

  • Kang, Byungmok;Kim, Jengo;Lee, Jaehoon;Cho, Jaeung;Han, Moonsik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.23 no.5
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    • pp.471-477
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    • 2015
  • In this study, the property of crack propagation and growth at high tension steel plate existed with center crack is investigated. The behaviors of fracture mechanics due to existence or not of hole near the center crack in specimen and the length of crack length are investigated when the load is applied at the one side end of specimen. Stress, deformation and deformation of this specimen are evaluated through simulation analysis. By the analysis results at this study, stress intensity factors are obtained. The damage happened at machine or structure with crack or defect can be estimated on the basis of study results.

On the mixed-mode crack propagation in FGMs plates: comparison of different criteria

  • Nabil, Benamara;Abdelkader, Boulenouar;Miloud, Aminallah;Noureddine, Benseddiq
    • Structural Engineering and Mechanics
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    • v.61 no.3
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    • pp.371-379
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    • 2017
  • Modelling of a crack propagating through a finite element mesh under mixed mode conditions is of prime importance in fracture mechanics. In this paper, two crack growth criteria and the respective crack paths prediction in functionally graded materials (FGM) are compared. The maximum tangential stress criterion (${\sigma}_{\theta}-criterion$) and the minimum strain energy density criterion (S-criterion) are investigated using advanced finite element technique. Using Ansys Parametric Design Language (APDL), the variation continues in the material properties are incorporated into the model by specifying the material parameters at the centroid of each finite element. In this paper, the displacement extrapolation technique (DET) proposed for homogeneous materials is modified and investigated, to obtain the stress intensity factors (SIFs) at crack-tip in FGMs. Several examples are modeled to evaluate the accuracy and effectiveness of the combined procedure. The effect of the defects on the crack propagation in FGMs was highlighted.

Application of the Static Photoelastic Experimental Hybrid Method to the Crack Propagation Criterion for Isotropic Materials (등방성체의 균열전파 기준에 정적 광탄성 실험 하이브리드 법 적용)

  • Shin Dong-Chul;Hawong Jai-Sug;Nam Sung-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.8 s.227
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    • pp.1229-1236
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    • 2004
  • The specimen materials used in this research are isotropic epoxy resins. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (r) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of isotropic epoxy resin.

A Study on the Interfacial Crack Propagation Criterion for Two Dissimilar Isotropic Bimaterial by the Static Photoelastic Experimental Hybrid Method (정적 광탄성 실험 하이브리드 법에 의한 두 상이한 등방성 이종재료의 계면균열전파 기준에 관한 연구)

  • Tche, Konstantin;Hawong, Jai-Sug;Shin, Dong-Chul;Nam, Sung-Su;Nam, Jeong-Hwan
    • Proceedings of the KSME Conference
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    • 2003.11a
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    • pp.1216-1221
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    • 2003
  • The specimen materials used in this research is bimaterial. The static photoelastic experiment was applied to them. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic hybrid method was introduced and it's validity had been assured. The static photoelastic hybrid method was applied to the Minimum Strain Energy Density Criterion, the Maximum Tangential Stress Criterion and Mode Mixity. Crack propagation criterion by the static photoelastic hybrid method was introduced and it was applied to the above various failure theories. Comparing the experimental initial angle of crack propagation with the theoretical initial angle of crack propagation from the various failure criterions. And then the optimal crack propagation criterion was suggested and it's validity was assured.

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A Study on the Crack Propagation Criterion of Orthotropic Material by the Static Photoelastic Experimental Hybrid Method (정적 광탄성 실험 하이브리드법에 의한 직교이방성체의 균열전파 기준에 관한 연구)

  • Shin, Dong-Chul;Hawong, Jai-Sug;Nam, Sung-Su;Kwon, O-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.28 no.11
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    • pp.1799-1806
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    • 2004
  • The static photoelastic experiment was applied to orthotropic materials. And then the specimens used in photoelastic experiment were fractured under static load. The static photoelastic experimental hybrid method for orthotropic material was introduced and its validity had been assured. Crack propagation criterion used the stress components, which are considered the higher order terms, obtained from the static photoelastic experimental hybrid method was introduced and it was applied to the minimum strain energy density criterion, the maximum tangential stress criterion and mode mixity. Comparing the actual initial angle of crack propagation with the theoretical initial angle of crack propagation obtained from the above failure criterions, the validities of the above two criterions are assured and the optimal distance (${\gamma}$) from the crack-tip is 0.01mm in order to get the initial angle of crack propagation of orthotropic material(C.F.E.C.).

Study on a rational repair and reinforcement by analysis of crack density in OO subway (지하철 터널 균열밀도 분석을 통한 합리적인 보수보강 방안 연구)

  • Yoon Tae-Gook;Shin Yong-Suk;Ahn Sang-Ro;Lee Song
    • 한국터널공학회:학술대회논문집
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    • 2005.04a
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    • pp.262-269
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    • 2005
  • The priority order about a rational repair and reinforcement is generally decided by subjective decision of engineer. An appearance investigation by tunnel scanner that is widely used in foreign nation was carried out to decide about a rational repair and reinforcement through systematic and objective analysis in box and NATM tunnel. We have decided on the order of priority of an rational repair and reinforcement through the crack density analysis by span, distance and location with the result of tunnel scanner.

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Effects of Non-Woven Tissue on the Mechanical Behavior of Angle-Ply Laminates (부직포가 예각 적층판의 기계적 거동에 미치는 효과)

  • 정성균
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.6
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    • pp.109-115
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    • 2001
  • This paper investigates the mechanical characteristics of angle-ply laminates with non-woven carbon tissue. The lami- nates were made by inserting non-woven carbon tissue at the interface. Specimens were rounded near the tabs by grinding and polishing to reduce the stress concentration. Cyclic loads were applied to the specimens and the stress and fatigue life curves were obtained. The matrix crack density was also evaluated to check the effects of non-woven carbon tissue on the fracture resistance of composite laminates. C-Sean technique was used to evaluate the delamination, and SEM was used to understand the fracture mechanisms of the laminates. Experimental results show that the fatigue strength and life of composite laminates were increased by inserting non- woven carbon tissues. The results also show that the matrix crack density and delamination area were reduced by inserting non-woven carbon tissues.

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Strategy for refinement of nodal densities and integration cells in EFG technique

  • Patel, Bhavana S.S.;Narayan, Babu K.S.;Venkataramana, Katta
    • Structural Engineering and Mechanics
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    • v.59 no.5
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    • pp.901-920
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    • 2016
  • MeshFree methods have become popular owing to the ease with which high stress gradients can be identified and node density distribution can be reformulated to accomplish faster convergence. This paper presents a strategy for nodal density refinement with strain energy as basis in Element-Free Galerkin MeshFree technique. Two popular flat plate problems are considered for the demonstration of the proposed strategies. Issue of integration errors introduced during nodal density refinement have been addressed by suggesting integration cell refinement. High stress effects around two symmetrical semi-circular notches under in-plane axial load have been addressed in the first problem. The second considers crack propagation under mode I and mode II fracture loading by the way of introducing high stress intensity through line crack. The computational efficacy of the adaptive refinement strategies proposed has been highlighted.