• Title, Summary, Keyword: Failure

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New Flexural Failure Mechanisms for Uniform Compression Stress Fields (균일한 압축장에 대한 새로운 휨 형태의 파괴 매캐니즘)

  • 홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.546-551
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    • 1997
  • New typology of failure mechanisms for uniform compression fields are presented based on the classical theory of plasticity, in particular th normality rule, and the limit theorem. The concrete is assumed as a rigid-perfectly plastic material obeying the modified Coulomb failure criteria with zero tension cut-off. The failure mechanisms are capable of explaining flexural types of crushing failure in uniaxial uniform compression stress fields which are called struts in truss models. The failure mechanisms consist of sliding failure along straight failure lines or hyperbolic failure curves and rigid body rotation. The failure mechanisms involving straight failure lines are explained by constant strain expansion in the first principal direction and rigid body rotation motion. The failure mechanisms presented are applied to the explanation of bond failure of bar combined with concrete crushing failure and flexural crushing failure of concrete.

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Fractography of the Wood Materials Ruptured by Shear Stress (구조용 목질재료의 전단파괴기구 해명을 위한 파면해석적 연구)

  • ;Juichi Tsutsumi
    • Journal of the Korea Furniture Society
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    • v.10 no.1
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    • pp.23-32
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    • 1999
  • The ultrastructural characteristics of shear fracture surfaces of laminated wood prepared from major four Korea wood specimens were examined. Commercial urea and urethan resin were used as adhesives for laminated woods of both homospecies and heterospecies. The morphology of fracture surface was observed using an optical microscopy and scanning electron microscopy. Three anatomical failure types were recognized : intercell failure, intrawall failure and transwall failure. In dry specimen, failure occurred mainly in woods. Laminated woods of softwoods showed mostly intrawall failure and transwall failure of tracheids, and them of hardwoods indicated mainly intrawall failure and interwall failure. Laminated woods prepared with urethan resin showed coarse fracture surface, on the other hand, those prepared with an urea formaldehyde resin had clean surface. In wet specimen, failure occurred dominantly in glue line. Intrawall failure and flags were characterized in laminated wood prepared with urethan resin. In heterospecies laminated woods, failure was occurred mainly in softwood. Consequently, fracture morphology of laminated wood may be influenced by adhesives, moisture content, species and anatomical characteristics.

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An Exploratory Research for the Conceptualization Failure knowledge (실패지식의 개념화를 위한 탐색적 연구)

  • Shim, Hyungseok
    • Knowledge Management Research
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    • v.12 no.4
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    • pp.121-132
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    • 2011
  • Failure, the research object, means situations when goals and their results are different, which has developed presenting various aspects from ancient times and modern times. Failure is a complex concept which essentially requires judgement, and also a relative concept which can be changed depending on how you set up time base and standard. There are four stages for failure study to have been developed from studying failure through historical facts to the approach of organizational theory and it has been studied by looking at the failure of an organization according to different categories such as a developmental stage, a type of business, a period and a course. Compared with success science, failure study has not been studied sufficiently and also the level of its analysis is low. Thus, since lessons of failure tend to repeat themselves instead of being didactically accumulated, there need more studies on this. This thesis identified the main cause of the failure through various studies regarding failure which have been conducted at home and abroad. What the main cause of the failure that more than three studies mentioned have in common was that it occurred because organizations concentrated on the inside without communicating with external environment. The key point of failure study is to analyze failure, utilize it as assets, and create a frame of failure management. This thesis focused on delivering fragmentary knowledge on failure study, but case studies regarding this subject should be done in the future.

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Major causes of failure and recent measurements of tunnel construction (터널시공 중 붕락발생 원인과 최신 보강기술)

  • Park, Bong-Ki;Hwang, Je-Don;Park, Chi-Myeon;Kim, Sang-Su
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.140-153
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    • 2005
  • During the tunnel construction the major failure mode can be categorized as: tunnel failure just after the tunnel excavation without support, failure after application of shotcrete and finally failure after setting the concrete lining. The failure mode just after the tunnel excavation without support, can be further classified as : bench failure, crown failure, face failure, full face failure, failure due to weak strata and failure due to overburden. Moreover the failure after application of shotcrete is classified as heading face failure, settlement of shotcrete support, local failure of shotcrete lining and invert shotcrete. To find out the major causes of tunnel collapse, the investigation was done in case of the second phase of Seoul subway construction. The investigation results depicted that the major causes of tunnel collapse were due to the weak layer of rock/fault and sudden influx of ground water from the tunnel crown. While the investigation results of the mountain road tunnels construction have shown that the major causes of tunnel failure were inadequate analysis of tunnel face mapping results, intersection of faults and limestone cavities. In this paper some recent measurement in order to mitigate such tunnel collapse are presented

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Estimation of Failure Probability Using Boundary Conditions of Failure Pressure Model for Buried Pipelines (파손압력모델의 경계조건을 이용한 매설배관의 파손확률 평가)

  • Lee, Ouk-Sub;Kim, Eui-Sang;Kim, Dong-Hyeok
    • Proceedings of the KSME Conference
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    • pp.310-315
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    • 2003
  • This paper presents the effect of boundary condition of failure pressure model for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function is used in order to estimate the probability of failure associated with various corrosion defects for long exposure periods in years. A failure pressure model based on a failure function composed of failure pressure and operation pressure is adopted for the assessment of pipeline failure. The effects of random variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress, material ultimate tensile strength and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the corrosion pipeline.

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Analysis of Influence Factors Related to Failure Characteristics of Excavated Slopes ; A Case of Southern Kyounggi Area along the Nat과l Road (절취 사면의 파괴 특성과 관련된 영향 요인 분석 ; 경기도 남부 국도 사례)

  • 김정환;윤운상;최재원
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.277-284
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    • 1999
  • This study describes the influence factors related to slope failure pattern and dimension in the southern Kyounggi area. Intrusive and metamorphic rocks are distributed in the study area. Geological condition, rainfall property and slope geometry are influence on slope failure characteristics in the study we& Geological factors related to slope failure are rock type, geological structure and weathering condition. Because of deep soil (RS-CW) depth of granite region, circular failure type is major failure pattern in granite region. Almost granite slopes with circular or surface failure pattern are failed during heavy rainfall season. But typical wedge failure type related to geological structure factor is a main failure pattern of metamorphic rock slope. Additionally failure dimension is influenced by geological factors and several factors, i.e. natural slope condition, failure type, rainfall intensity and etc. failure height/width ratio and thickness/length ratio of granite slope are 0.88 and 0.23. But the ratios of metamorphic rock slope are 1.36 and 0.19.

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Remarks on Education Method to Turn Failure Experience to Instructions for Engineering Design

  • Arimitsu, Yutaka;Yagi, Hidetsugu
    • Journal of Engineering Education Research
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    • v.13 no.2
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    • pp.74-77
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    • 2010
  • This article proposes to examine how the study of failure differs from other technical subjects, and how to turn failure experiences to one's advantage. The authors surveyed the properties of failures in PBL (Project Based Learning) and also examined students' interest and understanding of failure, after introducing failure examples. To investigate how students communicate failure experiences to third parties, reports of the failure experience in PBL were evaluated. From above mentioned surveys, we get the following results. The typical causes of failure in educational institutions are lack of skill in manufacturing and inadequate planning, which conversely are minor causes of failure in the industry. A knowledge database on failure, employed commonly in industry, is not effective in PBL, because projects in educational institutes are usually changed every year. Case studies in failure can be approached from many points of view including causes, processes, effects and safety measures. While teachers should emphasize the notable points in the failure examples in introducing examples of specific topics in machine design, teachers should explain the multiple aspects in the failure examples to educate students about the complexity of actual accidents.

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Progressive Failure Analysis and Strength Prediction based on Hashin Failure Criterion of Bolted Composite Joint (Hashin 파손이론을 이용한 복합재 볼트체결부의 점진적 파손 해석 및 강도 예측)

  • Kim, Seongmin;Kim, Pyunghwa;Doh, Sungchul;Kim, Hyounggun;Park, Jungsun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.936-938
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    • 2017
  • In this paper, the progressive failure analysis of a bolted composite joint which is used in combustion tubes of projectiles and weapon systems is performed. Hashin's failure criterion is considered as fiber tensile failure mode, fiber compressive failure mode, matrix tensile failure mode, and matrix compressive failure mode for this analysis. And this criterion is used to make user subroutine, UMAT. Through the progressive failure analysis we predicted failure strength and compared failure strength with specimen test result.

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Comparing the generalized Hoek-Brown and Mohr-Coulomb failure criteria for stress analysis on the rocks failure plane

  • Mohammadi, M.;Tavakoli, H.
    • Geomechanics and Engineering
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    • v.9 no.1
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    • pp.115-124
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    • 2015
  • Determination of mobilized shear strength parameters (that identify stresses on the failure plane) is required for analyzing the stability by limit equilibrium method. Generalized Hoek-Brown (GHB) and Mohr-Coulomb (MC) failure criteria are usually used for obtaining stresses on the plane of failure. In the present paper, the applicability of these criteria for determining the stresses on failure plane is investigated. The comparison is based on stresses on the real failure plane which are obtained from the Mohr stress circle. To do so, 18 sets of data (consist of principal stresses and angle of failure plane) presented in the literature are used. In addition, the values account for (VAF) and the root mean square error (RMSE) indices were calculated to check the determination performance of the obtained results. Values of VAF and RMSE for the normal stresses on the failure plane evaluated from MC are 49% and 31.5 where for GHB are 55% and 30.5, respectively. Also, for the shear stresses on failure plane, they are 74% and 36 for MC, 76% and 34.5 for GHB. Results show that the obtained stresses and angles of failure plane for each criterion differ from real ones, but GHB results are closer to the empirical results. Also, it is inferred that results are affected by the failure envelope not real failure plane. Therefore, obtained shear strength parameters are not mobilized. Finally, a multivariable regressed relation is presented for determining the stresses on the failure plane.

Premature failure Criteria of RC Beams Strengthened with FRP II (FRP보강 RC보의 조기파괴기준 II)

  • Kim, Tae-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.141-144
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    • 2005
  • Rip-off failure and Debonding failure were commonly reported premature failure modes. The main reasons of premature failure in RC beams bonded with FRP were strengthening length and the reinforcement ratio. in this study, On the basis of premature failure mechanism in RC beams bonded with FRP, premature failure criteria were proposed. Also It was verified that Rip-off failure and Debonding failure occured according to premature failure criteria

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