• Title/Summary/Keyword: Tool Failure

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A Study on the Characteristic of Acoutic Emission with Concrete Compressive Strength Level (콘크리트 강도수준별 음향방출(Acoustic Emission)의 특성에 관한 연구)

  • 이웅종;이종열;정연식;양승규;한상훈
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.05a
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    • pp.789-794
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    • 2001
  • The acoustic emission(AE) signal from concrete cylinder specimen during failure process under cycling compressive loads were recorded and analyzed. Different filters were set on the AE signal duration based on the characteristic of amplitude distribution. From the value of AE signal amplitude, which corresponds to the occurrence of the peak for AE hits, the AE signals from concrete compressive specimen were divided into five sections. The relationship between the AE signal section and the failure mechanism of these materials, analyzed on the meso-structure level was determined. Based on the experiments, the AE characteristics of each failure mechanism are given. The results show that the AE technique is a valuable tool to study the failure mechanism of concrete.

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A Study on Reliability Prediction for Korea High Speed Train Control System (한국형고속철도 열차제어시스템 하부구성요소 신뢰도예측에 관한 연구)

  • Shin Duc-Ko;Lee Jae-Ho;Lee Kang-Mi;Kim Young-Kyu
    • Journal of the Korean Society for Railway
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    • v.9 no.4 s.35
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    • pp.419-424
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    • 2006
  • In this paper we study on a method to predict and to demonstrate the reliability of the Korea high speed train control system in quantitative point of view. For the prediction of the reliability in train control system which is composed of electronic parts, Relax Software 7.7 automation tool is employed and MIL-HDBK-217 Handbook that is a standard for the prediction of the failure rate in electronic components is used. Mean Time Between Failure (MTBF) is predicted based on the failure rate of the subsystems, State Modeling and Markov Modeling method is used to express a reliability function of the train control system composed by hardware redundancy as a function of time. We propose a Reliability Test which is performed on the level of the subsystems and Failure Report, Analysing, Correction action system which use the test operation data to prove the predicted reliability.

Failure Zone Estimation from the correlation between the Temperature in Slope and the Soil Nail Strain (지중온도와 변형율과의 상관관계를 통한 활동영역의 추정)

  • Chang, Ki-Tae
    • Journal of the Korean Geophysical Society
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    • v.8 no.3
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    • pp.123-130
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    • 2005
  • It is necessary, in the light of the importance of long-term slope stability problem, to develop a simple method or tool which can figure out the possible failure zone resulted from weathering effect and other factors. The FBG sensor system is used to estimate the correlations between the temperature and the slope in Kimhae, and to find a failure zone in slopes effectively. This research is to seek for the correlation between the soil temperature distribution and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the correlation. For instance, the zone of high temperature fluctuation can be regarded as one of the possible sliding zone due to the weathering effect while the constant temperature depth of the ground, if exists would not be relatively affected by the weathering process.

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Analysis of Axial Splitting of Circular Metal Tubes by Using Element Deletion Method (요소 삭제 방법을 사용한 원형 금속 관의 축방향 파단 해석)

  • Lee, Sang-Hoon;Kim, Hyun-Gyu
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.6
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    • pp.496-503
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    • 2008
  • With the improvement of computer power and technology, fracture modelling by finite element methods has become a topic of extensive studies. However, fracture simulation much limited to an academic study of crack propagation with a fine mesh. Element deletion method is a useful tool for estimating damage due to accidental or extreme loads on structures, provided that an effective and realistic criterion is established for simulating the material failure and subsequent element deletion. In this study, ABAQUS/Explicit is used to simulate the material failure on the basis of experimental results by X. Huang et al. Through numerical experiments, we suggest a formulation to determine the failure strain associated with the size and thickness of removed elements.

Numerical modeling and prediction of adhesion failure of adhesively bonded composite T-Joint structure

  • Panda, Subhransu K;Mishra, Pradeep K;Panda, Subrata K
    • Structural Engineering and Mechanics
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    • v.74 no.6
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    • pp.723-735
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    • 2020
  • This study is reported the adhesion failure in adhesive bonded composite and specifically for the T-joint structure. Three-dimensional finite element analysis has been performed using a commercial tool and the necessary outcomes are obtained via an eight noded solid element (Solid 185-element) from the library of ANSYS. The structural analysis input has been incurred through ANSYS parametric design language (APDL) code. The normal and shear stress distributions along different layers of the joint structure have been evaluated as the final outcomes. Based on the stress distributions, failure location in the composite joint structure has been identified by using the Tsai-Wu stress failure criterion. It has been found that the failure index is maximum at the interface between flange and web part of the joint (top layer) which indicates the probable location of failure initiation. This kind of failures are considered as adhesion failure and the failure propagation is governed by strain energy release rate (SERR) of fracture mechanics. The different adhesion failure lengths are also considered at the failure location to calculate the SERR values i.e. mode I fracture (opening), mode II fracture (sliding) and mode III fracture (tearing) along the failure front. Also, virtual crack closure technique (VCCT) principle of fracture mechanics steps is used to calculate the above said SERRs. It is found that the mode I SERR is more dominating compared to other two modes of failure for the joint considered. Finally, the influences of various parametric (geometrical and material) effect on SERR of the joint structure are evaluated and discussed in details.

Tool Lifecycle Optimization using ν-Asymmetric Support Vector Regression (ν-ASVR을 이용한 공구라이프사이클 최적화)

  • Lee, Dongju
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.43 no.4
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    • pp.208-216
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    • 2020
  • With the spread of smart manufacturing, one of the key topics of the 4th industrial revolution, manufacturing systems are moving beyond automation to smartization using artificial intelligence. In particular, in the existing automatic machining, a number of machining defects and non-processing occur due to tool damage or severe wear, resulting in a decrease in productivity and an increase in quality defect rates. Therefore, it is important to measure and predict tool life. In this paper, ν-ASVR (ν-Asymmetric Support Vector Regression), which considers the asymmetry of ⲉ-tube and the asymmetry of penalties for data out of ⲉ-tube, was proposed and applied to the tool wear prediction problem. In the case of tool wear, if the predicted value of the tool wear amount is smaller than the actual value (under-estimation), product failure may occur due to tool damage or wear. Therefore, it can be said that ν-ASVR is suitable because it is necessary to overestimate. It is shown that even when adjusting the asymmetry of ⲉ-tube and the asymmetry of penalties for data out of ⲉ-tube, the ratio of the number of data belonging to ⲉ-tube can be adjusted with ν. Experiments are performed to compare the accuracy of various kernel functions such as linear, polynomial. RBF (radialbasis function), sigmoid, The best result isthe use of the RBF kernel in all cases

A Study on Database System of Road Cut Slope Management (일반국도 절토사면 유지관리 데이터베이스 시스템 개발연구)

  • Koo, Hobon;Baek, Yong;Kim, Jin-Hwan;Bae, Gyu-Jin
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.06a
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    • pp.23-32
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    • 2003
  • In order to reduce the damage of property and the loss of lives caused by slope failure, the development of an efficient cut slope management system and the proposal of an appropriate countermeasure are required. However, recognizing the cause of slope failure and proposing the adequate countermeasure for failure are difficult tasks because slope failure is occurred by many complicated failure reasons. Therefore, the cut slope database system is developed in this study for the effective tool which Is able to analyze the characteristics and relationship for reasons of slope failure. In addition, this system contributes to the curtailment of governmental budget spending for countermeasures of slope. Moreover, GIS system will be adopted to the database system and the investigation of characteristics relationship between one and another area is in progress.

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Analysis of post-failure response of sands using a critical state micropolar plasticity model

  • Manzari, Majid T.;Yonten, Karma
    • Interaction and multiscale mechanics
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    • v.4 no.3
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    • pp.187-206
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    • 2011
  • Accurate estimations of pre-failure deformations and post-failure responses of geostructures require that the simulation tool possesses at least three main ingredients: 1) a constitutive model that is able to describe the macroscopic stress-strain-strength behavior of soils subjected to complex stress/strain paths over a wide range of confining pressures and densities, 2) an embedded length scale that accounts for the intricate physical phenomena that occur at the grain size scale in the soil, and 3) a computational platform that allows the analysis to be carried out beyond the development of an initially "contained" failure zone in the soil. In this paper, a two-scale micropolar plasticity model will be used to incorporate all these ingredients. The model is implemented in a finite element platform that is based on the mechanics of micropolar continua. Appropriate finite elements are developed to couple displacement, micro-rotations, and pore-water pressure in form of unϕm and unpmϕm (n > m) elements for analysis of dry and saturated soils. Performance of the model is assessed in a biaxial compression test on a slightly heterogeneous specimen of sand. The role of micropolar component of the model on capturing the post-failure response of the soil is demonstrated.

Creation and Use of Process oriented Knowledge for Effective FRACAS (효과적인 FRACAS 운용을 위한프로세스 지식의 생성과 활용)

  • Lee, Jae-Hoon;Yoo, Ki-Hoon;Kim, Ki-Young;Seol, Dong-Jin;Jang, Joong-Soon
    • Journal of Applied Reliability
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    • v.8 no.3
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    • pp.113-124
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    • 2008
  • In reliability engineering, failure reporting, analysis, and corrective action system (FRACAS) is an useful tool for effective failure reporting and related operations. FRACAS is generally mainly focused on implementation of its closed-loop process, but also includes various related information which has to be effectively managed such as failure types, failure modes, failure mechanisms, and corrective actions. In this study, we adopt and utilize the concept of process knowledge, and create it through abstraction of FRACAS information. At each step of closed-loop process, the necessary type of knowledge, priority and usability are clearly defined. This study also suggests corresponding management tools such as business process management system, knowledge management system, and their key elements and functions to deal with process knowledge. A prototype system using simple closed-loop process with its process knowledge is presented to demonstrate the feasibility of the proposed work.

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Parametric study of earth dam failure simulation using material point method

  • Dong-Ju Kim;Geunwoo Park;Jong-Sub Lee;Thomas H.-K. Kang;Yong-Hoon Byun
    • Steel and Composite Structures
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    • v.53 no.6
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    • pp.703-715
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    • 2024
  • Aging and heavy rainfall can cause earth dams to undergo failure, which involves large displacements. Due to mesh distortion, however, the finite element method (FEM) is unsuitable for analyzing such large displacements. As an alternative, the material point method (MPM) ensures accurate simulation of large displacements, without the need for remeshing. This study uses MPM to investigate the post-failure behaviors of earth dams with various geometries and under different rainfall intensities. The MPM results are validated by comparing the MPM-derived pore water pressure with FEM-derived values for the same model, and a close alignment is confirmed. Different failure patterns are observed depending on the geometry and rainfall intensity. Under high water levels and rainfall conditions, the distributions and evolutions of the displacements and deviatoric strain are initially concentrated at the dam toe and gradually propagated from the downstream slope toe to the dam crest. Conversely, the distribution of pore water pressure remains relatively constant under high water levels, while rapid changes are observed under rainfall conditions. The runout distance, crest settlement, and sliding volume increase with increasing dam height, decreasing slope ratio, and increasing rainfall intensity. Therefore, MPM can be used as a promising tool for evaluating the entire failure mechanisms and post-failure behaviors of unsaturated earth dams.