• Title/Summary/Keyword: Failure Length

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Linear regression analysis for factors influencing displacement of high-filled embankment slopes

  • Zhang, Guangcheng;Tan, Jiansong;Zhang, Lu;Xiang, Yong
    • Geomechanics and Engineering
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    • v.8 no.4
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    • pp.511-521
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    • 2015
  • It is a common failure type that high-filled embankment slope sideslips. The deformation mechanism and factors influencing the sideslip of embankment slope is the key to reduce the probability of this kind of engineering disaster. Taking Liujiawan high-filled embankment slope as an example, the deformation and failure characteristics of embankment slope and sheet-pile wall are studied, and the factors influencing instability are analyzed, then the correlation of deformation rate of the anti-slide plies and each factor is calculated with multivariate linear regression analysis. The result shows that: (1) The length of anchoring segment is not long enough, and displacement direction of embankment and retaining structure are perpendicular to the trend of the highway; (2) The length of the cantilever segment is so large that the active earth pressures behind the piles are very large. Additionally, the surface drainage is not smooth, which leads to form a potential sliding zone between bottom of the backfill and the primary surface; (3) The thickness of the backfill and the length of the anti-slide pile cantilever segment have positive correlation with the deformation whereas the thickness of anti-slide pile through mudstone has a negative correlation with the deformation. On the other hand the surface water is a little disadvantage on the embankment stability.

Simulation of the tensile behaviour of layered anisotropy rocks consisting internal notch

  • Sarfarazi, Vahab;Haeri, Hadi;Ebneabbasi, P.;Bagheri, Kourosh
    • Structural Engineering and Mechanics
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    • v.69 no.1
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    • pp.51-67
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    • 2019
  • In this paper, the anisotropy of tensile behaviours of layered rocks consisting internal notch has been investigated using particle flow code. For this purpose, firstly calibration of PFC2D was performed using Brazilian tensile strength. Secondly Brazilian test models consisting bedding layer was simulated numerically. Thickness of layers was 10 mm and layered angularity was $90^{\circ}$, $75^{\circ}$, $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. The strength of bedding interface was too high. Each model was consisted of one internal notch. Notch length is 1 cm, 2 cm and 4 cm and notch angularities are $60^{\circ}$, $45^{\circ}$, $30^{\circ}$, $15^{\circ}$ and $0^{\circ}$. Totally, 90 model were tested. The results show that failure pattern was affected by notch orientation and notch length. It's to be noted that layer angle has not any effect on the failure pattern. Also, Brazilian tensile strength is affected by notch orientation and notch length.

Initial Crack Length Effect for the Interlaminar Mode I Energy Release Rate on a Laminated UHMWPE/CFRP Hybrid Composite (UHMWPE/CFRP 적층하이브리드 복합재의 층간 Mode I 에너지해방율에 미치는 초기균열길이의 영향)

  • Song, Sang Min;Kang, Ji Woong;Kwon, Oh Heon
    • Journal of the Korean Society of Safety
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    • v.34 no.3
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    • pp.1-7
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    • 2019
  • A variety of composite materials are applied to industries for the realization of light weight and high strength. Fiber-reinforced composites have different strength and range of application depending on the weaving method. The mechanical performance of CFRP(Carbon Fiber Reinforced Plastic) in many areas has already been demonstrated. Recently, the application of hybridization has been increasing in order to give a compensation for brittleness of CFRP. Target materials are UHMWPE (Ultra High Molecular Weight Polyethylene), which has excellent cutting and chemical resistance, so it is applied not only to industrial safety products but also to places that lining performance is expected for household appliances. In this study, the CFRP and UHMWPE of plain weave, which are highly applicable to curved products, were molded into laminated hybrid composite materials by autoclave method. The mechanical properties and the mode I failure behavior between the layers were evaluated. The energy release rate G has decreased as the initial crack length ratio increased.

A Study on Shape Optimization for Buckling and Postbuckling Behavior of Stiffened Laminated Composite Panels (보강된 복합적층 패널의 좌굴 및 좌굴후 거동의 형상 최적설계에 관한 연구)

  • Lee, Gwang-Rok;Jeong, Gi-Hyeon;Heo, Seong-Pil;Yang, Won-Ho;Jo, Myeong-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.1
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    • pp.106-114
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    • 2001
  • In this study, a shape optimization of stiffener was conducted to increase buckling load or failure load in each case with a different design value and a different objective function for stiffened laminated composite panel of I-type under compression loading. Regarding each of buckling load or failure load as objective function, optimum design was carried out. In respect of optimum design, the effects of relative length of web and cab of stiffener on buckling load or failure load of postbuckling were investigated.

Study on the Reliability of Engineering Ceramics (구조용 세라믹스 강도의 신뢰성 평가에 관한 연구)

  • 김부안;남기우
    • Journal of the Korean Ceramic Society
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    • v.34 no.2
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    • pp.157-162
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    • 1997
  • Silicon Nitride samples with different microstructure were prepared by hot pressing and subsequent heat treatment under N2 gas pressure. The fracture toughness (KIC)of Si3N4 increased with the increase of grain size, but the bending strength of plain specimen($\sigma$F) decreased. The relation between fracture stress($\sigma$c) and equivalent crack length(ae) agreed well with the calculated values by process zone size failure criterion. A probabilistic failure assessment curve is proposed based on both statistical character of $\sigma$F and KIC.

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Failure Behavior of Piercing Plug during Seamless Tube Manufacturing Process (심리스 튜브 제조공정 시 피어싱 플러그의 파손거동)

  • Lim, Young-Bin;Yoon, Jeong-Mo
    • Journal of the Korean Society for Heat Treatment
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    • v.30 no.5
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    • pp.207-214
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    • 2017
  • In this study, failure behavior of piercing plug for seamless tube manufacturing process was studied. Three different kinds of passed piercing plugs (10, 90, 215 times) were prepared. The shape deformation of the passed piercing plugs was observed by 3D coordinate measuring machine, and the oxidized layer on the surface of piercing plug was observed by optical microscopy. The length reduction of piercing plug presented at 215 times passed plug. It was found that the oxidized layer consisted of outer scale, inner scale and internal oxidation layers, and the inner scale layer had vertical cracks, and interfaces had horizontal cracks. We proposed the failure mechanism of piercing plug during seamless tube manufacturing process based on the formation of vertical and horizontal crack.

Fault-Tolerant Gait Generation of Hexapod Robots for Locked Joint Failures (관절고착고장에 대한 육각 보행 로봇의 내고장성 걸음새 생성)

  • Yang Jung-Min
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.54 no.3
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    • pp.131-140
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    • 2005
  • Fault-tolerant gait generation of a hexapod robot with crab walking is proposed. The considered fault is a locked joint failure, which prevents a joint of a leg from moving and makes it locked in a known position. Due to the reduced workspace of a failed leg, fault-tolerant crab walking has a limitation in the range of heading direction. In this paper, an accessible range of the crab angle is derived for a given configuration of the failed leg and, based on the principles of fault-tolerant gait planning, periodic crab gaits are proposed in which a hexapod robot realizes crab walking after a locked joint failure, having a reasonable stride length and stability margin. The proposed crab walking is then applied to path planning on uneven terrain with positive obstacles. i.e., protruded obstacles which legged robots cannot cross over but have to take a roundabout route to avoid. The robot trajectory should be generated such that the crab angle does not exceed the restricted range caused by a locked joint failure.

Failure Mode and Failure Strength of Homogeneous Metals & Dissimilar Metals Bonded Single Lap-Shear Joints (동종금속 및 이종금속 단일 겹침 접착 시편의 파손모드 및 파손강도에 관한 연구)

  • Park, Beom Chul;Chun, Heoung-Jae;Park, Jong Chan
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.32 no.1
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    • pp.1-5
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    • 2019
  • In this paper, the experimental study and finite elements analysis were conducted on homogeneous and dissimilar metals single lap-shear bonded joints to investigate the factor that affect the joint failure load. It was found that factors which have the significant effects on the failure load of the joint was stiffness of the adherends. And from experimental results, it can be confirmed that the failure load increases linearly with overlap length increases. And the failure load of dissimilar metal joints is approximately 1KN(10~17%) larger than homogeneous metal joints. In order to confirm this phenomenon, the stress distribution and strain distribution of the specimens were analyzed through the finite element analysis. The difference between homogeneous metals joints and dissimilar metals joints is that stress and strain in adhesive are concentrated at the end of the overlap zone close to aluminium which has lower rigidity than aluminium in case of dissimilar metals joints. From high rigidity of steel, the stress concentration in bonds are decreased and it cause increase of the failure strength at dissimilar metal joints.

Fracture Behaviors of Headed Bars with Different Plate Types (플레이트 형상에 따른 Headed Bars의 파괴거동에 관한 연구)

  • 박현규;윤영수;류영섭;이만섭
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.935-940
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    • 2002
  • This paper presents the failure mode on Headed Bars and prediction of tensile capacity, which is governed by concrete cone failure. 17 different plate types, three different concrete strengths and three different welding types of specimens were simulated. Static tensile load was applied Headed Bars were manufactured in different areas, and their shape and thickness are based on ASTM 970-98. Calculation of embedment length in concrete is conducted based on CSA 23.3-94, and static tensile load was applied. Tested pullout capacities were compared to the values determined using current design methods such as ACI-349 and CCD method.

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Mechanical Property of Polymer mortar Pipes (폴리머 모르터 원형관의 역학적 특성)

  • 연규석;함형길;김관호;김성순
    • Proceedings of the Korea Concrete Institute Conference
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    • 1993.10a
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    • pp.256-260
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    • 1993
  • The circular pipe was developed using polymer mortar. Pipe (inside diameter=170 mm and length=1,000 mm was made to evaluate structural performance. The average failure load for the pipes which were reduced its thickness by 41% was 2,000 kg which was higher than that of conventional concrete pipe of the same size. Reinforcement using glass fiber fabric highly increased the failure load, up to 9,500 kg.

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