• Title/Summary/Keyword: fractured surface

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Robust surface segmentation and edge feature lines extraction from fractured fragments of relics

  • Xu, Jiangyong;Zhou, Mingquan;Wu, Zhongke;Shui, Wuyang;Ali, Sajid
    • Journal of Computational Design and Engineering
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    • v.2 no.2
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    • pp.79-87
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    • 2015
  • Surface segmentation and edge feature lines extraction from fractured fragments of relics are essential steps for computer assisted restoration of fragmented relics. As these fragments were heavily eroded, it is a challenging work to segment surface and extract edge feature lines. This paper presents a novel method to segment surface and extract edge feature lines from triangular meshes of irregular fractured fragments. Firstly, a rough surface segmentation is accomplished by using a clustering algorithm based on the vertex normal vector. Secondly, in order to differentiate between original and fracture faces, a novel integral invariant is introduced to compute the surface roughness. Thirdly, an accurate surface segmentation is implemented by merging faces based on face normal vector and roughness. Finally, edge feature lines are extracted based on the surface segmentation. Some experiments are made and analyzed, and the results show that our method can achieve surface segmentation and edge extraction effectively.

A Study on the Failure Mechanism of Turbine Blade using X-Ray Diffraction and FEM (X선 회절과 유한요소법을 이용한 터빈 블레이드의 파괴기구에 관한 연구)

  • Kim, Seong-Ung;Hong, Sun-Hyeok;Jeon, Hyeong-Yong;Jo, Seok-Su;Ju, Won-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.8
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    • pp.1645-1652
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    • 2002
  • The failure analysis on fractured parts is divided into the qualitative method by naked eyes and metallurgical microscope etc. and the quantitative method by SEM and X-ray diffraction etc. X-ray fractography can be applied to contaminated surface as well as clean surface and gain the plastic deformation and the residual stress near the fractured surface. Turbine blade is subject to cyclic bending force by steam pressure and suffers fatigue damage according to the increasing operating time. Therefore, to clean up the fracture mechanism of torsion-mounted blade in nuclear plant, the fatigue and the X-ray diffraction test was performed on the 12%Cr steel fur turbine blade and the fractured parts. The correlation of X-ray parameter and fracture mechanics parameter was determined, and then the load applied to actual broken turbine blade was predicted. Failure analysis was performed by contact stress analysis and Goodman diagram of torsion-mounted blade.

A Study on Failure Analysis of Turbine Blade using AFM and FEM (AFM과 유한요소법을 이용한 터빈 블레이드의 파손해석에 관한 연구)

  • 최우성;이동우;홍순혁;조석수;주원식
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.489-493
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    • 2000
  • Turbine blade has trouble of cracking at root region. Fracture surface of blade root is surveyed by SEM and AFM to clear relation between fracture mechanical parameter and surface parameter (striation width and surface roughness). Service stress is predicted by maximum height roughness $R_{max}$, on fractured surface and stress analysis on turbine blade. It is to thought that turbine blade is fractured by abnormal condition such as incorrect fittings between pin and pin hole but isn't fractured by normal service conditions such as steam pressure, centrifugal force and torsional force.

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Slope Stability Analysis for Compound slope (복합사면의 사면안정해석에 관한 연구)

  • Shin, Eun-Chul;Kim, Jin-Soo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2010.03a
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    • pp.1279-1285
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    • 2010
  • Our country has a tendency to build many structures by cutting mountainous areas due to geographical features. Among these construction done in our country, road construction take the first spot in rank. As the construction is done, fractured inclining plane is created inevitability because of the natural properties of mountainous areas. The stability of the fractured inclining planes and slope formed in the opening, which are developed at the time of construction, need to be evaluated. Also, reinforcement plans for these matters are necessary. This paper is to go through an examination on the fractured inclining surface that is developed at the time of construction, especially the composite inclining plane that consists of soil and rocks. Furthermore, evaluating the stability by performing an analysis on stereographic projection and limit equilibrium, based on the examination results. using the stability evaluations, applications were explored for reinforcement methods of construction that fits the geological characters of this inclining surface.

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Application of black box model for height prediction of the fractured zone in coal mining

  • Zhang, Shichuan;Li, Yangyang;Xu, Cuicui
    • Geomechanics and Engineering
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    • v.13 no.6
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    • pp.997-1010
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    • 2017
  • The black box model is a relatively new option for nonlinear dynamic system identification. It can be used for prediction problems just based on analyzing the input and output data without considering the changes of the internal structure. In this paper, a black box model was presented to solve unconstrained overlying strata movement problems in coal mine production. Based on the black box theory, the overlying strata regional system was viewed as a "black box", and the black box model on overburden strata movement was established. Then, the rock mechanical properties and the mining thickness and mined-out section area were selected as the subject and object respectively, and the influences of coal mining on the overburden regional system were discussed. Finally, a corrected method for height prediction of the fractured zone was obtained. According to actual mine geological conditions, the measured geological data were introduced into the black box model of overlying strata movement for height calculation, and the fractured zone height was determined as 40.36 m, which was comparable to the actual height value (43.91 m) of the fractured zone detected by Double-block Leak Hunting in Drill. By comparing the calculation result and actual surface subsidence value, it can be concluded that the proposed model is adaptable for height prediction of the fractured zone.

Analysis on the Fatigue Fracture Surface of Gas Piping Material using the X-Ray Fractography (X-선 프랙토그라피에 의한 가스배관재의 피로파면해석)

  • Lim, Man-Bae
    • Journal of the Korean Society of Safety
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    • v.17 no.1
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    • pp.18-24
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    • 2002
  • This study verified the relationship between fracture mechanics parameters(${\Delta}K,\;K_{max}$) and X-ray parameters ($(\sigma}_r,;B$) for G365 steel at elevated temperature up to $300{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase in low ${\Delta}K$ region, reach to a maximum value at a certain value of $K_{max}$ or ${\Delta}K$ and then decrease. Residual stress was independent on stress ratio by arrangement of ${\Delta}K$ and half value breadth was independent by the arrangement of $K_{max}$. The equation of ${\sigma}_r-{\Delta}K$ was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

Evaluation of Flexural strength and surface porosity of three indirect composite resins (3종의 간접수복용 복합레진의 굴곡강도 비교 및 표면관찰)

  • Kim, Jun-Tae;Park, Jin-Young;Kim, Woong-Chul;Kim, Ji-Hwan
    • Journal of Technologic Dentistry
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    • v.39 no.1
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    • pp.9-16
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    • 2017
  • Purpose: The purpose of this study was to evaluate flexural strength, composite surface and fractured surface of three different indirect composite resins. Methods: Fifteen bar-shaped specimens ($25mm{\times}2mm{\times}2mm$) were fabricated for each FL group (Flow type and Light curing) and PLP group (Putty type and Light, Pressure curing) and PL group (Putty type and Light curing) according to manufacturer's instructions and ISO 10477. Fabricated specimens were stored in the distilled water for 24 hours at the temperature of $37^{\circ}C$. Three-point bending strength test was performed to measure flexural strength using universal testing machine at a crosshead speed of 1mm/min (ISO 10477). Surface and fractured surface of specimens were observed by digital microscope. Results were analyzed with Kruskal-wallis tests (${\alpha}=0.05$). Results: Mean (SD) of three different indirect composite resins were 83.38 (6.67) MPa for FL group, 139.90(16.53) MPa for PLP group and 171.72(16.74) MPa for PL group. Flexural strength were statistically significant (p<0.05). Differences were not observed at fractured surface among three groups. However, many pores over $100{\mu}m$ were observed at PL group in observing surface of specimen. Conclusion: Flexural strength of composite resins was affected by second polymerization method and content of inorganic filler.

EFFECT OF SURFACE TREATMENT ON BOND STRENGTH OF PORCELAIN LAMINATE VENEER TO ENAMEL (Laminate Veneer용 도재의 표면처리가 치질과의 결합강도에 미치는 영향)

  • Ban, Yong-Seok;Chung, Hyun-Gon;Hong, Soon-Ho
    • The Journal of Korean Academy of Prosthodontics
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    • v.29 no.1
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    • pp.255-264
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    • 1991
  • The purpose of this study was to evaluate the effect of the shear bond strength between porcelain laminate veneer and enamel according to the surface treatment and thermocycling. Group I, as a control group, was sandblasted only; group II was sandblasted and etched; group III was sandblasted and silane treated; and group IV was sandblasted, etched and silane treated. A porcelain block was placed onto the etched enamel under a 150g static load and the bonded site was light-cured from 4 directions for 1 minute each. The 72 bonded specimens were stored in water at $37^{\circ}C$ for 1 day. Half of each group were thermocycled at $4^{\circ}C$ and $60^{\circ}C$ for 100 cycles with a dwelling time in each bath of 1 min. Following thermocycling, the specimens were installed in an Instron universal testing machine and the shear bond strength was measured. After the specimens were fractured, the fractured surfaces were examined with SEM. The obtained results were as follows : 1. The shear bond strength of the sandblasted and etched and silane treated group(Group IV) was the strongest of all, and the shear bond strengths between the sandblasted group(Group I) and the sandblasted and silane treated group(Group III) were not statistically different(p>0.05). 2. When the shear bond strength was measured after thermocycling, only the sandblasted, etched and silane treated group(Group IV) was statistically different(p<0.05). 3. The scanning electron microscopic views of the fractured surfaces show more irregularities and more resin fragments in the etched group than in the unetched group. 4. The scanning electron microscopic views of the fractured surfaces show a more delicate surface after thermocycling and after silane treatment than before thermocycling and before silane treatment.

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Effect of size and slope angle of tooth-shaped asperity on shear fracturing characteristics (삼각형 돌출부의 크기 및 경사각이 전단파괴 형상 특성에 미치는 영향)

  • Kim, Won-Keun;Choi, Woo-Yong;Park, Jong-Deok;Lee, Seok-Won
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.15 no.4
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    • pp.431-442
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    • 2013
  • Most of previous studies have insufficiently investigated the shear behavior and fracturing characteristics, experimentally in respect to the change of size of tooth-shaped surface asperity such as length and slope angle in a broad range. This study investigates the influence of the length and slope angle of a tooth-shaped surface asperity on the fracturing characteristics and the interface shear strength by using direct shear test apparatus. A total of 36 interface direct shear tests were conducted by changing the three types of slope angle of surface asperity, four type of length, and three types of normal stress. The shape of fractured surface after the test was quantified by using a three-dimensional surface roughness measurement apparatus. Through the experimental test results, the characteristics of fractured shape of surface asperity according to the normal stress were investigated. In addition, fractured length and height were quantified at each slope angle of surface asperity under a certain normal stress condition.

A Study on the Analysis of Fatigue-fractured Surface of Aluminium for Aircraft (항공기용 Al의 피로파면 분석에 관한 연구)

  • Joo, Won-Kyung;Kwun, Yong-Gu;Bae, Sung-In;Song, Jung-Il
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.274-278
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    • 2007
  • The purpose of this study is to analyze the important loads related with crack-growth in aircraft. Al Alloys mainly used in aircraft are Al2024 and Al7075 in Duralumin. In random fatigue loading, it has been understood crack-growth characteristic using fractured surface photograph by SEM. In order to obtained CTOD, we measured a crack size in wing frame part. As a result of fatigue experiment that accumulating plenty of fatigue loadings, we find more cracks than that produces in the same fatigue loading. The important loads relating to crack-growth was found in the largest strain cycle. Applying strain block in fatigue experiment, it is actually loading in connection of aircraft. In conclusion, These results can be used for preventing an accident owing fatigue-fracture in aircraft.

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