• Title/Summary/Keyword: branching angle

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Influence of elastic T-stress on the growth direction of two parallel cracks

  • Li, X.F.;Tang, B.Q.;Peng, X.L.;Huang, Y.
    • Structural Engineering and Mechanics
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    • v.34 no.3
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    • pp.377-390
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    • 2010
  • This paper studies fracture initiation direction of two parallel non-coplanar cracks of equal length. Using the dislocation pile-up modelling, singular integral equations for two parallel cracks subjected to mixed-mode loading are derived and the crack-tip field including singular and non-singular terms is obtained. The kinking angle is determined by using the maximum hoop stress criterion, or the ${\sigma}_{\theta}$-criterion. Results are presented for simple uniaxial tension and biaxial loading. The biaxiality ratio has a noticeable influence on crack growth direction. For the case of biaxial tension, when neglecting the T-stress the crack branching angle is overestimated for small crack inclination angles relative to the largest applied principal stress direction, and underestimated for large crack inclination angles.

Analysis of the Surface Degradation in UV-irradiated High-Temperature Vulcanized Silicone Rubber (자외선 조사된 HTV 실리콘 고무의 표면열화 분석)

  • 연복희;이태호;허창수;이종한
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.5
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    • pp.411-419
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    • 2000
  • In this paper we have investigated the surface degradation by ultraviolet-irradiation in high-temperature vulcanized silicone rubber. Through the measurement of surface potential decay by corona-charging and of contact angle it is found that the change of surface electrostatic properties and the decrease of contact angle under UV-radiation. For the changes in micro-morphological and chemical structure of the UV-treated silicone rubber we utilized several analytical techniques such as SEM, ATR-FTIR,XPS. From this study it is shown that the chemical reactions(scissoring of side chain(S-$CH_3$) cross-linking and branching) occur on the surface of silicone rubber during the UV-irradiation. Also we obtained the results of the loss of low molecular weight chain by cross-linking and oxidation reaction.

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A New Cultivar of Gypsophila paniculata 'Double Shine' with Bright Colored Flower and Strong Stem (줄기가 강하고 밝은 화색의 절화용 안개꽃 '더블샤인' 육성)

  • Cheong, Dong-Chun;Choi, Chang-Hak;Song, Young-Ju;Lim, Hoi-Chun;Kim, Jeong-Man;Lee, Jin-Je;Lee, Jung-Soo
    • Horticultural Science & Technology
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    • v.30 no.1
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    • pp.93-96
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    • 2012
  • 'Double Shine', a cultivar of Gypsophila paniculata was newly developed for the cut flowers by Jeollabuk-do Agricultural Research & Extension Services. It has morphological characteristics of the spreading plant type, double florets of many petals and two pistils, emarginate petal tip and cup shaped calyx. Also 'Double Shine' has several traits such as strong flower stalk, bright colored flower, narrow branching angle and more or less resistance to powdery mildew and pest injury. Furthermore, 'Double Shine' produced higher primary branches, and longer flower stalk length with internodal length and than did a check variety 'Bristol Fairy' during summer cultivation in subalpine areas. Blooming of 'Double Shine' was delayed by 16 days, its floret had broader width, compared to 'Bristol Fairy'. Moreover, 'Double Shine' produced normal flowers with two pistils and 8.5 stamens, with little production of malformed flowers in the high temperature condition.

A New Cultivar of Gypsophila paniculata with Powdery Mildew Resistance and Double Florets of Pink Color, 'Dream Pink' (흰가루병에 강한 분홍색 절화용 안개꽃 '드림핑크' 육성)

  • Cheong, Dong-Chun;Lim, Hoi-Chun;Choi, Chang-Hak;Song, Young-Ju;Kim, Jeong-Man
    • Horticultural Science & Technology
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    • v.29 no.5
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    • pp.500-502
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    • 2011
  • 'Dream Pink', a cultivar of Gypsophila paniculata was newly developed for cut flowers by Jeollabuk-do Agricultural Research & Extension Services. It has morphological characteristics of the intermediate plant type, double florets with many petal and two pistils, emarginate petal tip and campanulate calyx shape. Also 'Dream Pink' had several other traits such as strong flower stalk, deep pink flower color, resistance to powdery mildew and pest injury. Furthermore, 'Dream Pink' produced higher number of nodes, primary branches, longer flower stalk length with long intermodal length. In subalpine area, 'Dream Pink' cultivar showed narrow branching angle as compare to 'My Pink', during the summer cultivation. Blooming in 'Dream Pink' was delayed by 5 days, its florets were broader with more number of petals as compare to 'My Pink'.

Three Ecotypes of Compsopogon coeruleus (Rhodophyta) from Orissa State, East Coast of India

  • Ratha, Sachitra Kumar;Jena, Mrutyunjay;Rath, Jnanendra;Adhikary, Siba Prasad
    • ALGAE
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    • v.22 no.2
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    • pp.87-93
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    • 2007
  • Three ecotypes of the freshwater red alga Compsopogon coeruleus (Balbis) Montagne were recorded from different freshwater and brackish water habitats of Orissa state in the east coast of India. These three had persistent differences in their branching pattern, e.g. (i) acute angle between main axis and lateral branch, (ii) equal or near to right angle between main axis and lateral branch, and (iii) short spine-like outgrowth instead of a branch in older filaments, besides having differences in the length, breadth and thickness of cortex of the thallus. Morphological observation of these taxa, and the ecological characteristics of the habitat of their occurrence is presented.

Exploring Branch Structure across Branch Orders and Species Using Terrestrial Laser Scanning and Quantitative Structure Model (지상형 라이다와 정량적 구조 모델을 이용한 분기별, 종별 나무의 가지 구조 탐구)

  • Seongwoo Jo;Tackang Yang
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.26 no.1
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    • pp.31-52
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    • 2024
  • Considering the significant relationship between a tree's branch structure and physiology, understanding the detailed branch structure is crucial for fields such as species classification, and 3D tree modelling. Recently, terrestrial laser scanning (TLS) and quantitative structure model (QSM) have enhanced the understanding of branch structures by capturing the radius, length, and branching angle of branches. Previous studies examining branch structure with TL S and QSM often relied on mean or median of branch structure parameters, such as the radius ratio and length ratio in parent-child relationships, as representative values. Additionally, these studies have typically focused on the relationship between trunk and the first order branches. This study aims to explore the distribution of branch structure parameters up to the third order in Aesculus hippocastanum, Ginkgo biloba, and Prunus yedoensis. The gamma distribution best represented the distributions of branch structure parameters, as evidenced by the average of Kolmogorov-Smirnov statistics (radius = 0.048; length = 0.061; angle = 0.050). Comparisons of the mode, mean, and median were conducted to determine the most representative measure indicating the central tendency of branch structure parameters. The estimated distributions showed differences between the mode and mean (average of normalized differences for radius ratio = 11.2%; length ratio = 17.0%; branching angle = 8.2%), and between the mode and median (radius ratio = 7.5%; length ratio = 11.5%; branching angle = 5.5%). Comparisons of the estimated distributions across branch orders and species were conducted, showing variations across branch orders and species. This study suggests that examining the estimated distribution of the branch structure parameter offers a more detailed description of branch structure, capturing the central tendencies of branch structure parameters. We also emphasize the importance of examining higher branch orders to gain a comprehensive understanding of branch structure, highlighting the differences across branch orders.

Crown Architecture of Pinus densiflora in Canopy Gap of Natural Forests at Mt. Joongwang in Kangwon-do (강원도(江原道) 중왕산(中旺山) 지역(地域) 소나무 천연림(天然林)내 숲틈 갱신(更新) 소나무의 수관(樹冠) Architecture)

  • Jin, Young Huan;Lee, Don Koo
    • Journal of Korean Society of Forest Science
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    • v.89 no.5
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    • pp.543-551
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    • 2000
  • This study was conducted to understand Pinus densiflora regeneration characteristics from canopy gaps due to disturbance in natural forests located at Mt. Joongwang in Kangwon-do. The line-transect method was adopted to analyze crown architecture of Pinus densiflora. The saplings of Pinus densiflora in the canopy gap showed high adaptation to growth environment at their early regeneration stage, and showed different characteristics in crown architecture. Variation of branching angle in the main branch of Pinus densiflora was small in canopy gap. Primary branch growth showed was high during 4~5 year-old period and slowly low after that period. Average 5 of primary branch were generated from stem in canopy. Average 4 of secondary branch were generated from primary branch in canopy gap. Primary branches generated from the stem were uniformly distributed at all cardinal directions. When canopy gap size is $100{\sim}120m^2$, secondary branches generated from primary branch had mostly high numbers between $S44^{\circ}E$ and $S90^{\circ}W$.

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Effects by the Magnitude of Shear Load on the Formation and Propagation of Mode II Branch Cracks (전단하중의 크기가 모드 II 분기균열의 형성과 전파에 미치는 영향)

  • 이정무;송삼홍
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.487-490
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    • 2004
  • In this paper, we investigated the characteristics of initiation and propagation behavior for fatigue crack observed by changing various shapes of initial crack and magnitudes of loading in modified compact tension shear(CTS) specimen subjected to shear loading. In the low-loading condition, the secondary fatigue crack was created in the notch root due to friction on the pre-crack face grew to a main crack. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Influenced by the shear loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. The propagation path of fatigue crack under the Mode II loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

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Intensity Factors for a Branched Crack in a Semi-Infinite Plate Under Tension and Bending Moments (인장과 굽힘을 받는 반 무한 평판내의 분기균열에 대한 강도계수)

  • 김유환;범현규;박치용
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.461-464
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    • 2000
  • A branched crack in a semi-infinite plate under tension and bending moment is considered. Intensity factors of the stress and moment for the branched crack are evaluated. The stress intensity factors are obtained by using the finite element method and the J-based mutual integral. The moment intensity factors are calculated by extrapolating the values of the moment near the crack tip. Approximate expressions are also obtained as functions of the branched crack length and branching angle.

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The Characteristics of Fatigue Crack Propagation Behavior in Shear Load (전단하중 하의 피로균열 전파거동의 특징)

  • Lee, Jeong-Moo;Song, Sam-Hong
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.302-307
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    • 2004
  • This paper reviewed characteristics of fatigue crack behavior observed by changing various shapes of initial crack and magnitudes of loading in compact tension shear(CTS) specimen subjected to shear loading. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Meanwhile, the secondary fatigue crack in the low-loading condition which was created in the notch root due to friction on the pre-crack face grew to a main crack. Influenced by the mode II loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. Propagation path of fatigue crack under the shear loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

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