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  • Open Access

    ARTICLE

    The Origin and Identity of the Calyculus in Loranthaceae: Inferred From the Floral Organogenesis of Loranthus tanakae Franch. & Sav.

    Ruozhu Lin1, Bei Cui1,2 and Wenxia Zhao1,*

    Phyton-International Journal of Experimental Botany, Vol.88, No.3, pp. 285-293, 2019, DOI:10.32604/phyton.2019.07182

    Abstract The flowers of the hemiparasitic family Loranthaceae are always subtended by a rimmed structure known as the calyculus. The origin and identity of the calyculus have been disputed for more than a century. Various hypotheses have been proposed, for example, an outgrowth of the axis, a reduced calyx, and a bracteolar (prophyllar) origin, but controversies remain. To obtain a plausible explanation of the origin of the calyculus, we investigated the flowers of Loranthus tanakae using scanning electron microscopy and light microscopy to observe the entire developmental process of the floral parts. Our results show that bracts are not present in… More >

  • Open Access

    ABSTRACT

    Elastoplastic Phase Field Model for Time-dependent Hydrogen Diffusion, Hydride (and Blister) Formation and Fracture Initiation in Zirconium

    San-Qiang Shi

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.2, pp. 35-36, 2011, DOI:10.3970/icces.2011.020.035

    Abstract Zirconium and its alloys are key structural materials used in the nuclear power industry. In service, these metals are susceptible to a slow corrosion process that leads to a gradual pickup of hydrogen impurities from the environment. It is well known that hydrogen impurity will be attracted to stress concentrators such as notch and crack tips. At a certain hydrogen level, a complicated pattern of hydride precipitates can develop around these stress concentrators. Because of the brittleness of these hydrides, the original strength of the alloys can be reduced by orders of magnitude, and the fracture through these hydrides may… More >

  • Open Access

    ABSTRACT

    Correlation of Crack Initiation Parameters with Life Estimation for Very-High-Cycle Fatigue of High Strength Steels

    Youshi Hong, Chengqi Sun, Aiguo Zhao

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.016.091

    Abstract The researches on the behavior of very-high-cycle fatigue (VHCF) for high strength steels have become a new branch in the field of metal fatigue since 1980s. The characteristics of crack initiation and propagation for high strength steels in VHCF regime differ from those in low cycle and high cycle fatigue regimes. One of the most distinct phenomena for VHCF regime is the interior or subsurface crack initiation at inclusions or at other inhomogeneities. In fact, the period of crack initiation and early growth dominates the fatigue life, which is extremely evident for the fatigue process containing VHCF regime. This paper… More >

  • Open Access

    ABSTRACT

    Review on Fatigue Crack Initiation Mechanisms of Interior Inclusion-induced Fracture of Metallic Materials in Very High Cycle Regime

    T. Sakai, W. Li, B. Lian, N. Oguma

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 7-8, 2011, DOI:10.3970/icces.2011.016.007

    Abstract Long term use of mechanical products provides us a lot of positive environmental effects such as saving resources, saving energy, reducing environmental load to globe and reducing the industrial wastes. Thus, fatigue property of metallic materials in very high cycle regime such as gigacycles has been a new important subject to ensure the long durability of actual mechanical structures during the latest decades. From this point of view, fatigue tests in the long life regime were performed for various kinds of metallic materials by many researchers and a series of experimental results were reported. One of most typical aspect in… More >

  • Open Access

    ABSTRACT

    Ultrasonic Fatigue Properties of Age-hardened Al Alloy in High Humidity

    Q. Chen, K. Kariya

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.1, pp. 3-4, 2011, DOI:10.3970/icces.2011.016.003

    Abstract Abstract Al alloys have been widely used as engineering materials in many machines and structures because of their excellent properties such as high specific strength, high resistance to corrosion and easy to recycle. Especially, high strength Al alloys are effective to reduce environment load through achieving low fuel consumption in automobile engines. On the other hand, high strength Al alloys have no definite fatigue limit and their fatigue strengths are very low in comparison with their high static strengths. It is important to know the fatigue strength of high strength Al alloys in the long life region beyond 107 cycles… More >

  • Open Access

    ABSTRACT

    Role of Microstructure on Small Fatigue Crack Initiation and Propagation behavior of Rolled and Forged Ti-6Al-4V Alloy

    Hideaki NISHIKAWA*, Yoshiyuki FURUYA

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.22, No.2, pp. 126-126, 2019, DOI:10.32604/icces.2019.05354

    Abstract Fatigue life is determined by microscopic fatigue crack initiation and growth. Since fatigue crack is generally initiated on the slip plane of microstructure and propagated by slip deformation of the crack tip, fatigue life should depends on microstructure. To computationally simulate the effect of microstructure on fatigue property, it is necessary to understand microstructural small fatigue crack initiation and growth behavior. Although Ti-6Al-4V alloy has superior fatigue strength, fatigue strength of forged pancake, used for such as airplane engine, is normally lower than that of rolled alloy. It is possibly comes from microstructural difference, such as micro-texture. However, it is… More >

  • Open Access

    ARTICLE

    A Coupled Mathematical Model of Cell Migration, Vessel Cooption and Tumour Microenvironment during the Initiation of Micrometastases

    Yan Cai1,2,3, Jie Wu4, Zhiyong Li1,2

    Molecular & Cellular Biomechanics, Vol.12, No.4, pp. 231-248, 2015, DOI:10.3970/mcb.2015.012.231

    Abstract We propose a coupled mathematical model for the detailed quantitative analyses of initial microtumour and micrometastases formation by including cancer cell migration, host vessel cooption and changes in microenvironment. Migrating cells are included as a new phenotype to describe the migration behaviour of malignant tumour cells. Migration probability of a migrating cell is assumed to be influenced by local chemical microenvironment. Pre-existing vessel cooption and remodelling are introduced according to the local haemodynamical microenvironment, such as interstitial pressure and vessel wall permeability. After the tumour cells and tumour vessels distribution are updated, the chemical substances are coupled calculated with the… More >

  • Open Access

    ARTICLE

    An FEM study on crack tip blunting in ductile fracture initiation

    N. Ramakrishnan1, P. Rama Rao2

    CMC-Computers, Materials & Continua, Vol.2, No.3, pp. 163-176, 2005, DOI:10.3970/cmc.2005.002.163

    Abstract Ductile fracture is initiated by void nucleation at a characteristic distance (Ic) from the crack tip and propagated by void growth followed by coalescence with the tip. The earlier concepts expressed Ic in terms of grain size or inter-particle distance because grain and particle boundaries form potential sites for void nucleation. However, Srinivas et al. (1994) observed nucleation of such voids even inside the crack tip grains in a nominally particle free Armco iron. In an attempt to achieve a unified understanding of these observations, typical crack-tip blunting prior to ductile fracture in a standard C(T) specimen (Mode I) was… More >

  • Open Access

    ARTICLE

    Cell Method Analysis of Crack Propagation in Tensioned Concrete Plates

    E. Ferretti1

    CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 253-282, 2009, DOI:10.3970/cmes.2009.054.253

    Abstract In this study, the problem of finding the complete trajectory of propagation and the limiting load in plates with internal straight cracks is extended to the non-linear field. In particular, results concerning concrete plates in bi-axial tensile loading are shown. The concrete constitutive law adopted for this purpose is monotonic non-decreasing, as following according to previous studies of the author on monotonic mono-axial loading. The analysis is performed in a discrete form, by means of the Cell Method (CM). The aim of this study is both to test the new concrete constitutive law in biaxial tensile load and to verify… More >

  • Open Access

    ARTICLE

    Masonry Walls under Shear Test: a CM Modeling

    E. Ferretti1, E. Casadio, A. Di Leo1

    CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.3, pp. 163-190, 2008, DOI:10.3970/cmes.2008.030.163

    Abstract In this study, the Cell Method (CM) is applied in order to investigate the failure mechanisms of masonry walls under shear force. The direction of propagation is computed step-wise by the code, and the domain is updated by means of a propagation technique of intra-element nodal relaxation with re-meshing. The crack extension condition is studied in the Mohr/Coulomb plane, using the criterion of Leon. The main advantage of using the CM for numerical analyses of masonry is that the mortar, the bricks and the interfaces between mortar and bricks can be modeled without any need to use homogenization techniques, simply… More >

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