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  • Open Access

    ARTICLE

    Isogeometric Shape Optimal Design of Elastic Structures under Design-dependent Loads

    Seonho Cho1, Seung-Hyun Ha, Bonyong Koo, Minho Yoon, Seung-Ho Ahn
    Structural Longevity, Vol.6, No.3, pp. 109-114, 2011, DOI:10.3970/sl.2011.006.109
    Abstract Using an isogeometric approach, a continuum-based shape optimization method is developed for elasticity problems. To obtain efficient and precise adjoint shape sensitivity, precise normal and curvature information should be taken into account in shape sensitivity expressions, especially for design-dependent problems. In this approach, the basis functions generated from NURBS are directly used to construct a geometrically exact model in response and shape sensitivity analyses. Refinements and design changes are easily implemented within the isogeometric framework. The isogeometric design sensitivity analysis provides more accurate sensitivity of complex geometries including higher order terms such as normal and curvature. Also, it vastly simplifies… More >

  • Open Access

    ARTICLE

    Determination of Physical Properties of Euler Bernoulli Beam via the Method of Inverse Vibration Problem

    Murat Balcı1, Ömer Gündoˇgdu2
    Structural Longevity, Vol.6, No.3, pp. 115-126, 2011, DOI:10.3970/sl.2011.006.115
    Abstract In this study, some physical properties of an Euler–Bernoulli beam was tried to be estimated by using the method of inverse vibration problem. The Euler –Bernoulli beam was first modeled and simulated on the ANSYS program for different boundary condition to obtain data to be used as experimental input to the optimization program aroused during the solution of inverse problem. An numerical model of the Euler-Bernoulli beam with unknown parameters was also developed using a two-dimensional finite element model. Then, these two models were embedded into the optimization program to form the objective function to be minimized using genetic algorithms.… More >

  • Open Access

    ARTICLE

    Study on Dynamic Energy Absorption Ability of Closed-cell Si-Al Foam Metals Considering Geometry Size

    Yishan Pan1, Xiangfeng Lv, Zhonghua Li, Xiaochun Xiao
    Structural Longevity, Vol.6, No.3, pp. 127-132, 2011, DOI:10.3970/sl.2011.006.127
    Abstract Geometry size has a great influence on energy absorption ability of closed-cell foam metals. Study on energy absorption ability of closed-cell Si-Al foam metals considering geometry size by impact experiment method. The results show that the strain and absorbing energy value are decreasing with the geometry size increasing, and also lead to the hole wall rupture or whole instability. The best height-width ratio for cube and cylinder are 1.0–1.5 and 1.0–2.0, respectively. With the increasing of material diameter, the compressive strength increasing quickly, but the strain reduces. It is clearly that height-width ratio 1.0 is better for cube and cylinder. More >

  • Open Access

    ARTICLE

    Numerical and Theoretical Studies of the Buckling of Shape Memory Tape Spring

    Zhengfa Li1, Weibin Song, Zhengdao Wang
    Structural Longevity, Vol.6, No.3, pp. 133-143, 2011, DOI:10.3970/sl.2011.006.133
    Abstract By using the high froze/recovery strains of shape memory polymers to meet the requirements of deployable space structures, the folding behavior of shape memory tape spring consisting of shape memory polymer and metal spring was analyzed. Firstly, numerical simulations were performed on the buckling modes and affecting factors under the equal- and opposite-sense bends. The results show that the folding deformations of such structure in the two cases are completely different. The equal-sense bending leads to the structure buckled abruptly, but gradual torsion buckling is received in the case of opposite-sense bending. The critical bending moments have big difference in… More >

  • Open Access

    ARTICLE

    Size and Composition Dependence of the Frozen Structures in Co-Based Bimetallic Clusters

    Guojian Li1, Qiang Wang1, Yongze Cao1, Jiaojiao Du1, Jicheng He1
    Structural Longevity, Vol.6, No.3, pp. 145-154, 2011, DOI:10.3970/sl.2011.006.145
    Abstract This paper studies the size-dependent freezing of Co, Co-Ni, and CoCu clusters by using molecular dynamics with a general embedded atom method. There is size effect occurs in these three types of clusters. The clusters with large sizes always freeze to form their bulk-like structures. However, the frozen structures for small sizes are generally related to their compositions. The icosahedral clusters are formed for Co clusters (for ≤3.2 nm diameter) and also for Co-Ni clusters but at a larger size range (for ≤4.08 nm). Upon Co-Cu clusters, decohedral structure is obtained for small size (for 2.47 nm). The released energy… More >

  • Open Access

    ARTICLE

    Theory, Analysis and Design of Fluid-Shell Structures

    Lakis A. A.1,2, Toorani M. H.1, Kerboua Y.1, Esmailzadeh M.1, Sabri F.1
    Structural Longevity, Vol.6, No.3, pp. 155-185, 2011, DOI:10.3970/sl.2011.006.155
    Abstract This paper review focuses mainly on development and application of a hybrid finite element approach used for linear and geometrically nonlinear vibration analysis of isotropic and anisotropic plates and shells, with and without fluidstructure interaction. Development of a hybrid element for different geometries of plates and shells is briefly discussed. In addition, studies dealing with particular dynamic problems such as dynamic stability and flutter of plates and shells coupled to flowing fluids are also discussed. This paper is structured as follows: after a short introduction on some of the fundamentals of the developed model applied to vibrations analysis of shells… More >

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