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  • Open Access

    ARTICLE

    Design of auxetic microstructures using topology optimization

    N.T. Kaminakis1, G.E. Stavroulakis1
    Structural Longevity, Vol.8, No.1, pp. 1-6, 2012, DOI:10.3970/sl.2012.008.001
    Abstract Microstructures can lead to homogeneous materials with negative Poisson’s ratio, the so-called auxetics. An automatic way to create such microstructures is provided by topology optimization for compliant mechanisms. Nonconvexity is addressed by a suitable hybrid algorithm, based on differential evolution. This technique is demonstrated in the present paper with numerical examples. More >

  • Open Access

    ARTICLE

    An Experimental Study on Crack Bifurcation by Optical Methods

    S. Suzuki1
    Structural Longevity, Vol.8, No.1, pp. 7-14, 2012, DOI:10.3970/sl.2012.008.007
    Abstract Two kinds of experiments are described on rapid crack bifurcation. One is static experiments with stationary bifurcated cracks. The static experiments demonstrate COD method that measures crack opening displacement, COD, to obtain stress intensity factor of bifurcated cracks. Moirè interferometry is used to measure COD. The other is dynamic experiments on bifurcation of fast propagating cracks. High-speed holographic microscopy is applied to take photographs of rapidly bifurcating cracks and to measure COD of the cracks. The measured CODs give the energy release rate of bifurcating cracks through the COD method developed in the static experiments. The experimental results say that… More >

  • Open Access

    ARTICLE

    Vibrations of circular graphene mono-layer as mass sensor

    A.S. Tsiamaki1, S.K. Georgantzinos1, N.K. Anifantis1
    Structural Longevity, Vol.8, No.1, pp. 15-21, 2012, DOI:10.3970/sl.2012.008.015
    Abstract This paper examines the vibrational behavior of a clamped circular graphene sheet with and without a mass lying on it. For this reason, a springbased finite element (FE) model is formulated and utilized. Interatomic bonded interactions and the relative movements between carbon atoms are simulated via the use of appropriate spring elements expressing the corresponding potential energies provided by molecular theory. The formulated model represents the graphene sheet-additional mass system and is analyzed using FE procedures. The effect of design parameters as the graphene diameter as well as the additional mass magnitude on the vibration characteristics is investigated in order… More >

  • Open Access

    ARTICLE

    Feedback Active Noise Control in a Crew Rest Compartment Mock-Up

    Delf Sachau1
    Structural Longevity, Vol.8, No.1, pp. 23-35, 2012, DOI:10.3970/sl.2012.008.023
    Abstract In the process of creating more fuel efficient aircraft, lightweight materials have found a broad spectrum of applications, especially in the design of aircraft cabin structures. However, in many cases considerations towards acoustic design specifications and work environment regulations require that the previously lightweight structures are treated with heavy and often bulky damping material. In some cases, as with the small rest areas of a crew rest compartment (CRC), this makes the use of active control systems attractive. In this study, the design and application of local active noise control methods in small aircraft cabin areas such as the CRC… More >

  • Open Access

    ARTICLE

    Evaluation of Fatigue Remaining Life of Typical steel plate girder Bridge under Railway Loading

    N. K. Banjara1, S. Sasmal2
    Structural Longevity, Vol.8, No.1, pp. 37-52, 2012, DOI:10.3970/sl.2012.008.037
    Abstract This paper presents various fatigue damage models available in the literature for calculating the damage index due to fatigue loading. Discussion on the effect of load level, load sequence and load interaction on the fatigue damage of the bridges is also presented. Experimental studies conducted to obtain the strain responses at the different critical sections of a typical steel plate girder bridge under railway loadings are briefly described. Strain time histories obtained at different locations including at the weld zone are used to evaluate the fatigue remaining life of the bridge considered in this study. Load spectrum is developed by… More >

  • Open Access

    ARTICLE

    An Approximate Method for Expansion of the Cumulative Distribution Function in the Asymptotic Tails

    Lyuben D. Ivanov1, Justin Y-T. Wu2
    Structural Longevity, Vol.8, No.1, pp. 53-70, 2012, DOI:10.3970/sl.2012.008.053
    Abstract An efficient approximate method is developed for calculation of very small values of a cumulative distribution function (CDF) or probability of exceedance (POE) located in the asymptotic tails of a continuous distribution. Only three properly selected CDF points are needed to model each of the two tails, while a total of nine points are sufficient to interpolate and extrapolate to cover the entire range of the distribution. The approximated CDF is fast to calculate and is exact at the fitting points while providing smooth transitions from point to point as well as from the end points to the extreme tails.… More >

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