The Experts below are selected from a list of 24 Experts worldwide ranked by ideXlab platform

Yang Yongqian - One of the best experts on this subject based on the ideXlab platform.

  • Symmetrical Mapping of Input Datum in the Calculation of the Sectional Property Parameters for Thin-walled Hull Beam
    Journal of Wuhan University of Technology, 2006
    Co-Authors: Yang Yongqian
    Abstract:

    Calculation of the Sectional Property parameters is one of the main tasks in the assessment of the bending-torsional strength for the large-deck-opening ships.Because of the factor of direction of the shear-flow,the whole section should be discretized for the calculation with enormous inputting datum and complex specification.The symmetrical feature of the hull section and the principle of topology are utilized to implement mapping the input datum for only one half of the section,so as to reduce the work of data preparation and raise the accuracy of calculation.

Gfj Hill - One of the best experts on this subject based on the ideXlab platform.

  • Design of composite helicopter rotor blades to meet given cross-Sectional properties
    The Aeronautical Journal, 2005
    Co-Authors: S.l. Lemanski, Paul M. Weaver, Gfj Hill
    Abstract:

    Abstract This paper examines the design of a composite helicopter rotor blade to meet given cross-Sectional properties. As with many real-world problems, the choice of objective and design variables can lead to a problem with a non-linear and/or non-convex objective function, which would require the use of stochastic optimisation methods to find an optimum. Since the objective function is evaluated from the results of a finite element analysis of the cross section, the computational expense of using stochastic methods would be prohibitive. It is shown that by choosing appropriate simplified design variables, the problem becomes convex with respect to those design variables. This allows deterministic optimisation methods to be used, which is considerably more computationally efficient than stochastic methods. It is also shown that the design variables can be chosen such that the response of each individual cross-Sectional Property can be closely modelled by a linear approximation, even though the response of a single objective function to many design parameters is non-linear. The design problem may therefore be reformulated into a number of simultaneous linear equations that are easily solved by matrix methods, thus allowing an optimum to be located with the minimum number of computationally expensive finite element analyses.

Alexander Epple - One of the best experts on this subject based on the ideXlab platform.

  • Technical Note Improved Computational Strategies for Rotor Blades Presenting High Gradients in Sectional Properties
    Journal of the American Helicopter Society, 2009
    Co-Authors: Olivier A. Bauchau, Alexander Epple
    Abstract:

    Sharp gradients in Sectional Property distributions are inherent to modern rotor blade design and manufacturing practices. The accuracy of finite element models of such rotor blades rapidly degrades if sharp Property gradients occur within a single finite element. To remedy this situation, two techniques are developed: first, a mesh optimization procedure based on a measure of local Sectional Property gradients, and second, a Sectional Property smoothing technique based on conservation arguments for mass properties and energy considerations for stiffness properties. Numerical experimentation shows that the use of both mesh optimization and Sectional Property smoothing considerably reduces computational errors in finite element predictions in the presence of Property gradients and leads to considerably more monotonic convergence characteristics of the computational process. When the proposed techniques are used, computational requirements are decreased because specified levels of accuracy are achieved for models featuring fewer degrees of freedom; furthermore, better accuracy is obtained when evaluating internal force and moment distributions in the blade.

Kathirvelu Baskar - One of the best experts on this subject based on the ideXlab platform.

  • Assessment of Load Carrying Capacity of Thin-Webbed Castellated Beam
    Lecture Notes in Civil Engineering, 2018
    Co-Authors: A. Cyril Thomas, Kathirvelu Baskar
    Abstract:

    Castellated beam (CB) is a type of expanded beam with hexagonal, circular and octagonal openings. This paper reports the nonlinear behaviour of thin-webbed castellated steel beams under different lengths (high, moderate and low shear) and the effect of cut-out geometry. The Sectional Property of the beam is considered as semi-compact by using the ratio of depth of the web (dw) to thickness of the web (tw). The main objective of this study is to understand the prominent failure modes and to propose an equation to find the load carrying capacity of thin-webbed CBs. For obtaining the failure modes and load carrying capacity, finite element models were developed with initial imperfections and material nonlinearities. The parametric study was carried out to propose an empirical equation to find the load carrying capacity of the thin-webbed CBs, and simultaneously the failure modes of CBs were observed and discussed.

Sau Chang Fan - One of the best experts on this subject based on the ideXlab platform.

  • Vibration and stability of cracked hollow-Sectional beams
    Journal of Sound and Vibration, 2003
    Co-Authors: D.y. Zheng, Sau Chang Fan
    Abstract:

    This paper presents simple tools for the vibration and stability analysis of cracked hollow-Sectional beams. It comprises two parts. In the first, the influences of Sectional cracks are expressed in terms of flexibility induced. Each crack is assigned with a local flexibility coefficient, which is derived by virtue of theories of fracture mechanics. The flexibility coefficient is a function of the depth of a crack. The general formulae are derived and expressed in integral form. It is then transformed to explicit form through 128-point Gauss quadrature. According to the depth of the crack, the formulae are derived under two scenarios. The first is for shallow cracks, of which the penetration depth is contained within the top solid-Sectional region. The second is for deeper penetration, in which the crack goes into the middle hollow-Sectional region. The explicit formulae are best-fitted equations generated by the least-squares method. The best-fitted curves are presented. From the curves, the flexibility coefficients can be read out easily, while the explicit expressions facilitate easy implementation in computer analysis. In the second part, the flexibility coefficients are employed in the vibration and stability analysis of hollow-Sectional beams. The cracked beam is treated as an assembly of sub-segments linked up by rotational springs. Division of segments are made coincident with the location of cracks or any abrupt change of Sectional Property. The crack's flexibility coefficient then serves as that of the rotational spring. Application of the Hamilton's principle leads to the governing equations, which are subsequently solved through employment of a simple technique. It is a kind of modified Fourier series, which is able to represent any order of continuity of the vibration/buckling modes. Illustrative numerical examples are included.