The Experts below are selected from a list of 60123 Experts worldwide ranked by ideXlab platform

Jung Youn Lee - One of the best experts on this subject based on the ideXlab platform.

  • free vibration analysis of functionally graded bernoulli euler Beams using an exact transfer matrix expression
    International Journal of Mechanical Sciences, 2017
    Co-Authors: Jung Woo Lee, Jung Youn Lee
    Abstract:

    Abstract In this paper, we developed an exact transfer matrix method to analyze the free vibration characteristics of a functionally graded Beam. The transfer matrix for the functionally graded Beam is deduced from the relationship of the displacements and forces at both ends of the Beam. Because the results obtained from the present method are independent of the number of subdivisions, this method can be used as a useful tool to produce the natural frequencies and mode shapes for such problems in which material properties such as the elastic modulus and density are assumed to vary continuously along the height direction of the Beam Cross-Section depending on a power-law form. The use of functionally graded materials leads to a sixth-order differential equation because of the coupling of the axial and bending displacements, and its effect is analyzed by varying the length to height ratio. The calculated natural frequencies to demonstrate the accuracy of the proposed method are compared with those discussed in previous papers. The various analyses for the natural frequencies and mode shapes of functionally graded Beams are performed via a parametric study. In addition, the effect of the power-law index on the eigenpairs of functionally graded Beams connected by two elements with different top and bottom properties is examined.

Rhys Pullin - One of the best experts on this subject based on the ideXlab platform.

  • correlation between acoustic emission distribution and stress variation through the depth of rc Beam Cross Sections
    Construction and Building Materials, 2017
    Co-Authors: Simeng Liu, Matthew R Pearson, Mark Jonathan Eaton, Rhys Pullin
    Abstract:

    Abstract Two established techniques for monitoring concrete under loading are Acoustic Emission (AE) and strain gauges. The distribution of strain, along with that of stress, on a Beam Cross Section is well established both theoretically and experimentally. However, the AE distribution through the depth of the Cross Section has received little attention previously. In addition, the correlation between the AE distribution and that of stress on the Section could provide valuable insight into the condition of a structure. Therefore, these topics are experimentally addressed in this article. Specifically, six Reinforced Concrete (RC) Beams were tested. AE and Digital Image Correlation (DIC) were employed to monitor the Beams during loading. Finally, the AE and stress distributions were analysed. The results showed that AE parameters are capable of characterising behaviours of RC Beams in the depth direction. Furthermore, the distribution of AE events strongly correlated with that of compressive stress, especially in the post-reinforcement yielding stage. According to these findings, it is highly possible to estimate stress levels of RC Beam structures in engineering and science by adopting the AE technique.

Aleksandr Bekshaev - One of the best experts on this subject based on the ideXlab platform.

  • localization and migration of phase singularities in the edge diffracted optical vortex Beams
    Journal of Optics, 2016
    Co-Authors: Aleksandr Bekshaev, Aleksey Chernykh, Anna Khoroshun, Lidiya Mikhaylovskaya
    Abstract:

    When a circularly-symmetric light Beam with optical vortex (OV) diffracts at an opaque screen with the sharp edge, the OV core is displaced from the Beam axis and, in case of the m-charged incident OV, decomposed into |m| single-charged ones. By means of numerical simulations and based on examples of incident Beams with topological charges |m| = 1, 2, 3 we show that, while the screen edge monotonously advances towards the Beam axis, the OVs in the diffracted Beam Cross Section move away from the incident Beam axis along spiral-like trajectories. The trajectories contain fine structure details that reflect the nature and peculiar spatial configuration of the diffracting Beam. For the Kummer Beams' diffraction, the trajectories contain self-Crossings and regions of 'backward' rotation (loops); in the case of Laguerre–Gaussian Beams, the trajectories are smoother. The numerical results are supported by analytical approximations and conform to experiments. The general shape of the trajectories and their local behavior show high sensitivity to the diffraction conditions (spatial structure of the diffracting Beam, its disposition with respect to the screen edge, etc), which can be used in diverse metrological applications.

  • localization and migration of phase singularities in the edge diffracted optical vortex Beams
    arXiv: Optics, 2015
    Co-Authors: Aleksandr Bekshaev, Aleksey Chernykh, Anna Khoroshun, Lidiya Mikhaylovskaya
    Abstract:

    When a circularly-symmetric light Beam with optical vortex (OV) diffracts at an opaque screen with the sharp edge, the OV core is displaced from the Beam axis and, in case of the m-charged incident OV, decomposed into |m| single-charged ones. By means of numerical simulations and based on examples of incident Beams with topological charges |m| =1, 2, 3 we show that, while the screen edge monotonously advances towards the Beam axis, the OVs in the diffracted Beam Cross Section move away from the incident Beam axis along spiral-like trajectories. The trajectories contain fine structure details that reflect the nature and peculiar spatial configuration of the diffracting Beam. For the Kummer Beams' diffraction, the trajectories contain self-Crossings and regions of "backward" rotation (loops); in case of Laguerre-Gaussian Beams, the trajectories are smoother. The numerical results are supported by analytical approximations and conform with experiment The general shape of the trajectories and their local behavior show high sensitivity to the diffraction conditions (spatial structure of the diffracting Beam, its disposition with respect to the screen edge, etc.), which can be used in diverse metrological applications.

  • rotational transformations and transverse energy flow in paraxial light Beams linear azimuthons
    Optics Letters, 2006
    Co-Authors: Aleksandr Bekshaev, M S Soskin
    Abstract:

    Paraxial Beams whose transverse structure rotates upon free propagation (spiral Beams) can be treated as analogs of azimuthons recently found in nonlinear media [Phys. Rev. Lett.95, 203904 (2005)]. These linear azimuthons have essentially a nonlocalized character and can possess an almost arbitrary rotation rate independent of the angular momentum of the Beam. Such Beams can be assimilated into fluent mechanical bodies with intrinsic mass flows determined by transverse energy redistribution over the Beam Cross Section.

Gengkai Hu - One of the best experts on this subject based on the ideXlab platform.

  • a finite element Beam model including Cross Section distortion in the absolute nodal coordinate formulation
    Nonlinear Dynamics, 2014
    Co-Authors: Zhenxing Shen, Pei Li, Gengkai Hu
    Abstract:

    A new class of Beam finite elements is proposed in a three-dimensional fully parameterized absolute nodal coordinate formulation, in which the distortion of the Beam Cross Section can be characterized. The linear, second-order, third-order, and fourth-order models of Beam Cross Section are proposed based on the Pascal triangle polynomials. It is shown that Poisson locking can be eliminated with the proposed higher-order Beam models, and the warping displacement of a square Beam is well described in the fourth-order Beam model. The accuracy of the proposed Beam elements and the influence of Cross-Section distortion on structure deformation and dynamics are examined through several numerical examples. We find that the proposed higher-order models can capture more accurately the structure deformation such as Cross-Section distortion including warping, compared to the existing Beam models in the absolute nodal coordinate formulation.

Jung Woo Lee - One of the best experts on this subject based on the ideXlab platform.

  • free vibration analysis of functionally graded bernoulli euler Beams using an exact transfer matrix expression
    International Journal of Mechanical Sciences, 2017
    Co-Authors: Jung Woo Lee, Jung Youn Lee
    Abstract:

    Abstract In this paper, we developed an exact transfer matrix method to analyze the free vibration characteristics of a functionally graded Beam. The transfer matrix for the functionally graded Beam is deduced from the relationship of the displacements and forces at both ends of the Beam. Because the results obtained from the present method are independent of the number of subdivisions, this method can be used as a useful tool to produce the natural frequencies and mode shapes for such problems in which material properties such as the elastic modulus and density are assumed to vary continuously along the height direction of the Beam Cross-Section depending on a power-law form. The use of functionally graded materials leads to a sixth-order differential equation because of the coupling of the axial and bending displacements, and its effect is analyzed by varying the length to height ratio. The calculated natural frequencies to demonstrate the accuracy of the proposed method are compared with those discussed in previous papers. The various analyses for the natural frequencies and mode shapes of functionally graded Beams are performed via a parametric study. In addition, the effect of the power-law index on the eigenpairs of functionally graded Beams connected by two elements with different top and bottom properties is examined.