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Earl H Dowell - One of the best experts on this subject based on the ideXlab platform.

  • effects of geometric structural nonlinearity on flutter and limit cycle oscillations of high aspect ratio wings
    Journal of Fluids and Structures, 2004
    Co-Authors: Deman Tang, Earl H Dowell
    Abstract:

    In this paper structural equations of motion based on nonlinear beam theory and the ONERA aerodynamic stall model are used to study the effects of geometric structural nonlinearity on flutter and limit cycle oscillations (LCO) of high-aspect-ratio wings. For example, the effects of large Static pre-flutter deformations in the vertical or torsional direction are considered. In particular, Static deformations in the vertical and torsional directions caused by a Static Angle of attack, gravity and/or manufactured curvature generally decrease system stiffness and flutter stability. The structural nonlinearity also leads to a sensitivity to initial conditions as well as any parameter that influences the Static equilibrium condition. A dynamic perturbation equation about a nonlinear Static equilibrium is derived which is used to determine the small perturbation flutter boundary. The effects of the geometric structural nonlinearity of the beam theory on both the perturbation flutter boundary and the nonlinear response are significant. Onset of a limit cycle oscillation is dependent upon the delicate between stall aerodynamics and structural nonlinear forces. LCO above and below the perturbation flutter boundary generally occurs over a limited range of flow velocity. LCO can occur below the perturbation flutter velocity due to large initial disturbances.

  • effects of geometric structural nonlinearity on flutter and limit cycle oscillations of high aspect ratio wings
    Journal of Fluids and Structures, 2004
    Co-Authors: Deman Tang, Earl H Dowell
    Abstract:

    In this paper structural equations of motion based on nonlinear beam theory and the ONERA aerodynamic stall model are used to study the effects of geometric structural nonlinearity on flutter and limit cycle oscillations (LCO) of high-aspect-ratio wings. For example, the effects of large Static pre-flutter deformations in the vertical or torsional direction are considered. In particular, Static deformations in the vertical and torsional directions caused by a Static Angle of attack, gravity and/or manufactured curvature generally decrease system stiffness and flutter stability. The structural nonlinearity also leads to a sensitivity to initial conditions as well as any parameter that influences the Static equilibrium condition. A dynamic perturbation equation about a nonlinear Static equilibrium is derived which is used to determine the small perturbation flutter boundary. The effects of the geometric structural nonlinearity of the beam theory on both the perturbation flutter boundary and the nonlinear response are significant. Onset of a limit cycle oscillation is dependent upon the delicate between stall aerodynamics and structural nonlinear forces. LCO above and below the perturbation flutter boundary generally occurs over a limited range of flow velocity. LCO can occur below the perturbation flutter velocity due to large initial disturbances.

Gianmauro Numico - One of the best experts on this subject based on the ideXlab platform.

Deman Tang - One of the best experts on this subject based on the ideXlab platform.

  • effects of geometric structural nonlinearity on flutter and limit cycle oscillations of high aspect ratio wings
    Journal of Fluids and Structures, 2004
    Co-Authors: Deman Tang, Earl H Dowell
    Abstract:

    In this paper structural equations of motion based on nonlinear beam theory and the ONERA aerodynamic stall model are used to study the effects of geometric structural nonlinearity on flutter and limit cycle oscillations (LCO) of high-aspect-ratio wings. For example, the effects of large Static pre-flutter deformations in the vertical or torsional direction are considered. In particular, Static deformations in the vertical and torsional directions caused by a Static Angle of attack, gravity and/or manufactured curvature generally decrease system stiffness and flutter stability. The structural nonlinearity also leads to a sensitivity to initial conditions as well as any parameter that influences the Static equilibrium condition. A dynamic perturbation equation about a nonlinear Static equilibrium is derived which is used to determine the small perturbation flutter boundary. The effects of the geometric structural nonlinearity of the beam theory on both the perturbation flutter boundary and the nonlinear response are significant. Onset of a limit cycle oscillation is dependent upon the delicate between stall aerodynamics and structural nonlinear forces. LCO above and below the perturbation flutter boundary generally occurs over a limited range of flow velocity. LCO can occur below the perturbation flutter velocity due to large initial disturbances.

  • effects of geometric structural nonlinearity on flutter and limit cycle oscillations of high aspect ratio wings
    Journal of Fluids and Structures, 2004
    Co-Authors: Deman Tang, Earl H Dowell
    Abstract:

    In this paper structural equations of motion based on nonlinear beam theory and the ONERA aerodynamic stall model are used to study the effects of geometric structural nonlinearity on flutter and limit cycle oscillations (LCO) of high-aspect-ratio wings. For example, the effects of large Static pre-flutter deformations in the vertical or torsional direction are considered. In particular, Static deformations in the vertical and torsional directions caused by a Static Angle of attack, gravity and/or manufactured curvature generally decrease system stiffness and flutter stability. The structural nonlinearity also leads to a sensitivity to initial conditions as well as any parameter that influences the Static equilibrium condition. A dynamic perturbation equation about a nonlinear Static equilibrium is derived which is used to determine the small perturbation flutter boundary. The effects of the geometric structural nonlinearity of the beam theory on both the perturbation flutter boundary and the nonlinear response are significant. Onset of a limit cycle oscillation is dependent upon the delicate between stall aerodynamics and structural nonlinear forces. LCO above and below the perturbation flutter boundary generally occurs over a limited range of flow velocity. LCO can occur below the perturbation flutter velocity due to large initial disturbances.

Pierfrancesco Franco - One of the best experts on this subject based on the ideXlab platform.

Schott D.l. - One of the best experts on this subject based on the ideXlab platform.

  • A hybrid particle-geometric scaling approach for elasto-plastic adhesive DEM contact models
    'Elsevier BV', 2020
    Co-Authors: Mohajeri M., Helmons R.l.j., Van Rhee C., Schott D.l.
    Abstract:

    The computation time of Discrete Element Method (DEM) simulations increases exponentially when particle size is reduced or the number of particles increased. This critical challenge limits the use of DEM simulation for industrial applications, such as powder flow in silos. Scaling techniques can offer a solution to reduce computation time. In this paper, we have developed a hybrid particle-geometric scaling approach with a focus on Elasto-Plastic Adhesive contact models. It established relationships between particle scaling factors and DEM contact input parameters. The isolated effects of varying particle size and geometric dimensions on bulk properties were also evaluated using uniaxial consolidation, Static Angle of repose, and ring shear tests. This paper shows how the particle scaling can be applied together with geometric scaling to incorporate two important aspects of bulk materials, their Elasto-Plastic behaviour and their cohesive forces.

  • A hybrid particle-geometric scaling approach for elasto-plastic adhesive DEM contact models
    'Elsevier BV', 2020
    Co-Authors: Mohajeri M., Helmons R.l.j., Van Rhee C., Schott D.l.
    Abstract:

    The computation time of Discrete Element Method (DEM) simulations increases exponentially when particle size is reduced or the number of particles increased. This critical challenge limits the use of DEM simulation for industrial applications, such as powder flow in silos. Scaling techniques can offer a solution to reduce computation time. In this paper, we have developed a hybrid particle-geometric scaling approach with a focus on Elasto-Plastic Adhesive contact models. It established relationships between particle scaling factors and DEM contact input parameters. The isolated effects of varying particle size and geometric dimensions on bulk properties were also evaluated using uniaxial consolidation, Static Angle of repose, and ring shear tests. This paper shows how the particle scaling can be applied together with geometric scaling to incorporate two important aspects of bulk materials, their Elasto-Plastic behaviour and their cohesive forces.Transport Engineering and LogisticsOffshore and Dredging EngineeringRivers, Ports, Waterways and Dredging Engineerin