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Author: search.filters.author.Jeenkour, Puttha

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    Analysis of a flexible web on a grooved concave surface under softEHL
    (2013-02-18)
    Mongkolwongrojn, Mongkol
    ;
    Jeenkour, Puttha
    This article describes characteristics of a flexible web moving through a grooved, concave, and soft surface in an elastohydrodynamic lubrication. Both trapezoidal and semi-elliptical grooved surfaces have been investigated under air lubrication. The modified Reynolds equation based on the first-order boundary slip and permeability of a soft bearing material has been formulated and solved numerically to obtain a traction characteristics between a polypropylene web and a grooved concave surface in the contact region. The concave shape was mainly considered under varying depths of grooves, flexible web velocities, normal loads, equivalent Young's moduli, curvatures and material permeability values. The simulation results are compared between friction coefficient for a trapezoidal grooved concave surface and a semi-elliptical grooved surface. © 2013 Elsevier Ltd.
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    Influence of speed-up and speed-down on internal stresses of wound rolls in web handling process
    (2012-02-23)
    Mongkolwongrojn, Mongkol
    ;
    Jeenkour, Puttha
    In web winding process, the effects of speed-up and speed-down on internal stresses of wound roll have been investigated. The air-entrainment can be obtained theoretically using the modified nonlinear Hakiel model. In this research work, air-entrainment model established by Hamrock and Dowson was applied to estimate the initial air film layers into a wound roll in the winding system with a nip-roller. Moreover, the characteristics of a wound roll were examined under varying tension and varying speed conditions. The numerical results showed the radial stress, tangential stress, and friction force distributions at central inside a wound roll under the condition for a wound roll without wrinkle and slippage phenomena. © (2012) Trans Tech Publications.
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    Optimum winding tension and Nip-load into wound webs for protecting wrinkles and slippage
    (2011-01-01)
    Hashimoto, Hiromu
    ;
    Jeenkour, Puttha
    ;
    Mongkolowongrojn, Mongkol
    This paper describes the novel optimization method of wind-up tension to prevent wound roll defects, mainly star defect (wrinkling) and telescoping (slippage), based on the optimum design technique. Modified Hakiel model with air entrainment effects is applied to analyze in-roll stress distributions in the radial and tangential directions. In the present optimization method, the wind-up tension is gradually changed in the radial direction to minimize the tangential stresses under the constraint of nonnegative tangential stresses. At the same time, we consider the friction conditions to prevent the slippage between web layers due to a decrease of radial stresses and friction force. Successive quadratic programming, which is a typical mathematical programming method, is used as the optimization technique. The optimized wind-up tensions are obtained for various winding conditions, and we confirmed theoretically and experimentally that the in-roll stress distributions are very much improved for preventing both wrinkling and slippage simultaneously by the optimization method being proposed. © 2011 The Japan Society of Mechanical Engineers.
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    Optimum winding tension and nip-load into wound webs for protecting wrinkles and slippage
    (2010-12-01)
    Hashimoto, Hiromu
    ;
    Jeenkour, Puttha
    ;
    Mongkolowongrojn, Mongkol
    This paper describes the novel optimization method of wind-up tension to prevent wound roll defects, mainly star defect (wrinkling) and telescoping (slippage), based on the optimum design technique. Modified Hakiel model with air entrainment effects is applied to analyze in-roll stress distributions in the radial and tangential directions. In the present optimization method, the wind-up tension is gradually changed in the radial direction to minimize the tangential stresses under the constraint of nonnegative tangential stresses. At the same time, we consider the friction conditions to prevent the slippage between web layers due to a decrease of radial stresses and friction force. Successive quadratic programming, which is a typical mathematical programming method, is used as the optimization technique. The optimized wind-up tensions are obtained for various winding conditions, and we confirmed theoretically and experimentally that the in-roll stress distributions are very much improved for preventing both wrinkling and slippage simultaneously by the optimization method being proposed. Copyright © 2010 by JSME.