The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Changwoo Lee - One of the best experts on this subject based on the ideXlab platform.
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an advanced model for the numerical analysis of the Radial Stress in center wound rolls
International Journal of Mechanical Sciences, 2016Co-Authors: Jongsu Lee, Changwoo LeeAbstract:Abstract In the case of roll-to-roll systems, winding is an important process and determines the quality of the final products. During the winding process, the winding tension determines the distribution of Stress in the Radial direction, i.e., the Radial Stress in the wound rolls. In order to optimize the winding tension, it is essential to have a model that can estimate the Radial Stress caused by the tension. However, to the best of our knowledge, no Radial Stress model that considers the effects of gravitation and the bending Stress in the wound roll has yet been reported. In this study, we developed an advanced Radial Stress model that considers the effects of both these parameters on the Radial Stress. The accuracy of the developed model was verified experimentally for wound rolls of various materials. Finally, the effects of gravitation, the bending Stress, and the winding tension on the Radial Stress were analyzed using the model. The model was found to be useful for analyzing the tension induced during the winding of several materials. Furthermore, the results of the performed analysis provided insights regarding how the Radial Stress is affected by the characteristics of the material being wound and the winding tension.
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effect of taper tension profiles on Radial Stress of a wound roll in roll to roll winding process
Journal of the Korean Society for Precision Engineering, 2014Co-Authors: Changwoo LeeAbstract:Winding is an integral operation in almost every roll-to-roll continuous process and center-winding is suitable and general scheme in the winding system. However, the internal Stresses within center-wound rolls can cause damage such as buckling, spoking, cinching, etc. It is therefore necessary to analyze the relationship between taper tension in winding section and internal Stress distribution within center-wound roll to prevent the winding failure. In this study, an optimal taper tension control method with parabolic taper tension profile for producing high quality wound roll was developed. The new logic was designed from analyzing the winding mechanism by using the Stress model in center-wound rolls. The performance of the proposed taper tension profile was verified experimentally.
Thomas H Hahn - One of the best experts on this subject based on the ideXlab platform.
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effect of Radial Stress relaxation on fibre Stress in filament winding of thick composites
Composites Manufacturing, 1995Co-Authors: Evan A Kempner, Thomas H HahnAbstract:Abstract During filament winding of thick cylinders, fibre wrinkling often occurs which severely decreases compressive strength. To eliminate fibre wrinkling, appropriate processing conditions must be found. Fibre migration and Stress relaxation due to resin flow are generally considered the most important factors affecting fibre buckling. Therefore, the effect of Stress relaxation on fibre wrinkling during the filament winding process was investigated. To study the Stress development during filament winding of thick cylinders, experiments were carried out using graphite/epoxy prepreg tows as well as dry graphite fibre. Cylinders of approximately 12 mm thickness were hoop wound on a 50.8 mm diameter aluminium mandrel. Winding tensions ranged from 13 to 34 N and winding speed was constant. A foil-type pressure sensor was applied on the mandrel to monitor the interface pressure throughout winding and storage of the cylinder. Significant Stress relaxation was found to occur during winding with prepreg tow. Mandrel pressure increased over the winding of the first eight layers or so. However, between the winding of one layer and the next, mandrel pressure dropped quickly. Also, it began to decrease after reaching a maximum value. A Stress relaxation analysis was carried out to determine the Stress in the cylinders during winding. Several parameters were not known a priori and had to be inferred from the data. Stress distributions following winding were calculated for each case. The Radial Stress in prepreg wound cylinders was found to relax nearly to zero in the inner part of the tubes. Compressive circumferential Stresses occurred throughout each of the cylinders. However, they reached greater magnitudes in the dry wound cylinders due to very low Radial moduli. No fibre wrinkling was evident in any of the wound cylinders.
Alfred J. Crosby - One of the best experts on this subject based on the ideXlab platform.
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draping films a wrinkle to fold transition
Physical Review Letters, 2010Co-Authors: Douglas P Holmes, Alfred J. CrosbyAbstract:A polymer film draping over a point of contact will wrinkle due to the strain imposed by the underlying substrate. The wrinkle wavelength is dictated by a balance of material properties and geometry; most directly the thickness of the draping film. At a critical strain, the Stress in the film will localize, causing hundreds of wrinkles to collapse into several discrete folds. In this Letter, we examine the deformation of an axisymmetric sheet and quantify the force required to generate a fold. We observe that the energy of formation for a single fold scales nearly linearly with the film thickness. The onset of folding, in terms of a critical force or displacement, scales as the thickness to the four-ninth power, which we predict from the energy balance of the system. The folds increase the tension in the remainder of the film causing the Radial Stress to increase, thereby decreasing the wavelength of the remaining wrinkles.
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surface wrinkling behavior of finite circular plates
Soft Matter, 2009Co-Authors: Derek Breid, Alfred J. CrosbyAbstract:Osmotically-driven surface buckling is a simple method for introducing controlled micro- and nano-scale topography onto material surfaces. To achieve a fundamental understanding of the buckling process and a library of the equilibrium and kinetically-trapped structures that can be attained, we observe the growth processes of a buckling silicate plate rigidly attached to an elastomeric substrate. The primary variable is the lateral extent of the silicate plate which is shown to dictate the location of buckle initiation, and thus the resulting morphology of the final buckled structure. We present a model to qualitatively describe the Radial Stress profile within the plate, based on both the diffusion-controlled local osmotic Stress and the ability of the plate to transfer this Stress to the relatively unconfined region surrounding it. These results and insights provide lessons for controlling the order and arrangement of buckled microstructures.
Jongsu Lee - One of the best experts on this subject based on the ideXlab platform.
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an advanced model for the numerical analysis of the Radial Stress in center wound rolls
International Journal of Mechanical Sciences, 2016Co-Authors: Jongsu Lee, Changwoo LeeAbstract:Abstract In the case of roll-to-roll systems, winding is an important process and determines the quality of the final products. During the winding process, the winding tension determines the distribution of Stress in the Radial direction, i.e., the Radial Stress in the wound rolls. In order to optimize the winding tension, it is essential to have a model that can estimate the Radial Stress caused by the tension. However, to the best of our knowledge, no Radial Stress model that considers the effects of gravitation and the bending Stress in the wound roll has yet been reported. In this study, we developed an advanced Radial Stress model that considers the effects of both these parameters on the Radial Stress. The accuracy of the developed model was verified experimentally for wound rolls of various materials. Finally, the effects of gravitation, the bending Stress, and the winding tension on the Radial Stress were analyzed using the model. The model was found to be useful for analyzing the tension induced during the winding of several materials. Furthermore, the results of the performed analysis provided insights regarding how the Radial Stress is affected by the characteristics of the material being wound and the winding tension.
Evan A Kempner - One of the best experts on this subject based on the ideXlab platform.
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effect of Radial Stress relaxation on fibre Stress in filament winding of thick composites
Composites Manufacturing, 1995Co-Authors: Evan A Kempner, Thomas H HahnAbstract:Abstract During filament winding of thick cylinders, fibre wrinkling often occurs which severely decreases compressive strength. To eliminate fibre wrinkling, appropriate processing conditions must be found. Fibre migration and Stress relaxation due to resin flow are generally considered the most important factors affecting fibre buckling. Therefore, the effect of Stress relaxation on fibre wrinkling during the filament winding process was investigated. To study the Stress development during filament winding of thick cylinders, experiments were carried out using graphite/epoxy prepreg tows as well as dry graphite fibre. Cylinders of approximately 12 mm thickness were hoop wound on a 50.8 mm diameter aluminium mandrel. Winding tensions ranged from 13 to 34 N and winding speed was constant. A foil-type pressure sensor was applied on the mandrel to monitor the interface pressure throughout winding and storage of the cylinder. Significant Stress relaxation was found to occur during winding with prepreg tow. Mandrel pressure increased over the winding of the first eight layers or so. However, between the winding of one layer and the next, mandrel pressure dropped quickly. Also, it began to decrease after reaching a maximum value. A Stress relaxation analysis was carried out to determine the Stress in the cylinders during winding. Several parameters were not known a priori and had to be inferred from the data. Stress distributions following winding were calculated for each case. The Radial Stress in prepreg wound cylinders was found to relax nearly to zero in the inner part of the tubes. Compressive circumferential Stresses occurred throughout each of the cylinders. However, they reached greater magnitudes in the dry wound cylinders due to very low Radial moduli. No fibre wrinkling was evident in any of the wound cylinders.
