Browsing by Author "Bhupender S. Gupta, Committee Member"

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    Modeling Tortuosity in Fibrous Porous Media using Computational Fluid Dynamics
    (2009-11-24) Vallabh, Rahul; Bhupender S. Gupta, Committee Member; Joel J. Ducoste, Committee Member; Abdel-Fattah Seyam, Committee Co-Chair; Pamela Banks-Lee, Committee Chair
    Tortuosity factor is often used to characterize the structure of the pore volume in fibrous porous media. This work involves the determination of tortuosity using computational fluid dynamic (CFD) simulation and particle tracking analysis. A new method has been adopted to generate 3-D geometry for modeling fibrous porous structures using ANSYS® Parametric Design Language (APDL). Computation fluid dynamics has been used to simulate permeability of modeled 3-D fiberweb structures. The simulated permeability results are in good agreement with the models proposed by other authors. The experimental results were found to be slightly higher compared to simulated results and existing models due to the layered configuration of the samples. Permeability is found to be significantly influenced by fiber diameter, and porosity as well as fiberweb thickness. The relationship between air permeability and fiberweb thickness has been used to develop an indirect method for determination of tortuosity factor. Tortuosity factor has also been determined using a more direct method involving CFD simulation and Particle Tracking analysis. Different models established using the direct and indirect methods of determination show that tortuosity is significantly influenced by porosity, fiber diameter and fiberweb thickness, whereas the models available in the literature express tortuosity as a function of porosity only.
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    A Study on the Effects of Textile Processing on Tensile Properties of Single Cotton Fibers - From raw cottno to washed garments
    (2005-03-02) Doh, Song Jun; Pamela Banks-Lee, Committee Member; Jacqueline M. Hughes-Oliver, Committee Member; Bhupender S. Gupta, Committee Member; Moon W. Suh, Committee Chair
    Effects of textile processing on breaking strength, breaking elongation, morphological properties and dimensional properties were investigated and analyzed. Cotton varieties were processed under various ginning and carding conditions into a T-shirts. The produced T-shirts were washed and dried repeatedly. Fibers were collected at various processing stages and tested by a Mantis® single fiber tensile tester. The breaking strength and breaking elongation of cotton fibers were reduced substantially due to textile processing. A higher ginning rate generated a higher average breaking strength and a lower breaking elongation compared to that from a lower ginning rate. A higher carding rate adversely affected the tensile properties for entire range of the processes. Using of 2 lint cleaners at the gin resulted in a lower tensile properties than that of 1 lint cleaner. Although the results were not statistically significant, use of 2 lint cleaners at gin resulted in a lower average length shrinkage in T-shirts and more damage to the fiber surface after repeated washing/drying. The progressive length shrinkage of the T-shirts during 32 washing/drying cycles was shown to be consistently higher for the higher ginning and carding rates. The progressive width and area shrinkage on the other hand did not show the effects of processing clearly. A limited microscopic study suggests that the number of lint cleaners in ginning may be the most significant contributor to fiber damage as shown by the broken fibrils and cracks on fiber surfaces.