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You searched for +publisher:"Georgia Tech" +contributor:("Carr, Wallace W."). Showing records 1 – 3 of 3 total matches.

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Georgia Tech

1. Harper, Richard Eugene. Development of novel synthetic turf infill materials.

Degree: PhD, Materials Science and Engineering, 2015, Georgia Tech

Mitigation of health and heat-build-up issues related to black, granulated crumb rubber infill (GCRI) in synthetic turf fields (STF) while maintaining acceptable impact absorption properties was the central goal of this study. The first step was establishing a STF baseline performance of GCRI samples that originated from several sources while elucidating the synergistic parameters between infill and turf that promulgate acceptable impact performance. Based on the knowledge base built on the GCRI-STF standard, three polymeric waste streams selected for their benign chemical contents, non-black colors and competitive low costs were evaluated as alternate turf infill materials: post-consumer carpet broadloom (PCCB), post-consumer carpet tile (PCCT) and recycled polyethylene terephthalate (PET) drink bottles. For ground PCCB carcass (the base on the carpet construction remaining after the face fibers were removed), the heterogeneous composition of unconfined fine particles and remaining short fibers prevented sufficient material integration to allow sufficient impact energy absorption. The ground PET homogeneous particles alone lacked sufficient impact absorption capabilities, and their synergistic interactions with the turf blade yarns were not sufficient to meet specified levels of impact performance. Only the PCCT infill crumb possessed a heterogeneous structure that effectively filled the STF to yield sufficient impact cushioning comparable to standard GCRI. In conclusion, PCCT was shown to be a technically-viable candidate for GCRI infill replacement, warranting further development to bring it into closer cost competitiveness to GCRI and ensure long-term wear and weathering performance in synthetic turf. Advisors/Committee Members: Cook, Fred L. (advisor), Muzzy, John D. (advisor), Wang, Youjiang (committee member), Carr, Wallace W. (committee member), Realff, Matthew J. (committee member).

Subjects/Keywords: Rubber; Infill; Synthetic turf; Gmax; Impact

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APA (6th Edition):

Harper, R. E. (2015). Development of novel synthetic turf infill materials. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/54346

Chicago Manual of Style (16th Edition):

Harper, Richard Eugene. “Development of novel synthetic turf infill materials.” 2015. Doctoral Dissertation, Georgia Tech. Accessed May 06, 2021. http://hdl.handle.net/1853/54346.

MLA Handbook (7th Edition):

Harper, Richard Eugene. “Development of novel synthetic turf infill materials.” 2015. Web. 06 May 2021.

Vancouver:

Harper RE. Development of novel synthetic turf infill materials. [Internet] [Doctoral dissertation]. Georgia Tech; 2015. [cited 2021 May 06]. Available from: http://hdl.handle.net/1853/54346.

Council of Science Editors:

Harper RE. Development of novel synthetic turf infill materials. [Doctoral Dissertation]. Georgia Tech; 2015. Available from: http://hdl.handle.net/1853/54346

2. Zhou, Wenchao. Interface dynamics in inkjet deposition.

Degree: PhD, Mechanical Engineering, 2014, Georgia Tech

Ink-jet deposition is an emerging technology that provides a more efficient, economic, scalable method of manufacturing than other traditional additive techniques by laying down droplets layer by layer to build up 3-D objects. The focus of this thesis is to investigate the material interface evolution during the droplet deposition process, which holds the key to understanding the material joining process. Droplet deposition is a complicated process and can be broken down into droplet impingement dynamics and droplet hardening. This research focuses on the study of the interface dynamics of droplet impingement. In order to study the interface dynamics, a novel metric is developed to quantify the evolving geometry of the droplet interface in both 2-D and 3-D for single and multiple droplets respectively, by measuring the similarity between the evolving droplet geometry and a desired shape. With the developed shape metric, the underlying physics of the interface evolution for single droplet impingement are examined with simulations using an experimentally validated numerical model. Results show that the Weber number determines the best achievable shape and its timing during the droplet impingement when Ohnesorge number is smaller than 1, while the Reynolds number is the determining factor when Ohnesorge number is larger than 1. A regime map is constructed with the results and an empirical splash criterion to guide the choice of process parameters for given fluid properties in order to achieve the best shape without splash for single droplet impingement. In order to study the interface dynamics for multiple droplet interaction, which is computationally prohibitive for commercial software packages, an efficient numerical model is developed based on the Lattice Boltzmann (LB) method. A new LB formulation equivalent to the phase-field model is developed with consistent boundary conditions through a multiscale analysis. The numerical model is validated by comparing its simulation results with that of commercial software COMSOL and experimental data. Results show our LB model not only has significant improvement of computational speed over COMSOL but is also more accurate. Finally, the developed numerical solver is used to study the interface evolution of multiple droplet interaction with the aid of the 3-D shape metric proposed before. Simulations are performed on a wide range of impingement conditions for two-droplet, a-line-of-droplet, and an-array-of-droplet interactions. The underlying physics of the interface coalescence and breakup coupling with the impingement dynamics are examined. For line-droplet interaction, the strategy for achieving the equilibrium shape in the shortest time is studied. An important issue is discovered for array-droplet interaction, which is the air bubble formation during the droplet interaction. The mechanism for the air bubble formation is investigated and the strategy to avoid this undesirable effect is also suggested. This thesis has largely reduced the gap between basic science of… Advisors/Committee Members: Rosen, David W. (advisor), Fedorov, Andrei G. (committee member), Degertekin, F. Levent (committee member), Grover, Martha A. (committee member), Carr, Wallace W. (committee member).

Subjects/Keywords: Interface dynamics; Inkjet deposition; Additive manufacturing; Ink-jet printing; Three-dimensional printing; Drops; Fluid dynamics; Microstructure

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Zhou, W. (2014). Interface dynamics in inkjet deposition. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/51817

Chicago Manual of Style (16th Edition):

Zhou, Wenchao. “Interface dynamics in inkjet deposition.” 2014. Doctoral Dissertation, Georgia Tech. Accessed May 06, 2021. http://hdl.handle.net/1853/51817.

MLA Handbook (7th Edition):

Zhou, Wenchao. “Interface dynamics in inkjet deposition.” 2014. Web. 06 May 2021.

Vancouver:

Zhou W. Interface dynamics in inkjet deposition. [Internet] [Doctoral dissertation]. Georgia Tech; 2014. [cited 2021 May 06]. Available from: http://hdl.handle.net/1853/51817.

Council of Science Editors:

Zhou W. Interface dynamics in inkjet deposition. [Doctoral Dissertation]. Georgia Tech; 2014. Available from: http://hdl.handle.net/1853/51817


Georgia Tech

3. Miller, Ryan Michael. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

A suspension flow model based on the "suspension balance" approach has been developed. This work modifies the model to allow the solution of suspension flows under general flow conditions. This requires the development of a frame-invariant constitutive model for the particle stress which can take into account the spatially-varying local kinematic conditions. The mass and momentum balances for the bulk suspension and particle phase are solved numerically using a finite volume method. The particle stress is based upon the computed rate of strain and the local kinematic conditions. A nonlocal stress contribution corrects the continuum approximation of the particle phase for finite particle size effects. Local kinematic conditions are accounted through the local ratio of rotation to extension in the flow field. The coordinates for the stress definition are the local principal axes of the rate of strain field. The developed model is applied to a range of problems. (i) Axially-developing conduit flows are computed using both the full two-dimensional solution and the more computationally efficient "marching" method. The model predictions are compared to experimental results for cross-stream particle concentration profiles and axial development lengths. (ii) Model predictions are compared to experiments for wide-gap circular Couette flow of a concentrated suspension in a shear-thinning liquid. With minor modification, the suspension flow model predicts the major trends and results observed in this flow. (iii) Comparisons are made to experiments for an axisymmetric contraction-expansion. Model predictions for a two-dimensional planar contraction flow test the influence of model formulation. The variation of the magnitude of an isotropic particle normal stress with local kinematic conditions and anisotropy in the in-plane normal stresses are both explored. The formulation of the particle phase stress is found to have significant effects on the solid fraction and velocity. (iv) Finally, for a rectangular piston-driven flow and an obstructed channel flow, a "computational suspension dynamics" study explores the effect of particle migration on the bulk flow field, system pressure drop and particle phase composition. Advisors/Committee Members: Forney, Larry (Committee Co-Chair), Morris, Jeffrey F. (Committee Co-Chair), Carr, Wallace W. (Committee Member), Koros, William J. (Committee Member), Wick, Timothy M. (Committee Member), Yiacoumi, Sotira Z. (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Two-phase flow; Suspension flow; Frame-invariant rheology; Finite volume method; Shear-induced migration; Suspension balance model; Shear flow; Finite volume method; Two-phase flow; Rheology; Continuum mechanics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Miller, R. M. (2004). Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/4864

Chicago Manual of Style (16th Edition):

Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Doctoral Dissertation, Georgia Tech. Accessed May 06, 2021. http://hdl.handle.net/1853/4864.

MLA Handbook (7th Edition):

Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Web. 06 May 2021.

Vancouver:

Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 May 06]. Available from: http://hdl.handle.net/1853/4864.

Council of Science Editors:

Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/4864

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