Processing and performance of bridge deck subcomponents using two schemes of resin infusion
ABSTRACT Due to their lightweight, ease of installation in the field, and potential life-cycle durability, fiber reinforced composites are increasingly being considered in applications such as replacement bridge decks. However, current costs associated with the fabrication of such decks are 4–5 times that of conventional reinforced concrete decks thus placing great importance on the development of cost-effective processes such as resin infusion. This paper describes results of a test program aimed at the assessment of two different resin infusion schemes for the fabrication of foam core filled truss-type bridge decks. Model flow studies and simple analytical procedures are used to assess flow phenomena. The results of process and performance comparisons show that although the use of a microgroove network can be more efficient than the use of a high-permeable medium, in terms of rate of infusion, and global structural performance may be comparable, there is a greater likelihood of defect formation. Process induced defect formation is different in the two schemes with the former having a higher susceptibility for localized effects. Defect types are identified, and comparisons of performance are made at both a local and global level.
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ABSTRACT: Problems involving fluid flow past permeable surfaces have customarily been solved by matching Darcy's Law with the Navier-Stokes equation via an empirical slip-flow boundary condition at these surfaces. The present analysis serves to place the semi-empirical theory proposed by Beavers and Joseph (1967) on a more rigorous physical and mathematical basis. It is demonstrated that the predictions of these workers may be derived independently, without having to formulate empirical boundary conditions, by employing Brinkman's extension of Darcy's Law within the porous medium. These predictions are in satisfactory agreement with experimental data, thereby providing a quantitative verification of Brink-man's equation to complement its theoretical verification presented recently by several authors.On a habituellement résolu les problèmes relatifs à l'écoulement de fluides au-delà de surfaces perméables en appariant la loi de Darcy avec l'équation de Navier et Stokes, au moyen d'une condition-limite empirique d'écoulement de glissement aux dites surfaces. L'analyse actuelle a pour but de placer la théorie semi-empirique proposée en 1967 par Beavers et Joseph sur une base physique et mathématique rigoureuse. On démontre qu'on peut obtenir indépendemment les prévisions de Beavers et Joseph, sans qu'il ne faille formuler des conditions-limites empiriques, en utilisant l'extension faite par Brinkman de la loi de Darcy dans le milieu poreux. Lesdites prévisions concordent d'une manière satisfaisante avec les données expérimentales; cela fournit une vérification quantitative de l'équation de Brinkman, qui complète la vérification théorique qu'ont présentée récemment plusieurs auteurs.The Canadian Journal of Chemical Engineering 03/2009; 52(4):475 - 478. · 1.00 Impact Factor
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ABSTRACT: The permeabilities of fabrics composed of carbon and glass fibers have been determined by utilizing both simple 1-dimensional and 2-dimensional radial flow measurements using silicone oil and motor oil as permeants. The carbon fabric is typical of that used in fabrication of aerospace grade polymer matrix composites, while the glass fabric is a 3-dimensional woven fabric that has been proposed as a standard reference material for permeability characterization. Our results indicate that reliable permeability data for fiber preforms with varying architectural complexity can be obtained provided that the experiments are performed with utmost care and that appropriate equations are used to analyze the data. In-plane permeabilities for the carbon fiber preforms from transient unidirectional constant flow rate and constant pressure experiments agreed within 5%, regardless of the preform orientation to the flow direction. Steady-state results on the same preforms showed agreement within 2% between constant flow rate and constant pressure experiments. The capillary pressure effect was shown to be negligible for the transient experiments. The maximum difference between the transient and steady state permeability values was 3%. The maximum difference between a permeability measured with unidirectional flow and the same permeability measured with radial flow is less than 10%.Polymer Composites 05/1997; 18(3):368 - 377. · 1.48 Impact Factor