The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform
Roland Hinterhoelzl - One of the best experts on this subject based on the ideXlab platform.
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The impact of air evacuation on the impregnation time of Out-of-Autoclave Prepregs
Composites Part A: Applied Science and Manufacturing, 2015Co-Authors: T. Kourkoutsaki, Sebastien Comas-cardona, Ch Binetruy, R. K. Upadhyay, Roland HinterhoelzlAbstract:Most Out-of-Autoclave Prepregs (OoA) are only partially impregnated with resin. Their impregnation completes during the cure cycle, solely driven by the difference between atmospheric and vacuum pressure. Increased part length leads to an impregnation time gradient caused by the transient air flow inside the fibrous medium. In this work, a novel numerical approach capable of predicting the local impregnation time of a fibrous domain with resin, at isothermal conditions, under the influence of transient air flow, is proposed (delayed air evacuation). Sensitivity studies prove the robustness of the numerical scheme, for a large range of flow time-scales. The same approach is used to predict the local impregnation time of a commercial OoA Prepreg Tow, for a wide range of part lengths. It is demonstrated that for manufacturing long parts OoA, accurately capturing the influence of the air pressure on the local impregnation state of the Tow, is important for quantifying the risk for residual Tow porosity.
T. Kourkoutsaki - One of the best experts on this subject based on the ideXlab platform.
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The impact of air evacuation on the impregnation time of Out-of-Autoclave Prepregs
Composites Part A: Applied Science and Manufacturing, 2015Co-Authors: T. Kourkoutsaki, Sebastien Comas-cardona, Ch Binetruy, R. K. Upadhyay, Roland HinterhoelzlAbstract:Most Out-of-Autoclave Prepregs (OoA) are only partially impregnated with resin. Their impregnation completes during the cure cycle, solely driven by the difference between atmospheric and vacuum pressure. Increased part length leads to an impregnation time gradient caused by the transient air flow inside the fibrous medium. In this work, a novel numerical approach capable of predicting the local impregnation time of a fibrous domain with resin, at isothermal conditions, under the influence of transient air flow, is proposed (delayed air evacuation). Sensitivity studies prove the robustness of the numerical scheme, for a large range of flow time-scales. The same approach is used to predict the local impregnation time of a commercial OoA Prepreg Tow, for a wide range of part lengths. It is demonstrated that for manufacturing long parts OoA, accurately capturing the influence of the air pressure on the local impregnation state of the Tow, is important for quantifying the risk for residual Tow porosity.
Carroll G. Grant - One of the best experts on this subject based on the ideXlab platform.
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Advanced Tow placement of composite fuselage structure
1992Co-Authors: Robert L. Anderson, Carroll G. GrantAbstract:The Hercules NASA ACT program was established to demonstrate and validate the low cost potential of the automated Tow placement process for fabrication of aircraft primary structures. The program is currently being conducted as a cooperative program in collaboration with the Boeing ATCAS Program. The Hercules advanced Tow placement process has been in development since 1982 and was developed specifically for composite aircraft structures. The second generation machine, now in operation at Hercules, is a production-ready machine that uses a low cost Prepreg Tow material form to produce structures with laminate properties equivalent to Prepreg tape layup. Current program activities are focused on demonstration of the automated Tow placement process for fabrication of subsonic transport aircraft fuselage crown quadrants. We are working with Boeing Commercial Aircraft and Douglas Aircraft during this phase of the program. The Douglas demonstration panels has co-cured skin/stringers, and the Boeing demonstration panel is an intricately bonded part with co-cured skin/stringers and co-bonded frames. Other aircraft structures that were evaluated for the automated Tow placement process include engine nacelle components, fuselage pressure bulkheads, and fuselage tail cones. Because of the cylindrical shape of these structures, multiple parts can be fabricated on one two placement tool, thus reducing the cost per pound of the finished part.
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Advanced fiber placement of composite fuselage structures
1991Co-Authors: Robert L. Anderson, Carroll G. GrantAbstract:The Hercules/NASA Advanced Composite Technology (ACT) program will demonstrate the low cost potential of the automated fiber placement process. The Hercules fiber placement machine was developed for cost effective production of composite aircraft structures. The process uses a low cost Prepreg Tow material form and achieves equivalent laminate properties to structures fabricated with Prepreg tape layup. Fiber placement demonstrations planned for the Hercules/NASA program include fabrication of stiffened test panels which represent crown, keel, and window belt segments of a typical transport aircraft fuselage.
Ch Binetruy - One of the best experts on this subject based on the ideXlab platform.
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The impact of air evacuation on the impregnation time of Out-of-Autoclave Prepregs
Composites Part A: Applied Science and Manufacturing, 2015Co-Authors: T. Kourkoutsaki, Sebastien Comas-cardona, Ch Binetruy, R. K. Upadhyay, Roland HinterhoelzlAbstract:Most Out-of-Autoclave Prepregs (OoA) are only partially impregnated with resin. Their impregnation completes during the cure cycle, solely driven by the difference between atmospheric and vacuum pressure. Increased part length leads to an impregnation time gradient caused by the transient air flow inside the fibrous medium. In this work, a novel numerical approach capable of predicting the local impregnation time of a fibrous domain with resin, at isothermal conditions, under the influence of transient air flow, is proposed (delayed air evacuation). Sensitivity studies prove the robustness of the numerical scheme, for a large range of flow time-scales. The same approach is used to predict the local impregnation time of a commercial OoA Prepreg Tow, for a wide range of part lengths. It is demonstrated that for manufacturing long parts OoA, accurately capturing the influence of the air pressure on the local impregnation state of the Tow, is important for quantifying the risk for residual Tow porosity.
R. K. Upadhyay - One of the best experts on this subject based on the ideXlab platform.
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The impact of air evacuation on the impregnation time of Out-of-Autoclave Prepregs
Composites Part A: Applied Science and Manufacturing, 2015Co-Authors: T. Kourkoutsaki, Sebastien Comas-cardona, Ch Binetruy, R. K. Upadhyay, Roland HinterhoelzlAbstract:Most Out-of-Autoclave Prepregs (OoA) are only partially impregnated with resin. Their impregnation completes during the cure cycle, solely driven by the difference between atmospheric and vacuum pressure. Increased part length leads to an impregnation time gradient caused by the transient air flow inside the fibrous medium. In this work, a novel numerical approach capable of predicting the local impregnation time of a fibrous domain with resin, at isothermal conditions, under the influence of transient air flow, is proposed (delayed air evacuation). Sensitivity studies prove the robustness of the numerical scheme, for a large range of flow time-scales. The same approach is used to predict the local impregnation time of a commercial OoA Prepreg Tow, for a wide range of part lengths. It is demonstrated that for manufacturing long parts OoA, accurately capturing the influence of the air pressure on the local impregnation state of the Tow, is important for quantifying the risk for residual Tow porosity.