This investigation completed the verification of a three-dimensional resin transfer molding/resin... more This investigation completed the verification of a three-dimensional resin transfer molding/resin film infusion (RTM/RFI) process simulation model. The model incorporates resin flow through an anisotropic carbon fiber preform, cure kinetics of the resin, and heat transfer within the preform/tool assembly. The computer model can predict the flow front location, resin pressure distribution, and thermal profiles in the modeled part. The formulation for the flow model is given using the finite element/control volume (FE/CV) technique based on Darcy's Law of creeping flow through a porous media. The FE/CV technique is a numerically efficient method for finding the flow front location and the fluid pressure. The heat transfer model is based on the three-dimensional, transient heat conduction equation, including heat generation. Boundary conditions include specified temperature and convection. The code was designed with a modular approach so the flow and/or the thermal module may be tu...
Journal of Reinforced Plastics and Composites, 1999
Resin film infusion (RFI) has been found to be a cost-effective technique for the fabrication of ... more Resin film infusion (RFI) has been found to be a cost-effective technique for the fabrication of complex shaped composite parts for primary structural applications. Dry textile preforms are infiltrated, consolidated, and cured in a single step, eliminating the labor to lay-up prepreg tape. The large number of processing variables and the complex material behavior during infiltration and cure make experimental optimization of the RFI process extremely inefficient. The objective of this work was to develop and verify a three-dimensional model to simulate the RFI process. For a specified pressure and temperature cure cycle the code can predict resin pressure, viscosity and degree of cure, flow front progression, and temperature distribution in the preform and tooling components. The model was divided into submodels which describe resin flow, heat transfer, and resin kinetics. A finite element/control volume approach was used to model the flow of the resin through the preform. Boundary ...
2012 IEEE/MTT-S International Microwave Symposium Digest, 2012
ABSTRACT This paper presents the characterization of rectangular micro-coaxial transmission lines... more ABSTRACT This paper presents the characterization of rectangular micro-coaxial transmission lines assembled in a high power test system. In addition to straight transmission lines, vertical solder transitions between stacked layers of rectangular coax are presented. These test assemblies utilize standard integration techniques and components: wire bond and flip-chip transitions and edge coaxial connectors. Assembled coax lines were tested at continuous wave power levels as high as 200 W at a frequency of 2 GHz. High frequency performance of the test assemblies is maintained throughout high power testing. Thermal models developed using a 3-D finite element method are utilized to understand limitations of micro-coaxial transmission lines at higher frequencies.
2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2018
A broadband, dual-polarized array that supports both electronic scanning and fixed-beam applicati... more A broadband, dual-polarized array that supports both electronic scanning and fixed-beam applications in a modular, scalable architecture is presented. A tightly-coupled dipole array is designed to cover 9.5-37 GHz. Six different instrument bands, both radiometry and synthetic aperture radar (SAR), share the common aperture with co-located phase centers. Element-level diplexing is demonstrated to enable precise aperture control across all bands. Amplitude tapering is implemented with unequal power combiners to control sidelobe levels and help equalize beamwidth across frequency for feeding a reflector. Measured realized gain patterns are provided vs array code predictions and ideal directivity calculations. Better than 10 dB return loss is measured for all six instrument bands. Digital scanning of measured sub-array patterns to 30 degrees is demonstrated in MATLAB.
This investigation completed the verification of a three-dimensional resin transfer molding/resin... more This investigation completed the verification of a three-dimensional resin transfer molding/resin film infusion (RTM/RFI) process simulation model. The model incorporates resin flow through an anisotropic carbon fiber preform, cure kinetics of the resin, and heat transfer within the preform/tool assembly. The computer model can predict the flow front location, resin pressure distribution, and thermal profiles in the modeled part. The formulation for the flow model is given using the finite element/control volume (FE/CV) technique based on Darcy's Law of creeping flow through a porous media. The FE/CV technique is a numerically efficient method for finding the flow front location and the fluid pressure. The heat transfer model is based on the three-dimensional, transient heat conduction equation, including heat generation. Boundary conditions include specified temperature and convection. The code was designed with a modular approach so the flow and/or the thermal module may be tu...
Journal of Reinforced Plastics and Composites, 1999
Resin film infusion (RFI) has been found to be a cost-effective technique for the fabrication of ... more Resin film infusion (RFI) has been found to be a cost-effective technique for the fabrication of complex shaped composite parts for primary structural applications. Dry textile preforms are infiltrated, consolidated, and cured in a single step, eliminating the labor to lay-up prepreg tape. The large number of processing variables and the complex material behavior during infiltration and cure make experimental optimization of the RFI process extremely inefficient. The objective of this work was to develop and verify a three-dimensional model to simulate the RFI process. For a specified pressure and temperature cure cycle the code can predict resin pressure, viscosity and degree of cure, flow front progression, and temperature distribution in the preform and tooling components. The model was divided into submodels which describe resin flow, heat transfer, and resin kinetics. A finite element/control volume approach was used to model the flow of the resin through the preform. Boundary ...
2012 IEEE/MTT-S International Microwave Symposium Digest, 2012
ABSTRACT This paper presents the characterization of rectangular micro-coaxial transmission lines... more ABSTRACT This paper presents the characterization of rectangular micro-coaxial transmission lines assembled in a high power test system. In addition to straight transmission lines, vertical solder transitions between stacked layers of rectangular coax are presented. These test assemblies utilize standard integration techniques and components: wire bond and flip-chip transitions and edge coaxial connectors. Assembled coax lines were tested at continuous wave power levels as high as 200 W at a frequency of 2 GHz. High frequency performance of the test assemblies is maintained throughout high power testing. Thermal models developed using a 3-D finite element method are utilized to understand limitations of micro-coaxial transmission lines at higher frequencies.
2018 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2018
A broadband, dual-polarized array that supports both electronic scanning and fixed-beam applicati... more A broadband, dual-polarized array that supports both electronic scanning and fixed-beam applications in a modular, scalable architecture is presented. A tightly-coupled dipole array is designed to cover 9.5-37 GHz. Six different instrument bands, both radiometry and synthetic aperture radar (SAR), share the common aperture with co-located phase centers. Element-level diplexing is demonstrated to enable precise aperture control across all bands. Amplitude tapering is implemented with unequal power combiners to control sidelobe levels and help equalize beamwidth across frequency for feeding a reflector. Measured realized gain patterns are provided vs array code predictions and ideal directivity calculations. Better than 10 dB return loss is measured for all six instrument bands. Digital scanning of measured sub-array patterns to 30 degrees is demonstrated in MATLAB.
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