5 research outputs found
Development of a Curved Layer LOM Process for Monolithic Ceramics and Ceramic Matrix Composites
A novel rapid prototyping technology incorporating a curved layer building style was developed. The new process, based on Laminated Object Manufacturing (LOM), was designed for efficient fabrication of curved layer structures made from ceramics and fiber reinforced composites. A new LOM machine was created, referred to as Curved Layer LOM. This new machine uses ceramic tapes and fiber prepregs as feedstocks and fabricates curved structures on a curved-layer by curved-layer basis. The output of the process is a three dimensional green ceramic that is capable of being processed to a seamless, fully dense ceramic using traditional techniques. A detailed description is made of the necessary software and hardware for this new process. Also reviewed is the development of ceramic preforms and accompanying process technology for net shape ceramic fabrication. Monolithic ceramic (SiC) and ceramic matrix composite (SiC/SiC) articles were fabricated using both the flat layer and curved layer LOM processes. For making curved layer objects, the curved process afforded the advantages of eliminated stair step effect, increased build speed, reduced waste, reduced need for decubing, and maintenance of continuous fibers in the direction of curvature
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Laser Cutting of Ceramic Composite Layers
The Laminated, Object Manufacturing (LOM) process lends itself to use of a variety of
materials that can be delivered in sheet format. Studies are underway to investigate the use of
monolithic and fiber reinforced (composite) ceramic tapes. The laser cutting process presents a
challenge due to the refractory properties of the fibers and, in some cases, their high thermal
conductivity. The cw CO2 laser's thermal degradation process currently used is not suitable for
these materials. The evaluation of potential alternative lasers has focused on pulsed systems that
use either photoablation together with thermal processes or thermal shock with thermal
degradation. We will describe preliminary results achieved in our study of the photoablation
process using a copper-vapor laser.Mechanical Engineerin
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Curved Layer LOM of Ceramics and Composites
A novel rapidprototyping (RP) technology incorporating a curved layer building
style has been developed. The new process,based on Laminated Object Manufacturing
(LOM), is suited for efficient fabrication of curved layer structures made from ceramics
and fibrous composites. Anew LOM machine was developedithatuses ceramic tapes
and fiberprepregs as a feedstock and outputs at11fee dimensional green form. The green
ceramic is then processed to a seamless, fully dense ceramic structure using traditional
ceramic techniques. Thisreport summarizes the new LOM process. and necessary
hardware. Also reviewed is the development of ceramic preforms and accompanying
process technology for net shape fabrication of ceramic matrix composites (CMCs).
Compared to making curved objeds with the standard flat.layer LOMprocess, the curved
process affordsthe advantages of eliminated stair-step effect,increased build speed,
reduced waste,reduced need for decubing, and the ability to maintain continuous fibers
in the direction of curvature.Mechanical Engineerin