ABSTRACT:The development of a new approach for the production of three-dimensional plastic parts, called infrared laser stereolithography, is presented. During the experimentation, a carbon dioxide (CO 2 ) laser beam at 10.6 m (infrared radiation) was focused on a sample composed of an epoxy resin, diethylene triamine (curing agent), and silica powder (filler). The CO 2 laser, adopted for cost reduction, led to no significant shrinkage, and almost no postcure treatment was required. With differential scanning calorimetry, it was possible to determine the reaction rate as a function of the temperature and the activation energy of the curing process. The solution of the heat equation, with the Ansys program simulating this process, was in general agreement with our previous observations of the stereolithography results. The experimental results of the production of solid parts layer by layer in three dimensions are presented.
ABSTRACT:In this work, to analyze a type of rapid prototyping technique, a numerical model was developed that was able to simulate the heat transfer at thermosensitive polymeric material during cure by laser irradiation. The analysis was carried out as a transient thermal problem using the general-purpose finite element software ANSYS. The technique analyzed was thermal stereolithography, which uses a CO 2 laser beam to cure (solidify) thermosensitive liquid resins in a selective way to produce three-dimensional parts. In this numerical analysis, the temperature distribution at thermoset material heated by a laser irradiation and its thermal properties are investigated. This resin is a high-viscosity sample composed of epoxy resin, diethylenetriamine, and silica powder, which become highly crosslinked when irradiated by infrared laser. The localized curing becomes critical when the amount of silica and laser parameters are not appropriate. Bearing this in mind, this work intends, by applying the numerical method developed, to analyze the thermal behavior of resins in function of amount of silica and the laser radiation conditions, so that it is possible to have a knowledge on these variables so as to achieve a product with the required specifications.
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