Part surface roughness on laser sintering and milling of maraging steel 300

International audienceThe additive manufacturing of metal parts provides new opportunities to freely design of molds with conformal cooling channels, which enhances the productivity of injected plastic parts. In contrast to this manufacturing process, the surface quality of laser sintering parts is limiting the application of such technology on mold manufacturing. This work intends to investigate the surface roughness of maraging steel 300 samples produced by direct metal laser sintering (DMLS) and post-processed with end milling. Based on a set of experiments, combining different laser sintering build directions and milling process the measurement of the resulting surface roughness expresses how these process parameters impact on the final surface quality

Improvement In Cranioplasty: Advanced Prosthesis Biomanufacturing

Additive manufacturing (AM) is a technology that enables the production of models and prosthesis directly from the 3D CAD model facilitating surgical procedures, implant quality and reducing risks. Furthermore, the additive manufacturing has been used to produce implants especially designed for a particular patient, with sizes, shapes and mechanical properties optimized, in many areas of medicine such as cranioplasty surgery. This work presents AM technologies applied to design and manufacture of a biomodel, in fact, an implant for the surgical reconstruction of a large cranial defect. A series of computed tomography data was obtained and software was used to extract the cranial geometry. The protocol presented was used for creation of anatomic biomodel of the bone defect for the surgical planning as well as to design and manufacture of the patient-specific implant, reducing duration of surgery besides improving the surgical accuracy due to preoperative planning of the anatomical details. (C) 2015 The Authors. Published by Elsevier B.V.492032082nd CIRP Conference on Biomanufacturing (CIRP-BioM)JUL 29-31, 2015Manchester, ENGLAN

Expert system for the assessment of power transformer insulation condition based on type-2 fuzzy logic systems

An efficient expert system for the power transformer condition assessment is presented in this paper. Through the application of Duval's triangle and the method of the gas ratios a first assessment of the transformer condition is obtained in the form of a dissolved gas analysis (DGA) diagnosis according IEC 60599. As a second step, a knowledge mining procedure is performed, by conducting surveys whose results are fed into a first Type-2 Fuzzy Logic System (T2-FLS), in order to initially evaluate the condition of the equipment taking only the results of dissolved gas analysis into account. The output of this first T2-FLS is used as the input of a second T2-FLS, which additionally weighs up the condition of the paper-oil system. The output of this last T2-FLS is given in terms of words easily understandable by the maintenance personnel. The proposed assessing methodology has been validated for several cases of transformers in service. © 2011 Elsevier Ltd. All rights reserved.Fil: Flores, Wilfredo C.. Universidad Nacional Autónoma de Honduras; Honduras. Universidad Nacional de San Juan; ArgentinaFil: Mombello, Enrique Esteban. Universidad Nacional de San Juan; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan; ArgentinaFil: Jardini, José. A.. Universidade de Sao Paulo; BrasilFil: Rattá Gutiérrez, Giuseppe Aníbal. Universidad Nacional de San Juan; ArgentinaFil: Corvo, Antonio M.. Companhia de Transmissão de Energía Elétrica Paulista; Brasi

EBSD-data analysis of an additive manufactured maraging 300 steel submitted to different tempering and aging treatments

This research was funded by FAPESP grants (2017/17697-5, 2019/00691-0, and 2020/09079-2) and was supported by LNNano – Brazilian Nanotechnology National Laboratory (CNPEM/MCTI) during the use of the electron microscopy open access facility. F. Conde acknowledges the Ph.D. scholarship CNPq 142440/2019-1. In addition, JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, of the Associate Laboratory Institute of Nanostructures, Nanomodelling, and Nanofabrication – i3N. Finally, Julian A. Avila is a Serra Hunter Fellow and a CNPq fellow. Publisher Copyright: © 2023 The AuthorsMaraging is a high alloy steel sensitive to the precipitation of intermetallics from a supersaturated solid solution during aging heat treatments. The precipitation phenomenon is well described in the literature, which gave rise to the alloy name regarding a martensite matrix with precipitates formed by aging treatment. Many studies have been performed to characterize this material, usually subjected to many sample preparations for transmission microscopy, which is very laborious, and few EBSD analyses. Therefore, in this work, a large study was conducted using electron backscatter diffraction (EBSD) to analyze maraging microstructures through band-contrast, kernel average misorientation (KAM), grain orientation spread (GOS), and misorientation distribution. Our results show that solubilization of the additive manufactured maraging steel resulted in a more homogeneous microstructure with new angle grain boundaries. Furthermore, tempering heat treatments relieve martensite strain, increasing band contrast values. Posterior aging presented a low impact on the results of EBSD analysis.publishersversionpublishe

Cytotoxicity Assessment of a Poly(methyl methacrylate) Synthesized for the Direct Fabrication of Bone Tissues

ABSTRACT A cytotoxicity study is performed on a poly(methyl methacrylate) polymer (PMMA) to be used for the fabrication of bone tissue by Rapid Prototyping (RP). The solution polymerization is conducted in a pilot plant reactor using more appropriated reagents in consideration of the medical application. Moreover, the polymer is efficiently handled to avoid the side effect of the monomer, reducing the concentration of this specie to 287,731 µg MMA/kg PMMA. The cytotoxicity of the polymer is determined through growth monitoring, adherence and morphology of L-929 cells. Additionally, MTT and LIVE/DEAD tests are performed. The results showed continuous and progressive growth of the cells on the surface of the specimens. Moreover, the material did not influence on the viability of mesenchymal cells and inverted fluorescence microscopy images showed a polyanionic dye calcein well retained in the cells in contact with the PMMA as well as the negative control after 72 hours. Thus, the polymer was efficiently synthesized and handled for the expected demands

Regenerative collagen biomembrane: Interim results of a Phase I veterinary clinical trial for skin repair [version 1; referees: 2 approved, 1 approved with reservations]

Background: The availability of commercial tissue engineering skin repair products for veterinary use is scarce or non-existent. To assess features of novel veterinary tissue engineered medical devices, it is therefore reasonable to compare with currently available human devices. During the development and regulatory approval phases, human medical devices that may have been identified as comparable to a novel veterinary device, may serve as predicate devices and accelerate approval in the veterinary domain. The purpose of the study was to evaluate safety and efficacy of the biomembrane for use in skin repair indications. Methods: In the study as a whole (3 year total length), 15 patients (animals), dogs and cats (male/female, 2 cm), with a wound depth equivalent to 2nd/3rd degree burns are to be studied from Day 0 to Day 120-240, post-application of the biomembrane. This interim report covers the 5 patients assessed to date and deemed eligible, of which 3 enrolled, and 2 have completed the treatment. Wound beds were prepared and acellular collagen biomembranes (Eva Scientific Ltd, São Paulo, Brazil) applied directly onto the wounds, and sutured at the margins to the patient's adjacent tissue. Wound size over time, healing rate, general skin quality and suppleness were assessed as outcomes. Qualitative (appearance and palpation) and quantitative (based on Image Analysis of photographs) wound assessment techniques were used. Results: Both patients’ wounds healed fully, with no adverse effects, and the healing rate was comparable in both, maxing out at approximately 1 cm2/day. Conclusions: Early results on the biomembrane's safety and efficacy indicate suitability for skin repair usage in veterinary patients

Broadband terahertz pulse generation driven by an ultrafast thin-disk laser oscillator

We demonstrate broadband THz generation driven by an ultrafast thin-disk laser (TDL) oscillator. By optical rectification of 50-fs pulses at 61 MHz repetition rate in a collinear geometry in crystalline GaP, THz radiation with a central frequency at around 3.4 THz and a spectrum extending from below 1 THz to nearly 7 THz are generated. We realized a spectroscopic characterization of a GaP crystal and a benchmark measurement of the water-vapor absorption spectrum in the THz range. Sub-50-GHz resolution is achieved within a 5 THz bandwidth. Our experiments show the potential of ultrafast TDL oscillators for driving MHz-repetition-rate broadband THz systems