DSpace Collection:https://repositorio.ufu.br/handle/123456789/54662026-09-06T03:39:34Z2026-09-06T03:39:34ZManufatura aditiva de parede fina de aço inoxidável duplex via deposição a arco com e sem resfriamento ativohttps://repositorio.ufu.br/handle/123456789/499442026-08-29T06:25:21Z2025-11-28T00:00:00ZTitle: Manufatura aditiva de parede fina de aço inoxidável duplex via deposição a arco com e sem resfriamento ativo
Abstract: Metal Additive Manufacturing (AM) has been consolidated as a strategic technology for the production of complex components, promoting production efficiency and cost reduction compared to conventional processes. Among its techniques, the Arc Deposition Additive Manufacturing (WAAM) process stands out for its high deposition rate and applicability in large parts. Thermal control during metal AM is even more relevant in thin-walled components, where steep thermal gradients and high localized temperatures can generate defects such as distortions, high residual stresses, and mechanical anisotropy. In this context, cooling techniques play a crucial role. In this context, the present study aimed to perform a comparative study between the Arc Deposition Additive Manufacturing of 2209 duplex stainless steel deposited by pulsed current using active cooling in water with natural air cooling. Duplex stainless steel was selected due to its two-phase ferrite/austenite microstructure, which provides an excellent combination of mechanical and corrosion resistance, which is widely required in critical industrial applications. The methodology involved the deposition of thin walls of duplex stainless steel by additive manufacturing via MADA process with pulsed current, using solid wire and commercially pure argon shielding gas. Two cooling conditions were compared: natural air cooling, similar to conventional welding processes, and near-immersion active cooling (NIAC), which consists of keeping the lower layers partially submerged in water or an aqueous mixture in order to reduce heat input. The samples produced underwent microstructural analyses, mechanical tests (tensile, bending, Charpy-V impact and hardness) and chemical characterizations by EDS and GDS. The results indicated that both cooling conditions allowed the fabrication of thin walls with good structural integrity and interlayer cohesion. The NIAC process showed better microstructural homogeneity, lower dispersion of mechanical results and reduced anisotropy, while natural cooling exhibited slightly higher hardness due to thermal heterogeneity. The chemical analysis confirmed the stability of the alloy and the preservation of the PREN (Pitting Resistance Equivalent Number) index, ensuring resistance to localized corrosion. It is concluded that MADA with pulsed current is a viable alternative for the manufacture of duplex stainless-steel components, and that active cooling by near-immersion represents an efficient strategy to improve thermal control, reduce residual stresses and increase process reliability.2025-11-28T00:00:00ZDesenvolvimento de equipamento acoplado a jogos sérios para reabilitação da escoliosehttps://repositorio.ufu.br/handle/123456789/498102026-08-26T06:18:51Z2026-08-14T00:00:00ZTitle: Desenvolvimento de equipamento acoplado a jogos sérios para reabilitação da escoliose
Abstract: This dissertation presents the development and evaluation of technological resources to
support Physiotherapeutic Scoliosis-Specific Exercises, including two serious games,
body tracking systems, and a physical support device. The proposal aims to make exercise
practice more interactive, traceable, and reproducible, without replacing
physiotherapeutic assessment. Initially, a literature review was carried out on Adolescent
Idiopathic Scoliosis, serious games, body tracking tools, and applications related to spine
rehabilitation. Next, the games Knight Run and Paint Maker were developed in Unity,
using C# programming, including profile management, exercise selection, performance
recording, series configuration, and data export. Game control was implemented through
two different strategies, one based on Nuitrack, using the Intel RealSense D435 depth
camera, and the other based on MediaPipe, using the Logitech C270 HD 720p webcam
(30 FPS). An adaptation for Android devices was also developed, restricted to the use of
MediaPipe. The users’ perception of the applications was evaluated with 10 participants,
using adapted forms based on the Game Experience Questionnaire and the Intrinsic
Motivation Inventory, resulting in overall scores of 73.12% for game experience and
83.33% for perceived motivation and usefulness. In parallel, a modular device was
designed to provide support, upper limb leveling, scapular support, and fixation points
for elastic resistance during the exercises. Finally, an experimental stage was carried out
comparing Nuitrack and MediaPipe with the Qualisys system, adopted as the reference,
during movements corresponding to the game controllers. The analysis considered
repetitions, total time, regularity, angles, and depth, when applicable. The results
indicated 0.00% error in repetition counting, temporal errors ranging from 0.21% to
7.60%, regularity errors predominantly below 8.33%, depth errors ranging from 0.27%
to 1.04% between Nuitrack and Qualisys, and angular errors below 7.88% in most
conditions, with greater deviations in frontal elevation trials using MediaPipe. It is
concluded that the developed resources showed potential as complementary, accessible,
and integrated tools to support scoliosis treatment, although future studies with patients,
larger samples, and clinical validation are still required.2026-08-14T00:00:00ZDesenvolvimento de módulos robóticos para instalação de amortecedores de vibração em cabos de alta tensãohttps://repositorio.ufu.br/handle/123456789/495882026-08-24T17:25:49Z2026-02-23T00:00:00ZTitle: Desenvolvimento de módulos robóticos para instalação de amortecedores de vibração em cabos de alta tensão
Abstract: The application of robots in high-voltage power line maintenance operations has gradually advanced over the past decades, with notable emphasis on mobile robot systems. However, despite the progress achieved, many challenges related to the development of such robots persist. Among the desirable features for these robots are: reliability, autonomous operation, low weight, high obstacle-transposing capability, and shielding against electromagnetic interference, many of which remain insufficiently addressed in existing robotic systems. Considering this, the present dissertation proposes the development of robotic modules for the installation of vibration dampers on high-voltage power lines. These robotic modules were designed to perform specific maintenance tasks in energized and hard-to-reach environments. This work describes the design, development, construction, and experimental testing of two robotic modules: one for the installation of Stockbridge-type dampers, and another for the installation of preformed-type vibration dampers. The dissertation also presents a shielding procedure for the robotic modules against electromagnetic interference and electrostatic discharges originating from transmission lines of up to 138 kV. Field tests carried out at the facilities of a power utility company demonstrated the modules’ effectiveness in overcoming a significant portion of existing limitations, positioning the developed solutions as promising alternatives in the field of high-voltage line maintenance robotics.2026-02-23T00:00:00ZImplementação de modelo de folga de backlash dinâmico em engrenagens para análise de dinâmica de rotaçãohttps://repositorio.ufu.br/handle/123456789/493012026-08-07T16:51:22Z2026-07-27T00:00:00ZTitle: Implementação de modelo de folga de backlash dinâmico em engrenagens para análise de dinâmica de rotação
Abstract: Gearboxes are essential components in industrial rotating machinery, but nonlinear phenomena
such as dynamic backlash and time-varying mesh stiffness (TVMS) introduce high complexity to their
overall structural response. Thus, it becomes necessary to develop tools capable of adequately representing
system behavior and aiding in the understanding of the involved phenomena. In this context, the objective
of this study was to develop a mathematical model capable of interpreting such effects and relating them
to rotational dynamics. To this end, a nonlinear meshing model was coded in Python and integrated into
the Rotordynamic Open-Source Software (ROSS) library, based on the Finite Element Method (FEM).
The original formulation of 3 degrees of freedom (DOF) per gear was expanded to 6 DOF per node,
enabling the inclusion of geometric parameters and helical gear forces. Additionally, a hyperbolic tangent
smoothing technique was incorporated to handle numerical discontinuities and optimize the convergence
of time integrators. To solve the differential equations of motion, the Newmark method combined with
the Newton-Raphson algorithm and adaptive time stepping was used. A simplified analytical model
was also developed to determine the natural frequencies of the gear pair. The results were validated
against literature, showing natural frequencies perpendicular and parallel to the Line of Action (LOA).
Bifurcation diagrams confirmed clear transitions between periodic and chaotic motion regimes at high
speeds. Finally, the integrated methodology was applied to a real practical case of a large-scale industrial
gearbox operated by Petrobras (input rotation of 1953 rpm and output of 12225 rpm) employing the full
mesh stiffness profile calculated by ROSS. For this case, the smoothing tool indicated a reduction of
approximately 7.3% in total computational processing time without loss of physical representativeness
of the dynamic system. It is concluded that the developed approach represents a solution for mechanical
design and fault diagnosis in complex industrial transmissions2026-07-27T00:00:00Z