Artigos
URI permanente para esta coleçãohttps://repositorio.fei.edu.br/handle/FEI/799
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42 resultados
Resultados da Pesquisa
- Biomechanical Analysis of Tissue Engineering Construct for Articular Cartilage Restoration—A Pre-clinical Study(2022-04-15) FARIA, R. R. DE; MAIZATO, M. J. S.; CESTARI, I. A.; HERNANDEZ, A. J.; BUENO, D. F.; Roberto Bortolussi; Cyro Albuquerque; FERNANDES, T. L.© 2022, Springer Nature Switzerland AG.The chondral lesion and osteoarthritis are conditions associated with an economic burden, since if left untreated may cause changes in the biomechanics of the joint and result in several injuries considered highly disabling to the individual. Mesenchymal Stem Cells (MSCs) have the immunomodulatory capacity and paracrine signaling that are useful for tissue bioengineering to treat bone and cartilage injuries. To the best of our knowledge, there is no institution in Brazil studying cartilage biomechanical properties in Good Manufacturing Practice (GMP) technique. Therefore, this study aims to describe biomechanics analysis for cartilage restoration by tissue engineering and cell therapy treatments in a GMP translational large animal model. A controlled experimental study in fourteen Brazilian miniature pigs was performed, using scaffold-free Tissue Engineering Construct (TEC) from dental pulp and synovial MSCs with 6 months follow-up. To compare the cartilage with and without TEC, indentation and maximum compressive tests were performed, as well as Finite Element model to simulate the osteochondral block and characterize its properties. The Young’s Modulus of each sample was determined, and the outcomes of maximum compressive test demonstrated the cartilage integrity. The proposed method was feasible and capable to properly evaluate articular cartilage restoration.
- SCRUM applied to foundry simulation projects(2021-01-05) DE SÁ, D. A.; WILLIAN GOMES, C.; PAULIELI COLOSSETTI, A.; SCHMIDT, J.; RODOLFO ABRAHAM, E.© 2021 SAE International.Process simulation has a growing role in the casting industry, considered as an essential tool by most foundries that aim to develop systems that deliver quality parts, with the highest possible yield and lowest scrap rate. The challenges of performing casting simulation as part of tool construction projects for permanent molds are presented here. Real schedules from tooling companies are analyzed and their bottlenecks are explored. Using the concepts of agile project management and the Scrum framework applied to a cast part, it was possible to verify that integration between tool construction and simulation can increase quality and robustness with no impact to product development time.
- Test and Validation of Vehicle Vertical Dynamics in a Multibody Software(2015-09-05) AFONSO, B.; CHICUTA, W.; Roberto BortolussiCopyright © 2015 SAE International.This paper shows the elaboration of studies about the driver's comfort in a Baja SAE vehicle in different track conditions. The multibody model was designed in ADAMS VIEW software with full vehicle components aim evaluate frequencies, accelerations and displacements in any part of the vehicle. Several tests and measurements were made to acquire springs, dampers and tire data to ensure the model represents the real vehicle. The full vehicle and also the driver were modeled through a CAD software, thus all geometries, mass and inertias were inputted in the multibody model based on the built vehicle. The vertical displacements were modeled in the multibody software simulating the road profile, so it was possible to analyze the vehicle ride behavior with different set ups in different tracks. The validation of multibody mathematical model was made by modeling the same maneuver that the vehicle instrumented with data acquisition was submitted. The mathematical model output and the data acquisition results were confronted and the results shows that the mathematical model can be considered validated. After the mathematical model be validated, it can be use in future analysis with high confidence level. This model will be helpful to evaluate design and make modifications in earlier phases of vehicle development, reducing cost, engineering time, prototype manufacturing and mainly time in test phase once that will be necessary just the fine tuning.
- Comparative Investigation into the Structural Braces Proposed at Baja SAE Competitions(2021-12-07) MUNIZ, B. P. L.; DE MELLO, L. T. R.; DA SILVA, G. R.© 2021 SAE International. All rights reserved.The BAJA SAE Brasil competition presents major technical challenges to its participants every year, including the design and manufacture of tubular frames according the Regulamento Administrativo e Técnico Baja SAE Brasil, RATBSB. The vehicle must have at least one of two possible bracing systems: front or rear, which differ in terms of the positioning of the main tubes for impact containment. The use of front braced frames is extremely widespread among Brazilian teams, due in part to the difficulty of designing rear braced frames, as they require more tubes and cause difficulties in accessing the engine compartment compared to the required structural configurations by international rules. The present study evaluates four structure configurations, these being the most comprehensive possible within the possibilities of the rules, defining loading scenarios coherent with possible accidents in competitions. There is the displacement of the structure and invasion of the survival cell, margin of safety of critical structural points through the Cozzone method, in addition to critical loads and linear buckling modes through their eigenvalues and eigenvectors, respectively. It was concluded that the requirements imposed by the Brazilian regulation, RATBSB, for rear bracing configurations do not bring outstanding additional security benefits in comparison to foreign configurations. A lower efficiency was also observed in relation to the safety of the 'nose' car configuration compared to the others.
- Life Cycle Assessment of Vehicular Electrification(2021-12-07) TOMAKI, E.; POLICARPO, E.; ROVAI, F.© 2021 SAE International. All rights reserved.Internal Combustion Engine vehicles (ICEV) have approximately 80% of their environmental impact during operation, 20% during manufacturing and disposal/recycling at the end of life. On the other hand, Battery Electric Vehicles (BEV) have a relatively lower impact during their use. However, BEVs produce proportionally higher equivalent-carbon dioxide (CO2e) emissions during vehicle manufacturing, which is adversely affected by the production of the battery. To account for the global environmental impact, a complete Life Cycle Assessment (LCA) needs to be done. In this work, data published by different sources and car manufacturers were used to predict the accumulated CO2e emissions along the vehicle life. In addition, a few scenarios with different assumptions were investigated. In particular, the impact of ICEVs and BEVs utilization in Brazil is lower than the world average due to the use of bioethanol as fuel and the low carbon intensity of the electricity. Most of the scenarios indicate that due to large environmental impact of the battery manufacturing, BEV CO2e emissions will break-even with the ICE vehicles only after several thousand km of usage. For some countries, the high carbon intensity of electricity will make the BEV a bad choice to mitigate climate change, as demonstrated by the higher life cycle CO2e emissions than those produced by ICEVs. For Brazil, the lower carbon intensity of the bioethanol combined with the existing fuel distribution infrastructure and the car plants indicate that moving from ICEV to BEV needs dedicated attention and may be attractive on high usage (taxi, shared cars etc.) which the higher initial CO2e impact, as well as cost, will be compensated along with car life).
- A method to simulate motor control strategies to recover from perturbations: Application to a stumble recovery during gait(2011-09-03) FORNER-CORDERO, A.; Marko Ackermann; DE LIMA FREITAS, M.Perturbations during human gait such as a trip or a slip can result in a fall, especially among frail populations such as the elderly. In order to recover from a trip or a stumble during gait, humans perform different types of recovery strategies. It is very useful to uncover the mechanisms of the recovery to improve training methods for populations at risk of falling. Moreover, human recovery strategies could be applied to implement controllers for bipedal robot walker, as an application of biomimetic design. A biomechanical model of the response to a trip during gait might uncover the control mechanisms underlying the different recovery strategies and the adaptation of the responses found during the execution of successive perturbation trials. This paper introduces a model of stumble in the multibody system framework. This model is used to assess different feedforward strategies to recover from a trip. First of all, normal gait patterns for the musculoskeletal system model are obtained by solving an optimal control problem. Secondly, the reference gait is perturbed by the application of forces on the swinging foot in different ways: as an instantaneous inelastic collision of the foot with an obstacle, as an impulsive horizontal force or using a force curve measured experimentally during gait perturbation experiments. The influence of the type of perturbation, the timing of the collision with respect to the gait cycle, as well as of the coefficient of restitution was investigated previously. Finally, in order to test the effects of different muscle excitation levels on the initial phases of the recovery response, several muscle excitations were added to selected muscles of the legs, thus providing a simulation of the recovery reactions. These results pave the way for future analysis and modeling of the control mechanisms of gait. © 2011 IEEE.
- Tribological Characterization of the ASTM F138 Austenitic Stainless-Steel Treated with Nanosecond Optical Fiber Ytterbium Laser for Biomedical Applications(2022-01-05) DE MATOS MACEDO, M.; BERNARDES, G. V. R.; LUNA-DOMINGUEZ, J. H.; VERMA. V.; Ronaldo Câmara Cozza© 2022, Springer Nature Switzerland AG.This study investigated the tribological behavior of the ASTM F138 austenitic stainless-steel – which is generally used in biomedical applications – treated with laser. Metallic biomaterial surfaces were treated under different nanosecond optical fiber ytterbium laser pulse frequencies, with the purpose to increase their surface hardness. Further, ball-cratering wear tests were conducted to analyze their tribological behavior on the basis of their wear volume and coefficient of friction. The obtained results showed that the nanosecond optical fiber ytterbium laser pulse frequency influenced the surface hardness of each specimen and, consequently, on the wear resistance of the ASTM F138 austenitic stainless-steel biomaterial. With an increase of laser pulse frequency, a decrease in the wear volume of the worn biomaterial was observed – which is the main tribological parameter to study the wear resistance of a metallic biomaterial. In contrast, the coefficient of friction values were found to be independent of the laser pulse frequency, surface hardness and the wear volume of the specimen.
- Advanced multi-metallic SOFC anode development by mechanical alloying route(2010-01-05) TESTIVO, T. A. G.; LEITE, D. W.; MELLO-CASTANHO, S. R. W.Anodes composed of Ni-YSZ (yttria-stabilised zirconia) cermets are the key material to allow direct biofuel feeding to Solid Oxide Fuel Cell (SOFC) devices due to its internal reforming capability. The main challenge among these materials is related to carbon deposition poisoning effect when C-bearing fuels are feed. The work deals with these issues by alloying Ni with some metals like Cu to conform a multi-metallic anode material. Mechanical alloying (MA) at shaker mills is chosen as the route to incorporate the metal and ceramic powders in the anode material, also leading to better sintering behaviour. A projected cermet material is conceived where a third metal can be added based on two criteria: low Cu solubility and similar formation enthalpy of hydrides regarding Ni. Refractory metals like Nb, W and Mo, seems to fulfil these characteristics, as well as Ag. The MA resulted powder morphology is highly homogeneous showing nanometric interpolated metal lamellae. The sintering behaviour is investigated by conventional dilatometry as well as by stepwise isothermal dilatometry (SID) quasi-isothermal method to determine the sintering kinetic parameters. Based on these tools, it is found the Cu additive promotes sintering to obtain a denser anode and therefore allowing lower process temperatures. The consolidation is achieved through the sintering by activated surface (SAS) method allied to liquid phase sintering process, where the third metal additive also has influenced. The final cermet can be obtained at one sole process step, dispensing pore-forming additives and reduction treatments. The sintered microstructure demonstrates the material is homogeneous and possesses suitable percolation networks and pore structure for SOFC anode applications. © (2010) Trans Tech Publications.
- Synthesis of Niobium Carbide (NbC) by powder metallurgy high energy milling technique(2010-10-05) ANTONELLO, R. T.; DE ARAÚJO FILHO, O. O.; GONZALEZ, C. H.; URTIGA FILHO, S. L.; AMBROZIO FILHO, F.The aim of this work is to obtain and characterize the Niobium Carbide (NbC) by a suitable high energy milling technique using a SPEX Mill vibratory type and niobium and carbon (graphite) powders. Since this carbide is scarced in the national market and it's necessary to apply this NbC as a reinforcement in two molybdenum high speed steels (AISI M2 and AISI M3:2) object of another work motivated this research. The powders were submitted to a high energy milling procedure for suitable times and conditions and then were characterized by means of Scanning Electronic Microscopy (SEM) and X-ray diffraction (DRX) techniques. The ball-to-powder weight ratio was 10:1. The analyzed samples showed that the high-energy milling is an alternative route of the NbC synthesis. © (2010) Trans Tech Publications.
- Effects of weld strength mismatch on estimation procedures for J fracture parameter using clamped SE(T) specimens(2010-07-30) Gustavo Donato; Rodrigo Magnabosco; RUGGIERI, C.This work presents an exploratory development of J estimation procedures for deep and shallow cracked tension SE(T) specimens based upon plastic eta factors which incorporate the effects of weld strength mismatch. The considered technique includes estimation of J from plastic work. The primary objective is to derive estimation procedures which are applicable to determine J fracture parameters for a wide range of a/W-ratios, material flow properties and different levels of weld strength mismatch using clamped SE(T) specimens of varying geometries. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement and crack mouth opening displacement, which are needed to determine the estimation procedures. Laboratory testing of a welded structural steel using SE(T) specimens provide the data needed to evaluate J evolution for the welded joints based upon the proposed methodology. The crack driving force evolution is compared against the results obtained using plastic eta factors for homogeneous specimens and demonstrates the importance of considering mismatch effects on crack-tip stress fields and fracture parameters. The present analyses, when taken together with previous studies, extend the body of results which serve to determine J integral using tension SE(T) specimens with varying geometries and mismatch levels. Copyright © 2009 by ASME.