823 resultados para Desgaste erosivo


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The machining of super alloys resistant to high temperatures such as nickel alloys, inconel 718 specifically, is a very difficult job to obtain improvements in the process, due to the difficulty of machining at high cutting speeds, the use of these alloys in industries showed great developments in recent years, its application in aeronautical industry spread being used in vane turbo, compressor parts, props and set elements. The automotive, chemical, medical and others also took advantage of the great features of inconel 718 and has used the material. The high temperature resistant alloys have high machining difficulty, a fact that is associated with high cutting forces generated during machining which result in high temperatures. High levels of temperatures can cause deterioration of the cutting edge, with subsequent deformation or breakage, wear most common obtained in machining such materials are flank wear the formation of built-up edge for cutting and notch wear. The experimental part of the work consists in machining of nickel-based alloy Inconel 718 heat treated for hardness, using a tool based ceramic silicon nitride Sandvik (Si3N4) in order to compare the best results obtained in the master's thesis of SANTOS (2010) who used a tool ceramics also the basis of silicon nitride which was developed in the doctoral thesis of SOUZA (2005). Assays were performed on a CNC lathe and was noted for each cutting edge results obtained. Tests were made starting from an initial condition of the tool with cutting speed of 200 m/min, feed 0.5 mm and 0.5 mm depth of cut was reduced cutting speed for the subsequent tests with the same conditions of feed and depth of cut. The tool presented wear instant under two 200 m/min and 100 m/min, premature rupture of 50 m/min and finally cut provided with difficulty... (Complete abstract click electronic access below)

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The weight of a vehicle has always been considered an extreme important factor, because it interferes in the performance, steering, consume, environmental impact, wear of components, among the others. Because of the new demand, consume reduction aim and gases emission increased the necessity to manufacture lighter vehicles, guaranteeing the complying with the gas emission international law. Besides the legal demand, the low weight will certainly be essential for the competitiveness for the next generation of vehicles. It is with this thinking the composite materials have been introduced in the automobilist industry, because those materials show an excellent relation of strength/weight, providing a reduction of consume and the increase of load capacity. Those factors justify the increase of interest of industry and the necessity of optimization of those materials and of their process. For this research, the field of application will be the Baja SAE Project, a project that is fully developed by engineering students, where they build a prototype single seat, off-road category, for use on hilly slopes with obstacle. This research aims to study two key components of the prototype are made of composite materials, analyzing all the processing. In addition, there is the analysis of the viability of this production parts to a Baja SAE vehicle, in order to increase their performance and reduce their weight without reducing the safety and robustness of the prototype. It was possible to achieve weight reduction of the steering subsystem with manufacturing the flywheel hybrid composite (carbon/glass) and the replacement of SAE 1010 steel by hybrid composite (carbon/aramid) in CVT box. The importance of this study is to obtain a good project for the vehicle of technical and scientific manner, contributing to the know-how to the team and providing a basis for optimization for upcoming projects

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When handling soil conservation practices isn’t applied correctly, they cause problems at the level of structure, cohesion and fertility in soils and lack of water availability. In the case of this monograph, conducted in a rural property located at Álvares Machado City, identified that most areas are intended for use activities of beef cattle and dairy and subsistence agriculture, which historically addition to withdraw native flora, resulting in problems such as compaction and increase soil exposure to climatic agents, generating a serious frame of erosion problems. In the case of water from rainfall, the soil exposed, causes the “splash” effect and therefore when it becomes runoff carries the spalled particles mainly for low land areas. Without the vegetation, especially trees or shrubs species, the velocity of runoff increases, initiating the appearance of furrows, which consequently may become a kind of ravine erosion and gully, which makes invalid any area in your surroundings... (Complete abstract click electronic access below)

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Engenharia Elétrica - FEB

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Pós-graduação em Engenharia Mecânica - FEB

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L'article Uma estréia no romance: A mocidade de Trajano veut revoir l'histoire de la publication de ce roman de 1871, renié,quelques années plus tard, par Alfredo d'Escragnolle Taunay. On y veut aussi vérifier les marques qui ce remettent à ceux de Macedo, surtout en ce qui concerne sa filiation au mélodrame (le mot pris dans son sens le plus vaste). Le regard de l'auteur sur le paysage, l'importance du rôle attribué par lui à la nature – scène idéaleopposés à la constatation des dégâts dans les rapports seigneur/esclave, surtout dans les grandes propriétés rurales, pendant le XIXe., ont, eux aussi, été objet de réflexions. Finalement, dans cet article on a essayé de remarquer la filiation idéologique du personnage Trajano à des valeurs européennes, notamment françaises.

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This monograph proposes the implementation of a low cost PID controller utilizing a PIC microcontroller, and its application in a positioning system previously controlled by a dedicated integrated circuit for a positioning system. Applying the closed-loop PID control, the system instability was reduced, and its response was smoother, eliminating vibrations and mechanical wear compared to its response with the dedicated integrated circuit, which has a very limited control action. The actuator of the system is a DC motor, whose speed is controlled by the Pulse Width Modulation (PWM) technique, using a Full-Bridge circuit, allowing the shift of direction of rotation. The utilized microcontroller was the PIC16F684, which has an enhanced PWM module, with its analog converters used as reference and position feedback. The positioning sensor is a multiturn potentiometer coupled to the motor axis by gears. The possibility of programming the PID coefficients in the microcontroller, as well as the adjustment of the sampling rate, allows the implemented system achieving high level of versatility

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This work addresses the erosion caused by rain, describing their steps and factors that most influence the intensity and volume of transported material. The work presents the Universal Soil Loss Equation that quantifies the erosion, with the influence of different factors that affect it. The following notes the occurrence of this process in cutting slopes. They suffer with removal of the vegetation and surface soil layer, making them even more susceptible to this process. In this way it's necessary a protection model for the slopes. Some protection methods are presents with their main features, advantages and disadvantages, implementation process, especially to survey the approximate cost of each method and their application restrictions

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Pós-graduação em Engenharia Mecânica - FEG

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Pós-graduação em Ciências Sociais - FFC

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Posterior teeth restorations have changed the contemporary treatment philosophy influenced by the aesthetic demand of patients, progress of adhesive material science and techniques for preservation and rehabilitation of affected teeth by dental caries and trauma. The development of Onlay restorations with semi-direct technique in endodontically teeth treated aims to preserve the remaining surfaces, to reduce the possibility of fracture and polymerization shrinkage. In addition, better restoration adaptation and marginal seal, resistance to wear and dimensional stability are achieved. This case reports the rehabilitation of an endodontically treated permanent maxillary first molar in a 13 years old- patient who attended the Araraquara School of Dentistry, Brazil, using Miris 2 Composite resin with semi-direct technique and obtaining an aesthetic and functional restoration in a single appointment. The fundaments and clinical guidelines of the procedure are detailed, based on the review of the literature that supports this conservative treatment.

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The aim of this study was to evaluate the effect of the working angle variation of the magnetoestritive ultrasonic (MU) and air polishing devices (APD) on the roughness and wear of dental root. Fifty bovine incisive teeth were used in this study. The proximal surfaces of the teeth were divided in three regions: coronal, median, and an apical. The coronal region was treated with a manual scaler, the apical region was treated with APD or with a MU and the medium region was maintained untreated to serve as a control. The teeth were divided in 11 groups according to the treatment applied: MU-0º; MU-30º; MU-45º; MU-60º; MU-90º; AP-0º; AP-30º; AP-45º; AP-60º; AP-90º; MS: manual scaler. To the statistical analysis, data submitted to the Anova and Tukey's test (p < 0.05). The manual curette promotes less roughness and higher tooth wear in comparison with the both ultrasonic and air polishing devices (p < 0.05). The angles of 45º, 60º and 90º caused higher rate of tooth wear and roughness when the MU was used (p < 0.05), while the angle of 90° caused a higher tooth wear than the angle of 30° when the APD was used (p < 0.05). The working angle variation influenced the tooth wear and roughness promoted by MU, whereas when using APD, the working angle variation influenced only the tooth wear.

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Introduction: Bruxism has been defined as an oral parafunctional activity that includes clenching and/or grinding the teeth while asleep or awake. In addition to sleep bruxism (SB), various other orofacial movements sporadically occur during sleep. Occasional regurgitation and heartburn due to gastroesophageal reflux (GER) are frequent in the general population. GER refers to the presence of symptoms that are secondary to the reflux of gastric content through the esophagus with or without signs of esophageal mucosal lesions. Dentists are often the first health care professionals to diagnose GER through observation of its oral manifestation. Objective: The aim of the present case reports was to discuss the diagnosis and clinical procedures followed in two patients with SB and GER, thereby contributing to the dissemination of knowledge about these two entities. We therefore recommend dentists to be alert to identifying the first signs of GER that appear in the oral cavity. Conclusion: At this point, we highlight the importance of treating the patient as a whole, in an endeavor to identify other sources of the problems that could contribute as factors aggravating these conditions.

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The use of different methods and materials should be considered during the planning of implant-supported prostheses. Complications such as fractures of the acrylic resin base, wear and fracture of teeth can occur frequently, creating the need for careful planning for each patient, which can make the selection of the type of treatment more complex. Thus, this article describes the oral rehabilitation of a completely edentulous patient with bimaxillary fixed implant-supported prosthesis, with complaints on aesthetics, loss of vertical dimension and fracture of acrylic resin teeth of the upper arch. After the restoration of vertical dimension, his dentures were replaced with new bimaxillary implant-supported fixed prostheses, ceramic and acrylic resin were used as veneering material for maxilla and mandible, respectively. At the end of the treatment, the patient received bimaxillary flat occlusal splints to protect the teeth and implants of possible parafunctional habits. The approach for the treatment allowed a quick and effective resolution, with aesthetic and functional outcomes very favorable for the patient.