Esforcos hidraulicos dinamicos em turbomaquinas

A measurement device has been developed to measure force and torque components acting on the impeller of a model pump-turbine, which uses crystal quartz load transducers installed on the rotating shaft. These kinds of load transducers allow greater stiffness than arrangements using strain gauges. Therefore, the dynamics behavior of the measurement device has to be taken into account. Some results of measurements are present in the whole operating range of model pump-turbine.

A load cell for grain-propelled ballistic rocket thrust measurement

A 1000-kgf resistive strain-gauge load cell has been developed for quality testing of rocket propellant grain. A 7075-T6 aluminum alloy has been used for the elastic column, in which 8 uniaxial, 120-Ω strain gauges have been bonded and connected to form a full Wheatstone bridge to detect the strain. The chosen geometry makes the transducer insensitive to moments and, also, to the temperature. Experimental tests using a universal testing machine to imposed compression force to the load cell have demonstrated that its behavior is linear, with sensitivity of 2.90 μV/kgf ± 0.34%, and negligible hysteresis. The designed force transducer response to a dynamic test has been comparable to that of a commercial load cell. © 2005 IEEE.

In vitro evaluation of the precision of working casts for implant-supported restoration with multiple abutments

Objective: The purpose of this study was to compare the accuracy of two working cast fabrication techniques using strain-gauge analysis. Methods: Two working cast fabrication methods were evaluated. Based on a master model, 20 working casts were fabricated by means of an indirect impression technique using polyether after splinting the square transfer copings with acrylic resin. Specimens were assigned to 2 groups (n=10): Group A (GA): type IV dental stone was poured around the abutment analogs in the conventional way; Group B (GB), the dental stone was poured in two stages. Spacers were used over the abutment analogs (rubber tubes) and type IV dental stone was poured around the abutment analogs in the conventional way. After the stone had hardened completely, the spacers were removed and more stone was inserted in the spaces created. Six strain-gauges (Excel Ltd.), positioned in a cast bar, which was dimensionally accurate (perfect fit) to the master model, recorded the microstrains generated by each specimen. Data were analyzed statistically by the variance analysis (ANOVA) and Tukey's test (α= 5%). Results: The microstrain values (με) were (mean±SD): GA: 263.7±109.07με, and GB: 193.73±78.83με. Conclusion: There was no statistical difference between the two methods studied.

Development of a prototype for measuring plantar forces

Studies on the distribution of plantar pressure between the sole of the foot and the ground were developed before the 19th century. Currently, the most often employed plantar pressure measurement systems are Pedar® and FScan®, which have restrictions such as operational difficulty and high cost. In the present study, a device was constructed from two pressure plates capable of measuring plantar forces in discreet areas of the feet at a low cost, using strain-gages attached to sixteen strategic points of the mechanical elements. Sixteen prismatic beams were soldered to each frame, for which the free extremity of each beam represented a specific point of the foot. Two strain gauges were attached to each beam - one near the upper fixed extremity and the other near the lower fixed extremity. Using a Wheatstone bridge electric circuit, the gauges were used to measure the force acting on the extremity of the beam. Precision and accuracy of the prototype was about 10%. In some measurements, accuracy was 2%. The low precision and accuracy were mainly due to the restrictions of the available equipment, which only permitted four measurements at a time. Thus, it was necessary for participants to stand on the plates four separate times, which signified possible changes in the position of the feet on the pressure plates. Despite some limitations, the aim was achieved. The prototype has been used in some studies and represents a contribution to biomechanics, demonstrating the viability of using strain gauges.

Eficiência de três cimentos de ionômero de vidro como dissipadores de cargas em bases de restaurações de resina composta: análise por meio da extensometria elétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ponte mista de madeira-concreto em vigas treliçadas de madeira

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Um dispositivo mecânico para avaliação da rigidez de tornozelo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Analise de tensões através do método dos elementos finitos de um vaso de pressão projetado conforme código ASME

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise estrutural e de fadiga de juntas rebitadas de uso aeronaútico utilizando o método dos elementos finitos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Extensometria: estudo das deformações ao redor de três implantes cone morse, com posicionamento linear, sob carga axial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo das microdeformações geradas ao redor de implantes de hexágono interno com roscas convencionais e implantes com platôs, sob a aplicação de carga vertical

Pós-graduação em Odontologia Restauradora - ICT

Analise eletromiográfica e dinamométrica durante o ciclio da pedalada em cicloergômetro aquático

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo do comportamento biomecânico em protocolos modificados de Branemark (conceito All-on-Four): análise por extensometria linear elétrica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação, por extensometria, da deformação superficial no substrato de retenção dos implantes gerada por próteses fixas implanto suportadas em função do cantilever

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Extensometria: avaliação de implantes de sextavado externo posicionados na configuração linear e compensada (offset), sob carregamento axial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)