Comparação do efeito da fadiga muscular no andar livre e adaptativo entre adultos jovens e idosos

A fadiga muscular é definida como uma falha no sistema neuromuscular na capacidade de gerar uma força requerida ou esperada. Quanto maior a idade do indivíduo, maior é a probabilidade de chegar à fadiga, aumentando o risco de quedas. Dessa forma, a fadiga pode influenciar no andar dos indivíduos, causando prejuízos no controle postural e podendo causar lesões músculo-esqueléticas A partir dos estudos realizados, percebe-se que a fadiga muscular pode prejudicar o desempenho do andar, sendo ele adaptativo ou não. O objetivo do estudo foi analisar e comparar a influência da fadiga muscular sobre os parâmetros cinemáticos do andar livre e adaptativo entre adultos jovens e idosos. Participaram do estudo 20 indivíduos, distribuídos em dois grupos etários: Adulto Jovem - 20 a 40 anos; e Idoso - a partir de 60 anos. Os participantes realizaram o andar livre e adaptativo percorrendo uma distância retilínea de 8 metros sobre um carpete de borracha com 1,4m de largura. Foram realizadas 6 tentativas para cada condição experimental. Para a coleta dos dados cinemáticos dos ciclos do andar definidos foi utilizado um sistema tridimensional (3D) optoeletrônico de análise do movimento (OPTOTRAK Certus – 3D Motion Measurement System, NDI), com precisão de 0,1 mm, posicionado no plano frontal, face anterior, ao movimento do participante, com frequência de 100 Hz. A indução a fadiga será através da tarefa de sentar e levantar. Para a comparação entre os dois grupos foram analisados as seguintes variáveis espaciais e temporais do andar livre e adaptativo: comprimento de cada passo, largura de cada passo, velocidade média do andar, distância horizontal pé-obstáculo antes da ultrapassagem, distância horizontal depois do obstáculo e distância vertical péobstáculo. Estas variáveis foram analisadas durante o ciclo do andar antes e após fadiga muscular.

Efeitos da fadiga relacionada ao trabalho sobre a força manual em funcionários do restaurante universitário e da administração do IGCE da Unesp

Têm-se preocupado cada vez mais com a saúde do trabalhador manual, que vem sendo prejudicada com as altas demandas de trabalho repetitivo sem a devida recuperação, aumentando os riscos de lesão. A fadiga muscular tem se mostrado um importante fator responsável pelo aumento do risco de lesão, pois deixa a musculatura enrijecida e com pouca resistência muscular para suportar a demanda de trabalho. Este estudo pretende evidenciar a diminuição da força de resistência muscular devido ao acúmulo de fadiga residual do trabalho, através da dinamometria manual. Foram escolhidos 16 sujeitos, funcionários do Restaurante Universitário e da administração do Instituto de Geociências (IGCE) da UNESP campus Rio Claro, que realizam trabalho manual repetitivo. Entre os 16 sujeitos, haviam 11 mulheres (com média de idade 48,8 ± 12,4, e média de IMC 26,9 ± 4,8) e 5 homens (com média de idade 45,9 ± 14,8 e média de IMC 25,3 ± 6,5). Foi realizado o teste de preensão manual onde os sujeitos realizavam 10 contrações rápidas e de máxima força, com intervalo de 3 segundos entre cada contração, mas foram utilizadas para análise as contrações 1, 5 e final.. O teste foi realizado com ambas as mãos na Segunda-feira e na Sexta-feira, no período da manhã e da tarde. Analisando-se os resultados obtidos para a mão não-dominante, pudemos observar uma queda nos valores de média de força manual ao longo das contrações, sendo que na sexta-feira a queda é maior que na segunda-feira, e à tarde a queda é maior que no período da manhã. Para a mão dominante, essa queda maior ocorreu na sextafeira à tarde, momento de maior acúmulo de fadiga residual. Podemos concluir com este estudo, que a fadiga residual do trabalho interfere na queda de desempenho de força dos funcionários, sendo a mão não-dominante mais influenciada pela fadiga...(Resumo completo, clicar acesso eletrônico abaixo)

Estudo de falhas por fadiga em caldeiras

In recent years, increasing demand for energy has led to studies to increase the amount of electricity produced. Due to this fact, more and more boilers are becoming important sources of electricity generation. To raise the efficiency of energy generated in the boilers is necessary to raise the steam pressure and temperature to values previously unimaginable. The use of more resistant materials and maintenance practices and most appropriate operation made it possible. The objective of this study is to test the main types of failure in a chemical recovery boiler, in particular due to fatigue in the superheater, because it is a component subjected to high temperatures and thus more subject to different failures. In this manner this study aims to reduce the incidence of unscheduled maintenance shutdowns, increasing the operation time under appropriate conditions. Modeling performed in this study, the failure did not occur, because we considered only the mechanical stress. Under normal conditions, mechanical stress in combination with thermal stresses can cause cracks in the tubes due to cyclical stresses, leading to fatigue failure

Influências multi-escala da paisagem e limiar da fragmentação em morcegos no cerrado

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Análise de fadiga em rodas automotivas utilizando método dos elementos finitos

The increasing search for better performance at the automotive industry, especially on the matter of fuel consumption, caused a progressive evolution of industrial technology. For the wheel this study is based on the try of reducing mass and decreasing the moment of inertia, characteristics that directly reflect on the performance parameter, as consumption and acceleration, so that it also is effective on the growth of the profit margin, since it reduces the costs of the locomotion. In this paper will be applied the Finite Element Analysis to explain the wheel behavior and identify ways to improve the performance. To the analyze it will be simulated a test condition established by ABNT NBR 6751:2009 foreseeing a possible collapse through general yielding and fatigue. The load here presented results from the equation presented on the norms and in the datas provided by the manufacturer

Fadiga axial do aço inoxidável 15-5 PH tratado pela implantação iônica por imersão em plasma

When materials for application in aircraft structural components are studied, it must be considered that they will be submitted to cyclic loading, and this is an important parameter to design the study in fatigue life of the materials. Whereas, for example, a landing gear operation, the study of fatigue life and corrosion in the materials used in it is essential, especially when you want to use new techniques for surface treatments. The objective is to study the influence of surface treatment of immersion ion implantation nitrogen plasma, in axial fatigue of Stainless steel 15-5 PH in 39-42 HRC condition. Stainless steel 15-5 PH was tested in axial fatigue and corrosion in salt spray. It was also performed microindentation tests, optical microscopy for microstructural analysis and scanning electron microscopy for fractographic analysis. It was observed that the 3IP had no effect on the thickness of the material and not the hardness of it, and still provided a significant increase in fatigue life of the material

Estudo do efeito do processo de shot peening na taxa de propagação de trinca por fadiga na liga aeronáutica 2024 - T3

Pós-graduação em Engenharia Mecânica - FEG

Fadiga em compósitos 5HS carbono/epóxi processados via RTM: relação entre cargas axiais no plano e modos de delaminação

Pós-graduação em Engenharia Mecânica - FEG

Influência de três tratamentos de superfície para cerâmicas a base de zircônia na resistência adesiva e no comportamento à fadiga do material

Pós-graduação em Odontologia Restauradora - ICT

Cidade média de limiar superior: um estudo a partir de Ribeirão Preto (SP)

This papper aims to discuss Ribeirão Preto as a switched-over intermediate city classification, contrastating with the concept of Metropolitan Region of Ribeirão Preto. The agribusiness sector will be analysed as the main responsible for the representation of Ribeirão Preto city as an Agribusiness Center. Due to this fact, Sertãozinho city example will be presented as Agribusiness City, where acctually concentrates the agro-industrial complex of sugarcane production, while Ribeirão Preto is in fact centralizes management activities. According to the balance of trade analysis, other elements showed up and fortifies the role of this cities. These elements unfolded the analysis of higher education guideline and shopping malls. We also analyzed the urban network of Ribeirão Preto under the concept of the Região de Influência das Cidades (REGIC) and the creation of the project Metropolitan Region of Ribeirão Preto in order to strengthen the central hypothesis as a switched-over medium sized city. In order to reach this point, besides the analysis of the data we had t literature review of the Medium Sized Cities and Urban Network concepts and Spatial Interactions and Switched- over terms

Estudo da fadiga em liga de alumínio aeronáutico 7475-T761

This work will address the study of fatigue conditions with constant load in an alloy of aluminum analysis 7475 - T761, so we can better understand the conditions of the aircrafts which contain this alloy in their structures. A literature review, which was discussed the concepts of fracture mechanics, fatigue, aeronautical components, chemical analysis of aluminum alloys, fatigue problems that appears in the aircrafts, metallographic analysis, and testing of optical microscopy tensile, fatigue and microhardness, surface analysis (MEV) study of the chemical composition of the alloy in question, the main causes of crashes, was performed, completing the work, analysis of data from tensile test, hardness and fatigue together with the interpretation of images of optical microscopy and scanning electron was taken. The data indicated the high mechanical strength of the alloy, along with its microstructure indicating elongated grains and high surface contour, which shows such resistance by hindering the movement of dislocations. The grooves are clearly shown in the MEV images as well as the classic with increased fatigue loading and subsequent reduction of the number of cycles to rupture behavior shown in the graphs. Therefore we observed the optimal behavior is supported by the league when subjected to fatigue loadings

Estudo do comportamento em fadiga das ligas AA6005, AA6063 e AA6351

Aluminum alloys have shown great potential for the automotive industry, especially aluminum alloys 6xxx series. This category has good mechanical strength and excellent corrosion resistance, important for the areas of construction and transport. The automotive industry has always shown great interest in the study of fatigue behavior, because structural components are subjected to cyclic and vibration loads, generating cracks and fracturing. The mechanical response depends on the material properties, applications, surface condition and microstructure. In this work was study the fatigue behavior of high cycle of machined bodies (not polished) and the effect of roughness on the fatigue life for three aluminum alloys of 6xxx series: AA6005, AA6351 and AA606, all in the T6 condition . S / N curves were made from fatigue tests in rotating bending (R = -1). The influence of roughness was studied by measuring the roughness of each specimen. Was compare the fatigue behavior of polished specimen and not polished specimens. The fractured surfaces of samples were observed by MEV, and it was observed that most of nucleation sites for fatigue crack is initiated below the surface

Estudo do comportamento em fadiga de um tubo de aço microligado, grau API 5L X70

This work focuses on a study on the fatigue behavior of a microalloyed steel API 5L X70, used in pipes lines to transport oil and gas. These types of steels have excellent mechanical resistance values and ductility and therefore increased their study driven by increased demand for oil and especially natural gas, which consequently raises the need to build new pipelines to transport these products. The oil extraction units, composed of the risers (pipelines connecting the oil well to the ship), are dimensioned to remain installed for periods of 20 to 30 years in the marine environment, a hostile environment for high pressure, corrosion, low temperatures and the stresses caused by the movement of water and tides. For analysis, the S-N (stress versus number of cycles) curves were obtained from data collected from bodies-of-proof cylindrical longitudinal, transverse and that one removed from the weld area of the pipe, tested in accordance with ASTM E466. Tensile tests were performed for characterizing the mechanical properties of the samples and welded joints, concluded that the values meet the specifications of the standard API 5L. To characterize microstructural material, also metallographic analysis was made of regions of the base metal and the HAZ. The results of fatigue tests demonstrated a higher life for the specimens removed from the longitudinal direction the pipe, followed by those in the transverse direction and, finally, the welded joint. The origins of the fatigue cracks were determined by scanning electron microscopy (SEM)

Resistência à flexão em porcelana feldspática: efeito da ciclagem mecânica e limite de fadiga pelo método escada

This study evaluated the fatigue limit (FL) by the staircase method and the effect of mechanical cycling on the flexural strength (FS) of Duceragold feldspathic porcelain. Specimens (25 x 5 x 2 mm) were made according to manufacturer’s directions and submitted to three-point flexural strength test (n = 10). To determine FL (n = 30; 10,000 cycles; 2 Hz), an initial loading of 60% of the FS and an incremental loading (step) of 3% of the FS were used. Data were analyzed by Anova and Tukey´s test (p < 0.05). Although the proposed cycles have not reduced FS significantly, fractography analysis showed striation, characteristic signs of mechanical fatigue.

Determinação de fatores de correção da intensidade de limiar anaeróbio em diferentes séries de treinamento intermitente na natação

Pós-graduação em Ciências da Motricidade - IBRC