<p>With the advances in MEMS technology, the studies of the properties of magnetic crystals have reached the microscopic level. Critical information such as the magnetization and susceptibility of a magnetic sample can be obtained using a microtorque magnetometer, such as ones incorporating piezoresistive or capacitive detection that have been fabricated and tested by earlier research groups. This type of magnetic information is useful in the study of superconductivity, for example. The microtorque magnetometer designed and fabricated in this thesis has the potential of being used in this field of study.</p> <p>This thesis describes the design, fabrication and testing of a capacitive microtorque magnetometer. By using ANSYS, a computer modelling program, an ideal model of the rotating microtorque magnetometer was devised. Fabrication involved testing a variety of procedures before establishing the successful and efficient method of building the microtorque magnetometer. A fifth order resonant mode was successfully detected during the testing stage. A method of studying the desired resonant mode has been devised and explained in the later chapters of this thesis.</p> / Master of Applied Science (MASc)

The effects of aging on the muscle length (as inferred by joint angle)-tension relationship was studied in the ankle dorsiflexors of male and female subjects aged 20-40 years (x=25.3; 15d, 159) and 60-80 years (x=68.8; 15d, 159) at 10 joint angles {15°0 through 30°P, in 5° increments). Isometric twitches, voluntary contractions, and 1-sec evoked tetanic contractions {20, 50 & 80 Hz) were measured in the R-tibialis anterior muscle. The resting joint angle for the ankle dorsi flexors was similar between elderly and young adults {13°P ± 3.44). On average, evoked and voluntary torque output increased upon muscle lengthening beyond resting length, and decreased upon shortening. Evoked single twitches of the TA revealed that peak total torque occurred at the extreme of plantarflexion (30°P} in both elderly and young adults. Most importantly, elderly individuals produced similar twitch torque values at all joint angles compared to young adults. Maximal voluntary torque was stronger at the more plantarflexed compared to the dorsiflexed angles, for all subjects, regardless of age, with maximum torque plateauing at 15°P. Elderly subjects demonstrated much reduced MVC torque values compared to young adults at all joint angles (ave.= 18% reduction, p<O.Ol) while maintaining no less than 96% motorunit activation (MUA) . Stimulation of the dorsiflexors at 20, 50, & 80 Hz revealed that the 1-sec peak tetanic torques declined from a maximum at 30°P through to 15°0 for all subjects. Elderly adults produced significantly less tetanic torque at all joint angles compared to young adults (p<0.05). There was no difference between the elderly and young adults in the rate at which the rise in tetanic torque was developed at all joint angles, but elderly adults displayed a significantly greater twitch/tetanus ratio as compared to young adults (p<0.005). In conclusion, these results suggest that there is no age-associated change in the elastic properties of the ankle dorsiflexors, and thus, the length-tension relationship of this muscle group is similar between elderly and young adults. / Thesis / Master of Science (MSc)

Hip fractures are serious injuries that are associated with high rates of morbidity and mortality in older adults. While much of the increased risk of hip fracture with age can be explained by age-related decreases in bone mineral density, muscles and motor control are altered by aging as well. Muscles forces in vivo are thought to have a prophylactic effect that can reduce shear and bending in the femur. This is beneficial because bone is stronger in compression than in shear or tension, and shear plays an important role in fatiguing bone. Understanding how aging and muscular loads affect strains in the proximal femur could lead to improvements in clinical screening and preventative measures for hip fracture. Three studies were performed to investigate age-related changes in neuromuscular function during gait and how these changes affect strains in the proximal femur. Study 1 examined age differences in peak lower extremity joint torques during walking with controlled speed and step length. Studies 2 and 3 applied muscle forces estimated during gait to finite element models of the femur. Study 2 examined age differences in femoral strains, and Study 3 examined the sensitivity of strains to individual muscle forces. The results support the idea that older adults walk with reduced contributions from the ankle plantar flexors and increased contributions from the hip extensors. Interactions between age and speed indicate that older adults utilized a different neuromuscular strategy than young adults to vary the speed of their gait. No age differences were found for the largest magnitude strains in the proximal femur. However, young adults were able to apply larger loads to the femur without corresponding increases in femoral strains. Strains in the femoral neck were found to be sensitive to muscle forces, particularly hip abductor forces. Strains in the sub-trochanteric region tended to be larger than those in the femoral neck, and less sensitive to muscle forces. These results increase our understanding of neuromuscular changes that occur with age, and the effects of these changes on the femur. / Ph. D.

This study examines a specific application of button-head type twist-off bolts. Currently, the Research Council on Structural Connections Specification (2000) removes the requirement for ASTM F436 washers (ASTM 2000a) under the bolt head of twist-off bolts where the head diameter equals or exceeds that of an ASTM F436 washer when oversized and slotted holes are used. The need for washers is also removed for A490 strength bolts used on steels with specified yield strengths less than 40 ksi provided that the head diameter equals or exceeds an ASTM F436 washer. The ASTM F1852 Specification (ASTM 2000b) allows for head diameter dimensions that are slightly smaller than an ASTM F436 washer. Following the RCSC Specification, manufacturers that produce bolts using the ASTM F1852 dimensions are required to use ASTM F436 washers under the bolt head. The discrepancies between the specifications lead to this study, which involved the testing of button-head type twist-off bolts with two different head diameters, both of which were smaller than an ASTM F436 washer. Five bolt diameters between 5/8 in and 1-1/8 in. were tested in standard, oversized, and long-slotted holes. The performance of the twist-off bolts was determined by measuring and comparing the achieved relaxed pretension force in the bolt after tightening. It was found that twist-off bolts with head diameters less than an ASTM F436 washer had no trouble attaining their required minimum pretension force. Bolt head diameter and hole size were found to have no significant influence on the pretension force that was achieved for all bolts tested. / Master of Science

This study focuses on the design and implementation of a humanoid robot for disaster response. In particular, this thesis investigates the lower body design in detail with the upper body discussed at a higher level. The Tactical Hazardous Operations Robot (THOR) was designed to compete in the DARPA Robotics Challenge where it needs to complete tasks based on first-responder operations. These tasks, ranging from traversing rough terrain through driving a utility vehicle, suggest a versatile platform in a human sized form factor. A physical experiment of the proposed tasks generated a set of joint range of motions (RoM). Desired limb lengths were determined by comparing existing robots, the test subject in the experiment of proposed tasks, and an average human. Simulations using the desired RoM and limb lengths were used to calculate baseline joint torques. Based on the generated design constraints, THOR is a 34 degree of freedom humanoid that stands 1.78 [m] tall and weighs 65 [kg]. The 12 lower body joints are driven by series elastic linear actuators with multiple joints actuated in parallel. The parallel actuation mimics the human body, where multiple muscles pull on the same joint cooperatively. The legs retain high joint torques throughout their large RoM with some joints achieving torques as high as 289 [Nm]. The upper body uses traditional rotary actuators to drive the waist, arms, and head. The proprioceptive sensor selection was influenced by past experience on humanoid platforms, and perception sensors were selected to match the competition. / Master of Science

Switched Reluctance Motors (SRMs) are gaining recognition due to their robust design, cost-effectiveness, fault tolerance, and reliable high-speed performance, positioning them as promising alternatives to traditional electric motors. However, SRMs face high torque ripples, vibration, acoustic noise, and nonlinear modeling complexities. Through careful geometry design optimization, these drawbacks can be mitigated. Design optimization for SRMs is a multi-objective and nonlinear problem that requires an accurate finite element analysis (FEA) model to relate designable parameters to output objectives. The geometric design process follows a multi-stage and iterative approach, leading to prohibitive computational time until the optimal design is reached. Machine learning algorithms (MLAs) have recently acquired attention in electric machine design. This study introduces an extensive analysis of various MLAs applied to SRM modeling and design. Additionally, it presents a robust framework for a comprehensive evaluation of these MLAs, facilitating the selection of the optimal machine learning topology for SRM design. Existing research on the geometry optimization of SRMs using MLAs has focused only on the machine’s static characteristics. This thesis introduces an advanced optimization method utilizing an MLA to act as a surrogate model for both static and dynamic characteristics of the SRM. The dynamic model incorporates conduction angles optimization to enhance the torque profile. The proposed MLA is applied to map out the SRM geometrical parameters, stator and rotor pole arc angles and their dynamic performance metrics, such as average torque and torque ripples. The optimal design improves the average torque and significantly reduces the torque ripples. Radial forces constitute a critical objective that should be considered alongside average torque, efficiency, and torque ripple in the design optimization of SRMs. Accurate modeling of radial forces is a prerequisite for optimizing motor geometry to mitigate their adverse effects on vibrations and acoustic noise. This work presents an MLA-based surrogate model for the most influential radial force harmonic components, facilitating the integration of radial force reduction into a multi-objective optimization framework. The proposed optimization framework employs two MLA-based surrogate models: the first correlates SRM pole arc angles with average torque and torque ripples, while the second models the most significant radial force harmonics. A genetic algorithm leverages these surrogate models to predict new geometrical parameters that enhance the SRM's torque profile and reduce radial forces. The optimization framework significantly reduced torque ripples and radial forces while slightly increasing average torque. The optimal design candidates were verified using FEA and MATLAB simulations, confirming the effectiveness of the proposed method, which offers significant computational time savings compared to traditional FEA techniques. / Thesis / Doctor of Philosophy (PhD)

A new torque transfer standard using metallic TBTF resonant sensor was developed to overcome the overload capability problem which occurs with conventional metallic resistance strain gauges. Previous research work, however, has shown that the first prototype of the metallic TBTF resonant sensor was not suitable for use in a torque transfer standard due to its size and subsequent sensitivity to parasitic lateral forces. To maximize the benefits from this sensor, particularly overload capability and long-term stability, in the high accuracy torque measurement application area, there is a need to develop significantly smaller devices. The aim of this thesis is to research through FEA modelling and experimental characterisation the key performance parameters required to produce a miniaturised metallic TBTF resonant sensor that provides better performance when applied in a torque measurement system. For high accuracy any torque transducer using these sensors ought to have low sensitivity to parasitic influences such as bending moments and lateral forces, which can only be achieved with reduced size. The problems with the existing design, key design issues, possible configuration and packaging solutions of the metallic TBTF resonant sensor that could be used for achieving a higher accuracy torque transfer standard are considered. Two designs of miniaturised metallic TBTF resonant sensors, SL20 and SL12, are considered and experimentally investigated. The lateral forces are reduced by 52% for SL20 design and by 80% for SL12 design when compared to the original SL40 design. A torque transducer using the SL20 design was calibrated falling into the Torque Transfer Standard class of accuracy 1 category, uncertainty 0.8%. A torque transducer using the SL12 design was made and calibration showed a class of accuracy 0.5 category, uncertainty 0.2%. The results from this research indicate that the SL12 design is suitable for use in a torque transfer standard. The SL12 design is optimal and the smallest size possible based on the overload capability design criteria requiring the tine cross sectional area to remain constant.

Para avaliação das propriedades físico-mecânicas de implantes tri-channel Dérig, quanto ao efeito de acréscimo de 0,25mm no corpo do implante 3.5 NP (em relação ao controle 3.5 NP) e à influência da plataforma switching (em diâmetros iguais de 4,3 mm e plataformas distintas - NP e RP), o presente estudo relacionou resistência ao torque de inserção (avaliação do microgap entre implante/pilar protético - mensurações bi e tridimensionais), em microtomografia computadorizada (CT); resistência à fratura e resistência à fadiga. Para a resistência ao torque de inserção, os implantes foram divididos, aleatoriamente, em quatro subgrupos (n=10), segundo torque: GT45: 45 N.cm; GT80: 80 N.cm; GT120: 120 N.cm; GT150: 150 N.cm. Os conjuntos implante/pilar/parafuso foram levados às análises de deformação bi e tridimensional em CT. Para o teste de resistência à fratura, os conjuntos implantes/munhões foram levados à máquina de ensaios universais, até a falha e, posteriormente, às microscopias óptica e eletrônica de varredura. Para a resistência à fadiga, os conjuntos (n=12) foram submetidos a ensaio cíclico (5 Hz, 5° - 55° C, cargas em 80, 120, 160, 200, 240, 280 e 320 N, máximo de 2x104 ciclos) e carregados até a falha (ou máximo de 14x104 ciclos) (análise de sobrevivência Life Table Survival Analysis). Para o envelhecimento mecânico, os conjuntos (n=12) foram submetidos a 106 ciclos (2 Hz, 120 N, 5º - 55º C) e, novamente, levados às análises microscópicas. Após a análise estatística (2-way ANOVA, Bonferroni, p<0,05), para a análise da porcentagem de deformação bi e tridimensional dos torques de inserção em CT, há diferenças significantes (p<0,05) em todas as comparações, à exceção de 4.3 NP x 4.3 RP (45N). As microtomografias evidenciaram microgaps em conjuntos novos e aumento, qualitativo, dos mesmos, em diâmetros e plataformas menores. A comparação linear com conjuntos novos demonstrou diferenças significantes (p<0,05) em 3.5 NP e 3.75 NP (todos os torques) e 4.3 NP (120 e 150 N.cm). Para o ensaio de resistência à fratura (1-way ANOVA, Tukey B, p<0,05), 4.3 NP apresentou força máxima de deformação maior (p<0,05) que 3.75 NP e 3.5 NP (p=0,004), mas não houve diferença significante entre 4.3 RP, 3.5 NP e 3.75 NP (p>0,05). Quanto aos ensaios de resistência à fadiga, o envelhecimento mecânico levou ao afrouxamento dos parafusos de todos os grupos analisados, sendo que, à exceção de 3.75 NP, houve diferenças significativas (p<0,05) entre perdas de torques inicial e final; para a fadiga acelerada, ambos os grupos de 4,3 mm (NP e RP) sobreviveram ao final do ensaio, sendo que houve fratura de todas as amostras de 3.5 NP. Finalmente, quanto à probabilidade de sobrevivência, houve diferença significante (p<0,05) entre 3.5 NP e 3.75 NP, com taxa de 92% para este último. Conclui-se que o diâmetro 4,3 mm é mais resistente que 3,5 mm; 4.3 NP apresentou maior resistência à fratura; o envelhecimento mecânico leva à perda de torque; a fadiga mecânica acelerada tem influência em diâmetros menores e a metodologia em CT é válida para análises bi e tridimensional / To investigate the physical-mechanical properties of Dérigs tri-channel implants, regarding the 0.25 mm addition in 3.75 NP implant structure (in relation to 3.5 NP as control) and the influence of platform switching (in equal diameters of 4.3 mm and different platforms - Narrow and Regular), this study related the resistance to insertion torque (microgap evaluation between implant and abutment - bi and tridimensional measurements), computerized microtomography (CT); resistance to fracture and fatigue. For the resistance to insertion torque, the samples were randomly divided into four subgroups (n=10), according to the torque applied: GT45: 45 N.cm; GT80: 80 N.cm; GT120: 120 N.cm; GT150: 150 N.cm. The implant/abutment/screw assemblies were taken to bi and tridimensional deformation analyzes in CT. For the fracture strength test, the implant/abutment assemblies were taken to the universal test machine until failure and then to optical and scanning electron microscopes. For the fracture resistance, the sets (n=12) were subjected to a cyclic test (5 Hz, 5° - 55° C, loads in 80, 120, 160, 200, 240, 280 and 320 N, maximum of 2x104 cycles) and loaded to failure (or maximum of 14x104 cycles) (Life Table Survival Analysis). For mechanical aging, the sets (n=12) were submitted to 106 cycles (2 Hz, 120 N, 5º - 55º C) and, again, to microscopic analysis. After statistical analysis (2-way ANOVA, Bonferroni, p<0.05), there were statistical differences (p<0.05) in all comparisons for the bi and three-dimensional deformation percentages of the insertion torques in CT, except between 4.3 NP x 4.3 RP (45N). The microtomographies evidenced microgaps in new sets and a qualitative increase of the same sets in diameters and smaller platforms. The linear comparison with new sets showed significant differences (p<0.05) in 3.5 NP and 3.75 NP (all torques) and 4.3 NP (120 and 150 N.cm). As for the fracture resistance test (1-way ANOVA, Tukey B, p<0.05), 4.3NP had a higher maximum deformation force (p<0.05) than 3.75 NP and 3.5NP (p=0.004), but there was no significant differences between 4.3 RP, 3.5 NP and 3.75 NP (p>0.05). Regarding the fatigue strength tests, the mechanical aging led to the screw loosening of all groups analyzed, and by the exception of 3.75 NP, there were significant differences (p<0.05) between initial and final torque applied; for the accelerated fatigue, both groups of 4.3 mm (NP and RP) survived at the end of the test, with fractures in all 3.5 NP samples. Finally, regarding the survival rate, there was a significant difference (p<0.05) between 3.5 NP and 3.75 NP, with a 92% rate for this last one. It could be concluded that the diameter 4.3 mm is stronger than 3.5 mm; 4.3 NP presented higher fracture resistance; the mechanical aging leads to screw loosening; the accelerated mechanical fatigue has influence in smaller diameters and the methodology in CT is valid for bi and three-dimensional analyzes

A Ti-35Nb-7Zr é uma liga Ti-&szlig; desenvolvida pelo Grupo de Biomateriais da Escola de Engenharia de Lorena da Universidade de São Paulo, que demonstrou, em estudos anteriores, propriedades mecânicas favoráveis para ser usada como biomaterial, tais como, limite de resistência (~800 Mpa), resistência à corrosão e baixo módulo de elasticidade (33 GPa). Uma vez que o implante dentário traz melhores resultados no tocante à função mastigatória, fonação, conforto e estética, melhorando a qualidade de vida das pessoas, o presente estudo descreve a avaliação da biofuncionalidade dos implantes dentários da liga Ti-35Nb-7Zr comparados aos implantes comerciais de Ti-Cp da marca Titaniumfix. A biofuncionalidade foi avaliada por meio de testes in vitro e in vivo. A avaliação in vitro foi realizada com células mesenquimais indiferenciadas retiradas da medula óssea de fêmures de ratos, que foram cultivadas em meio de cultura osteogênico e posteriormente realizados os testes de citotoxicidade, quantificação de proteína total e avaliação da atividade da fosfatase alcalina. A avaliação in vivo compreendeu a realização de implantes de Ti-Cp Titaniumfix e da liga Ti-35Nb-7Zr em tíbias de coelhos para avaliação histológica, histomorfométrica por meio do cálculo da Fração da área óssea ocupada (BAFO) e aposição óssea, e de remoção ao torque com intuito de avaliar a osteointegração. Considerando os resultados obtidos nesta pesquisa, com relação aos testes in vitro, é possível concluir que a liga possui maior hidrofilicidade que o Ti-Cp; apresenta espraiamento celular similar ao Ti-Cp o que corrobora para o resultado de viabilidade celular classificando-a como não citotóxica. Nos testes de quantificação de proteína total e atividade da fosfatase alcalina a liga apresenta resultados similares ao Ti-Cp, favorecendo a ocorrência de diferenciação e proliferação das células osteoblásticas. Desta forma, pode-se concluir que a liga possui boa compatibilidade in vitro. Os resultados obtidos nas avaliações in vivo, por meio da fração de área óssea ocupada (BAFO), comprovam a semelhança entre a liga e o Ti-Cp pois tiveram o valor percentual de osso neoformado similar. A análise de fluorescência, após a administração dos marcadores tetraciclina e alizarina, mostra que a aposição óssea também foi semelhante entre a liga e o Ti-Cp nos períodos estudados. Com relação a força de interação avaliada pelo torque de remoção é possível afirmar que a liga apresenta osteointegração comparável aos implantes comerciais Ti-Cp. Esses resultados demonstraram que os implantes da liga Ti-35Nb-7Zr apresentaram biocompatibilidade e biofuncionalidade semelhantes ao dos implantes de Ti-Cp. Além de possuir um baixo módulo de elasticidade, a liga apresentou uma osteointegração bem similar ao Ti-Cp, reunindo características que demonstram seu potencial para ser usada como biomaterial intraósseo. / Ti-35Nb-7Zr is a Ti-&szlig; alloy developed by the Biomaterials Group of the Lorena School of Engineering of the University of São Paulo, which demonstrated, in previous studies, favorable mechanical properties to be used as biomaterial, such as resistance (~800 Mpa), corrosion resistance and low modulus of elasticity (33 GPa). Since the dental implant brings better results regarding masticatory function, phonation, comfort and aesthetics, improving the quality of life of the people, the present study describes the evaluation of the biofunctionality of the Ti-35Nb-7Zr ally dental implants compared to the Titaniumfix implants of Ti-Cp. The biofunctionality was evaluated by means of in vitro and in vivo tests. The in vitro evaluation was perfomed with undifferentiated mesenchymal cells removed from the bone marrow of rat femurs, which were cultured in osteogenic culture medium and subsequently perfomed cytotoxicity tests, total protein quantification and evaluation of alkaline phosphatase activity. The in vivo evaluation included the implantation of Ti-Cp Titaniumfix and Ti-35Nb-7Zr alloy implants in rabbit tibiae for histological, histomorphometric evaluation by calculating the Bone Area Fractional Occupied (BAFO) and bone apposition, and torque removal in order to evaluate the osseointegration. Considering the results obtained in this research, related to in vitro tests, it is possible to conclude that the alloy has a higher hydrophilicity than Ti-Cp; Show cellular spreading similar to Ti-Cp, which corroborates the result of cell viability classifying it as non-cytotoxic. In the tests of total protein quantification and alkaline phosphatase activity the alloy presents results similar to Ti-Cp, favoring the occurrence of differentiation and proliferation of osteoblastic cells. In this way, it can be concluded that the alloy has good compatiblity in vitro. The results obtained in the in vivo evaluations, through the BAFO, confirm the similarity between the alloy and Ti-Cp, since they had the percentage value similar to neoformed bone. Fluorescence analysis, after administration of the tetracycline and alisarin markers, show that bone apposition was also similar between the alloy and Ti-Cp in the periods studied. Regarding the interaction force evaluated by the removal torque, it is possible to affirm that the alloy show osseointegration comparable to commercial Ti-Cp implants. These results demonstrated that Ti-35Nb-7Zr alloy implants had similar biocompatibility and biofunctionality to Ti-Cp implants. In addition to having a low modulus of elasticity, the alloy presented an osseointegration very similar to Ti-Cp, bringing together characteristics that demonstrate its potential to be used as an intraosseous biomaterial.

O desenvolvimento de protocolos de fortalecimento muscular, tanto na reabilitação quanto no treinamento, é realizado por exercícios resistidos, os quais envolvem a aplicação de sobrecargas externas ao músculo exercitado. Estas sobrecargas podem ser do tipo constante ou variável. Dentre os recursos existentes para a aplicação da resistência variável, os tubos elásticos são amplamente utilizados por sua versatilidade e viabilidade econômica. No entanto, é um material que ainda não possui parâmetros de aplicação claramente delineados. Alguns estudos realizaram a caracterização biomecânica dos materiais elásticos e as formas de aplicação nos diferentes tipos de exercícios, mas poucos registraram o comportamento do músculo quando exercitado por esse tipo de resistência. Neste contexto, o objetivo deste trabalho foi caracterizar o comportamento do grupo muscular isquiotibial, no que se diz respeito a sua geração de força interna e a atividade eletromiográfica (EMG), durante exercícios resistidos, com tubo elástico e peso fixo. Este trabalho envolveu: o estudo das propriedades de tubos elásticos nacionais e importados, por meio de ensaios mecânicos realizados no EMIC; a avaliação da força exercida pelos isquiotibiais em exercícios resistidos, com o indivíduo em diferentes posições, utilizando-se simulações realizadas no Origin 6.0 e MatLab 6.5 e baseadas no modelo biomecânico; e análise do sinal EMG do músculo bíceps femoral, o qual correlacionado com a força e o torque dos isquiotibiais, durante ensaios experimentais. Estes ensaios foram realizados em 10 voluntários do sexo masculino, os quais foram posicionados no sistema mecânico de exercício em decúbito dorsal para a realização de movimentos de flexo extensão do joelho, com resistência elástica e fixa. A captação do sinal EMG foi feita no módulo condicionador de sinais modelo EMG1000. Registrou-se também, a posição angular da perna por meio do eletrogoniômetro e a força aplicada, por uma célula de carga. Os dados foram tratados em rotina desenvolvida em MatLab 6.5. Os resultados mostraram que não existem diferenças significativas na relação tensão-deformação entre os tubos elásticos nacionais e importados. A otimização da escolha do tipo de resistência, baseada na resposta de força muscular, depende também da escolha da posição adotada pelo indivíduo para realizar a flexão do joelho. A relação entre a força dos isquiotibiais e o sinal EMG da cabeça longa do bíceps femoral foi independente do tipo de sobrecarga utilizada. O sinal EMG dos exercícios realizado com peso foi menos harmônico e o músculo agiu numa menor extensão do movimento. E, por fim, o torque foi proporcional ao sinal EMG, nos casos de resistência constante e elástica / The development of protocols of strengthening, as in the rehabilitation as in the training, it is carried through resistives exercises, which involve the application of external overloads to the exercised muscle. These overloads can be of the constant or variable type. Among the existing resources for the application of the variable resistance, the elastic tubing are widely used by its versatility and economic viability. However, it is a material that still haven`t possess parameters of application delineated clearly. Some studies had carried through the biomechanic characterization of the elastic materials and the forms of application in the different types of exercises, but few had registered the behavior of the muscle when exercised by this type of resistance. In this context, the aim of this work was to characterize the behavior of the hamstrings, connected to generation of internal force and the electromyography (EMG) activity, during resisted exercises, with elastic tubing and constant weight. This work involved: the study of the properties of national and imported elastic tubing, during the experiments in the EMIC; the evaluation of the force exerted for hamstrings in resisted exercises, with the individual in different positions, through simulations realized by 6,0 Origin and MatLab 6,5, based in the biomechanic model; analysis of EMG activity of the femoral biceps, which was correlated with the force and torque of the hamstrings, during the experiments. These experiments had been carried out in 10 voluntaries of the masculine gender, that had been located in the mechanical system of exercise in supino position for the accomplishment knee of flexion-extension of the knee, with elastic and constant resistance. The captation of EMG activity was made by conditioning module of signals model EMG1000. It was also registered the angular position of the leg through goniometer and the applied force through a load cell. The data had been treated in routine developed in MatLab 6.5. The results had shown no significant differences in the tension-deformation relation between the national and imported elastic tubes. The improvement of the choice of type of resistance, based on the reply of muscular force, also depends on the choice of the position adopted for the individual to carry out the knee flexion. The relation between the force of the hamstrings and EMG signal of the long head of the femoral biceps was independent of the type of used overload. The EMG activity of the exercises carried out with weight was less harmonic and the muscle acts in a less extension of the movement. Finally, the torque was proportional to EMG signal in the cases of constant and elastic resistance