The Element Free Galerkin (EFG) method, which is based on the Moving Least Squares (MLS) approximation, is developed here for vibration, buckling and static analysis of homogenous and FGM plate with curvilinear stiffeners. Numerical results for different stiffeners configurations and boundary conditions are presented. All results are verified using the commercial finite element software ANSYS® and other available results in literature. In addition, the vibration analysis of plates with curvilinear stiffeners is carried out using Ritz method. A 24 by 28 in. curvilinear stiffened panel was machined from 2219-T851 aluminum for experimental validation of the Ritz and meshfree methods of vibration mode shape predictions. Results were obtained for this panel mounted vertically to a steel clamping bracket using acoustic excitation and a laser vibrometer. Experimental results appear to correlate well with the meshfree and Ritz method results. In reality, many engineering structures are subjected to random pressure loads in nature and cannot be assumed to be deterministic. Typical engineering structures include buildings and towers, offshore structures, vehicles and ships, are subjected to random pressure. The vibrations induced from gust loads, engine noise, and other auxiliary electrical system can also produce noise inside aircraft. Consequently, all flight vehicles operate in random vibration environment. These random loads can be modeled by using their statistical properties. The dynamical responses of the structures which are subjected to random excitations are very complicated. To investigate their dynamic responses under random loads, the meshfree method is developed for random vibration analysis of curvilinearly-stiffened plates. Since extensive efforts have been devoted to study the buckling and vibration analysis of stiffened panel to maximize their natural frequencies and critical buckling loads, these structures are subjected to in-plane loading while the vibration analysis is considered. In these cases the natural frequencies calculated by neglecting the in-plane compression are usually over predicted. In order to have more accurate results it might be necessary to take into account the effects of in-plane load since it can change the natural frequency of plate considerably. To provide a better view of the free vibration behavior of the plate with curvilinear stiffeners subjected to axial/biaxial or shear stresses several numerical examples are studied. The FEM analysis of curvilinearly stiffened plate is quite computationally expensive, and the meshfree method seems to be a proper substitution to reduce the CPU time. However it will still require many simulations. Because of the number of simulations may be required in the solution of an engineering optimization problem, many researchers have tried to find approaches and techniques in optimization which can reduce the number of function evaluations. In these problems, surrogate models for analysis and optimization can be very efficient. The basic idea in surrogate model is to reduce computational cost and giving a better understanding of the influence of the design variables on the different objectives and constrains. To use the advantage of both meshfree method and surrogate model in reducing CPU time, the meshfree method is used to generate the sample points and combination of Kriging (a surrogate model) and Genetic Algorithms is used for design of curvilinearly stiffened plate. The meshfree and kriging results and CPU time were compared with those obtained using EBF3PanelOpt. / Ph. D.

This thesis describes the design, manufacture and characterisation of thick vacuum plasma sprayed tungsten (W) coatings on steel substrates. Fusion is a potentially clean, sustainable, energy source in which nuclear energy is generated via the release of internal energy from nuclei. In order to fuse nuclei the Coulomb barrier must be breached - requiring extreme temperatures or pressures – akin to creating a ‘star in a box’. Tungsten is a promising candidate material for future fusion reactors due to a high sputtering threshold and melting temperature. However, the large coefficient of thermal expansion mismatch with reactor structural steels such as the low activation steel Eurofer’97 is a major manufacturing and in-service problem. A vacuum plasma spraying approach for the manufacture of tungsten and tungsten/steel graded coatings has been developed successfully. The use of graded coatings and highly textured 3D interface surfi-sculpt substrates has been investigated to allow the deposition of thick plasma sprayed tungsten coatings on steel substrates. Finite element models have been developed to understand the residual stresses that develop in W/steel systems and made use of experimental measurements of coating thermal history during manufacture and elastic moduli measured by nano-indentation. For both the graded and surfi-sculpt coating, the models have been used to understand the mechanism of residual stress redistribution and relief in comparison with simple W on steel coatings, particularly by consideration of stored strain energy. In the case of surfi-sculpt W coatings, the patterned substrate gave rise to regular stress concentrating features, and allowed 2mm thick W coatings to be produced reproducibly without delamination. Preliminary through thickness residual stress measurements were compared to model predictions and provided tentative evidence of significant W coating stress relief by regulated coating segmentation.

Since the advent of the Internet, the number of individuals and organisations using tools such as the World Wide Web and cell phones has increased, and is continuing to grow at a rapid pace. Social media has provoked fundamentally different ways of doing business, and organisations rapidly had to get on this social media bandwagon to stay up to date with the latest market trends and ahead of the competition. Although social media is already broadly used among South African businesses, the perception regarding the use of social media as a promotional mix element has not been investigated sufficiently in South Africa. The primary purpose of this study was therefore to determine the perception of star-graded accommodation establishments, operating in the Western Cape province of South Africa, regarding the use of social media as a promotional mix element. A broad and in-depth literature review was conducted on the use of social media and social media as a probable promotional mix element. An empirical study was conducted, in which data was collected from star-graded accommodation establishments operating in the Western Cape by means of a web-based (computer-assisted) self-administered questionnaire. A quantitative approach was followed in order to satisfy the research objectives of this study. The results of this research study indicate that social media is perceived to be an instrumental marketing element in star-graded accommodation establishments and can indeed be considered an element of the promotional mix. / Business Management / M. Com. (Business Management)

Metal Additive Manufacturing (AM) technologies in particular powder bed fusion processes such as Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) are capable of producing a fully-dense metal components directly from computer-aided design (CAD) model without the need of tooling. This unique capability offered by metal AM has allowed the manufacture of inter-connected lattice structures from metallic materials for different applications including, medical implants and aerospace lightweight components. Despite the many promising design freedoms, metal AM still faces some major technical and design barriers in building complex structures with overhang geometries. Any overhang geometry which exceeds the minimum allowable build angle must be supported. The function of support structure is to prevent the newly melted layer from curling due to thermal stresses by anchoring it in place. External support structures are usually removed from the part after the build; however, internal support structures are difficult or impossible to remove. These limitations are in contrast to what is perceived by designers as metal AM being able to generate all conceivable geometries. Because support structures consume expensive raw materials, use a considerable amount of laser consolidation energy, there is considerable interest in design optimisation of support structure to minimize the build time, energy, and material consumption. Similarly there is growing demand of developing more advanced and lightweight cellular structures which are self-supporting and manufacturable in wider range of cell sizes and volume fractions using metal AM. The main focuses of this research is to tackle the process limitation in metal AM and promote design freedom through advanced self-supporting and low-density Triply Periodic Minimal Surface (TPMS) cellular structures. Low density uniform, and graded, cellular structures have been developed for metal AM processes. This work presents comprehensive experimental test conducted in SLM and DMLS processes using different TPMS cell topologies and materials. This research has contributed to new knowledge in understanding the manufacturability and mechanical behaviour of TPMS cellular structures with varying cell sizes, orientations and volume fractions. The new support structure method will address the saving of material (via low volume cellular structures and easy removal of powder) and saving of energy (via reduced build-time).

This diploma thesis Extensive reading - Position and Practices of Using Graded Readers in Prague Grammar schools and Students' Attitudes to a Particular Programme presents the phenomenon of extensive reading. It looks into its history, theoretical grounding, the existing body of empirical research, graded readers and benefits for English language teaching and learning. The analytical part gives reasons for the contrast between the great potential of extensive reading for the student's improvement on the one hand, and the implementation which has been infrequent and often at odds with the principles on the other. To find the reasons, the theoretical part analysed the situation of the English language teaching in countries which had implemented extensive reading into the curriculum. In the research part it assesses the scale and the practices of using graded readers in all relevant grammar schools in Prague. In the second part of the survey of grammar schools, it focuses on a grammar school in Mělník, which has been systematically using GRs. It examines the students' attitudes towards the practices of reading GRs in order to assess the potential and the limits of the European Union financed project I read, you read, we read. Key words: Extensive reading, Methodology of English Teaching, Implicit...

This work is a numerical and analytical study of wave motion through dynamic materials (DM). This work focuses on showing several results that greatly extend the applicability of the checkerboard focusing effect. First, it is shown that it is possible to simultaneously focus dilatation and shear waves propagating through a linear elastic checkerboard structure. Next, it is shown that the focusing effect found for the original €œperfect€� checkerboard extends to the case of the checkerboard with smooth transitions between materials, this is termed a functionally graded (FG) checkerboard. With the additional assumption of a linear transition region, it is shown that there is a region of existence for limit cycles that takes the shape of a parallelogram in (m,n)-space. Similar to the perfect case, this is termed a €œplateau€� region. This shows that the robustness of the characteristic focusing effect is preserved even when the interfaces between materials are relaxed. Lastly, by using finite volume methods with limiting and adaptive mesh refinement, it is shown that energy accumulation is present for the functionally graded checkerboard as well as for the checkerboard with non-matching wave impedances. The main contribution of this work was to show that the characteristic focusing effect is highly robust and exists even under much more general assumptions than originally made. Furthermore, it provides a tool to assist future material engineers in constructing such structures. To this effect, exact bounds are given regarding how much the original perfect checkerboard structure can be spoiled before losing the expected characteristic focusing behavior.

Ce travail vise à améliorer la compréhension et la modélisation de la rupture des matériaux métalliques à gradient de propriétés. L'application se fait sur des pignons en acier 20MnB5 carbonitrurés insérés dans un "recliner", mécanisme de sécurité des siègesautomobiles. Le traitement de carbonitruration consisteà enrichir en carbone et azote une couche externe despièces en les chauffant dans le domaine austénitiquedans une atmosphère riche en ces deux éléments. Puisles pièces sont trempées afin de déclencher unetransformation martensitique. On obtient ainsi unmatériau à gradient de propriétés, intéressant pour despièces de transmission de puissance comme lesengrenages. Ce projet a commencé par l’analyse de larupture de mécanismes de sièges en test industriel. Celaa confirmé le double comportement à rupture binaire dumatériau : fragile sur une couche externe, ductile àl’intérieur. Un banc d’essai, spécialement conçu pour ceprojet, soumet une dent à un effort latéral jusqu’àrupture complète. Des observations in situ sonteffectuées et la courbe force-déplacement estenregistrée, montrant la diversité de comportement enfonction de la profondeur d'engagement des dents et dela présence ou non de la couche carbonitrurée. Desessais de traction, de flexion 4 points et de cisaillementsur éprouvettes papillons sont utilisés pour mesurer lespropriétés plastiques et calibrer les critères de rupturede la couche carbonitrurée comme de l'acier de base. Laplasticité de Von Mises avec une loi d'écrouissagesimple rend très bien compte de tous ces essaismécaniques. Différents critères de rupture ductile issusde la littérature sont calibrés; ils ne parviennent pas àreprésenter correctement tous les essais réalisés.Un critère plus adapté est donc proposé enconclusion de cette campagne expérimentale. Lasimulation de la rupture dans LS-Dyna est réaliséeavec une technique d'érosion d'éléments dont leslimitations sont discutées. La comparaison avec larupture de dent expérimentale permet d'évaluer lescritères numériques identifiés et d'analyser leslimites actuelles de la simulation, en particulier lanécessité de prendre en compte plus finement àl'avenir le gradient de propriétés mécaniques ainsique les contraintes résiduelles de compression dela couche carbonitrurée. / This work aims at a better understanding and modeling of the failure of gradient metallic materials. It is applied to carbonitrided pinions made out of 20MnB5 steel, inserted in a "recliner", a safety mechanism of automotive seats. Carbonitriding induces high surface hardness while preserving significant core ductility. The experimental analysis of the fracture behavior of seat recliners in an industrial test confirmed the dual failure behavior of the component : brittle external layer, ductile core material. A test bench has been specifically designed for the project: one tooth is submitted to a lateral force until complete failure. In situ observations are performed and the load-displacement curve recorded, showing a variety of behaviors as a function of the teeth engagement depth and of the presence or not of the carbonitrided layer. Experimental tests with various tress states were conducted to measure plastic properties as well as to calibrate fracture criteria, for the carbonitrided layer and for the core steel. Von Mises plasticity and a simple strain hardening curve fit very well all these experiments. As fracture criteria from the literature were unable to predict failure correctly for all the mechanical tests, an adapted criterion has therefore been proposed as an outcome of this extensive mechanical testing campaign. Fracture simulation in LS Dyna has been performed using the element erosion technique, the limitations of which are discussed. Comparison with the experimental tooth fracture measurements allows evaluation of the proposed failure criteria, and enables to stress out and discuss the present limits of the simulation, concluding that it will be necessary in future work to account more finely for the mechanical property gradient together with the compressive residual stresses in the carbonitrided layer.

La mise en oeuvre de matériaux acoustiques est une méthode efficace et très utilisée pour réduire le bruit le long de sa propagation. Les propriétés acoustiques de nouvelles structures sandwich multifonctionnelles et de matériaux absorbants poreux sont étudiées dans la thèse. Les principales contributions de la thèse sont les suivantes: Les panneaux sandwich ont généralement d'excellentes propriétés mécaniques et un bon indice de perte en transmission sonore (STL), mais aucune capacité d'absorption acoustique. De nouvelles structures sandwich multifonctionnelles sont développées en intégrant des microperforations et des matériaux absorbants poreux aux panneaux sandwich ondulés et en nid d’abeilles conventionnels, structurellement efficaces pour obtenir de bons STL et de bonnes absorptions en basses fréquences. Le coefficient d'absorption acoustique (SAC) et la perte en transmission (STL) des panneaux sandwich ondulés sont évalués numériquement et expérimentalement en basse fréquence pour différentes configurations de perforations. Les modèles éléments finis (EF) sont construits en tenant compte des interactions vibro-acoustiques sur les structures et des dissipations d'énergie, visqueuse et thermique, à l'intérieur des perforations. La validité des calculs FE est vérifiée par des mesures expérimentales avec les échantillons testés obtenus par fabrication additive. Par rapport aux panneaux sandwich ondulés classiques sans perforation, les panneaux sandwich perforés (PCSPs) avec des perforations dans leur plaque avant présentent non seulement un SAC plus élevé aux basses fréquences, mais aussi un meilleur STL, qui en est la conséquence directe. L'élargissement des courbes des indices d’absorption et de transmission doit être attribué à la résonance acoustique induite par les micro-perforations. Il est également constaté que les PCSPs avec des perforations dans les plaques avant et les parois internes onduleés ont les fréquences de résonance les plus basses de tous les PCSPs. En outre, les performances acoustiques des panneaux sandwich en nid d'abeilles avec une plaque avant microperforée sont également examinées. Un modèle analytique est présenté avec l'hypothèse que les déplacements des deux plaques sont identiques aux fréquences inférieures à la fréquence de résonance des plaques. Le modèle analytique est ensuite validé par des modèles d'éléments finis et des résultats expérimentaux existants. Contrairement aux panneaux sandwich en nid d'abeilles classiques qui sont de piètres absorbeurs de bruit, les sandwichs en nid d'abeilles perforés (PHSPs) conduisent à un SAC élevé aux basses fréquences, ce qui entraîne en conséquence un incrément dans le STL basse fréquence. Les influences de la configuration du noyau sont étudiées en comparant les PHSPs avec différentes configurations de noyaux en nids d'abeilles. […] / Implementation of acoustic materials is an effective and popular noise reduction method during propagation. Acoustic properties of novel multifunctional sandwich structures and porous absorbing materials are studied in the dissertation. The main contributions of the dissertation are given as, Sandwich panels generally have excellent mechanical properties and good sound transmission loss (STL), but no sound absorption ability. Novel multifunctional sandwich structures are developed by integrating micro perforations and porous absorbing materials to the conventional structurally-efficient corrugated and honeycomb sandwich panels to achieve good SAC and STL at low frequencies. Low frequency sound absorption and sound transmission loss (STL) of corrugated sandwich panels with different perforation configurations are evaluated both numerically and experimentally. Finite element (FE) models are constructed with considerations of acousticstructure interactions and viscous and thermal energy dissipations inside the perforations. The validity of FE calculations is checked against experimental measurements with the tested samples provided by additive manufacturing. Compared with the classical corrugated sandwich panels without perforation, the perforated corrugated sandwich panels (PCSPs) with perforations in its face plate not only exhibits a higher SAC at low frequencies but also a better STL as a consequence of the enlarged SAC. The enlargement of SAC and STL should be attributed to the acoustical resonance induced by the micro perforations. It is also found that the PCSPs with perforations in both the face plates and corrugated cores have the lowest resonance frequencies of all the PCSPs. Besides, the acoustic properties of honeycomb sandwich panels with microperforated faceplate are also explored. An analytical model is presented with the assumption that displacements of the two faceplates are identical at frequencies below the faceplate resonance frequency. The analytical model is subsequently verified by finite element models and existing experimental results. Unlike classical honeycomb sandwich panels which are poor sound absorbers, perforated honeycomb sandwiches (PHSPs) lead to high SAC at low frequencies, which in turn brings about increment in the low frequency STL. Influences of core configuration are investigated by comparing PHSPs with different honeycomb core configurations. In order to enlarge the SAC bandwidth of perforated sandwich panels, porous absorbing materials are added to the cores of novel perforated sandwich panels. FE models are set up to estimate the SAC and STL of perforated sandwich panels with porous materials. Results show that perforated sandwich panels with porous material can provide SAC with broader bandwidth and lower resonance frequency than that without porous materials. Whereas the peak values in the SAC and STL curves are reduced due to the weakened acoustical resonance by the porous materials. […]

Para que um transdutor ultrassônico gere e transmita um pulso curto e receba ecos com elevada sensibilidade, além de uma camada de retaguarda que absorva as ondas emitidas para trás, é necessário que haja um bom casamento de impedância acústica entre a cerâmica piezelétrica e o meio externo (camada de acoplamento). Quando comparado ao acoplamento em líquido, o acoplamento em ar é ainda mais complexo, pois este tipo resulta em perdas elevadas durante a transmissão e a recepção dos sinais acústicos, devido à grande diferença de impedância acústica entre a cerâmica e o ar. Certas aplicações requerem um acoplamento em ar e, para isso, os transdutores ultrassônicos usados devem ter banda larga, além de uma baixa impedância acústica. O aumento da largura de banda de um transdutor piezelétrico pode ser alcançado com o emprego de piezocompósitos, de uma camada de retaguarda, de camadas de acoplamento frontal e melhorias na parte eletrônica. A contribuição deste trabalho visa a estudar e desenvolver piezocompósitos com maior largura de banda para aplicação em transdutores de ultrassom para acoplamento em ar. De modo geral, os piezocompósitos possibilitam um maior fator de acoplamento eletromecânico e uma menor impedância acústica quando comparado às cerâmicas piezelétricas convencionais. Neste trabalho foram realizadas a modelagem, a construção e a caracterização de três tipos de piezocompósitos: piezocompósitos com gradação da densidade, piezocompósitos 2-2, e piezocompósitos 1-3. Naqueles com gradação da densidade,variaram-se os parâmetros profundidade, largura e distribuição dos cortes. O método de elementos finitos foi utilizado para analisar a influência dos parâmetros dos cortes. Os piezocompósitos foram construídos a partir de piezocerâmicas circulares e retangulares. Alguns dos piezocompósitos construídos foram submetidos a experimentos de interferometria a laser, mostrando a variação da distribuição dos deslocamentos máximos na superfície em função da frequência. A partir do espectro de frequência da condutância e dos valores inferiores e superiores da largura de banda foram analisados os deslocamentos máximos nas diversas regiões da superfície dos piezocompósitos. Nos piezocompósitos gradados observou-se que os deslocamentos máximos em determinadas regiões da superfície do piezocompósito dependiam da frequência de excitação. Desse modo, os piezocompósitos gradados apresentaram fator de acoplamento eletromecânico e largura de banda maiores do que os dos piezocompósitos 1-3. Transdutores com emissão em ar construídos a partir de piezocompósito gradado e do tipo 1-3 foram caracterizados e medidos os parâmetros largura de banda e fator de acoplamento eletromecânico. O transdutor construído a partir do piezocompósito gradado apresentou maior largura de banda quando comparado com o transdutor do tipo 1-3. / In order to generate and emit a short pulse and receive the echoes with high sensitivity, an ultrasound transducer requires a backing layer to attenuate the signal going backwards and a matching layer to match the acoustical impedances of the piezoceramic and the medium. When compared to liquid coupling, air coupling is further complicated because the large mismatch in acoustic impedance between the ceramic and air results in high losses during transmission and reception of acoustic signals. Certain applications require air-coupling and, therefore, the ultrasonic transducers used must be broadband and have low acoustic impedance. The increase of the bandwidth of a piezoelectric transducer can be achieved with the use of piezocomposites, a back layer, frontal coupling layers and improvements in the electronic part. The contribution of this work aims to study and develop piezocomposites with higher bandwidth for application in ultrasonic transducers with air coupling. In general, the piezocomposites allow a higher electromechanical coupling factor and a lower acoustic impedance when compared to conventional piezoelectric ceramics. In this work, three types of piezocomposites were made: piezocomposites with density gradation, piezocomposites 2-2, and piezocomposites 1-3. In those with density gradation, depth, width and distribution of the cuts were varied. The finite element method was used to analyze the influence of the cut parameters. The piezocomposites were constructed from circular and rectangular piezoceramics. Some of the constructed piezocomposites were submitted to laser interferometry experiments, which showed the variation of the distribution of the maximum displacements in the surface as a function of the frequency. From the frequency spectrum of the conductance curve and of the lower and upper values of bandwidth, the maximum displacements in the various surface regions of the piezocomposites were analyzed. In the graded piezocomposites it was observed that the maximum displacements in certain regions of the surface of the piezocomposite depend on the frequency of excitation. Thus, the graded piezocomposites presented higher electromechanical coupling factor and bandwidth than the piezocomposites 1- 3. Air-coupled transducers constructed from graded piezocomposite and type 1-3 were characterized and measured the parameters bandwidth and electromechanical coupling factor. The transducer constructed from the graded piezocomposite presented higher bandwidth when compared to the type 1-3 transducer.

O judô é um esporte de combate com características intermitentes, com alta demanda fisiológica. O desenvolvimento da potência aeróbia máxima em atletas de judô pode contribuir para a recuperação e a manutenção da intensidade dos esforços durante o combate, e para a recuperação entre os diferentes combates de uma competição. Em geral, a avaliação dessa capacidade física tem sido realizada por meio da aplicação de testes progressivos até a exaustão em esteira ou ciclo-ergômetro, os quais possuem baixa validade ecológica e não permitem a obtenção de parâmetros para a prescrição do treinamento específico da modalidade. Dessa forma, o objetivo deste estudo foi elaborar e testar a validade, reprodutibilidade e sensibilidade de um teste progressivo até a exaustão utilizando-se do uchi-komi (entrada de golpes), para mensurar a potência aeróbia máxima de atletas de judô. Doze atletas de judô do sexo masculino participaram desse estudo e foram submetidos a quatro sessões de avaliação, em dias distintos e, separadas por um intervalo de, no mínimo, 48 horas, exceto para a última sessão, que foi conduzido sete dias após a realização da terceira sessão. Para determinar a validade de critério, foram conduzidos três testes progressivos até a exaustão: teste de membros superiores (MMSSteste), membros inferiores (MMIIteste) e teste de uchi-komi (UKteste), os quais foram aleatorizados e distribuídos entre a primeira e a segunda sessões. Na etapa seguinte os mesmos atletas foram avaliados na terceira e quarta sessões para determinar a reprodutibilidade do UKteste. Além disso, também foi confirmado se os atletas alcançaram o verdadeiro consumo máximo de oxigênio, por meio de um teste de confirmação (UKconf). Para essa finalidade, 12 atletas de judô, incluindo 6 atletas que participaram do estudo de validade e reprodutibilidade, realizaram dois testes (UKteste e UKconf), separados por um intervalo de 20 minutos. A análise descritiva de todas as variáveis dependentes foi apresentada como média e desvio padrão. A validade do UKteste foi determinado por intermédio de uma análise de variância a um fator (tipo de teste) pela comparação do UKteste, MMSSteste e MMIIteste e pelo coeficiente de correlação de Pearson. Quando observada diferença significante, foi conduzido o teste de post-hoc de Bonferroni. A reprodutibilidade do UKteste foi determinada por meio do teste t de Student para dados pareados, coeficiente de correlação intraclasse (CCI), erro típico (ET) e ET como coeficiente de variação (CV). A sensibilidade do UKteste foi calculada pela menor variação detectável (MVD) para diferentes tamanho de efeito (0,2; 0,6 e 1,2 multiplicado pelo desvio padrão entre sujeitos) e classificados como marginal, médio, e bom, respectivamente. Além disso, a mínima mudança detectável (MMD) em uma dada variável foi calculada por meio da equação: ET x 1,96 * ?2. O nível de significância foi estabelecido em p < 0,05. A validade do UKteste foi confirmado pelo coeficiente de correlação de Pearson com valores de consumo pico de oxigênio (V? O2pico) classificados como quase perfeita. Não houve diferença nas variáveis mensuradas no UKteste e UKconf, além disso, os resultados mostraram que o UKteste possui boa reprodutibilidade relativa com CCI classificado como muito alta para a percepção subjetiva de esforço e quase perfeita CCI para o V? O2pico, frequência cardíaca máxima e intensidade aeróbia máxima. Adicionalmente, o teste apresentou boa reprodutibilidade absoluta, apresentando um ET como CV menor que 5%. Variações médias no tamanho do efeito podem ser adequadamente detectadas para o V? O2pico, intensidade aeróbia máxima e frequência cardíaca máxima. Em conclusão, o UKteste mostrou ser um teste válido e reprodutível para avaliar a potência aeróbia máxima de atletas de judô / Judo is a combat sport with intermittent characteristics and high physiological demand. The development of maximal aerobic power in judo athletes can contribute to the recovery and maintenance of efforts intensity during a combat, and to the recovery between different combats in a competition. In general, the evaluation of this physical capacity has been performed through the application of graded exercise tests in treadmill or cycle ergometer, which have low ecological validity, and do not enable the collection of parameters for specific training prescription to the modality. Thus, the objective of this study was to elaborate and test the validity, reliability and usefulness of a graded exercise tests using uchi-komi (repetition training), to measure the maximal aerobic power of judo athletes. Twelve male judo athletes participated in this study. They were submitted to 4 assessment sessions on different days separated by at least 48 hours, except in the last session which was performed 7 days after the 3rd session. In order to determine the criterion validity, 3 graded exercise tests were performed: upperbody (UBtest), lower-body cycle ergometer tests (LBtest) and uchi-komi (UKtest), which were randomized and distributed between 1st and 2nd sessions. In the next step, the same athletes were evaluated in the 3rd and 4th sessions to determine the reliability of the UKtest. Further, it was also confirmed whether athletes achieved true maximum oxygen uptake through a confirmation test (UKconf). For this purpose, 12 judo athletes, including 6 athletes who participated in the validity and reliability studies, performed 2 tests (UKtest and UKconf), separated by a 20-minute interval. The descriptive analysis of all dependent variables was presented by mean and standard deviations. The validity of the UKtest was determined through a one-way analysis of variance (test type), comparing the UKtest, UBtest and LBtest, and by the Pearson correlation coefficient. When a significant difference was observed, the Bonferroni post-hoc test was conducted. The UKtest reliability was determined by the test-retest comparison, using Student\'s t-test for paired data, intraclass correlation coefficient (ICC) and typical error (TE) as coefficient of variation (CV). The UKtest usefulness was calculated by the smallest worthwhile change (SWC) for different effect sizes (0.2, 0.6 and 1.2 multiplied by the standard deviation among subjects) and classified as marginal, average and good, respectively. In addition, the minimal detectable change (MDC) in each variable was calculated using the equation: TE × 1,96 × ?2. The significance level was set at p < 0.05. The validity of the UKtest was confirmed by the Pearsom correlation coefficient with values of peak oxygen consumption (V? O2peak) classified as nearly perfect. There were no differences between variables measured in the UKtest and in the UKconf. Also, results showed that the UKtest had good relative reliability, with ICC classified as very large (rated perceived exertion) and almost perfect (V? O2peak, maximal heart rate and maximum aerobic intensity). Moreover, the test presented good absolute reliability, with a TE as CV lower than 5%. Mean variations in effect size could be adequately detected for V? O2peak, maximal aerobic intensity and maximal heart rate. In conclusion, the UKtest proved to be a valid and reliable test to evaluate the maximal aerobic power of judo athletes