All vehicles have changing payloads that affect their dynamic response. Compared to passenger vehicles, heavy machinery have larger and more greatly varying payload masses, higher centers of mass, and encounter larger disturbances. These factors lead to significant increases in the amount of vibration experienced by heavy machinery operators. This fact, when coupled with the large amount of exposure time that a typical heavy machinery operator incurs, leads to much greater vibration dosage values for the heavy machinery operator. In addition, the heavy machinery operator faces equal or greater opportunity for accident. The chance of accident, along with the increased vibration dosage, leads to an operating condition with significant safety risks, both short and long term. It has been shown that payloads affect both the stability and vibration isolation properties of a vehicle. Large payloads reduce vehicle stability while increasing the amount of vibration transmitted to the operator. A method to compensate for these loading affects would prove to be a useful technique to increase the safety of the vehicle, both in terms of accident avoidance and long term health effects of vibration. This thesis provides such payload compensation techniques. Improved vehicle dynamics were accomplished with the use of both active and semi-active suspension control. The active systems used are optimal control based, and provided the greatest improvements in vehicle performance. An optimal controller designed around a nominal payload, however, proved insufficient for operation over the entire payload range due to too large peak actuator forces at low payloads. A multiple model approach was used to remedy this problem. Semi-active systems based on a Linear Quadratic Regulator with output feedback and damping selection via static deflection were developed. The semi-active systems would require far less power than the active systems, with the need for knowledge of fewer systems states. It was shown that despite these lower demands, the semi-active systems closely approach the performance of the fully active systems.

In the modem automotive industry product times to market are being increasingly compressed. In the earthmoving and construction machine industry this is also true with the manufacturer having to respond to new customer requirements quickly and decisively. Virtual prototyping is a vital tool in the vehicle engineer's armoury, allowing a large portion of developmental investigation to be done on the virtual model with the attendant savings in time and cost and allowing often dangerous manoeuvres to be predicted and investigated prior to actual physical prototype testing. The University of Natal BELL Equipment collaborative effort involves the vehicle dynamics modelling and model validation of a BELL Equipment manufactured B40C Articulated Dump Truck (ADT). The modelling was completed using the multibody system (MBS) simulation software package, ADAMS. Initial modelling and simulation results are presented with specific attention paid to the introduction of valid data for compliant joints in the MBS as well as modelling of the tire. The physical testing of the ADT is also presented as well as a discussion of the data acquisition system. Key results from the physical testing of the ADT are also presented and discussed. / Thesis (M.Sc.Eng.)-University of Natal,Durban, 2003.

Orientador: Ely Carneiro de Paiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-22T23:12:16Z (GMT). No. of bitstreams: 1 Cordeiro_RafaeldeAngelis_M.pdf: 9321021 bytes, checksum: ff7bb113095dc020ed982e7d7c28311a (MD5) Previous issue date: 2013 / Resumo: Veículos terrestres autônomos tem recebido uma atenção especial dos estudos de robótica nos últimos anos. Suas aplicações incluem segurança na condução, exploração de locais inóspitos e automatização agrícola. O enfoque deste trabalho situa-se no projeto VERO, em parceria com o CTI, e tem por objetivo o desenvolvimento de aplicações de controle de trajetória para um veículo do tipo todo-terreno. Para tal, um modelo completo (dinâmico e tridimensional) é desenvolvido, com uma atenção especial para os modelos de interação entre solo e pneu, responsáveis pelas forças não lineares atuantes sobre o veículo. Em seguida, dois modelos reduzidos e linearizados são obtidos e estes são utilizados para a síntese de controladores LQR. Uma comparação entre os controladores é realizada e a resposta de um deles é detalhada para uma análise sobre a influência das características do modelo veicular sobre o controle do veículo. Por fim, três abordagens são propostas para melhorar a resposta obtida pelos controladores / Abstract: Autonomous ground vehicles have received special attention from robotics studies in past years. Their applications include advanced driver assistance systems (ADAS), exploration of inhospitable environments and harvest autonomous machines. In partnership with CTI, this master's thesis focuses in the development of path tracking controllers applied to off-road vehicles. In order to simulate vehicle characteristics, a complete three-dimensional nonlinear dynamic model was proposed with emphasis on tire-road interaction models, which are responsible for most of the vehicle's nonlinearities. In sequence, two vehicle reduced linear models are presented and applied to synthesize LQR controllers, whose results are compared. One of them was chosen to analyze the effect of vehicles's three-dimensional dynamics on path tracking control. Finally, three different approaches are proposed to enhance controllers performance / Mestrado / Planejamento de Sistemas Energeticos / Mestre em Engenharia Mecânica

Orientador: Mauricio Vicente Donadon / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T06:12:50Z (GMT). No. of bitstreams: 1 Santos_MarcosAugustoAzevedodos_M.pdf: 10750432 bytes, checksum: 34498e6ae857842760b5a562b4e58bc8 (MD5) Previous issue date: 2011 / Resumo: Este trabalho consiste em analisar de forma dinâmica, via elementos finitos (FEA), um radiador de água utilizado em um veículo comercial pesado, com capacidade de carga acima de 22 toneladas e motorização acima de 220 cavalos vapor (cv), com foco específico no suporte lateral do radiador, responsável por fixar o conjunto de arrefecimento (radiador de água e radiador de ar) à longarina do caminhão. A análise baseia-se em dados coletados no campo de prova do cliente em questão e replicados à peça atual, a qual já passou por todos os testes de validação como bancada de vibração em três eixos ("hydro-pulse") e rodagem no campo de prova - rota de durabilidade com 35.204Km. Tendo como resultado do FEA aprovado, propor-se-á uma nova espessura de suporte de fixação, visando o limite da redução sem comprometer a vida em fadiga. Um modelamento simplificado do radiador será feito para que seja possível otimizar e reduzir o tempo de simulação, permitindo propor uma eventual mudança no conceito de análise de elementos finitos da empresa. Neste trabalho também será focado na vida em fadiga, estudando referências bibliográficas que suportarão o conceito para análise de durabilidade do componente em questão. Por se tratar de uma dissertação de Mestrado Profissional e o intuito final será replicar o conhecimento dentro da Behr Brasil, empresa que apóia este trabalho (um maior foco será dado abaixo), faremos uma correlação entre a metodologia atual utilizada na companhia e esta aqui empregada / Abstract: This job consists in analyzing dynamically, through Finite Elements (FEA), a water radiator used in heavy duty truck, with load capacity over 22 tons and engine with over 220 horse Power (HP), with a specific focus on the side bracket, which is used to fix the cooling module (water radiator and charge air cooler) into the truck chassis. The analysis is based on data gathered on customer's proving ground and replied to the current part, which has already passed through all validation tests, such as the 3 axis test bench ("hydro-pulse") and field test - durability route with 35.204Km. Having the FEA result validated a new side bracket thickness will be proposed, looking for the reduction without compromise the fatigue life expectation. A simplified model of the water radiator will be made, in order to optimize and reduce the simulation time, allowing eventually a concept change from the company's finite elements analysis methodology. In this job fatigue life expectation will be also addressed. The study will be based on references that allow the component durability analysis. For being a professional master, the expected final results consist of replying the learned knowledge inside the Behr Brasil Company (a deeper focus on the company will be given later), as well as the correlation between the current methodology used in the company and the one used in the present study / Mestrado / Dinâmica / Mestre em Engenharia Automobilistica

Two vehicular optimal control problems are visited. The first relates to the minimum lap time problem, which is of interest in racing and the second the minimum fuel problem, which is of great importance in commercial road vehicles. Historically, minimum lap time problems were considered impractical due to their slow solution times compared with the quasi-steady static (QSS) simulations. However, with increasing computational power and advancement of numerical algorithms, such problems have become an invaluable tool for the racing teams. To keep the solution times reasonable, much attention still has to be paid to the problem formulation. The suspension of a Formula One car is modelled using classical mechanics and a meta-model is proposed to enable its incorporation in the optimal control problem. The interactions between the aerodynamics and the suspension are thereby studied and various related parameters are optimised. Aerodynamics plays a crucial role in the performance of Formula One cars. The influence of a locally applied perturbation to the aerodynamic balance is investigated to determine if a compromise made in design can actually lead to lap time improvements. Various issues related to minimum lap time calculations are then discussed. With the danger of climate change and the pressing need to reduce emissions, improvements in fuel consumption are presently needed more than ever. A methodology is developed for fuel performance optimisation of a hybrid vehicle equipped with an undersized engine, battery and a flywheel. Rather than using the widely used driving cycles, a three-dimensional route is chosen and the optimal driving and power management strategy is found with respect to a time of arrival constraint. The benefits of a multi-storage configuration are thereby demonstrated. Finally, the nonlinear stability of a vehicle model described by rational vector fields is investigated using region of attraction (RoA) analysis. With the aid of sum-of-squares programming techniques, Lyapunov functions are found whose level sets act as an under-approximation to the RoA. The influence of different vehicle parameters and driving conditions on the RoA is studied.

Orientador: Milton Dias Júnior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T17:39:07Z (GMT). No. of bitstreams: 1 Simionatto_ViniciusGabrielSegala_M.pdf: 5623305 bytes, checksum: 1fa9e5b17f2a168dfa754ee947f53417 (MD5) Previous issue date: 2011 / Resumo: O desenvolvimento de novas tecnologias na área automotiva e as restrições cada vez mais apertadas com relação a emissões culminaram em veículos cada vez mais leves, silenciosos e potentes. Por este motivo, os trens de potência atuais são cada vez mais susceptíveis a fenômenos de NVH. Além disso, pelo fato de os motores atuais emitirem menor nível de ruído, alguns destes fenômenos tornam-se mais perceptíveis. Neste contexto se encaixa o trabalho atual. Sabe-se que muitos problemas desta área são solucionados realizando alterações no disco de embreagem, e por isto, neste trabalho estuda-se a influência dos parâmetros de seu pré amortecedor nos fenômenos de shuffle e clunk. São feitas análises do trem de potência linearizado, por este ser um procedimento muito comum na área de desenvolvimento deste sistema. Após isso, analisa-se o mesmo sistema, através de simulações numéricas, porém considerando não linearidades no disco de embreagem e nos engrenamentos, onde foi considerado o impact damping. Identifica-se os pares engrenados que mais contribuem para o surgimento do fenômeno de clunk, e a influência dos parâmetros do pré-amortecedor sobre ambos os fenômenos / Abstract: The development of new technologies on automotive engineering and the toughening emissions laws led to the design of lighter, more silent and more powerful vehicles. For this reason, today's powertrains are more prone to NVH phenomena. Furthermore, the noticeability of those phenomena is increased since newer engines produce lower noise levels. This is the subject in which this work fits into. It is known that many of the NVH phenomena can be attenuated by performing changes on the parameters of the clutch disc, and because of it, the influence of the parameters of the clutch damper on shuffle and clonk is studied in this work. For being a widely used procedure on the development of drivelines, a inear analysis is performed on a linearized model of a powertrain. After that, using umerical integration methods, further analyses are performed on a nonlinear model of the driveline, considering that the clutch disc and the gear meshes are nonlinearities. The latter's energy loss is modeled used impact damping. The geared pairs that contribute most for the clunk phenomenon are identified, and finally the influence of the parameters of the clutch damper on both phenomena are stated / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Milton Dias Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-17T18:54:27Z (GMT). No. of bitstreams: 1 Miyasato_HugoHeidy_M.pdf: 3357683 bytes, checksum: 9fcd8bd237500580084498c606879165 (MD5) Previous issue date: 2011 / Resumo: Fenômenos de ruído, vibração e sua severidade (NVH) são uma grande preocupação da indústria automotiva desde o século 20. A fim de atingir uma vantagem competitiva, as montadoras têm se focado na melhora do desempenho de NVH dos seus produtos para lidar com um cenário de mercado global competitivo. No intuito de verificar o comportamento do sistema durante o processo de desenvolvimento, métodos computacionais são aplicados para encontrar melhores abordagens e na previsão de problemas, economizando tempo e orçamento da empresa gastos na construção de protótipos e testes. Nesse trabalho, gear rattle, um ruído induzido por impacto cuja causa são as engrenagens sem carga da transmissão, será modelado e simulado. É diagnosticado com maior intensidade em veículos com motores diesel em marcha lenta e excitado especificamente quando uma faixa de frequências que causa grande amplitude de vibração nos elementos internos da caixa de câmbio é alcançada. Modelos lineares do trem de potência em ponto morto ou em tração serão estudados, compreendendo as suas características básicas, tais como frequências naturais e modos associados que podem ser representativos do fenômeno. Esse sistema possui elementos com fortes não-linearidades, tais como a rigidez estratificada com histerese da embreagem e a folga entre os dentes dos engrenamentos. Uma caracterização mais realista será incluída no modelo com uma rigidez variante no tempo para o engrenamento helicoidal, utilizado em todas transmissões manuais, com uma componente dissipativa adequada aos impactos. Para verificar condições de operação que podem somente ser avaliadas segundo formulação não-linear, simulações serão realizadas para verificar a eficácia de orientações de solução e propostas de modificação encontradas na literatura / Abstract: Noise, Vibration and Harshness (NVH) phenomena are a great concern of the automotive industry since the twentieth century. In order to achieve a commercial advantage, manufacturers have focused on improving the NVH performance of their products to cope with a competitive global market scenario. To verify the behavior of the system during the design process, computational methods are applied to find a better approach and foresee problems, saving company budget and time spent in prototypes and tests. In this work, gear rattle, a impact-induced noise caused by the unloaded gear teeth inside the gearbox, will be modeled and simulated. It is diagnosed with a higher intensity in diesel vehicle engines at idle speed and in a more specific way excited when a range of frequency that causes large amplitude of vibration in the internal elements of the gearbox is reached. Linear models of the powertrain operating in idle and traction will be studied, in order to understand its basic characteristics, such as natural frequencies and associated vibration modes that could be representative to this phenomena. This system has elements with strong nonlinearities such as the stratified stiffness with hysteresis of the clutch and the backlash between the gear teeth. A more realistic feature will be included in the model with a time variable stiffness for the helical gear mesh, used in all manual transmissions, with a suitable dissipative component for the impacts. To verify operational conditions which can only be evaluated with nonlinear formulation, simulations will be made to verify the effectiveness of solution guidelines and modification procedures found in literature / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Milton Dias Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-22T19:22:01Z (GMT). No. of bitstreams: 1 RoldaoPerestrelo_LeandroTadeu_M.pdf: 15158370 bytes, checksum: 84a10bb14b3381b619db8ff9bb97be9c (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Marco Lúcio Bittencourt / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-24T08:50:44Z (GMT). No. of bitstreams: 1 Villalva_SergioGradella_M.pdf: 11688581 bytes, checksum: df8c433816377fee9fe37ecd07dfb3a1 (MD5) Previous issue date: 2014 / Resumo: O virabrequim é um dos componentes mais importantes de um motor de combustão interna. É responsável, juntamente com as bielas, por transformar o movimento de translação dos pistões em movimento rotativo, capaz de transmitir torque. Durante o funcionamento do motor, o virabrequim é submetido a cargas axiais, torcionais e de flexão, as quais resultam em regiões com níveis elevados de tensões ao longo da peça. Além disso, o virabrequim apresenta altos níveis de carga de torção devido às vibrações torcionais, que é uma das maiores causas de falhas de vibrabrequins e de outros acessórios do motor, como polias, correias, trens de engrenagem etc. Este trabalho consiste no estudo e desenvolvimento de um programa computacional, denomidado CrankLab, para cálculo analítico de tensões e coeficientes de segurança de fadiga em virabrequins, que possa ser utilizado como uma ferramenta simples para a fase inicial de concepção do virabrequim. O estudo abrange o cálculo dos esforços dinâmicos, provenientes da combustão nos cilindros do motor e das forças inerciais devido ao movimento das partes móveis do motor de combustão interna, e o cálculo das amplitudes de vibração torcional. O método analítico desenvolvido considera o virabrequim como um eixo equivalente de seção circular, onde são aplicados os esforços radiais provenientes das bielas e os torques de vibração torcional, apoiado nos mancais principais. Os momentos fletores e torçores são calculados a partir da integração das equações de equilíbrio estático, considerando um modelo hiperestático, a partir dos quais são determinadas as tensões equivalentes. Ainda neste trabalho, foi realizado um estudo comparativo da aplicação de alguns tipos de absorvedores de vibrações torcionais e seus efeitos nas amplitudes de resposta, tendo como consequência a redução nas tensões no virabrequim. Dois casos foram estudados: um motor Otto de dez cilindros em V e um motor Diesel de seis cilindros em linha. Foram analisados regimes críticos de operação de cada motor: máximo torque, máxima potência e máxima rotação. Um experimento de análise modal do virabrequim de seis cilindros foi realizada de forma a validar as frequências naturais e os modos de vibração dos modelos propostos. Análises dinâmicas transientes com modelos flexíveis foram realizadas para ambos os casos, de forma a correlacionar com os resultados do modelo analítico. Os resultados de análise modal obtidos com os métodos analíticos, flexíveis e experimental foram bastante correlatos entre si, com erros menores que 5%. Os resultados de vibração torcional calculados pelo programa CrankLab também apresentaram excelente correlação com o modelo analítico do programa AVL Excite e o uso de absorvedores resultaram em considerável redução das amplitudes de vibração. Os resultados de tensões obtidos pelo CrankLab apresentaram a mesma ordem de grandeza dos obtidos pelos modelos flexíveis, com erros variando de 1% a 38%. Estes erros podem ser considerados aceitáveis uma vez que as condições de contorno e as simplificações do modelo analítico diferem bastante daquelas utilizadas nos modelos flexíveis. Tem-se como grande vantagem do programa CrankLab o menor tempo de pré processamento e cálculo, podendo ser inferior a 10% na maioria dos casos / Abstract: The crankshaft is one of the most important moving components of an internal combustion engine. It is responsible for converting the oscillating pistons movement into rotating movement by the connecting rods. During engine operation, the crankshaft is submitted to axial, bending and torsional loads, which results in high stressed regions on the component. Due to the phased cylinder combustions, the crankshaft has high levels of torsion load, being the torsional vibration one of the main causes of failures in crankshafts or engine accessories, as pulleys, belts and gears. The present thesis consists in the development of a computational program, called CrankLab, for analytical calculation of stress and fatigue safety factors on automotive crankshafts, which could be applied as a simple engineering tool during the initial crankshaft concept design phase. The study covers the determination of dynamic loads, from the combustion inside the engine cylinders and from the moving parts inertia, and the torsional vibration amplitudes calculation. The analytical method developed considers the crankshaft as an equivalent circular cross section shaft which is supported by the main bearings and where the connecting-rods radial forces and the vibration torques are applied on. The bending and torsion moments are calculated from integration of the static equilibrium equations, considering a hyperestatic model, thus the equivalent stresses can be calculated. Also in this study, a comparison was performed for some torsional vibration damper types, covering the calculation of optimum parameters of inertia, stiffness and damping, evaluating the effects on the output amplitudes within the entire engine speed range and the influence on the crankshaft stresses. The theory was applied for two different cases of study: an Otto V-type ten cylinders engine and a Diesel in-line six cylinders engine. Critical engine operation conditions were analyzed, at the speeds related to peak torque, rated power and overspeed. A modal analysis experiment was performed in order to validate the natural frequencies and modal shapes obtained by the proposed models for the six cylinders crankshaft. Moreover, transient dynamic analyses with flexible bodies were performed in order to compare with the stress results obtained from the analytical model for both cases. The modal analyses results obtained from the analytical, flexible and experimental methods were very good correlated with errors lower than 5%. The torsional vibration results calculated by CrankLab also presented excelent correlation with the analytical module of AVL Excite software. Moreover, the torsional dampers allowed considerable reduction in the vibration amplitudes. The stress results calculated by CrankLab have shown same order of magnitude of those from flexible models with errors variation between 1% and 38%. These errors can be acceptables once the boundary conditions and the analytical model simplifications are great different from those regarded in the flexible models. The most importante advantage of CrankLab is lower time spent in pre processing and calculation tasks, achieving a time saving around 10% in most cases / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Indiana University-Purdue University Indianapolis (IUPUI) / Belt-drives are used in many applications such as industrial machines, washing ‎machines, and accessory drives for automobiles and other vehicles. Multibody dynamics/finite ‎element numerical models have become an effective way to predict the dynamic response of ‎belt-drives. In this thesis, a high fidelity numerical model was built using a multibody ‎dynamics/finite element code to simulate a belt-drive. The belt-drive transmits power from a ‎turbine of a Rankin cycle (that uses the exhaust waste heat of the internal combustion engine as ‎heat source) to the crank shaft of the engine. The code uses a time-accurate explicit numerical ‎integration technique to solve the multibody dynamics differential equations. The belt was ‎modeled using three-node beam elements to account for the belt axial and bending ‎stiffness/damping, while the pulleys, shafts and tensioner body were modeled as rigid bodies. ‎The penalty technique was used to model normal contact between the belt and the pulleys. An ‎asperity-based friction model was used to approximate Coulomb friction between the belt and ‎the pulleys. The dynamic response predicted using the model was validated by comparing it to ‎experimental results supplied by Cummins Inc. A parameter sensitivity study was performed to ‎evaluate the change in response due to change in various belt-drive parameters. A fatigue ‎model was developed to predict the belt fatigue life using output from the explicit finite ‎element code including normal and tangential forces between the belt and the pulleys and belt ‎tension. The belt fatigue life was evaluated for alternative belt-drive configurations in order to ‎find the configuration with the longest life.‎