Ao Professor Tiago Becker, pela contribuição na definição da metodologia de realização dos ensaios experimentais e pelas correções realizadas.A Empresa Helios Coletivos e Cargas Ltda., por ceder seus ônibus para realização dos ensaios experimentais, e pelo interesse demonstrado durante a realização do estudo.Aos demais Professores da banca, pela contribuição para o resultado final deste trabalho.Aos meus pais, Nelson e Ivone pelo apoio durante esta caminhada.A minha esposa Grasiela, pelo enorme apoio e incentivo, que foram fundamentais para a realização deste trabalho.A todas as pessoas que auxiliaram direta ou indiretamente no desenvolvimento deste trabalho. ABSTRACTThe purpose of this work is to evaluate the vibratory levels the ones that the passengers of inter-municipal road buses are submitted; and fulfill a changing project in body/seat that attenuates such effect. The reduction of these levels is a necessity, because the passengers who use buses as half of transport in trips of long distance can be exposed to the vibratory effect that the chassis transmits to the body, and also the consequential vibration of the external effect, which is generated when the bus transits on roads. These effects can also generate risks of the structural components braking of the body. In this study measurements of the accelerations produced in the vertical direction were fulfilled in accordance with Norma ISO 2631, collated with the curve-limit of comfort, established health and fatigue in this norm. There is a necessity to quantify the vibration level that the bus passenger is submitted being seated in the armchair and to quantify how long it can use the transport without risks to its health. It is also necessary the body's behavior knowledge related to the vibratory effect to measure the structure components in a way they can resist to these effects. For the project modification it was developed a methodology of dynamic analysis, through the numerical model of the body, armchair and chassis experimentally applied to the numerical model, the rugosity of measured asphalt floors, allowing visualizing numerically the vibratory effect in the structure of the armchair and, consequently, to generate a changing project tempering such effect.
OBJECTIVES:To evaluate and compare the magnitude and distribution of stresses generated on implants, abutments and first molar metal-ceramic crowns using finite element analysis.METHODS:Preliminary three-dimensional models were created using the computer-aided design software SolidWorks. Stress and strain values were observed for two distinct virtual models: model 1 - Morse taper and solid abutment; model 2 - Morse taper and abutment with screw. A load (250 N) was applied to a single point of the occlusal surface at 15° to the implant long axis. Von Mises stresses were recorded for both groups at four main points: 1) abutment-retaining screws; 2) abutment neck; 3) cervical bone area; 4) implant neck.RESULTS AND CONCLUSION:Model 1 showed a higher stress value (1477.5 MPa) at the abutment-retaining screw area than the stresses found in model 2 (1091.1 MPa for the same area). The cervical bone strain values did not exceed 105 µm for either model.
The uniformity and quality of spraying depend on the stability of the spray boom, defined as the suspension system between the boom and the machine chassis. This paper presents a procedure for improving the performance of passive spray bar suspensions through parameter adjustment. Two multibody dynamics models of a tractor sprayer set were developed to evaluate their suspension systems: a rigid body dynamics model (RBDM) and a finite element model (FEM) using deformable bodies. To calibrate the models in the experiment, an accelerating force was applied to the suspension, and the displacements of the shock absorber and the rubber springs were monitored. The FEM is more suitable for the evaluation of the horizontal oscillations of the bar, based on root mean square (RMS) values and a standard curve used to evaluate the stability of the bar. The horizontal stiffness of the bar significantly influences the oscillatory displacement and must be included in the simulation models. Resizing the structure can reduce the horizontal oscillations of the bar.
The objective of this work is to evaluate the levels and vibratory effects that the passengers who use intermunicipal road buses are submitted. In the study, measurements of the accelerations produced in the vertical direction had been carried through according with norm ISO 2631, in two bus bodyworks, of different manufacturers, in a normal situation of use, in three points of it (frontal, central and back). With the measurements it was possible to point which are the places in the bodywork interior and the points in the seats that produce greater accelerations r.m.s. The results had been evaluated and compared with the curves values established for norm ISO 2631 in relation to health and comfort and in relation to fatigue, comparing the two tested bodyworks.
To improve the safety of the intercity bus structure against impact scenarios and to reduce the injuries and death in traffic accidents it is crucial in a country with continental dimensions like Brazil, where the road transport matrix is fundamental in the traffic of people and goods. In this context in the present article, a numerical model of an intercity bus was built with elastoplastic beam implemented in a commercial software Ls-Dyna. This model was submitted to different frontal and semi frontal impact crash scenarios. With this model were analyzed different accidents which happened in the Brazilian highways, it was also simulated a frontal impact test and the results obtained were compared with the experimental results. Finally two numerical approaches were compared, they are: a simple model made with lumped masses and non-linear springs series connected, and the elastoplastic beam model. The different comparisons carried out let us validate the intercity bus model created using elastoplastic beam elements and propose to use this model as an effective tool to search for more efficient bus structural configurations against impact scenarios. KeywordsFinite element method, intercity bus, frontal and semi frontal impact scenarios.
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