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Land vehicles are known sources of vibration. Several studies show that depending on the exposure levels and durations, such exposure can be extremely uncomfortable or cause health problems for the occupants. Therefore, awareness of these levels is very important for designing safe and comfortable vehicles in relation to human vibration. In general, due attention is not paid on the influence of pavement type and/or speed the vehicles travel on the measured whole body vibration (WBV) levels as it is the objective of the present work. This study measures WBV levels on three different car models, traveling on two different types of pavements (asphalt and stone paved roads) to show their relationship to car speed. Considering the values suggested as safe for health in ISO2631-1:1997 (Amendment 1. International Standardization Organization, Geneva, 2010), correlations were obtained between the speed and exposure time for each type of pavement used. Additionally, for each pavement investigated, numerical expressions were also obtained as a function of speed, considering the average vertical vibration for all car models tested. It is worth to mention that the stone pavement commonly used in Brazil differs from the ones used abroad. In Brazil, the stones are neither regular, nor paved evenly. Consequently, presenting these levels is a contribution of this study. Moreover, with the given data it is possible to study the effects of vehicular WBV on people's health and comfort in controlled environments without being limited to the tested conditions, allowing better cars to be produced.

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ABSTRACT. This paper deals with an analytical model of a rigid rotor supported by hydrodynamic journal bearings where the plane separation technique together with the Artificial Neural Network (ANN) is used to predict the location and magnitude of the correction masses for balancing the rotor bearing system. The rotating system is modeled by applying the rigid shaft Stodola-Green model, in which the shaft gyroscopic moments and rotatory inertia are accounted for, in conjunction with the hydrodynamic cylindrical journal bearing model based on the classical Reynolds equation. A linearized perturbation procedure is employed to render the lubrication equations from the Reynolds equation, which allows predicting the eight linear force coefficients associated with the bearing direct and cross-coupled stiffness and damping coefficients. The results show that the methodology presented is efficient for balancing rotor systems. This paper gives a step further in the monitoring process, since Artificial Neural Network is normally used to predict, not to correct the mass unbalance. The procedure presented can be used in turbo machinery industry to balance rotating machinery that require continuous inspections. Some simulated results will be used in order to clarify the methodology presented.Key words: rigid balancing, rotor balancing, artificial neural network.RESUMO. Balanceamento de um rotor rígido, usando redes neurais artificiais para a predição das massas de correção. Este trabalho foi desenvolvido com o objetivo de empregar a técnica de balanceamento de separação de planos juntamente com Redes Neurais Artificiais (RNA) para a predição da localização e massas de correção para o balanceamento de um sistema rotor-mancal, para tal, foi empregado um modelo analítico consitituído por um rotor rígido apoiado em mancais hidrodinâmicos. O sistema rotativo foi modelado com base no modelo de eixo rígidos de Stodola-Green, no qual foram considerados o efeito girocópico e a inércia rotatória, além de um modelo de mancal hidrodinâmico cilíndrico baseado nas equações de Reynolds que permitiu a determinação de oito coeficientes lineares de força associados com os coeficientes de rigidez e amortecimento diretos e cruzados do mancal. Os resultados mostraram que a metodologia apresentada foi eficiente para o balanceamento de rotores. Este trabalho fornece grande contribuição para o processo de monitoramento, uma vez que Redes Neurais Artificiais normalmente são empregadas para identificação, e não para a correção do desbalanceamento. O procedimento apresentado pode ser empregado no balanceamento de turbomáquinas industriais, as quais necessitam de contínuas avaliações. Resultados simulados são apresentados com o objetivo de ilustrar metodologia de balanceamento proposta.Palavras-chave: balanceamento rígido, balanceamento, redes neurais artificiais.

The well being of people needs to be a priority in the modern world. In that respect, vibration cannot be one more cause of stress. Besides that, vibration comfort is very important, since high levels may cause health or even tasks' accomplishment problems. Several parameters may influence the levels of vibration a human being supports. Among them, one can mention the influence of gender, age, corporeal mass index (CMI), temperature, humor, anxiety, hearing, posture, vision, etc. The first three parameters mentioned were already investigated in previous studies undertaken by GRAVI (Group of Acoustics and Vibration) researchers. In this paper, the influence of vision is evaluated. The main objective with this series of tests performed is to try to quantify in a future the influence of each parameter in a global vibration comfort level. Conclusions are presented for the parameter investigated.

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