ABSTRACT Objective: To evaluate if participants, subjected to whole-body vibration, two different types of media (paper versus tablet) and two lighting environments (fluorescent versus LED), present a difference in eye-movement parameters during reading tasks. Methods: Fourteen adults silently read two different texts in each one of the eight randomized testing conditions (whole-body vibration versus media versus lighting), resulting in 16 different texts read per individual. Whole-body vibration was applied in the vertical direction, 5Hz and 0.8 m/s2 root-mean-square amplitude, a condition similar to those experienced by forklift truck drivers. Participants were in a sitting position with a backrest. An eye-tracker evaluated the eye-movements during the reading task. Results: Whole-body vibration significantly reduced the number of ocular fixations, and cross-correlation; and increased the reading efficiency, fixation duration, directional attack, and binocular anomalies. Neither the type of media nor the lighting environment interfered significantly with the eye-movements, both in situations with and without vibration. Conclusion: The results indicate that whole-body vibration interfered in the eye-movements during the reading task. This may impose a difficulty to process the visual information and to synchronously coordinate the binocular movements under vibration environments.

RESUMO Objetivo: Avaliar se participantes submetidos à vibração de corpo inteiro, a dois tipos diferentes de mídia (papel versus tablet) e a dois ambientes de iluminação (fluorescente versus LED) apresentam diferença nos parâmetros de movimento dos olhos durante tarefas de leitura. Métodos: Quatorze adultos leram silenciosamente dois textos diferentes em cada uma das oito condições de teste (vibração de corpo inteiro versus mídia versus iluminação), de forma aleatória, resultando em 16 textos diferentes lidos por indivíduo. A vibração de corpo inteiro foi aplicada no sentido vertical, com amplitude de 5Hz e 0,8m/s² da raiz do valor quadrático médio, em condição semelhante às vivenciadas pelos motoristas de empilhadeiras. Os participantes permaneceram em postura sentada com encosto. Um rastreador ocular avaliou os movimentos oculares durante a leitura. Resultados: A vibração de corpo inteiro reduziu significativamente o número de fixações oculares e a correlação cruzada entre os olhos e aumentou a eficiência de leitura, duração da fixação, ataque direcional e anomalias binoculares. Nem o tipo de mídia nem as condições de ambientes de iluminação interferiram significativamente nos movimentos oculares, tanto em situações com ou sem vibração. Conclusão: Os resultados indicam que a Vibração de Corpo Inteiro pode interferir nos movimentos oculares durante a leitura. Isso pode impor uma dificuldade no processamento da informação visual e na coordenação síncrona dos movimentos binoculares em ambientes de vibração.

Abstract This work presents the effect of the high curvature to thickness ratio on the characteristics of Lamb Waves propagating over the skins of composite structures. It is accessed how the curvature on composite skins affects the group velocity of the symmetrical (S0) and asymmetrical (A0) wave modes. It is also accessed the gradient of curvature effect, when the wave propagates from a flat to a curved part on the skin. The results are intended to be used for the improvement of structural health monitoring of wings and wind turbine blades. This is accomplished through dynamic explicit linear finite element method simulations of plates with flat and curved parts made of Eglass-epoxy bidirectional laminate. As the skin structures are often designed to withstand torsional loads, the fibers are aligned with 45 degrees from the leading edge (curved region) throughout the analysis. Several skins with different curvature to thickness ratios are generated and simulated. Results and trends are presented and can be used to improve the algorithms for damage detection on those structures. It is shown that the group velocity of the incoming waves change considerably with the presence of curvature, for both main modes of vibration.

In this work, tensile and shear modulus, as well as Poisson's ratio of a woven orthotropic nanocomposite plate were determined from vibration data. Plates used in the experiment were 16 layers S2-glass/epoxy composite manufactured by vacuum assisted wet layup. The nanocomposite plate was obtained by adding 0%, 1%, 2%, 5% and 10% nanoclays in weight to the epoxy matrix. A Finite Element model of the composite plate combined with a gradient method was applied to obtain an approximate numerical solution to experimental data in order to estimate the mechanical properties. Two different modal procedures were employed: the Laser Anemometry and Hammer test. A modal analysis was made in both cases to determine structural mode shape and associated frequencies, modal and mechanical properties for different nanoclay composite plates, as well as assessing its sensitivity to Modal Analysis.