Fatigue evaluation in maintenance and assembly operations by digital human simulation

Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realize the comparison of physical status. An assembly case in airplane assembly is simulated and analyzed under the framework. The endurance time and the decrease of the joint moment strengths are simulated. The experimental result in simulated operations under laboratory conditions confirms the feasibility of the theoretical approach

Influence of suction matrica the flow and conditions slope stability Dam Fishing

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoA importÃncia do comportamento de solos nÃo saturados tem sido reconhecida no Ãmbito da mecÃnica dos solos, de forma que, nas Ãltimas dÃcadas a geotecnia tem evoluÃdo muito no sentido de compreender-se o comportamento dos solos com o objetivo de melhoria e aperfeiÃoamento dos projetos de engenharia. Uma das particularidades dos solos nÃo saturados consiste no acrÃscimo de tensÃes internas devido ao fenÃmeno da sucÃÃo. Este acrÃscimo de tensÃes tem influÃncia comprovada em muitas caracterÃsticas do solo como na sua permeabilidade, compressibilidade, resistÃncia ao cisalhamento, etc., porÃm muitos estudos realizados atualmente utilizam os conceitos da mecÃnica dos solos tradicional, nÃo levando em consideraÃÃo o comportamento dos solos nÃo saturados, dentre eles estÃo as anÃlises de estabilidade em barragens de terra. Este trabalho tem como principal meta avaliar a influÃncia da nÃo saturaÃÃo dos solos em anÃlises de estabilidade de taludes em barragens de terra durante o enchimento. Para este fim, foi realizado um estudo de fluxo e estabilidade na Barragem Pesqueiro-CE. Para a determinaÃÃo dos parÃmetros geotÃcnicos do maciÃo, foram obtidas amostras deformadas e indeformadas para a realizaÃÃo de ensaios de caracterizaÃÃo, compactaÃÃo, permeabilidade e cisalhamento direto. TambÃm foram realizados ensaios para a determinaÃÃo da curva caracterÃstica do solo por meio do mÃtodo do papel-filtro. A partir dos resultados dos ensaios geotÃcnicos, foram feitos simulaÃÃes transientes para um perÃodo de 60 (sessenta meses) de operaÃÃo da barragem Pesqueiro. Pelas simulaÃÃes de fluxo, foi possÃvel conhecer as condiÃÃes de fluxo durante o perÃodo analisado. Com base nos resultados do estudo de percolaÃÃo transiente, foram realizadas anÃlises de estabilidade no talude de jusante para o perÃodo de enchimento do reservatÃrio. As simulaÃÃes de estabilidade foram feitas por duas metodologias: levando em consideraÃÃo a sucÃÃo presente no maciÃo e outra baseada na metodologia tradicional. Nos resultados obtidos foi constatada a influÃncia na estabilidade de talude ao considerar a sucÃÃo, visualizando uma reduÃÃo no fator de seguranÃa conforme ocorre o avanÃo da frente de saturaÃÃo. TambÃm foi constatado que nos resultados em que foi considerada a sucÃÃo nas anÃlises de estabilidade, os valores dos fatores de seguranÃa foram mais elevados que os apresentados pela metodologia tradicional, constatando o conservadorismo da metodologia tradicional.The importance of the unsaturated soil behavior has been recognized within the soil mechanics, so that in recent decades the geotechnical has much evolved in order to understand the behavior of soils with the objective of improving and improvement of engineering projects. One of the soil characteristics not saturated is the increase of internal stresses due to the suction phenomenon. This one voltage increase has proven influence on many characteristics of the soil as in its permeability, compressibility, shear strength, etc., but many studies currently performed using the concepts of the mechanics of traditional soil, not taking into account the behavior of unsaturated soils, among them are Stability analysis on earth dams. This work has as main goal to evaluate the influence of non-soil saturation on slope stability analysis in dam ground during filling. To this end, it conducted a flow analysis and stability in Fishing dam-CE. To determine the geotechnical parameters of the massif, were Soil samples taken for performing characterization tests, compression, permeability and direct shear. Also tests were performed for determining soil characteristic curve by the method of the filter paper. Starting from results of geotechnical, transient simulations were made for a period of 60 (sixty months) of operation Fishing dam. For flow simulations, it was possible know the flow conditions over the analysis period. Based on the results of the transient percolation study were performed stability analysis in the downstream slope period for filling the reservoir. The stability simulations were made by two methodologies: taking into account the suction present in massive and one based on traditional methodology. The results obtained was found to influence the stability of slope to consider suction, seeing a reduction in safety factor as It is the advance of the saturation front. It was also found that the results it was suction considered in stability analysis, the values of the factors of safety were higher than that provided by traditional methodology, noting the conservatism of traditional methodology