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Utsumi M.,IHI Corporation | Utsumi M.,Technical Machine
Journal of Spacecraft and Rockets | Year: 2013

A review of earlier studies in the area of sloshing shows that, although there are extensive studies on the main flow analysis, theoretical investigations of viscous damping are scarce, especially for arbitrary axisymmetric tanks. In this paper, an analytical method for calculating the viscous damping ratio of low-gravity sloshing in arbitrary axisymmetric tanks is presented, and its dependence on the Bond number and the filling level is examined. Using two systems of spherical coordinates, an analytical expression of bidirectional flow in the boundary layer is derived. By substituting this expression into the virtual work expression of the Navier-Stokes equations' viscous terms, the modal damping term is determined. It is shown that as the Bond number decreases the damping ratio increases, due to prolongation of the natural period rather than to increase in the damping coefficient. Anotable finding is that for high filling levels the damping coefficient decreases with decreasing Bond number, unlike the damping ratio. The reason for this is explained by introducing a correlation parameter whose Bond number dependence is similar to that of the damping coefficient. The analysis is verified by comparing with earlier experimental results. © 2012 AIAA.

Hu S.,Technical Machine
Advanced Materials Research | Year: 2012

Motion accuracy is one of the key point for parallel robots. In the paper, error modeling and motion error analysis of a 3-DOF parallel robot 3-PRS has been studied in this paper. First, the 3-PRS parallel robot and its kinematics has been introduced with its kinematics analysis. Based on the reverse kinematics analysis of 3-PRS, the motion error has been modeled. Then, motion error analysis has been performed for 3-PRS. The analysis results show the clear tendency of structural error effects on the motion errors. © (2012) Trans Tech Publications.

Khaniya K.,Technical Machine
2013 International Conference on Interactive Collaborative Learning, ICL 2013 | Year: 2013

The basis of the design of a multi-level training, including a methodology for teaching engineering and institutionalization of the facility design, the theory of forecasting of the development of educational systems with the use of Foresight technology and risk assessment on the bases of an integrative approach. Distribution network is promising model of this system. © 2013 IEEE.

Jirapattarasilp K.,King Mongkuts University of Technology Thonburi | Kaewkuekool S.,King Mongkuts University of Technology Thonburi | Phongphatrawut W.,Technical Machine
Advanced Materials Research | Year: 2012

The aim of this research was to study factors, which was influenced on surface roughness in vertical milling of hardened medium carbon steel. The specimen was medium carbon steel grade JIS S50C that was hardened at 56±2 HRC. Full factorial experimental design was conducted by 3 factors and 3 levels (3 3 design) with 2 replications. Studied factors were consisted of cutting speed, feed rate, and air coolant pressure. The results revealed that influenced factor affected to surface roughness was cutting speed and feed rate which showed significantly different. Higher cutting speed would cause on better surface quality. On the other hand, poorer surface quality was produced by higher feed rate. However, factors interaction were found between cutting speed with air coolant pressure and feed rate with air coolant pressure that significantly influenced to surface roughness. The interaction of high cutting speed with high air coolant pressure would be better quality of surface finish and lower feed rate with high air coolant pressure would be better surface quality.

Winczek J.,Technical Machine
Journal of Materials Processing Technology | Year: 2012

In this paper computational methodology of elasto-plastic states for rods subjected to thermal loads is presented. The dependence of stresses on strain was assumed on the basis of tension curves taking into account temperature. The computations of strains and stresses in a rod made of S235 steel, loaded by thermal fields generated by a point welding heat source of different intensities, were investigated. The analysis of development of plastic strains was carried out. Experimental tests were made for surfaced rod, with geometry and welding parameters assumed in numerical simulations, to verify the correctness of modelling. A simplified method was proposed to determine the longitudinal stresses in surfaced rods. © 2012 Elsevier B.V.

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