• Journal of Advanced Marine Engineering and Technology
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• 제30권3호
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• pp.359-368
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• 2006

The trend on marine diesel engine productions and refinements has led to a higher mean effective pressure and thermal efficiency. These resulted in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. In view of this. the crankshaft should be able to withstand the dynamic stresses caused by load variations. Different factors including size, material and stress concentration factors should also be considered to ensure the reliability of the shafting system. As such, crankshaft must be designed and compacted within its fatigue strength. In this paper, the strength analysis of crankshaft Is carried out by: simplified method recommended by IACS(International Association Classification Societies) M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are then compared.

• Proceedings of the KIEE Conference
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1950-1953
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• 1996

A $1\;{\times}\;4$ micro mirror array is designed and fabricated. In contrast to other micro mirrors which utilize torsional flexure hinges or cantilevers for restoring torque and supporting purpose, we have placed a substrate hinge structure under each mirror. Each micro mirror consists of address electrode, substrate hinge consisting of pin and staple, supporter post, and mirror plate. Electrical connection between mirror plate and ground electrode is established by substrate hinge. Mirror undergoes a rotational motion due to electrostatic force when voltage difference is applied between address electrode and mirror plate. Micro mirrors with two different types of staple shape and two different pin sizes are designed and fabricated. Each mirror is designed to have ${\pm}\;10^{\circ}$ of deflection angle and have $100\;{\times}\;110\;{\mu}m^2$ of size.

• Proceedings of the KSME Conference
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• 대한기계학회 2008년도 추계학술대회A
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• pp.155-160
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• 2008

Using a three-dimensional (3-D) FE analyses, this paper provides the shape optimization of the standard test specimen for the torsion test, as well as a method for analyzing effects of misalignment under the angular and concentric misalignment. For verification, FE analysis is performed, which is designed for the perfectly full-model. To optimize the design shape of the torsion-controlled fatigue test specimen, we performed sensitivity analysis using shape parameters. Additionally, two kinds of misalignment (angular misalignment and concentric misalignment) are applied to the circular and tubular specimens to show effects of misalignments in the FE analysis. The present results will provide valuable information for designing shafts for every kind of mechanical system under torsional force.

• Journal of Mechanical Science and Technology
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• 제20권3호
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• pp.409-417
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• 2006

Polymer nanofibers can be generated by a electrospinning process. The process involves electrically charged jet of polymer solutions evolving from a droplet. The jet stretches in vertical direction due to the difference between charged particle and constant current located at the collector, while the Coulomb and viscoelastic forces start to contribute to radial and azimuthal (torsional) stretching. In this paper, the unstable dynamics of the liquid polymer jet is examined experimentally and theoretically. A complex viscoelastic rheological model has been adopted to analyze the behavior of a charged liquid jet. The model includes complex phenomena of stress relaxation of the liquid jet resulting from the competing force components. The experimental data of the jet paths captured by high-speed videocamera also confirm the similar behavior with the predictions.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제11권9호
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• pp.398-405
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• 2001

The maximum and mean indicated pressure of two stroke low speed diesel engine has been continuously increased with a view of increasing engine power and also reducing fuel consumption. As a result, axial excitation has been increased comparing to that of the previous one. So the axial vibration damper in standard one is applied to all two stroke low speed diesel engine at the free end of crankshaft. Though many studies were carried out for marine use, few has been made for diesel power plant because there was little demand for power plant. Nowadays, diesel engine is much to be used for many benefits. In this paper, the optimum design of axial vibration on the 65 kW diesel power plant with tow 9K80MC-S engines of 9 cylinders was carried out. And the axial-torsional coupled vibration of this shafting system is identified by theoretical analysis and vibration measurement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.66-72
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• 2006

Marine diesel engine production and refinements sought a continuous increase on mean effective pressure and thermal efficiency. These results in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. As such, crankshaft should be designed and compacted within its fatigue strength. In this paper, the 8H25/33P($3,155ps{\times}900rpm$) engine for ship propulsion was selected as a case study, and tile strength analysis of its crankshaft is carried out by. simplified method recommended by IACS M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are compared with each other.

• International Journal of Aeronautical and Space Sciences
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• 제7권1호
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• pp.99-105
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• 2006

In this study, nonlinear static and dynamic aeroelastic analyses for a high-aspect-ratio wing have been performed. To achieve these aims, the transonic small disturbance (TSD) theory for the aerodynamic analysis and the large deflection beam theory considering a geometrical nonlinearity for the structural analysis are applied, respectively. For the coupling between fluid and structure, the transformation of a displacement from the structural mesh to the aerodynamic grid is performed by a shape function which is used for the finite element and the inverse transformation of force by work equivalent load method. To validate the current method, the present analysis results of a high-aspect-ratio wing are compared with the experimental results. Static deformations in the vertical and torsional directions caused by an angle of attack and gravity loading are compared with experimental results. Also, static and dynamic aeroelastic characteristics are investigated. The comparisons of the flutter speed and frequency between a linear and nonlinear analysis are presented.

• Proceedings of the Korean Geotechical Society Conference
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.626-633
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• 2009

A large scale resonant column testing equipment is under development. The would-be equipment is aiming to test 150mm-diameter specimens, which can contain as large a grain size as 25mm. Such a large specimen is hardly excitated with the existing fixed-free end condition because the torsional force cannot be effectively coupled to the specimen. The specimen will be rather resonated with free-free condition and the scheme is implemented with a rotational bearing installed between coil-magnet exciter and base pedestal. Presently the equipment was assembled and is under calibration with a cylindrical brass specimen.

• Steel and Composite Structures
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• 제20권6호
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• pp.1391-1409
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• 2016

Masonry infill has a significant effect on stiffness contribution, strength and ductility of masonry-infilled frames. These effects may cause damage of weak floor, torsional damage or short-column failure in structures. This article presents experiments of 1/2.5-scale steel reinforced recycled aggregates concrete (SRRC) frames. Three specimens, with different infill rates consisted of recycled concrete hollow bricks (RCB), were subjected to static cyclic loads. Test phenomena, hysteretic curves and stiffness degradation of the composite structure were analyzed. Furthermore, effects of axial load ratio, aspect ratio, infill thickness and steel ratio on the share of horizontal force supported by the frame and the infill were obtained in the numerical example.

• Transactions of the Korean Society of Machine Tool Engineers
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• 제10권6호
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• pp.8-14
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• 2001

We develop a method to analyze dynamic behavior off multi-stage gear train system. The example system consists of three shafts supported by ball bearings at the ends of them and two pairs of spur gear set. For exact analysis, the meshing tooth pair of gear set is modeled as spring and damper having time-dependent meshing stiffness and damping. The bearing is modeled as spring. The result of this analysis is compared to that of other model having mean mesh stiffness. The effect of the excitation force by the unbalance off rotor off motor is also analyzed. Finally, the change ova natural frequency of the whole system due to the change of an angle between three shafts is compared in each case, and from this analysis, the avoiding angle for design is advised.