• Structural Engineering and Mechanics
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• 제74권2호
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• pp.283-296
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• 2020

The coupled hydro-mechanical loading conditions commonly occur in the geothermal and petroleum engineering projects, which is significantly important influence on the stability of rock masses. In this article, the influence of flaw inclination angle of fracture behaviors in rock-like materials subjected to both mechanical loads and internal hydraulic pressures is experimentally studied using the 3-D X-ray computed tomography combined with 3-D reconstruction techniques. Triaxial compression experiments under confining pressure of 8.0 MPa are first conducted for intact rock-like specimens using a rock mechanics testing system. Four pre-flawed rock-like specimens containing a single open flaw with different inclination angle under the coupled hydro-mechanical loading conditions are carried out. Then, the broken pre-flawed rock-like specimens are analyzed using a 3-D X-ray computed tomography (CT) scanning system. Subsequently, the internal damage behaviors of failed pre-flawed rock-like specimens are evaluated by the 3-D reconstruction techniques, according to the horizontal and vertical cross-sectional CT images. The present experimental does not only focus on the mechanical responses, but also pays attentions to the internal fracture characteristics of rock-like materials under the coupled hydro-mechanical loading conditions. The conclusion remarks are significant for predicting the rock instability in geothermal and unconventional petroleum engineering.

• Journal of Korean Tunnelling and Underground Space Association
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• 제10권1호
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• pp.91-104
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• 2008

In tunnels, safety factor concept has been suggested to estimate their stability quantitatively. It is merely limited in the framework of mechanical analysis. However safety factor concept has not been applied in hydro-mechanical coupled analyses due to their modelling complexity. Recently studies on this topic are being actively made. In this study, induced drainage modelling methods for hydro-mechanical coupled analyses are compared and analyzed to estimate safety factor of a subsea tunnel exactly. To this end, methods both controlling hydraulic characteristic of shotcrete and using a drainage well are considered. Sensitivity analysis were carried out on rock class, thickness of shotcrete, and hydraulic properties of rock mass. As the results of this study, it turned out that the induced drainage modelling using a drainage well would give more reliable results than that of controlling hydraulic characteristic of shotcrete in estimating tunnel stability in hydro-mechanical coupled analyses.

• Transactions of the Korean Society of Mechanical Engineers
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• 제16권5호
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• pp.873-882
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• 1992

The study is concerned with the rigid-plastic element analysis for axisymmetric hydromechanical deep drawing in which the fluid flow influences the metal deformation. Due to the fluid pressure acting on the sheet material hydromechanical deep drawing is distinguished from the conventional deep drawing processes. In considering the pressure effect, the governing equation for fluid pressure is solved and the result is reflected on the global stiffness matrix. The solution procedure consists of two stages ; i.e., initial bulging of the sheet surface before the initiation of steady fluid flow in the flange and fluid-lubricated stage. The problem is decoupled between fluid analysis and analysis of solid deformation by deformation by iterative feedback of mutual computed results. The corresponding experiments are carried out for axisymmetric hydro-mechanical deep drawing of annealled aluminium sheet as well as for deep drawing. It has been shown from the experiments that the limit drawing ratio for hydro-mechanical deep drawing is improved as compared with deep drawing. The computed results are in good agreement with the experiment for variation of punch head and chamber pressure with respect to the punch travel and for distribution of thicknees strain. It is thus shown that the present method of analysis can be effectively applied to the analysis of axisymmetric hydro-mechanical deep drawing processes.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제20권5호
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• pp.1426-1435
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• 1996

In this paper. a network theory for generaltransmission systme was extended considering the direction of power flow. Also, a modified network model was suggested for a node with 4 shafts in order to verify the power flow. Based on the extended network theory, a simulation program was developed to analyze a hydro-mecaanical tranmission(HMT) system consistion of two hydrostatic pump motors, severeal planetary gear trains steer differential gear. The simulation result showed that the extendednotwork analysis program develped can predict the power circulation as well as the magnitude of torque and speed for each transmission element and can be used design tool for genaral power transmission system.

• Tribology and Lubricants
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• 제21권5호
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• pp.201-208
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• 2005

This paper presents the FEM analysis on the contact behavior characteristics of mechanical face seals in a small hydro-power turbine. Especially, the axial displacement and contact normal stress between a seal ring and a seal seat of a primary sealing unit have been analyzed as functions of rotating speed of a hydro-turbine, sealing gap, water and cooling fluid temperature. Those are strongly related to a leakage of water and wear between a seal ring and a seal seat. The FEM computed results present that the rotating speed of a hydro-turbine may be kept less than 800 rpm, and the sealing gap in a primary sealing unit is restricted $0.5\~5$. The coolant temperature in which is most influential parameter to the contact behaviors of a sealing unit may be kept less than $15^{\circ}C$ for a safe operation of a sealing unit without a leakage and wear.

• Journal of Drive and Control
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• 제13권4호
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• pp.45-51
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• 2016

The power train of a hydro-mechanical, continuously variable transmission for forklifts makes use of hydro-static units, hydraulic multi-wet disc brakes & clutches, and complex helical & planetary gears. The complex helical & planetary gears are very important parts of the transmission because of a strength problem. In the present study, we calculated the specifications of the complex helical & planetary gear train, and analyzed the gear bending and compressive stresses of the gears. It is necessary to analyze the gear bending and compressive stresses thoroughly for optimal design of the complex helical & planetary gears with respect to cost and reliability. In this paper, we analyze the actual gear bending and compressive stresses of complex helical & planetary gears using the Lewes & Hertz equation, and we also verify the calculated specifications of the complex helical & planetary gears by evaluating the results of the data of allowable bending and compressive stress using the Stress vrs Number of Cycles curves of gears.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제22권2호
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• pp.117-128
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• 2024

The 300 concrete silo systems installed and operated at the site of Wolsong nuclear power plant (NPP) have been storing CANDU spent nuclear fuel (SNF) under dry conditions since 1992. The dry storage system must be operated safely until SNF is delivered to an interim storage facility or final repository located outside the NPP in accordance with the SNF management policy of the country. The silo dry storage system consists of a concrete structure, liner steel plate in the inner cavity, and fuel basket. Because the components of the silo system are exposed to high energy radiation owing to the high radioactivity of SNF inside, the effects of irradiation during long-term storage must be analyzed. To this end, material specimens of each component were manufactured and subjected to irradiation and strength tests, and mechanical characteristics before and after irradiation were examined. Notably, the mechanical characteristics of the main components of the silo system were affected by irradiation during the storage of spent fuel. The test results will be used to evaluate the long-term behavior of silo systems in the future.

• Geomechanics and Engineering
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• 제3권4호
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• pp.267-284
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• 2011

The aim of the paper is to study the hydro-mechanical behaviour of a tuff and calcareous sand mixture. A first experimental phase was carried out in order to find the optimal mixture. This showed that the material composed of 80% tuff and 20% calcareous sand provides the maximum mechanical strength. The second experimental phase concerns the study of the drying- wetting behaviour of the optimal mixture. Triaxial shear tests in saturated and unsaturated states at constant water content were carried out on samples initially compacted at the MPO. Experimental results let to deduce the parameters necessary for the prediction of the hydro-mechanical behaviour of pavement formulated from tuff and calcareous sand mixtures, related to moisture. This optimal mixture satisfies the regulation rules and hence constitutes a good local eco-material, abundantly available, for the conception of pavements.

• Steel and Composite Structures
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• 제26권3호
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• pp.303-314
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• 2018

Drying shrinkage in concrete caused by drying and the associated decrease in moisture content is one of the most important factors influencing the long-term deflection of steel-concrete composite slabs. The presence of profiled steel decking at the bottom of the composite slab causes non-uniform drying from top and bottom of the slab resulting non-uniform drying shrinkage. In this paper, a hydro-mechanical analysis method is proposed to simulate the development of non-uniform shrinkage through the depth of the composite slab. It also demonstrates how this proposed analysis method can be used in conjunction with previously presented structural analysis model to calculate the effects of non-uniform shrinkage on the long-term deflection of the slab. The method uses concrete moisture diffusion model to simulate the non-uniform drying of composite slab. Then mechanical models are used to calculate resulting shrinkage strain from non-uniform drying and its effect on the long-term behaviour of the composite slabs. The performance of the proposed analysis method is validated against experimental data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• 제5권3호
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• pp.51-57
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• 2006

Hydro-mechanical punching was developed for preventing burr formation. Circular hole punching and Finite element method(FEM) analysis were conducted to investigate shearing characteristics of this process in comparison with conventional and mechanical counter punching. In this process hydrostatic pressing with appropriate medium was utilized instead of counter punch, which resulted in the delay of the point that the fracture is initiated and clean shearing surface was obtained. FEM analysis was utilized to find out optimum processing parameters and shearing mechanism for burr-free hole punching.