• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.54-62
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• 1998

In this study, collapse behavior of frame composed of thin-walled rectangular tube is investigated. Considering the collapse of frame, the bending and compression members undergo large deformation. The stiffness of the compound element is obtained from analytical moment-rotation relationship and approximated load-deflection relationsh- ip of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state of each element for bending and compression.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.199-209
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• 2002

This research is experimental thesis to prepare the structural safety of the upper bridge for support type on tunnel and the effect of settlement. Unit weight test and uni-axial compression test have been performed to simulate the physical property of foundation on the tunnel. Tunnel model of slip form type for centrifuge model has been developed to performed the tunnel excavation while field stress is activated. And the support type of tunnel such as umbrella arch method and large diameter steel pipe reinforce method has been tested for the centrifuge model. After the analysis of experiment, results show that internal displacement of large diameter steel pipe reinforce method is smaller than that of the umbrella arch method.

• Geotechnical Engineering
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• v.13 no.2
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• pp.29-38
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• 1997

Strain softening is observed for geomaterials such as rocks when they are sheared. The proper computational modelling for strain softening is very important because this behavior is closely related to failure in geotechnical problems. In this paper, we have investigated the proper FEM techniques for modelling strain softening in order to simulate failure behavior numerically. In showing numerical examples, the effects of element shape, mesh pattern and of imperfection and the difference between small and large deformation theories, of displacement control and pressure control after peak have been discussed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3441-3453
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• 1996

A finite element anlaysis is performed for large deformations of a felxible beam. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. The finite elements results are confirmed for several cases of deformations through comparison to a first order elasticity solution obtained by numerical integration, and the agreement between the two is found to be excellent. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformation in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement.

• Structural Engineering and Mechanics
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• v.22 no.4
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• pp.433-447
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• 2006

The problem of very large deflection of a circular cantilever arc device subjected to inward or outward polar force is studied. An exact elliptic integral solution is derived for the two cases and the results are checked using large displacement finite element analysis via the ANSYS package by performing a new novel modeling simulation technique for this problem. Excellent agreements have been obtained between the exact analytical solution and the numerical approach. From this study, a design chart for engineers is developed to predict the required value for the inward polar force for the device to switch on for a given angle forming the circular arc (${\theta}_o$). This study has several interesting applications in mechanical engineering, integrated circuit technology, nanotechnology and especially in microelectromechanical systems (MEMs) such as a MEM circular device switch subjected to attractive or repulsive magnetic forces due to the attachments of two magnetic poles at the fixed and at the free end of the circular cantilever arc switch device.

• Korean Journal of Materials Research
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• v.17 no.2
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• pp.121-123
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• 2007

Energy harvesting from the vibration through the piezoelectric effect has been studied for powering the wireless sensor node. As piezoelectric unimorph cantilever structure can transfer low vibration to large displacement, this structure was commonly deployed to harvest electric energy from vibrations. Piezoelectric unimorph structure was composed of small stiff piezoelectric ceramic on the large flexible substrate. As there is the large Young's modulus difference between the flexible substrate and stiff piezoelectric ceramic, flexible substrate could not homogeneously transfer the vibration to stiff piezoelectric ceramic. As a result, most piezoelectric ceramics had been broken at the certain point. We measured and analyzed the stress distribution on the piezoelectric ceramic on the cantilever.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.06a
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• pp.45-54
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• 2001

In this study, slope stability analysis of LCRS(Leachate Collection Removel System) in waste landfill was peformed by large scale field test. Geocomat is new type of geocomposite product. Gecomat is a sort of Geocomposite product. It is composed of nonwoven geotextiles, woven geotextile, and geonet. Large scale field tests were performed on the slope of different two LCRSsections with static loading condition. One is LCRS section witch consist of GCL, HDPE and Geocomat, another is GCL, HDPE, and woven type geocomposite. The behavior of geosynthetics lined slope was monitored by incorporating instrumentation including vertical soil pressure meter, settlement plate, strain gauges, potential meter, displacement pin.. Based on the field monitoring, the Geocomat LCRS section is less sliding than the conventional geocomposite LCRS section.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.311-318
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• 2020

This study introduces a technique for improving the elastomeric-isolator performance using modular devices. The modular devices are shear resistance block, polymer spring, displacement acceptance guide, and anti-falling block. They are installed on the elastomeric isolator as a supplementary device. Each modularized device improves the isolator performance by performing step-by-step actions according to the seismic intensity and displacement. The PRB isolation device works in four stages, depending on the seismic magnitude, to satisfy the target performance. It is designed to accommodate design displacement in the first stage and large magnitude of earthquakes in the second and third stages. This design prevents superstructures from falling in the fourth stage due to large-magnitude earthquakes by increasing the capacity limit of the elastomeric isolator. In this study, the PRB isolation device is analyzed using finite element analysis to verify that the PRB isolation device works as intended and it can withstand loads corresponding to large-magnitude earthquakes. The performance of the PRB isolation device is validated by the analysis, which is further corroborated by actual experiments.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.157-171
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• 2012

The slope design of an open-pit mine must ensure slope stability and economic feasibility. The overall slope angle of the pit is therefore the main factor of concern because of limited support or reinforcement options available in such a setting. This study examines the optimal measurement system for monitoring the behavior of the slope in an open-pit mine using displacement measurement, data analysis, and numerical simulations for a coal mine at Pasir, Indonesia. The area of slope to be managed is extensive and the maximum displacement, as calculated by numerical analysis, is about 3,000 mm. The displacement data, measured by inclinometer and GPS, were analyzed, and the applicability of SSR (slope stability radar) was reviewed in comparison with other monitoring systems.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1601-1623
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• 2015

Electroactive polymers have attracted considerable attention in recent years due to their sensing and actuating properties which make them a material of choice for a wide range of applications including sensors, biomimetic robots, and biomedical micro devices. This paper presents an effective modeling strategy for nonlinear large deformation (small strains and moderate rotations) dynamic analysis of polymer actuators. Considering that the complicated electro-chemo-mechanical dynamics of these actuators is a drawback for their application in functional devices, establishing a mathematical model which can effectively predict the actuator's dynamic behavior can be of paramount importance. To effectively predict the actuator's dynamic behavior, a comprehensive mathematical model is proposed correlating the input voltage and the output bending displacement of polymer actuators. The proposed model, which is based on the rigid finite element (RFE) method, consists of two parts, namely electrical and mechanical models. The former is comprised of a ladder network of discrete resistive-capacitive components similar to the network used to model transmission lines, while the latter describes the actuator as a system of rigid links connected by spring-damping elements (sdes). Both electrical and mechanical components are validated through experimental results.