• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.9-12
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• 2002

A parametric study has been conducted to investigate the effect of the geometry on the strength of an unidirectional and fabric hybrid laminated composite joint. Tests are conducted for the specimens with nine different edge-to-hole diameter or width-to-hole diameter ratios. For the finite element analysis, the characteristic length method is used, and the tests for determining the characteristic length are performed additionally. Nonlinear contact problem between the pin and laminate is modeled by the gap element in MSC/NASTRAN. Tsai-Wu failure criteria is applied to the stress on the characteristic curve. The finite element and experimental results shows good agreement in strength of composite joint. Results of the parametric study shows the effect of the geometry is remarkable in the specimens with width-to-hole diameter ratio less than 2.8 and edge-to-hole diameter ratio less than 1.4.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.11
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• pp.1103-1109
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• 2008

Since the flexible joint robots with motor dynamics are represented by the fifth-order nonlinear sγstem, it is difficult and complex to design the controller for electrically driven flexible-joint (EDFJ) robots. In this paper, we propose a simple adaptive control method to solve this problem. It is assumed that the model uncertainties of the robots dynamics, joint flexibility, and motor dynamics are unknown. For the simple control design, the dynamic surface design method is applied, and all uncertainties in the robot and motor dynamics are compensated by using the adaptive function approximation technique. It is proved that all signals in the controlled closed-loop system are uniformly ultimately bounded. Simulation results for three-link EDFJ manipulators are provided to validate the effectiveness of the proposed control system.

• Structural Engineering and Mechanics
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• v.46 no.6
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• pp.843-852
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• 2013

This paper presents results of the effect of different bolt tightening sequences and methods on the performance of gasketed bolted flange joint using nonlinear finite element analysis. Bolt preload scatter due to elastic interactions, flange stress variation and bolt bending due to flange rotation and gasket contact stress variation is difficult to eliminate in torque control method i.e. tightening one bolt at a time. Although stretch control method (tightening more than one bolt at time) eradicates the bolt preload scatter, flange stress variation is relatively high. Flange joint's performance is compared to establish relative merits and demerits of both the methods and different bolt tightening sequences.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.315-320
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• 2007

An effective reinforcement method for steel tubular joints having a large chord diameter is the use of internal ring stiffeners. This paper presents the results of a numerical study on the static strength of internally ring-stiffened tubular X- and T-joints subjected to brace axial compression loading. Nonlinear finite element analyses are used to compute the joint strength. The influence of geometrical parameters has been studied and the maximum reinforcement effect of a ring stiffener has been evaluated. A strength ratio is defined. by the ratio of ring-stiffened joint strength to unstiffened joint strength, and an equation for this strength ratio is derived by regression analysis. Design optimization for ring stiffener of tubular joints is carried out using metropolis genetic algorithm.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.71-74
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• 2004

A composite-aluminum hybrid joint of composite external fuel tank of an aircraft has been analyzed by a 3-dimensional finite element method. Curvature and contact of the joint structure were considered in the analysis. Yamada-Sun failure criteria was utilized for the failure evaluation. A finite element program ABAQUS was used for the nonlinear contact analysis. The joint structure was predicted to be safe in both the test and analysis.

• Structural Engineering and Mechanics
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• v.56 no.3
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• pp.355-367
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• 2015

This paper deals with a new designed joint system for single-layer spatial structures. As the stability of these structures is greatly influenced by the joint behaviour, the aim of this paper is the characterization of the joint response in bending through Finite Element Method (FEM) analysis using ABAQUS. The behaviour of the joints studied here was influenced by many geometrical factors, such as bolts and plate sizes, distance between bolts and end-plate thickness. The study comprised five models of joints with different values of those parameters. The numerical results were compared to the results of previous experimental tests and the agreement was good enough. The differences between the numerical and experimental initial stiffness are attributed to the simplifications introduced when modelling the bolt threads as well as the presence of residual stresses in the test specimens.

• Computers and Concrete
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• v.13 no.2
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• pp.221-234
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• 2014

A nonlinear finite element analysis using ANSYS is used to evaluate the seismic behavior of reinforced concrete exterior beam-column joints. The behavior of the finite element models under cyclic loading is compared with the experimental results. Two beam-column joint specimens (SH and SHD) with square hoop confinement in joint and throughout the column with detailing as per IS 13920 are studied. The specimen SHD was provided with additional diagonal bars from column to beam to relocate the plastic hinge formation from beam-column interface. The load-displacement relationship, joint shear stress and strain in beam obtained from numerical study showed good agreement with the experimental results. This investigation proves that seismic behaviour of reinforced concrete beam-column joints under reversed cyclic loading can be evaluated successfully using finite element modeling and analysis.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2983-2985
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• 1999

This paper presents the attitude control of the double inverted pendulum with compliant joint. The biped robot with compliant ankle joint instead of a motor have a good contact between it's sole and ground in the uneven ground. The compliant ankle joint proposed here is composed of springs and mechanical constraint. The lower link is hinged on the plate to free for rotation in the vertical plate. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The algorithm for controlling a proposed inverted pendulum is nonlinear feedback controller. Simulation with mathematical model are conducted to show the validity of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10a
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• pp.882-885
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• 1987

The path of an industrial manipulator in a crowded workspace generally consists of 8 set of Cartesian straight line path connecting a set of two adjacent points. To achieve the Cartesian straight line path is, however, a nontrivial task and an alternative approach is to place enough intermediate points along a desired path and linearly interpolate between these points in the joint space. A method is developed that determines the subtravelling- and the transition-time such that the total travelling time for this path is minimized subject to the maximum joint velocities and accelerations constraint. The method is based on the application of nonlinear programming technique, i.e., FTM (Flexible Tolerance Method). These results are simulated on a digital computer using a six-joint revolute manipulator to show their applications.

• Ocean Systems Engineering
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• v.14 no.3
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• pp.237-259
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• 2024

Although the investigation on the effect of loaded out-of-plane braces on the values of the stress concentration factor (SCF) in offshore tubular joints has been the objective of numerous research works, a number of quite important cases still exist that have not been studied thoroughly due to the diversity of joint types and loading conditions. One of these cases is the multi-planar tubular KK-joint subjected to axial loading. Tubular KK-joints are among the most common joint types in jacket substructure of offshore wind turbines (OWTs). In the present research, data extracted from the stress analysis of 243 finite element (FE) models, verified against available experimental data, was used to study the effects of geometrical parameters on the chord-side SCFs in multi-planar tubular KK-joints subjected to axial loading. Parametric FE study was followed by a set of nonlinear regression analyses to develop three new SCF parametric equations for the fatigue analysis and design of axially loaded multi-planar KK-joints.