• Structural Engineering and Mechanics
• /
• v.58 no.4
• /
• pp.613-625
• /
• 2016

Contact interaction of a beam (flexible element) with an elastic half-plane is considered, when a soft inhomogeneous (functionally graded) interlayer is present between them. The beam is bent under the action of a distributed load applied to the surface and a reaction of the elastic interlayer and the half-space. Solution of the contact problem is obtained for different values of thickness and parameters of inhomogeneity of the layer. The interlayer is assumed to be significantly softer than the underlying half-plane; case of 100 times difference in Young's moduli is considered as an example. The influence of the interlayer thickness and gradient of elastic properties on the distribution of the contact stresses under the beam is studied.

• Structural Engineering and Mechanics
• /
• v.36 no.6
• /
• pp.669-678
• /
• 2010

In general means, the stress concentration problem of elastic plate with a rectangular hole can be investigated by numerical methods, and only approximative results are derived. This paper deduces an analytical study of the stress concentration due to a rectangular hole in an elastic plate under bending loads. Base on classical elasticity theory and FEM applying the U-transformation technique, the uncoupled governing equations with 3-DOF are established, and the analytical displacement solutions of the finite element equations are derived in series form or double integral form. Therefore, the stress concentration factor can then be discussed easily and conveniently. For the plate subjected to unidirectional bending loads, the non-conforming plate bending element with four nodes and 12-DOF is taken as examples to demonstrate the application of the proposed method. The inner force distribution is obtained. The solutions are adequate for the condition when the hole is far away from the edges and the thin plate subjected to any transverse loadings.

• Journal of Korean Vacuum Science & Technology
• /
• v.7 no.1
• /
• pp.1-7
• /
• 2003

The pressure distributions in the test stand built for developing KSTAR NBI ion sources were obtained using a network system composed of conductance elements modeling the ion source, the neutralizer, and other beam line components. The allowable regime was defined on the coordinates of the gas supply rate to the ion source and the neutralizer, considering the proper conditions of the three critical parameters, the ion source pressure for good arc discharge, the pressure integral in the neutralizer for sufficient neutralization, and the chamber pressure for minimum neutral beam loss. The neutral beam evolution along the path from the ion source extraction grid to the calorimeter through the neutralizer, the bending magnet and the vacuum chamber was estimated for typical pressure distributions.

• Proceedings of the KIEE Conference
• /
• 1993.07a
• /
• pp.177-179
• /
• 1993

Best generation mix belongs to a multi attribute decision making, because we should consider many uncertain factors and choose the best one of the alternatives. Sugeno's fuzzy integral has been used as the solution of multi attribute decision making, but the exact value of the coefficient $\lambda$ hat not known yet which is needed to calculate fuzzy measure. This paper proposes the new method to calculate fuzzy measure without fixing the value of $\lambda$. The proposed method considers $\lambda$ as a probability distribution function and calculated expectation of fuzzy measure. The method is applied to the test system and the validity of the method is verified.

• Journal of the Korean Society of Safety
• /
• v.19 no.1
• /
• pp.38-43
• /
• 2004

Many analysis methods, including finite element method, have been suggested and used for assessing the integrity of cracked structures. In the paper, in order to analyze arbitrary three dimensional cracks, the finite element alternating method is extended. The crack is modeled by the symmetric Galerkin boundary element method as a distribution of displacement discontinuities, which is formulated as singularity-reduced integral equations. And the finite element method is used to calculate the stress values for the uncracked body only. Applied the proposed method to several example problems for planner cracks in finite bodies, the accuracy and efficiency of the method were demonstrated.

• Journal of Power Electronics
• /
• v.8 no.2
• /
• pp.131-140
• /
• 2008

This paper presents a new control approach of DSTATCOM (distribution static compensator) for compensation of reactive power, unbalanced loading and harmonic currents under unbalanced non-sinusoidal ac mains. The control of DSTATCOM is achieved using Adaline based current estimator based on LMS algorithm to maintain source currents real and undistorted. The dc bus voltage of voltage source converter (VSC) working as DSTATCOM is maintained at constant voltage using a proportional-integral (PI) controller. The DSTATCOM system alongwith proposed control scheme is modeled in MATLAB to simulate the behavior of the system. The practical implementation of the DSTATCOM is carried out using dSPACE DS1104 R&D controller having TMS320F240 as a slave DSP. Simulated and implementation results are presented to demonstrate the effectiveness of the DSTATCOM with Adaline based control to meet the severe load perturbations with different types of loads (linear and non-linear) under distorted and unbalanced AC mains.

• Journal of Mechanical Science and Technology
• /
• v.17 no.8
• /
• pp.1120-1132
• /
• 2003

A problem of a circular elastic inhomogeneity interacting with a crack under uniform loadings (mechanical tension and heat flux at infinity) is solved. The singular. integral equations for edge and temperature dislocation distribution functions are constructed and solved numeric-ally, to obtain the stress intensity factors. The effects of the material property ratio on the stress intensity factor (SIF) are investigated. The computed SIFs are used to predict the kink angle of the crack when the crack grows.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.24 no.3
• /
• pp.293-303
• /
• 2020

The present work aims to analyzed the transient thermoelastic stress analysis of a thin circular plate with uniform internal heat generation. Initially, the plate is characterized by a parabolic temperature distribution along the z-direction given by T = T₀(r, z) and perfectly insulated at the ends z = 0 and z = h. For times t > 0, the surface r = a is subjected to convection heat transfer with convection coefficient h_c and fluid temperature T_∞. The integral transform method used to obtain the analytical solution for temperature, displacement, and thermal stresses. The associated thermoelastic field is analyzed by making use of the temperature and thermoelastic displacement potential function. Numerical results are carried out with the help of computational software PTC Mathcad Prime-3.1 and shown in figures.

• Advances in materials Research
• /
• v.3 no.1
• /
• pp.237-257
• /
• 2014

In this paper, we adopted a two-dimensional analytical electro-elastic model to predict the stress distributions of the piezoelectric actuator in 3D case. The actuator was embedded in an elastic host structure under electrical loadings. The problem is reduced to the solution of singular integral equations of the first kind. The interfacial stresses and the axial normal stress in both plane stress state and plane strain state were obtained to study the actuation effects being transferred from the actuator to the host. The stress distributions of the PZT actuator in different length and different thickness were analyzed to guarantee the generality. The validity of the present model has been demonstrated by application of specific examples and comparisons with the corresponding results obtained from the Finite Element Method.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1153-1161
• /
• 2019

A current sharing controller is proposed in this paper for parallel-connected converters. The proposed controller is based on the calculation of the magnitudes of system current space vectors. Good current distribution between parallel converters is achieved with only one Proportional-Integral (PI) compensator. The proposed controller is analyzed and the circulating current impedance is derived for paralleled systems. The performance of the new control strategy is experimentally verified using two parallel connected converters employing Space Vector Pulse Width Modulation (SVPWM) feeding a passive RL load and a 2.2 kW three-phase induction motor load. The obtained test results show a reduction in the current imbalance ratio between the converters in the experimental setup from 53.9% to only 0.2% with the induction motor load.