• Computers and Concrete
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• v.22 no.2
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• pp.143-152
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• 2018

This paper deepens the finite element modeling (FEM) method to reproduce the compressive behavior of partially steel-jacketed (PSJ) RC columns by means of the Concrete Damaged Plasticity (CDP) Model available in ABAQUS software. Although the efficiency of the CDP model is widely proven for reinforced concrete columns at low confining pressure, when the confinement level becomes high the standard plasticity parameters may not be suitable to obtain reliable results. This paper deals with these limitations and presents an analytically based strategy to fix the parameters of the Concrete Damaged Plasticity (CDP) model. Focusing on a realistic prediction of load-bearing capacity of PSJ RC columns subjected to monotonic compressive loads, a new strain hardening/softening function is developed for confined concrete coupled with the evaluation of the dilation angle including effects of confinement. Moreover, a simplified efficient modeling approach is proposed to take into account also the response of the steel angle in compression. The prediction accuracy from the current model is compared with that of existing experimental data obtained from a wide range of mechanical confinement ratio.

• Steel and Composite Structures
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• v.23 no.6
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• pp.715-726
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• 2017

The paper presents a numerical analysis of a steel-soil composite (SSC) culvert in the scope of static (dead and live) loads. The Abaqus program based on the finite element method (FEM) was used for calculations. Maximum displacements were obtained in the shell crown, and the largest stresses in the haunches. Calculation results were compared with the experimental ones and previous calculations obtained from the Autodesk Robot Structural Analysis (ARSA) program. The shapes of calculated displacements and stresses are similar to those obtained with the experiment, but the absolute values were generally higher than measured ones. The relative differences of calculated and measured values were in the range of 5-23% for displacements, and 15-42% for stresses. Developed calculation model of the SSC culvert in the Abaqus program allows obtaining reasonable values of internal forces in the culvert. Using both calculation programs, the relative differences for displacements were in the range of 15-39%, and 17-44% for stresses in favour of the Abaqus program. Three design methods (Sundquist-Pettersson, Duncan and CHBDC) were used to calculate the axial thrusts and bending moments. Obtained values were compared with test results. Generally, the design methods have conservative assumptions, especially in the live loads distribution, safety factors and consideration the interaction between soil and steel structure.

• Smart Structures and Systems
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• v.20 no.5
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• pp.595-605
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• 2017

The present article reported the thermal buckling strength of the sandwich shell panel structure and subsequent improvement of the same by embedding shape memory alloy (SMA) fibre via a general higher-order mathematical model in conjunction with finite element method. The geometrical distortion of the panel structure due to the temperature is included using Green-Lagrange strain-displacement relations. In addition, the material nonlinearity of SMA fibre due to the elevated thermal environment also incorporated in the current analysis through the marching technique. The final form of the equilibrium equation is obtained by minimising the total potential energy functional and solved computationally with the help of an original MATLAB code. The convergence and the accuracy of the developed model are demonstrated by solving similar kind of published numerical examples including the necessary input parameter. After the necessary establishment of the newly developed numerical solution, the model is extended further to examine the effect of the different structural parameters (side-to-thickness ratios, curvature ratios, core-to-face thickness ratios, volume fractions of SMA fibre and end conditions) on the buckling strength of the SMA embedded sandwich composite shell panel including the different geometrical configurations.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.624-629
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• 2001

Two types of bolted lap joints, one with a viscoelastic layer and the other without the viscoelastic layer were chosen to analyze the dynamic characteristics of the joints with the mechanical properties of the bolts of the joints being taken as computational variables. The finite element method was used along with the impact hammer technique to verify the FEM model. The results in the bolted lap joints reveal that the higher the Young's Modulus for the bolts are the higher the natural frequencies results for the joints. However, the natural frequency differences in the first and second mode are not substantial but become noticeable in the higher modes. Lower natural frequencies were obtained for the bolted lap joints with the viscoelastic layer when compared with those of the bolted lap joints without the viscoelastic layer. And the differences in the natural frequencies for the two types of joints are relatively small in the first and second mode whereas in the higher mode the differences become significant. The loss factors were observed to be significant especially in the second mode for the bolted lap joints with the viscoelastic layer.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.82-87
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• 2012

The purpose of this study is to produce a side impact beam with high tensile steel using a roll forming process. The door side impact beam plays an important roll in a car because it protects passengers from external crash. The roll forming process is a continuous bending process wherein a long metal sheet is bended as it continuously passes several rolls. The characteristic of this study is that an impact beam is produced by a continuous process using a ultra high strength steel without a hardening heat treatment. A model was determined by analysing plasticity of a cross section shape considering high strength. Design parameters of the impact beam was determined by crash-analysing the model. Workpiece products were manufactured by designing dies for roll forming and setting them up in a following process line. Results of a bending test and a FEM analysis was considered and reviewed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.93-100
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• 2013

This paper presents the development process for a bicycle monocoque frame using bolt fastening. Traditionally, bicycle frames have been constructed with metal tubes joined at their ends by welding. These frames have been brazed or soldered onto metal lugs, forming the frame. Because stress loads become greatest at the joint of the bicycle tube frame, joint construction strongly influences frame design and construction. To avoid the inherent problems of material discontinuity at frame joints, numerous designers have attempted to reduce or eliminate the number of joints in tube frames. Nevertheless, the manufacture of high quality, reliable, one-piece and jointless frames has proven difficult and expensive. In this study, a new monocoque frame adapted to a hybrid bike is proposed. The advantage of the monocoque frame, is theat is has a rechargeable battery system that is built into the frame; as a result, the emotional quality for the customer is improved. In order to estimate the design compatibility compared with that of tube frames, structural analysis is performed using finite element method. A prototype based on a modified design has also been made and stability testing has been carried out.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.48-53
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• 2005

The world, coming into the 21st century, is preparing a new revolution called a knowledge-based society after the industrial society. The interest of the world is concentrated on information technology, nano-technology and biotechnology. In particular, the nano-technology of which study was originally started from an alternative for overcoming semiconductor micro-technology. It can be applied to most industry subject such as electronics, information and communication, machinery, chemistry, bioengineering, energy, etc. They are emerging into the technology that can change civilization of human beings. Specially, ultra precision machining is quickly applied to nano-technology in the field of machinery. Lately, with rapid development of electronics industry and optic industry, there are needs for super precision finishing of various core parts required in such related apparatuses. This paper handles stability of a super precision micro cutting machine that is a core unit of such a super precision finisher, and analyzes the results depending on the hinge type and material change, using FEM analysis. By reviewing the stability, it is possible to achieve the effect of basic data collection for unit control and to reduce trials and errors in unit design and manufacturing.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.419-425
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• 2010

To machine the micro hole, laser machining system is widely used, however, the system cannot fabricate the micro hole with high aspect ratio and good surface finish. To break the obstacles, the high frequency vibration mechanism with PZT (Piezoelectric Transducers) is proposed in this paper. The mechanism will vibrate the laser beam in vertical direction so that the aspect ratio and surface finish may be higher than the conventional. The mechanism vibrates the eyepiece of laser optics. In addition to the benefits, the mechanism enables us to have high precision and flexibility. It decreases burr and debris during machining. And it is able to machine various materials of workpiece. This research include high frequency and large travel range of the proposed mechanism. The PZT motion of mechanism and analysis on the sensitivity of design parameters are extracted from a finite element method (FEM) simulation. In the analysis, the target vibration mode without parasitic motion is designated to have the target frequency and high amplitude.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.54-60
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• 2012

In this paper, a new permanent-magnet (PM) linear motor is proposed, in which both the magnets and armature windings are placed in the short mover, while the long stator consists of iron core only. Hence, this new PM linear motor can be called a primary permanent-magnet linear motor. It exhibits the advantages of robustness, low cost, high efficiency, high power factor, and high thrust force density. It is especially suitable for long stator applications such as urban rail transit. In this paper, the topology and operation principle of this motor are discussed in detail. The steady-state characteristics including field distributions, flux-linkage, back-EMF, phase inductance and thrust force are investigated. In addition, the technique of skewing stator teeth is adopted to improve the electromagnetic performance. Results from finite element method (FEM) verified the theoretical analysis results.

• Journal of the Optical Society of Korea
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• v.20 no.5
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• pp.567-574
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• 2016

We propose a highly birefringent and dispersion compensating photonic crystal fiber based on a double line defect core. Using a finite element method (FEM) with a perfectly matched layer (PML), it is demonstrated that it is possible to obtain broadband large negative dispersion of about -400 to -427 ps/(nm.km) covering all optical communication bands (from O to U band) and to achieve the dispersion coefficient of -425 ps/(nm.km) at 1.55μm. In addition, the highest birefringence of the proposed PCF at 1.55 μm is 1.92 × 10^-2 and the value of birefringence from the wavelength of 1.26 to 1.8 μm (covering O to U bands) is about 1.8 × 10^-2 to 1.92 × 10^-2. It is confirmed that from the simulation results, the confinement loss of the proposed PCF is always less than 10^-3 dB/km at 1.55 μm with seven fiber rings of air holes in the cladding.