• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.70-76
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• 2008

Periodic cellular metals (PCMs) are actively being investigated because of their excellent specific strength and stiffness, and multi-functionality such as a heat disperse structure bearing external loading. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling and lower anisotropy than other truss PCMs. In this paper, the out-of-plane compressive responses of the WBK specimens have been measured, theoretically predicted and numerically analyzed. Three specimens of two-layered WBK are fabricated and tested for measuring the responses. The peak stress of compressive behavior and effective elastic modulus are predicted based on the equilibrium equation and elastic energy conservation. Moreover, the structure of the specimen is modeled using the commercial mesh generation code, PATRAN and the finite element analysis for the model under the compression is carried out using the commercial FE code, ABAQUS. Finally, the obtained results are compared with each other to analyze the compressive characteristics of Wire-woven Bulk Kagome (WBK).

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.343-350
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• 2005

A constitutive model was implemented in ABAQUS code. The constitutive equation can model the behavior for overall range of strain level from small to large deformation, which is based on anisotropic hardening rule and total stress concept. The formulation includes (1) finite strain formulation on the basis of Jaumann rate, (2) implicit stress integration and (3) consistent tangent moduli. Therefore the mathematical background was established in order that large deformation analysis can be performed accurately and efficiently with the anisotropic constitutive model. In the large deformation analyses, geometric nonlinearity was considered and the result of analyses with the proposed model was compared with that of Mises model for the overall strain range behavior.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.113-116
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• 2003

Hem quality can be determined mainly by turn-down and roll-in. Turn-down, that is created by the elastic recovery, can't be easily detected and measured since it is usually as small as 0.03 m. This study is focused on the precise evaluation of the hemming defects through analytical and experimetal approaches, and on the investigation of the influence of process parameters on the final hem quality. Implicit finite element analysis of plane-strain hemming process is performed by using a commercial code ABAQUS/Standard. Experiment and measurement is also carried out for steel and aluminium sheet metals, and the results are compared with those of analysis.

• Transactions of Materials Processing
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• v.17 no.7
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• pp.496-500
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• 2008

Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity. But plastic parts are usually distorted after injection molding due to the residual stress after filling, packing, cooling process, and etc. And plastic material is to be deteriorated according to various temperature conditions and operating time, which can be characterized by stress relaxation and creep. The viscoelastic behavior of plastic materials in time domain can be expressed by the Prony series of the commercial code, ABAQUS. In the paper, the process to predict the post deformation under cyclic thermal loadings was suggested. The process was applied to the real panel, and the deformation predicted by the analysis was compared with that of real test, which showed the possibility of applying the suggested process to predict the post deformation of plastic product under thermal loadings.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.183-190
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• 2000

Effective range of Hydraulic Hammer Compaction was studied by numerical analysis instead of empirical method. Numerical analyses were carried out with commercial FEM code, ABAQUS, and verified by comparing the numerical results with field tests of Hydraulic Hammer Compaction. Most of material properties were evaluated by data from laboratory and in-situ tests. Vertical effective range was estimated by distribution curve of plastic strain energy dissipated through soil layers under dynamic load and these results were in good agreement with field tests. Based on verification, the effects of governing properties of Hydraulic Hammer Compaction such as number of hit can be determined by numerical analyses. In addition, vertical effective range can also be determined by Menard's empirical equation using the external work at converging time of plastic strain energy in numerical analysis. This implies that the minimum energy of Hydraulic Hammer Compaction for improvement can be determined by Menard's equation.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.111-119
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• 1993

In this study, the transient impact structural stress analysis of tracked vehicle structures under recoil impact load is investigated. ANSYS, ABAQUS Code are used for modelling and analytical procedures. The highest maximum Tresca stress occurs on race ring portion and its stress level is (.sigma.$_{T}$)$_{max}$ =20-40kgf/m $m^{2}$. The second highest stress occurs on upper plate of chassis and down plate of turret. The maximum stress level increases with loading direction and elevation angle. The results from liner static load analysis are very much different with impact analysis. Therefore, the practical solutions of structures under impact load can be obtained by only nonlinear transient impact analysis. The impact stress analysis of the steel vehicle structures is conducted. The maximum stress level is less than (.sigma.$_T/)$_{max}$m $m^{2}$. So, the design concept of steel structures can be adapted for new alternatives.s.s.s..s.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03a
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• pp.172-184
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• 1996

Superplastic forming of thin sheet into complex shape is an important manufacturing process especially in aerospace industry. The main interest in modeling the superplastic forming process is to predict the forming pressure cycle to maintain optimum strain rate and the resulting thickness distribution. Many researchers have attemped to model superplastic forming using the various techniques including finite element method. But in most of their researches have disregarded the strain hardening effect which which occurs in several superplastic materials. In this study ABAQUS finite element code was used for prediction of process variables for axisymmetric cup forming of Supral 100 and 7075Al alloys considereing strain hardening. The performance of numerical results were compared with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.331-334
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• 2004

In clinical use, coronary stents keep coronary arteries open after expansion with a balloon catheter and prevent the expanded artery from collapsing. Coronary stents are positioned in artery by catheter with a balloon along a guide wire to the lesion site. Flexibility is one of important ability for delivery. In this paper, Palmaz-Schatz stent and Tenax complete stent were selected because these are the most representative of tubular stents. Finite element analyses for the stent system were performed using ABAQUS/Standard code. The present study estimated the flexibility of coronary stents due to loading directions. Moreover the present paper suggests a numerical method to test the flexibility of stents. In conclusion this paper shows how the finite element analysis can be effectively organized in the stent development.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.41-49
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• 1997

Laser spot welding offers a unique combination of high speed. precision and low heat distortion, compared with conventional resistance spot welding. This combinatin of advantages is especially attractive for the automotive industry. Until now automobile fabrication is widely used resistance spot welding, however, because of geometric and structural problem, spot welding is required many welding machine in that reason by substituting spot welding with laser welding, it save the equipment cost. In the present study we measured ultimate strength and observed bead cross section of laser welded specimen and compared with that of the resistance spot welding results in order to adapt laser welding in automobile industry. Also for strength esti- mation we calculated the residual stress of laser welded zone. All calculations are performed with the ABAQUS code on a workstation.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.139-144
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• 2004

Dynamic crack initiation in ductile steel is investigated by means of impact loaded 3 point bend(PB) specimens. Results from non-viscoplastic and viscoplastic materials are compared. Their materials are applied with various impact velocities and static strain rates. The specimen has the size 320${\times}$750 mm with a thickness of 10 mm. A modified 3PB specimen design with reduced width at the ends has been developed in order to avoid the initial compressive load of the crack tip and also to avoid the uncertain boundary conditions at the impact heads. Numerical simulations are made by using the FEM code ABAQUS. Therefore, their results are plotted by shapes of the von Mises plastic stress and equivalent plastic strain of the specimens applied by various impact velocities.