• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.3
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• pp.58-63
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• 2004

In the present work a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of multi-stage stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation Multi-Stage stamping is analyzed by using dynamic-explicit finite element method. Further, the simulated results for the panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.63-72
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• 2004

In this paper, a finite element formulation using dynamic-explicit time integration scheme is used for numerical analysis of auto-body panel stamping processes. The lumping scheme is employed for the diagonal mass matrix and dynamic explicit formulation. Auto-body panel forming is analyzed by using dynamic-explicit finite element method. Further, the simulated results of the auto-body panel stamping processes are shown and discussed. Its application is being increased especially in the stamping industrial area for the cost reduction, weight saving, and improvement of strength.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.4
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• pp.21-29
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• 1987

In this paper the liquid sloshing effects in vertical storage tanks under earthquake loadings are studied. The study focuses on the investigation of the effect of the flexibility of the tank wall on the hydrodynamic forces exerted on it. The tank structure is modelled using finite elements. The motion of the liquid is expressed by the Laplace equation. The equation of motion of the fluid shell system is formulated including the coupling effect between the shell motion and the sloshing motion. A procedure is developed to obtain the natural frequencies and the mode shapes of the sloshing motion as well as the shell vibration. Dynamic analyses have been carried out for several tanks with different dynamic characteristics utilizing the time history method as well as the response spectra method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.1
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• pp.35-42
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• 1997

Subsea cable systems have a large information transmission capacity and play an important role in domestic and global information networks. However since the cables are under harsh marine environment, they are exposed to various hazards with high potential risks of damage resulting in serious economic loss. In this research a computer simulation program based on the finite difference algorithm was developed. The program is able to simulate two dimensional dynamic behaviour of a submarine cable during its laying. In order to verify the numerical results, they are compared to analytical results, showing a good agreement between the two results.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.4
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• pp.185-191
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• 2004

A mooring system can be applied to keep the position of a floating structures. In this study, the structural analysis is carried out to analyze the dynamic characteristics of a mooring line for a floating breakwater. A three-dimensional equations of motion for a submerged chain are derived. Bending stiffness is considered for the necessary restoring force in the regions of zero tension. A fortran program is to be developed by employing finite difference method. In the algorithm, an implicit time integration and Newton-Raphson iteration are adopted. The results of simulation show good agreement in tension response pattern with the experimental results of a reference. The results of this study can contribute for the design of mooring system for a floating breakwater.

• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.5
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• pp.413-430
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• 2011

Consideration on the explosion resistant design of infrastructure has increased in the recent years. The explosion load is caused by gas explosion or bomb blast. In this study an analytical model is developed, whereby the tunnel structure is divided in several elements that are schematized as single degree of freedom mass-spring-dashpot systems on gas explosion. Using this simple model a sensitivity analysis has been carried out on tunnel structure design parameters such as explosive peak pressure, duration of the load, thickness of structure, burial depth. Finite element method was used to investigate the dynamic response and plastic zone of a tunnel under gas explosion. And it was found from the comparison of the analysis results that there are slight differences in the response of the intermediate wall between the single degree of freedom mass-spring-dashpot model and FEM.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.3
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• pp.311-320
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• 2005

In this paper an enhanced quadratic finite element for static and dynamic analysis of plate structures is presented. The performance of a proposed plate element is improved by the coupled use of non conforming displacement modes, the selective integration scheme, and the assumed shear strain fields. An efficient direct modification method is also applied to this element to solve the problem such as failure of the patch test due to the adoption of non conforming modes. The proposed quadratic finite element does not show any spurious mechanism and does not produce shear locking phenomena even with distorted meshes. It is shown that the results obtained by this element converged to analytical solutions very rapidly tough numerical tests for standard benchmark problems. It is also noted that this element is applicable to transient dynamic analysis of Mindlin plates.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.117-126
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• 2001

도로교의 대표적인 기초형식인 말뚝기초에 대한 내진설계방법으로 여러 가지 방법들이 제안되어 있다. 이 중 동적해석법과 같은 복잡한 절차에 의한 해석은 적용성에 한계가 있을 수 있고, 실무에서의 적용상 많은 어려움이 예상되었다. 본 연구에서는 등가정적해석법을 이용한 도로교 기초 말뚝에 대한 간편한 내진설계절차를 제안하였으며, 사례에 적용하였다. 또한, 제안된 간편한 내진설계절차에 사용할 수 있는 해석코드의 적용성을 확인하기 위하여 수식적 정해에 의한 계산결과를 기준 값으로 하여 해석코드에 의한 해석결과들을 비교.분석하였다. 또한, 지진 진동을 이용한 동적 해석결과와 SPS 상호작용(Superstructure - pile - soil interaction)을 고려한 해석결과를 수식적 정해에 의한 결과와 비교.분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.297-303
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• 2014

Using the bond-based peridynamics and the parallel computation with binary decomposition, an adjoint shape design sensitivity analysis(DSA) method is developed for the dynamic crack propagation problems. The peridynamics includes the successive branching of cracks and employs the explicit scheme of time integration. The adjoint variable method is generally not suitable for path-dependent problems but employed since the path of response analysis is readily available. The accuracy of analytical design sensitivity is verified by comparing it with the finite difference one. The finite difference method is susceptible to the amount of design perturbations and could result in inaccurate design sensitivity for highly nonlinear peridynamics problems with respect to the design. It turns out that $C^1$-continuous volume fraction is necessary for the accurate evaluation of shape design sensitivity in peridynamic discretization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.311-318
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• 2015

A nonlinear dynamic response structural optimization process is proposed for the television (TV) packing system that protects the damage from a drop situation using the equivalent static loads (ESLs). Topology optimization using ESLs is carried out for conceptual design, and shape optimization using stress ESLs for a virtual model is performed for detailed design. Stress ESLs are static loads that generate the same displacement as well as the stress fields of linear static analysis as those of nonlinear dynamic analysis. Thus, the response of nonlinear dynamic analysis can be utilized as a constraint in the linear static structural optimization. An actual example is solved to validate the process. The drop test of a television packaging system is analyzed by LS-DYNA, and NASTRAN is used for optimization.