• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.2 s.233
• /
• pp.262-269
• /
• 2005

Optimization of a satellite structure under severe space launching environments is performed considering various design constraints. Simulate annealing, one of combinatorial optimization techniques, is used to optimize the satellite. The optimization results by the simulated annealing are compared to those by the method of modified feasible direction and genetic algorithm. Ten bar truss structure is optimized for feasibility study of the simulated annealing. Finally, the satellite structure is optimized by the simulated annealing algorithm under space environment. Weights of the satellite upper platform and propulsion module are minimized with consideration of several static and dynamic constraints. MSC/NASTRAN is used to find the static and dynamic responses. Simulated annealing has been programmed and integrated with the finite element analysis program for optimization. It is shown that the simulated annealing algorithm can be extended to the optimization of space structures.

• Computational Structural Engineering
• /
• v.3 no.2
• /
• pp.13-29
• /
• 1990

구조해석 및 설계분야에서의 컴퓨터 이용은 이미 일반화 되어 수많은 프로그램들이 개발되어 사용되고 있다. 70년대 초에 SAP, NASTRAN 같은 범용 해석프로그램이 개발되어 보급되면서, 구조해석 및 설계업무에서의 컴퓨터의 이용은 확산되었다. 이제는 국내의 소규모의 용역회사나 설계사무소에서도 컴퓨터를 이용하여 구조해석 및 설계를 하는 것이 상당히 보편화되었다고 할 수 있다. 구조해석 및 설계에 사용되는 컴퓨터프로그램은 SAP, STRUDUL 같은 대형 범용 프로그램에서부터 특수한 구조물을 해석 또는 설계하기 위하여 개발된 전용 프로그램까지 매우 다양하다. 또한 수많은 프로그램들이 개발되었기 때문에, 자기에게 당면해 있는 문제를 해결하기 위하여 기존의 프로그램 중 어떤 것을 선택하는 것이 가장 효율적인 것인가, 또는 새로운 프로그램을 개발해양 하는 것인가를 결정하기 어려운 경우가 많다. 이러한 관점에서 국내에서 현재 사용 또는 판매되고 있는 구조해석 및 설계용 프로그램의 현황을 조사하여, 그 결과를 정리하였다.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.51 no.1
• /
• pp.9-15
• /
• 2015

A Korean-designed cruiser class sailing yacht, based on the form of traditional yachts, has been developed. In this paper, structural design procedures for the yacht are studied. The scantling of structural members and loads is carried out based on the guidelines suggested by Australian Standard 4132-1993, the American Bureau of Shipping (ABS) and the International Organization for Standardization (ISO). Patran/Nastran finite element analysis is performed on models of the trial sailing boat, and from these results, the structural strength of the ship's hull is verified.

• Journal of Energy Engineering
• /
• v.23 no.3
• /
• pp.221-230
• /
• 2014

Simplified finite element model of spark ignition (SI) engine to analyse combustion heat transfer is presented. The model was discredited with 3D thermal elements of global length 5 mm. The fuel type is petrol. Internal nodal temperature of cylinder body is defined as 21000C to represent occurrence of gasoline combustion. Material information and isotropic material properties are taken from published report. The heat transfer analysis is done for the instant of combustion. The model is validated by comparing the computed maximum temperature at the piston surface with the published result. The computed temperature gradient at the crucial parts are plotted and discussed. It has been found that the critical top surface suffered from thermal and the materials used to construct the engine parts strongly influenced the temperature distribution in the engine. The model is capable to analyze heat transfer in the engine reasonably and efficiently.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.9
• /
• pp.2252-2263
• /
• 1993

The purpose of this study is to verify the vibration and damping characteristics of elastic-viscoelastic-elastic structures, theoretically and experimentally. The forth-order differential equations of motion are derived for the transverse vibration of three-layered plates with viscoelastic core layer. The equations consider both transverse displacements of the constraining layer and the bare base plate as variable and account for the effect of the transverse normal strain and the shear strain of viscoelastic core layer on the vibration of the plates. Finite difference analysis of the equations and experimental measurements are performed on the three-layered plates of completely free boundary condition. Comparative investigations on the theory and the results of direct frequency analysis of NASTRAN are carried out on the same structures.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1116-1122
• /
• 2008

The reciprocating type hydrogen compressor has a pulsation due to the reciprocative characteristics which results in noise and vibration. Snubber is installed for the relaxation of pulsation, but it causes reduction of compressor efficiency because of pressure loss. Five types of snubber were modeled for the numerical investigation of the effect of the relative position of inlet and outlet and buffer angle on the pulsation amplitude and pressure loss. MSC/NASTRAN is used as a numerical tool to identify the vibration characteristic of each type. Frequency responses in forced vibration mode are compared for various cases and buffer angles.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.65-67
• /
• 1996

The spacer is solid insulator which supports main conductor in GIS and seperates gas area. The 800kV spacer was designed and manufactured considering the results of electrical and structural analysis using commercial package MSC/NASTRAN. Temperature test and water pressure test were carries out, and the results from water pressure test were compared with the calculated ones from MSC/NSATRAN.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1991.10a
• /
• pp.75-80
• /
• 1991

The purpose of this study is to ascertain the robustness of p-version model with hierarchic intergrals of Legendre shape functions in various applications including plane stress/strain, axisymmetric and shell problems. The most important symptoms of accuracy failure in modern finite elements are spurious mechanisms and a phenomenon known as locking which are exhibited for incompressible materials and irregular shapes which contain aspect ratios(R/t, a/b), tapered ratio(d/b), and skewness. The condition numbers and energy norms are used to estimate numerical errors, convergence characteristics and algorithmic efficiencies for verifying the aforementioned symptoms of accuracy failure. Numerical results from p-version models are compared wi th those from NASTRAN, SAP90, and Cheung's hybrid elements.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.13-18
• /
• 2001

This paper deals with finite element analysis for free vibration and forced sine vibration of Ka- and Ku- bend antenna structures using MSC/PATRAN/NASTRAN. The structures are designed to satisfy minimum resonance frequency requirement in order to decouple the dynamic interaction of the satellite with the spacecraft bus structure. From the forced sinusoidal vibration, we have observed output acceleration versus input in X-,Y- and Z- direction, based on base excitation using large mass method. The results of finite elements analysis can be used as the reference data for the experimental test of satellite antenna, resulting in the reduction of cost and time by predicting and complementing experimental data.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.147-150
• /
• 2001

In the present work, a linear static analysis is presented for thin-walled prismatic box-beams made of generally anisotropic materials. A mixed beam theory has been used to model and carry out the analysis. Three different constitutive relations are assessed into the beam formulation. Simple layup cases having symmetric or anti-symmetric configuration have been chosen and tested to clearly show the effects of elastic couplings of the beam. Both 2D and 3D finite element structural analysis using the MSC/NASTRAN has been performed to validate the current analytical results. Results show that appropriate assumptions for the constitutive equations are important and prerequisite for the accurate prediction of beam stiffness constants and also for the beam behavior.