• 한국소음진동공학회논문집
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• 제17권4호
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• pp.350-355
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• 2007

Accelerometer mounting fixtures were prepared with the different materials(Ti and SUS). The dynamic characteristics of the mounting fixture were analyzed by finite element method(FEM), and the mode shape of each order and the displacement response for modelling the mounting fixture were analyzed by ANSYS, then resonant frequencies of the mounting fixtures with Ti and SUS were 22.700 and 23.390 kHz, respectively. The dynamic characteristics of the mounting fixture with the different positions were obtained by using laser interferometer. The response of the accelerometer was nearly a constant from 40 Hz to 500 Hz, but the change of the acceleration was increased with an increase of the frequency above 500 Hz.

• Structural Engineering and Mechanics
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• 제47권3호
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• pp.345-359
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• 2013

For the purpose of investigating the free vibration response of the spatial curved beams, the governing equations are derived in matrix formats, considering the variable curvature and torsion. The theory includes all the effects of rotary inertia, shear and axial deformations. Frobenius' scheme and the dynamic stiffness method are then applied to solve these equations. A computer program is coded in Mathematica according to the proposed method. As a special case, the dynamic stiffness and further the natural frequencies of a cylindrical helical spring under fixed-fixed boundary condition are carried out. Comparison of the present results with the FEM results using body elements in I-DEAS shows good accuracy in computation and validity of the model. Further, the present model is used for reciprocal spiral rods with different boundary conditions, and the comparison with FEM results shows that only a limited number of terms in the resultant provide a relatively accurate solution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.591-593
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• 2005

This paper presents the dynamic analysis of a humanoid robot using Nastran that is one of FEM analysis program. Generally, computer program based on the Lagrange-Euler method or Newton-Euler method was used for dynamic analysis of a robot. The Lagrange-Euler method requires much calculation performance and it is also hard to apply to complex structure, and the Newton-Euler method limits accurate modeling and calculation for closed structure like a humanoid robot. In this paper, mechanical and structural data are obtained from the Nastran. It is possible for Nastran to make model similar to real system and can apply a physical properties and laws to model. So, accurate simulation is possible. From this result, accurate data is gained by Nastran. Furthermore, this method is shown to be a useful method that guarantees accuracy for trajectory planning.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.900-905
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• 2004

Development of color printer, postal classification machine, ATM and so on requires higher moving performance of the flat belt. Skew of the flat belt running over misaligned roller has a bad effect on performances of media transport. The vibration of loose side of belt causes the escape of the belt from roller and the drop of velocity of driven roller after the start of driving roller revolution. The skew of flat belt is investigated by FEM and dynamic simulation. FEM results show parameters which affect the skew of belt and match with dynamic results qualitatively. The shape of loose side of belt can be found by dynamic simulation. Increase of the acceleration time and initial tension have diminished the unstable movement of the loose side of belt.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.249-252
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• 1999

A numerical analysis was perfomed to predict flow curves and dynamic recrystallization behaviors of Al-5%Mg alloy on the basis of results of hot compression tests. The hot compression tests were carried out in the ranges of 350-50$0^{\circ}C$ and 5$\times${{{{ {10 }^{-3 } }}}}~3$\times${{{{ {10 }^{0 } }}}}/sec to obtain the Zener-Hollmon parameter. In the modelling equation the effects os strain hardening and dynamic recrystallization were taken into consideration. A model for predicting the evolution of microstructure in Al-5%Mg alloy during thermomechanical processing was developed in terms of dynamic recrystallization phenomena, The microstructure model was combined with finite element modeling(FEM) to predict microstructure development Model predictions showed good agreement with microstructures obtained in compression tests.

• 대한기계학회논문집A
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• 제27권2호
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• pp.294-301
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• 2003

It is of often important to accurately predict the flow-induced vibration or dynamic instability of a pipeline conveying internal high speed flow in advance, which requires a very accurate solution method. In this study, first the dynamic equations for the axial and transverse vibrations of a pipeline are reduced from a set of pipe-dynamic equations derived in the previous study and then the spectral element model is formulated. The accuracy of the spectral element method (SEM) is then verified by comparing its results with the results obtained by finite element method (FEM). It is shown that the present spectral element model provides very accurate solutions by using an extremely small number of degrees-of-freedom when compared with FEM. The dynamics of a sample pipeline is investigated with varying the axial tension and the speed of internal flow.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.72-77
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• 2011

In this study, the natural frequencies and mode shape of an external mounting pod were verified using the modal analysis and modal testing technique for a pod mounted on an aircraft. The procedure associated with the FEM building of an external mounted pod to predict the dynamic behavior of aircraft structures is described. The simplified FEM reflecting the results of the modal testing of a pod is built through the optimization, applied to the structural dynamic model of an Aircraft, used to verified the stability of vibration and flutter of an aircraft.

• 한국정밀공학회지
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• 제19권9호
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• pp.82-89
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• 2002

There is an intensifying demand fur linear motors in vast range of industry applications such as in factory automation and semi-conductor manufacturing equipment due to their high positioning accuracy, high static stiffness, high thrust and excellent dynamic characteristics. This paper presents an iron core type linear motor for machine tool whose rated thrust is up to 6000N. For electromagnetic field and dynamic analysis, finite element method (FEM) is implemented to predict motor performance. Various design parameters are considered to reduce thrust ripple and to improve dynamic performance with the least sacrifice of effective thrust. Experimental results on thrust and static stiffness are also followed to confirmed the validity of the analysis.

• 소성∙가공
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• 제17권2호
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• pp.117-123
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• 2008

In this study, optimum processing condition of rolled AZ31 Mg alloy was investigated by utilizing processing map and constitutive equation considering microstructure evolution(dynamic recrystallization) occurring during hot-working. A series of mechanical tests were conducted at various temperatures and strain rates to construct a processing map and to formulate the recrystallization kinetics in terms of grain size. Dynamic recrystallization(DRX) was observed to occur at a domain of $250^{\circ}C$ and 1/s(maximum dissipation-efficiency region). The effect of DRX kinetics on microstructure evolution was implemented in a commercial FEM code followed by remapping of the state variables. The volume fraction and grain size of deformed part were predicted using a modified FEM code and were compared with those of actual hot forged part. A good agreement was observed between the experimented results and predicted ones.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.31-34
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• 2007

In this study, optimum processing condition of AZ31 Mg alloy was investigated utilizing processing map and constitutive equation considering microstructure evolution (dynamic recrystallization) during hot-working. A series of mechanical tests were conducted at various temperatures and strain rates to construct a processing map and to formulate the recrystallization kinetics and grain size relation. Dynamic recrystallization (DRX) was observed to occur revealing maximum intensity at a domain of $250^{\circ}C$ and 1/s. The effect of DRX kinetics on microstructure evolution was implemented in a commercial FEM code followed by remapping of the state variables. The volume fraction and grain size of deformed part were predicted using a modified FEM code and compared with those of actual hot forged one. A good agreement was observed between the experimental results and predicted ones.