• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.132-135
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• 2003

Mechanical anchorage can substitute a standard hook. To enhance the workability and economical benefit of mechanical anchorage, the size of anchor plate should be optimized. In this paper, the pull-out behaviors such as strength, failure mode, and crack patterns of mechanically anchored reinforcement in concrete are investigated using nonlinear finite element analysis. The nonlinear finite element analysis results are consistent with the experimental results. These results show that the optimal anchor plates can be designed using the nonlinear finite element analysis.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.221-233
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• 2017

The array equations are commonly used for analysis and conceptual design of active sonar projector arrays. Calculation of the radiation impedance matrix poses a major computational bottleneck for the solution of the array equations, which leads to a dramatic increase in computational load as the number of constituent transducers increases. Here, we propose an iteration-based solution method that does not require the calculation of the radiation impedance matrix, as a computationally efficient alternative to the status quo. The validity of the iteration-based analysis is judged against the full finite-element analysis that includes the entire array as well as the medium. The array equations for the 1/3-sector of a cylindrical array comprised of 48 Tonpilz transducers are augmented by the lumped element models, and are solved iteratively for the acoustic and electro-mechanical characteristics. The iteration-based analysis exhibits rapid convergence and accuracy comparable with the FE analysis. Simulations also reveal that the acoustic coupling between transducers has more pronounced effects on the electro-mechanical characteristics of individual transducers than the acoustic performance of the array.

• Journal of Mechanical Science and Technology
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• 제17권7호
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• pp.1073-1082
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• 2003

Many researchers have investigated the blood flow characteristics through bileaflet mechanical heart valves using computational fluid dynamics (CFD) models. Their numerical approach methods can be classified into three types; steady flow analysis, pulsatile flow analysis with fixed leaflets, and pulsatile flow analysis with moving leaflets. The first and second methods have been generally employed for two-dimensional and three-dimensional calculations. The pulsatile flow analysis interacted with moving leaflets has been recently introduced and tried only in two-dimensional analysis because this approach method has difficulty in considering simultaneously two physics of blood flow and leaflet behavior interacted with blood flow. In this publication, numerical calculation for pulsatile flow with moving leaflets using a fluid-structure interaction method has been performed in a three-dimensional geometry. Also, pulsatile flow with fixed leaflets has been analyzed for comparison with the case with moving leaflets. The calculated results using the fluid-structure interaction model have shown good agreements with results visualized by previous experiments. In peak systole. calculations with the two approach methods have predicted similar flow fields. However, the model with fixed leaflets has not been able to predict the flow fields during opening and closing phases. Therefore, the model with moving leaflets is rigorously required for advanced analysis of flow fields.

• 드라이브 ㆍ 컨트롤
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• 제16권1호
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• pp.36-44
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• 2019

Variable displacement swash plate piston pump analysis requires electric, hydraulics and dynamics which are similar to the one's incorporated in the complex fluid power and mechanical systems. The main variable capacity for the swash plate piston pumps, hydraulics or simple kinematic (swash plate degree, piston displacement) models are analyzed using AMESim, a multi-physics analysis program. AMESim is a multi-physics hydraulic analysis program that is considered good for the environment but not appropriate for environmental analysis for multibody dynamics. In this study, the analytical model of the swash plate type hydraulic piston pump variable capacity is modeled by combining the hydraulic part and the dynamic part through co-simulation of multibody dynamics program (Virtual.lab Motion) and multi-physics analysis (AMESim). This paper describes the whole modeling analysis method on the mechanical analysis of the multi-body dynamics program and how the hydraulic analysis in multi-physics analysis program works. This paper also presents a methodology for analyzing complex fluid power systems.

• 에너지공학
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• 제23권3호
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• pp.231-234
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• 2014

The crankshaft is a complex component, and as such, the influence of its geometric parameters on stresses seen under service loads is not well understood. The objectives of this work is to investigate the effects of a wide range of geometric parameters on stresses in crankshafts, to find correlation between results and to formulate simple methods of predicting peak stress levels: It is intended to achieve this by use of fatigue method. Analyses are carried out in 2D and 3D, making use of symmetry as far as possible. Variations in stresses are plotted over a wide range for each of the parameters. The analysis methods give accurate results for stress analysis of crankshafts and offer several advantages over traditional experimental techniques; they are ideally suited to parametric analyses, can be carried out relatively quickly, results are repeatable because boundary conditions can be exactly defined, and the cost of analysis is significantly reduced.The analysis is carried out in ANSYS for crankshaft along for single cylinder camless engine.

• Journal of Advanced Marine Engineering and Technology
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• 제34권5호
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• pp.695-702
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• 2010

Numerical analysis information will be very useful to improve fluid system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas coming to the cylinder of a reciprocating compressor are presented in this paper. Suction-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the Hydrogen system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement, such as reducing the varying flow parameters and flow reorientation should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• 한국기계가공학회지
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• 제12권5호
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• pp.50-56
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• 2013

Machine tools are the cores of industrial development in recent period. It is difficult to develop a system which can do cutting and grinding process in the one system. Hybrid Vertical Grinding System is capable of processing in a single apparatus cutting or grinding. The modal analysis and structural analysis for the development of Hybrid Vertical Grinding System is the first time of domestic work. In this study, Hybrid Vertical Grinding System bed was designed and analyzed by using SS401 and FC300 as materials. And by using Finite Element Methods, the design and material of the bed was analysed. Finally, we can make a better choice of structure and material of the bed by comparing the analysis results.

• International Journal of Precision Engineering and Manufacturing
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• 제9권3호
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• pp.59-63
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• 2008

A static load analysis of twin-screw kneaders is required not only for the dynamic analysis, but also because it is the basis of the stiffness and strength calculations that are essential for the design of bearings. In this paper, the static loads of twin-screw kneaders are analyzed, and a mathematical model of the force and torque moments is presented using a numerical integration method based on differential geometry theory. The calculations of the force and torque moments of the twin-screw kneader are given. The results show that the $M_x$ and $M_y$ components of the fluid resistance torque of the rotors change periodically in each rotation cycle, but the $M_z$ component remains constant. The axis forces $F_z$ in the female and male rotors are also constant. The static load calculated by the proposed method tends to be conservative compared to traditional methods. The proposed method not only meets the static load analysis requirements for twin-screw kneaders, but can also be used as a static load analysis method for screw pumps and screw compressors.

• 대한기계학회논문집A
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• 제36권1호
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• pp.117-124
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• 2012

본 논문에서는 유한요소법을 이용하여 블레이드에서 발생하는 동력을 발전기로 전달하는 체결부에 대한 연구를 수행하였다. 블레이드 체결부의 유한요소 모델을 수립하기 위하여 실험적 모드해석을 이용하여 각 부품의 고유진동수 및 고유모드를 추출하였으며, 사용프로그램인 ANSYS를 이용한 모드해석을 통하여 추출된 유한요소 모델의 고유진동수와 고유모드 비교를 통하여 모델을 검증하였다. 검증된 유한요소 모델을 이용하여 정격풍속 상태와 한계풍속 상태에서 응력해석을 수행하였으며, 해석 시 작동상태의 경계조건과 중력 및 바람에 의한 하중이 고려되었다.

• Structural Monitoring and Maintenance
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• 제6권1호
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• pp.33-46
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• 2019

In present study, Operational Modal Analysis (OMA) was employed to carry out the dynamic and vibration analysis of the threshing unit of the combine harvester thresher as a mechanical component. The main study is to find the causes of vibration and to decrease it to enhance the lifetime and efficiency of the threshing unit. By utilizing OMA, structural modal parameters such as mode shapes, natural frequencies, and damping ratio was calculated. The combine harvester was excited by engine to vibrate different parts and accelerometer sensor collected acceleration signals at different speeds, and OMA was utilized by nonparametric and frequency analysis methods to obtain modal parameters while vibrating in real working conditions. Afterwards, finite element model was designed from the thresher and updated using the data obtained from the modal analysis. Using the conducted analyses, it was specified that proximity of the thresher pass frequency to one of the natural frequencies (16.64 Hz) was the most important effect of vibration in the thresher. Modification process of the structure was carried out by increasing mass required for changing the natural frequency location of the first mode to 12.4 Hz in order to reduce resonance and vibration of the thresher.