• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2600-2608
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• 2011

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research about the development of the small scale simulator and the bogie has been conducted. As this paper, To predict the dynamic behavior of railway vehicle, we studied running stability test of 1/5 scaled bogie that similarity laws is applied using small scale derailment simulator. For the operation of the small scale derailment simulator, it is required to investigate the performance and characteristics of the system. This could be achieved by a comparative study between an analysis and an experiment. This paper presented the analytical model which could be used for verifying of the test results and understanding of the physical behavior of the dynamic system comprising the small scale bogie and the simulator.

• Journal of Astronomy and Space Sciences
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• 제26권4호
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• pp.693-702
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• 2009

액체로켓엔진의 구성품 중 하나인 산화제 라인 시스템의 3차원 모델과 유동해석을 수행하였다. 전체 시스템의 유동해석에 앞서 각 구성품들의 개별적인 유동해석과 단순화된 모델을 통해 최적의 위치를 결정하였다. 그 결과 가스발생기 라인의 입구는 압력보상이 필요하며 오리피스의 위치에 따라 출구 유동의 형태가 달라지는 것을 확인할 수 있었다. 전체적으로 해석된 라인 시스템은 주어진 요구조건을 만족하는 것으로 나타났으며 이는 실제 제품 제작과 시험을 통해 확인할 예정이다.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.659-667
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• 2017

Rail support failure is inevitably subjected to track geometric deformations. Due to the randomness and evolvements of track irregularities, it is naturally a hard work to grasp the trajectories of dynamic responses of railway systems. This work studies the influence of rail fastener failure on dynamic behaviours of wheel/rail interactions and the railway tracks by jointly considering the effects of track random irregularities. The failure of rail fastener is simulated by setting the stiffness and damping of rail fasteners to be zeroes in the compiled vehicle-track coupled model. While track random irregularities will be transformed from the PSD functions using a developed probabilistic method. The novelty of this work lays on providing a method to completely reveal the possible responses of railway systems under jointly excitation of track random irregularities and rail support failure. The numerical results show that rail fastener failure has a great influence on both the wheel/rail interactions and the track vibrations if the number of rail fastener failure is over three. Besides, the full views of time-dependent amplitudes and probabilities of dynamic indices can be clearly presented against different failing status.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.623-640
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• 2017

The full nonlinear equations of an unmanned aerial vehicle ground taxiing mathematical dynamic model are built based on a type of unmanned aerial vehicle data in LMS Virtual.Lab Motion. The flexible landing gear model is considered to make the aircraft ground motion more accurate. The electric braking control system is established in MATLAB/Simulink and the experiment of it verifies that the electric braking model with the pressure sensor is fitted well with the actual braking mechanism and it ensures the braking response speediness. The direction rectification control law combining the differential brake and the rudder with 30% anti-skid brake is built to improve the directional stability. Two other rectifying control laws are demonstrated to compare with the designed control law to verify that the designed control is of high directional stability and high braking efficiency. The lateral displacement increases by 445.45% with poor rectification performance under the only rudder rectifying control relative to the designed control law. The braking distance rises by 36m and the braking frequency increases by 85.71% under the control law without anti-skid brake. Different landing conditions are simulated to verify the good robustness of the designed rectifying control.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.14-22
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• 2010

In this study, a large bus is tested for measuring the steering response based on the slarom test and step steer test. A full car model by using ADAMS/Car is established for computer simulation. For bus modeling, user defined templates are made and used in the simulation. Simulation results according to the slarom and step steer test are compared to the physical experiments, in which several sensors are installed to measure vehicle responses. The results obtained from the comparison show a good agreement with regard to the vehicle velocity and steering angle.

• 한국산업융합학회 논문집
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• 제20권1호
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• pp.27-33
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• 2017

An agriculture machines are subjected to different loads conditions. Due to this loads variations there will be certain deformations and stress which affect the performance of the electric vehicle in adverse manner. The purpose of this paper is to analyze the total deformation and stress of the electric farm vehicle middle frame based on the finite element method. The proposed electric farm vehicle has lifting and dumping capability. Therefore, in this research four operational condition such as normal condition, dumping condition, lifting condition, and lifting-dumping condition was analyzed. In this research, the design for whole frame structure is elaborated. According to the mechanical characteristics of the frame, materials are selected and manufacturability requirements are limited. Based on ANSYS 15 software, the finite element model of electric farm vehicle is established to carry out static analysis on full-loaded conditions. The simulation results shows that the proposed design meet the strength requirements and displacement requirements. The maximum deformation 0.53611 mm and maximum stress 30.163 MPa occurred at lifting-dumping condition.

• Smart Structures and Systems
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• 제23권4호
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• pp.347-357
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• 2019

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.570-573
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• 2003

Wheels for passenger car support the car weight with tires. and they transmit rolling and braking power into the ground. Whittliing away at wheel weight is more effective to boost fuel economy that lighting vehicle body structure. A shape of hole in disk is optimized for minimizing the weight of steel wheel. Pro/ENGINEER program is used for formulating the design model. and ANSYS package is selected for analyzing the design model. It has difficulties 10 interface these commercial software directly. For combining both programs. response surface methodology is applied to construct approximation functions for maximum stresses and maximum displacements are obtained by full factorial design of five levels. This steel wheel is modeled in 14-inch diameter of rim. and wide parameter of hole in disk is only selected as design variable for reducing the weight of steel wheel. PLBA(Pshenichny·Lim-Belegundu_arora) algorithm. which uses the second-order information in the direction finding problem and uses the active set strategy. is used for solving optimization problems.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.84-92
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• 2005

This paper is concerned with optimum design of a center-pillar assembly induced by the high-speed side impact of the vehicle. In order to simulate deformation behavior of the center-pillar assembly, simplified finite element model of the center-pillar and a moving deformable barrier are developed based on results of the crash analysis of a full vehicle model. In optimization of the deformation shape of the center-pillar, S-shaped deformation is targeted to guarantee reduction of the injury level of a driver dummy in the crash test. Tailor-welded blanks are adopted in the simplified center-pillar model to control the deformation shape of the center-pillar assembly. The thickness of each part which constitutes the simplified model is selected as a design parameter. The thickness of parts which have significant effect on the deformation mechanism are selected as design parameters with sensitivity analysis based on the design of experiment technique. The objective function is constructed so as to minimize the weight and lead to an S-mode deformation shape. The result shows that the simplified model can be utilized effectively for optimum design of the center-pillar members with remarkable saving of computing time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.441-446
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• 2008

The source transfer receiver model ('Source $\times$ Transfer = Response' model) which is widely used by NVH development process of vehicle/transport/machinery to analyze effectively and manage efficiently the structural dynamic behavior is also applicable to construction structure. If the evaluation assessment of the vibration level does not meet the target level, there are two methods, one is source treatment or replacement and the other is the reduction treatment on the transfer structure. In case of source treatment, it is done by source supplier and so, the latter is more practical method to reduce the vibration level. In this study, in order to get the accurate Transfer FE model(floor structure FE model), Experimental modal analysis of part of floor structure and FEM modal analysis of full floor structure are performed, then updating of FE model is performed after correlation analysis between these two results and finally, the modal model and FRF are compared between FE and Experimental results.