• 한국소음진동공학회논문집
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• 제15권5호
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• pp.604-611
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• 2005

The relationship between floor impact sound and vibration has been studied by field measurements, and the vibration modal characteristics have been analyzed. Vibration levels impacted by a standard heavy-weight impact source have been predicted according to the main design parameters using finite element method. Experimental results show that the dominant frequencies of the heavy impact sounds range below 100 Hz and that they are coincident with natural frequencies of the concrete slab. In addition, simple 2-dimensional finite element models are proposed to substitute 2 types of 3-dimensional models of complicated floor structural slabs those by The analytical result shows that the natural frequencies from first to fifth mode well correspond to those by experiments with an error of less than $12\%$, and acceleration peak value iscoincident with an error of less than $2\%$. Using the finite element model. vibration levels areestimated according to the design Parameters, slab thickness, compressive strength, and as a result, the thickness is revealed as effective to increase natural frequencies by $20\~30\%$ and to reduce the vibration level by 3$\~$4 dB per 30 mm of extra thickness.

• 한국소음진동공학회논문집
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• 제23권4호
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• pp.301-307
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• 2013

MRU(motor reduction unit) for KTX is a assembled complex structure that is equipped with a lot of parts at the express train KTX and that is the core power source operating variable speeds. This study is recorded the dynamic characteristics analysis results tested by EMA which is done through the parts and assembly test, transient analysis and stoped train test in order to design the online monitoring system for KTX MRU. And the mode shapes result from critical vibration frequency explain the relation with variable speeds of express train over 250 km/hr. Also these variable speeds make variable operational frequencies at pinion, axle gear mesh frequency and normal bearing fault frequencies. As the specified speed can make resonance with natural frequencies of the MRU, for the train operating stability, this study also presents the MRU's critical speeds calculated by the each train speed.

• 한국생산제조학회지
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• 제18권6호
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• pp.642-651
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• 2009

The history of excavator design is not long enough which still causes most of the design considerations to be focused on static analysis or simple functional improvement based on static analysis. However, the real forces experiencing on each component of excavator are highly transient and impulsive. Therefore, the prediction and the evaluation of the movement of the excavator by dynamic load in the early design stage through the dynamic transient analysis of the excavator and ensuring of design technique plays an importance role to reduce development-cost, shorten product-deliver, decrease vehicle-weight and optimize the system design. In this paper, Commercial software DADS and ANSYS help to develop the track model of the crawler type excavator, and to evaluate the performance and the dynamic characteristics of excavator with various simulations. For that reason, the track of crawler type excavator is modelled with DADS Track Vehicle Superelement, and the reaction forces on the track rollers were predicted through the driving simulation. Also, the upper frame and cabin vibration characteristics, at the low RPM idle state, were evaluated with engine rigid body modelling. And flexibility body effects were considered to determine the more accurate joint reaction forces and accelerations under the upper frame swing motion.

• 한국소음진동공학회논문집
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• 제15권1호
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• pp.63-71
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• 2005

In this study, structural vibration analyses of a composite smart unmanned aerial vehicle (UAV) have been conducted considering dynamic hub-loads of tilt-rotor. Practical computational structural dynamics technique based on the finite element method is applied using MSC/NASTRAN. The present smart UAV(TR-S2) structural model is constructed as full 3D configurations with both the helicopter flight mode and the airplane flight mode. Modal based transient response and frequency response analyses are used to efficiently investigate vibration characteristics of structure and installed electronic equipments. It is typically shown that the helicopter flight mode with the 90-deg tilting angle is the most critical case for the induced vibration of installed electronic equipments in the front.

• Composites Research
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• 제20권3호
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• pp.63-66
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• 2007

Structural analysis of automotive engine cover under vibration excitation is performed by finite element analysis (FEA) in order to identify the critical area of the structure. Assembly load due to the tightening of the bolts as well as the vibration excitation were considered to describe the actual loading condition. Natural frequencies of the system were extracted considering the damping effect of the structure. Dynamic analysis was performed based on the extracted natural frequency of the system. Experimental modal analysis (EMA) and measurement of strains were performed to verify the results of the analysis. Analysis results correlated closely with the experimental results. Analysis and experiments showed that contribution of the assembly load should not be ignored to predict the structural failure of the engine cover.

• Journal of Power Electronics
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• 제19권2호
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• pp.540-548
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• 2019

In this work a new configuration of E-core stator Switched Reluctance Motor (SRM) with permanent magnets and auxiliary windings embedded in the stator yoke is proposed. For the proposed configuration of SRM electromagnetic analysis is performed using Finite Element Analysis (FEA) based computer aided design package MagNet and to emphasize its merits a comparison is drawn with existing hybrid excitation configuration of SRM. In addition, the vibration characteristics of the motor are analyzed by performing modal and transient analysis using the ANSYS package. Results of the analysis reveals that the proposed configuration of SRM exhibits better electromagnetic and vibration characteristics and is capable of competing with the existing topologies in the variable speed market.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1056-1061
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• 2004

The vibration of rotor systems is caused by various factors, such as misalignment, unbalance, gear meshing, error of assembly, etc. Modal test and TDA/ODS analysis were done. The dynamic analysis of the armature was done with SAMCEF which is a commercial software for finite element and kinematic analysis. The transient response of the armature is calculated by the SAMCEF with the consideration of magnetic force and bearing stiffness, which are the essential elements for the design of high speed cutter. Main frequency of the vibration is due to the unbalance of the armature. The FEM analysis model considering unbalance and the high speed cutter have same vibration properties. The vibration sources of the high speed cutter is proved to be unbalance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.233-237
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• 2014

In this paper, the finite element modeling of the RK4 rotor kit system (RK4) and then frequency analysis and transient analysis, and was compared with the actual experimental results. RK4 manufactured by General Electric for the purpose of education and research. It is composed of two shaft, Two shaft is connected using a flexible coupling, one disk is mounted. The analytical model is modeled by using the ANSYS finite element analysis program commercially available. Based on impact hammer test results, material properties and the stiffness of the bearing and coupling was tuned. Considering the operating conditions and the vibration response of the analytical model were compared with experimental results.

• 한국전산구조공학회논문집
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• 제19권3호
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• pp.295-302
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• 2006

본 논문은 자이로콥터의 유한요소 모델링과 로터의 회전에 의한 동하중을 고려한 전산진동해석을 수행하였다. 이를 위해 자이로콥터의 최종 조립된 3차원 CATIA 모델을 구축하였으며, 3차원 데이터를 바탕으로 비구조 질량을 포함한 구조진동해석을 위한 유한요소모델을 생성하였다. 실용적인 전산구조동역학 해석을 위해 상용 유한요소 해석프로그램인 MSC/NASTRAN과 자체 개발한 프로그램을 병용하여 사용하였다. 비행 중 회전하는 로터에 의해 발생하는 동하중은 상용 CFD 프로그램인 FLUENT를 이용하였다. 유체해석과 구조진동해석의 결합을 위해 자체적으로 통합 연계 시스템을 구축하였다. 3차원 구조의 효율적인 진동특성을 고찰하기 위해 모달영역에서 천이응답해석과 주파수응답해석을 수행하였다. 실제 자이로콥터의 연료조건과 비행조건을 고려하였으며, 전산해석을 통하여 고유진동, 주파수 응답 및 천이응답 특성을 고찰하였다.

• 한국기계가공학회지
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• 제19권10호
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• pp.87-97
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• 2020

In general, tires require various sensors and power supply devices, such as batteries, to obtain information such as pressure, temperature, acceleration, and the friction coefficient between the tire and the road in real time. However, these sensors have a size limitation because they are mounted on a tire, and their batteries have limited usability due to short replacement cycles, leading to additional replacement costs. Therefore, vibration energy harvesting technology, which converts the dynamic strain energy generated from the tire into electrical energy and then stores the energy in a power supply, is advantageous. In this study, the output voltage and power generated from piezoelectric elements are predicted through finite element analysis under static state and transient state conditions, taking into account the dynamic characteristics of tires. First, the tire and piezoelectric elements are created as a finite element model and then the natural frequency and mode shapes are identified through modal analysis. Next, in the static state, with the piezoelectric element attached to the inside of the tire, the voltage distribution at the contact surface between the tire and the road is examined. Lastly, in the transient state, with the tire rotating at the speeds of 30 km/h and 50 km/h, the output voltage and power characteristics of the piezoelectric elements attached to four locations inside the tire are evaluated.