• Title/Summary/Keyword: resonance excitation

Search Result 333, Processing Time 0.055 seconds

A Study on Dynamic Stiffness of Inspection Robot Frame Considering Sub-span Oscillation (서브스판 진동을 고려한 송전선로 검사로봇 프레임 구조 설계에 관한 연구)

  • Kim, Moon Young;Lee, Jun Young;Lee, Taikjin;Yim, Hong Jae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.10a
    • /
    • pp.827-829
    • /
    • 2014
  • This paper presents a design methodology for improving dynamic stiffness of an inspection robot frame to prevent resonance. Finite element models of robot frame are developed for natural frequency analysis. Natural frequency analysis of robot frame is conducted to compare with sub-span oscillation which is excitation frequency. Reinforcement beams are applied to the sensitive parts of the robot frame to improve dynamic stiffness using case study. To reduce mass of the robot frame, thickness optimization of the robot frame is carried out by utilizing response surface method. The result of optimization show that dynamic stiffness of robot frame is increased. As a result, natural frequency of an optimal model is not included in range of frequencies of the sub-span oscillation.

  • PDF

Elastic modulus measurement of thin films using laser generated guided ultrasonic waves (레이저 초음파 기법을 이용한 박막 탄성계수 측정)

  • Cho, Seung Hyun;Heo, Taehoon;Ji, Bonggyu;Ahn, Bongyoung;Jang, Gang-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2014.10a
    • /
    • pp.550-554
    • /
    • 2014
  • Regarding thin films in MEMS/NEMS structures, the exact evaluation of mechanical properties is very essential to enhance the reliability of their design and manufacturing. However, such methods as a tensile test and a resonance test, general methods to measure elastic moduli, cannot be applied to thin films since its thickness is so small. This work concerns guided wave based elastic modulus measurement method. To this end, guided wave excitation and detection system using a pulsed laser and a laser interferometry has been established. Also an elastic modulus extraction algorithm from the measured guided wave signal was developed. Finally, it was applied to actual thin film structures such as Ni-Si and Al-Si multilayers. From experimental results, we confirm that the proposed method has considerable feasibility to measure elastic properties of thin films.

  • PDF

A Coupled Vibration Analysis of Railway Track System with Consideration of Contact Stiffness (접촉강성을 고려한 차량-레일계의 연성진동해석)

  • 류윤선;조희복;김사수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 1997.04a
    • /
    • pp.241-246
    • /
    • 1997
  • Corrugation of railway track can be caused by the various dynamic behaviors of traveling wheels and track. In this paper, the coupled vibrations of traveling wheel and railway track are analyzed as the cause of corrugations. To analyze the coupled vibration, the track supported by the sleepers and the traveling wheels are identified to the elastically supported infinite beam and the spring-mass system which runs at constant speed. The Hertzian contact spring is considered between the infinite beam and spring-mass system. The dynamic responses of elastically supported infinite beam and spring-mass system are calculated. The cause and development of rail corrugation are discussed in the view point of contact force fluctuation affected by the elastic supports and the corrugated surface profile on the track. By the obtained results, the possibilities of resonance are checked between the excitation by the corrugated surface profile and the natural frequency of contact spring-mass system. It may be thought to a development of railway corrugation.

  • PDF

Vibration Reduction of Reciprocating Compressor (왕복동식 컴프레셔의 진동 저감 사례)

  • Chae, Sang Il;Kim, Byoung Su;Lim, Woo Seop;Yang, Bo Suk
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • 2012.10a
    • /
    • pp.779-783
    • /
    • 2012
  • The gas compressor is one of the important machine in the petrochemical industry. It is likely to have high vibration problems due to having large reaction source and structural characteristic. In this paper we analyze the cause of high vibration in the reciprocating compressor and present a solution to this problems. By performing this case study, we confirm the effectiveness of vibration reduction through excitation source changes.

  • PDF

Relationship between Magnetic Properties of YIG Ferrites and Intermodulation Characteristics of Microwave Isolators

  • Nukaga, Masako;Henmi, Sakae
    • The Korean Journal of Ceramics
    • /
    • v.6 no.3
    • /
    • pp.300-303
    • /
    • 2000
  • The generation of the intermodulation noises in microwave isolators has been studied in relation to the characteristics of YIG ferrites designed for this application. We have investigated the influences of porosity and crystalline anisotropy related to the magnetic loss, which causes the generation of intermodulation signals. The power dependence of the intermodulation power level is stressed as the crystalline anisotropy decreases. These results are consistent with the nonlinear effects of a single normal mode before the excitation of the spin-waves. It also appears that this power level is proportional to the magnitude of dc bias magnetic field.

  • PDF

Design Modification of Bearing Walkout of Water Pump by a Finite Element Analysis (유한요소해석을 이용한 워터펌프 베어링돌출 설계 개선)

  • Yang, Chull-Ho;Han, Moon-Sik
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.14 no.3
    • /
    • pp.164-169
    • /
    • 2006
  • A systematic methodology has been proposed to establish a reliable design of water pump system. A simplified steady-state dynamic model of water pump system has been developed to study the response of water pump system to the dynamic load mainly due to the run-out and unbalance. Design modifications are needed to strengthen the structural integrity of existing designs. Increasing the natural frequency of system is pursued to prevent a resonance from occurring in the engine excitation range. A computational reliability methodology combined with finite element analysis is used to identify the most significant factor affecting the system performance. This method considered influence of design control parameters for the performance of design. By including control factors to the system model in a systematic way, more reliable design is expected.

Avidin Induced Silver Aggregation for SERS-based Bioassay

  • Sa, Youngjo;Chen, Lei;Jung, Young Mee
    • Bulletin of the Korean Chemical Society
    • /
    • v.33 no.11
    • /
    • pp.3681-3685
    • /
    • 2012
  • We developed a simple and effective method for the SERS-based detection of protein-small molecule complexes and label-free proteins using avidin-induced silver aggregation. Upon excitation with light of the appropriate wavelength (633 and 532 nm), the aggregated silver nanoparticles generate a strong electric field that couples with the resonance of the molecules (atto610 and cytochrome c), increasing the characteristic signals of these molecules and resulting in sensitive detection. The detection limit of biotin with the proposed method is as low as 48 ng/mL. The most important aspect of this method is the induction of silver aggregation by a protein (avidin), which makes the silver more biocompatible. This technique is very useful for the detection of protein-small molecule complexes.

The Field of Power/Ground Planes influenced by the HPEM Source, and its Damage Reduction

  • Kahng, Sung-Tek;Kim, Hyeong-Seok
    • Journal of Electrical Engineering and Technology
    • /
    • v.7 no.3
    • /
    • pp.406-410
    • /
    • 2012
  • This paper looks into the field inside the wide rectangular box structure that is excited by the High Power Electromagnetic(HPEM) source as a potential threat to electric grid and communication networks causing malfunction or destruction. The rectangular box is assumed power/ground planes and its internal field is calculated by the cavity model with the lightning strike excitation as an HPEM pulse. The accuracy of the calculation method employed here is validated through a $156mm{\times}106mm{\times}508{\mu}m$ parallel metallic plate case which is manufactured and tested, and is applied to the size of a building. With the help of the cavity model that takes into account loading, the level of the electric field is shown to decrease when a metal pillar is loaded between the power and ground planes.

Dynamic response of empty steel tanks with dome roof under vertical base motion

  • Virella, Juan C.;Godoy, Luis A.
    • Steel and Composite Structures
    • /
    • v.9 no.2
    • /
    • pp.119-130
    • /
    • 2009
  • This paper reports results of the structural response of empty steel tanks under vertical ground motions. The tanks are modeled using a finite element discretization using shell elements, and the vertical motion is applied and analyzed using nonlinear dynamics. Several excitation frequencies are considered, with emphasis on those that may lead to resonance of the roof. The computational results illustrate that as the base motion frequency is tuned with the frequency of the first roof-mode of the tank, the system displays large-amplitude displacements. For frequencies away from such mode, small amplitude displacements are obtained. The effect of the height of the cylinder on the dynamic response of the tank to vertical ground motion has also been investigated. The vertical acceleration of the ground motion that induces significant changes in the stiffness of the tank was found to be almost constant regardless of the height of the cylinder.

Vibration Control of Engine Body for Two Stroke Low Speed Diesel Engine using Dynamic Vibration Absorber (동흡진기에 의한 저속 2행정 디젤엔진의 본체진동 제어)

  • 이돈출;유정대;김정렬
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.26 no.6
    • /
    • pp.631-637
    • /
    • 2002
  • Two stroke low speed diesel engines are used as a power supplier not only for marine vessel but also diesel power plant with a benefit of its higher mobility and durability than the other thermal engines. However, there are some disadvantages such as the bigger vibrating excitation forces generated by high combustion pressure in cylinders which various kinds of vibrations are caused. In this paper, it is theoretically studied to control engine body vibration using dynamic vibration absorber. As an actual case, dynamic absorbers are designed for controlling X-mode vibration of 9K80MC-S engine on the diesel power plant and its performance is identified by the vibration test both in shop and site