• 제목/요약/키워드: Mechanical fault

검색결과 514건 처리시간 0.02초

A Fault Isolation Filter Design Using Left Eigenstructure Assignment Scheme

  • Choi, Jae-Weon;Lee, Shi-Bok;Lee, Dae-Young;Park, Un-Sik;Suh, Young-Soo
    • Journal of Mechanical Science and Technology
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    • 제14권6호
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    • pp.583-589
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    • 2000
  • This paper presents a novel fault isolation filter design method using left eigenstructure assignment scheme proposed by the first author et al. The proposed method shows good performance of fault isolation with an exact eigenstructure assignment and guarantees that the corrupted ${\gamma}$ faults can be isolated simultaneously when the number of available output measurements are equal to or larger than (${\gamma}+1$). A numerical example for the fault isolation filter is also included.

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연속 웨이블렛 변환의 확대된 위상 지도를 이용한 기어의 초기 퍼팅 결함 진단 (Fault Detection of a Gear with Initial Pitting using the Boomed Phase Map of Continuous Wavelet Transform)

  • 이상권;심장선
    • 대한기계학회논문집A
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    • 제25권11호
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    • pp.1759-1766
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    • 2001
  • Vibration transient generated by developing localized fault in gear can be used as indicators in gear fault detection. In this paper, we propose the zoomed phase map for a fault signal using continuous wavelet transfers to detect this vibration transient. Local fault induces the abrupt fluctuation of load exciting tooth and phase lag in the vibration signal measured on the gearbox. The relatively large fault like "tip breakage" easily can be detected by the clear fluctuation of exciting load. However, minor fault like "initial pitting"cannot be detected using the load fluctuation. To defect this kind of minor fault, the phase map for a fault signal is taken into account. The phase lag by minor fault is observed well in the zoomed phase map.

HMM/ANN복합 모델을 이용한 회전 블레이드의 결함 진단 (Fault Diagnosis of a Rotating Blade using HMM/ANN Hybrid Model)

  • 김종수;유홍희
    • 한국소음진동공학회논문집
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    • 제23권9호
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    • pp.814-822
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    • 2013
  • For the fault diagnosis of a mechanical system, pattern recognition methods have being used frequently in recent research. Hidden Markov model(HMM) and artificial neural network(ANN) are typical examples of pattern recognition methods employed for the fault diagnosis of a mechanical system. In this paper, a hybrid method that combines HMM and ANN for the fault diagnosis of a mechanical system is introduced. A rotating blade which is used for a wind turbine is employed for the fault diagnosis. Using the HMM/ANN hybrid model along with the numerical model of the rotating blade, the location and depth of a crack as well as its presence are identified. Also the effect of signal to noise ratio, crack location and crack size on the success rate of the identification is investigated.

흡수식 냉동시스템의 고장현상 분석과 진단 (Fault Symptom Analysis and Diagnosis for a Single-Effect Absorption Chiller)

  • 한동원;장영수;김용찬
    • 설비공학논문집
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    • 제27권11호
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    • pp.587-595
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    • 2015
  • In this study, fault symptoms were simulated and analyzed for a single-effect absorption chiller. The fault patterns of fault detection parameters were tabulated using the fault symptom simulation results. Fault detection and diagnosis by a process history-based method were performed for the in-situ experiment of a single-effect absorption chiller. Simulated fault modes for the in-situ experimental study are the decreases in cooling water and chilled water mass flow rates. Five no-fault reference models for fault detection of a single-effect absorption chiller were developed using fault-free steady-state data. A sensitivity analysis of fault detection using the normalized distance method was carried out with respect to fault progress. When mass flow rates of the cooling and chilled water decrease by more than 19.3% and 17.8%, respectively, the fault can be detected using the normalized distance method, and COP reductions are 6.8% and 4.7%, respectively, compared with normal operation performance. The pattern recognition method for fault diagnosis of a single-effect absorption chiller was found to indicate each failure mode accurately.

모델 기반 연료전지 스택 온도 센서 고장 감지 및 판별 (Model - Based Sensor Fault Detection and Isolation for a Fuel Cell in an Automotive Application)

  • 한재영;김영현;유상석
    • 대한기계학회논문집B
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    • 제41권11호
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    • pp.735-742
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    • 2017
  • 본 연구에서는 PEM 연료전지 온도 센서의 고장을 감지 및 판별할 수 있는 모델 기반 센서 고장 감지 방법이 적용된다. 연료전지 차량이 작동하는 과정에서 스택 온도는 연료전지의 내구성에 영향을 미친다. 따라서 고장 진단 알고리즘이 고장 신호를 감지하는 것은 중요하다. 센서 고장 감지의 주요 목적은 연료전지 시스템의 안정적인 작동을 보장하여 고온과 저온으로부터 스택을 보호하는 것이다. 상태 공간에 기반한 패러티 방정식이 스택 온도와 냉각수 입구 온도와 같은 센서 고장을 감지하는데 적용되며, 잔차는 정상적인 온도 신호와 비교된다. 그리고 잔차는 현재의 센서 고장을 감지하는 다양한 고장 시나리오에 의해 평가된다. 결론적으로, 본 연구에서 설계된 고장 알고리즘이 고장 신호를 감지할 수 있다.

원심펌프용 메커니컬 씰 결함 검출 신호 특성 (Fault Detection Signal for Mechanical Seal of Centrifugal Pump)

  • 정래혁;이병곤
    • 한국안전학회지
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    • 제27권3호
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    • pp.20-27
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    • 2012
  • Mechanical seals are one of main components of high speed centrifugal pumps. So, it is very important to detect the faults (scratch, notch, indentation, wear) of mechanical seals since the damage of seal can cause a critical failures or accidents of machinery system. In the past, many researchers mainly performed to detect the seal fault using the time signals measured from sensors. Recently, studies are focused on the development of on-line real time monitoring system. But study on the feature parameters used for fault detection of mechanical seals has a little been performed. In this paper, we showed feature parameters extracted from accelerated and acoustic signals by using the discrete wavelet transform (DWT), alpha coefficient, statistical parameters. And also verified the possibility for fault detection of mechanical seal.

Some Worthy Signal Processing Techniques for Mechanical Fault Diagnosis

  • Chan, Jin
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.39-52
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    • 2002
  • Research Direction The significant research direction in mechanical fault diagnosis area: Theorles and approaches for fault feature extracting and fault classification. Identification Complicated fault generating mechanism and its model Intelligent fault diagnosis system (including the expert system and network based remote diagnosis system) One of the Key Points: Fault feature extracting techniques based on (modern) signal processing(omitted)

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외란 억제 및 고장 분리를 위한 고유구조 지정기법 (Eigenstructure Assignment Method for Disturbance Suppression and Fault Isolation)

  • 서영봉;최재원
    • 제어로봇시스템학회논문지
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    • 제8권5호
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    • pp.357-362
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    • 2002
  • The underlying principle of fault detection via unknown input observer is to make the state estimation error independent of disturbances(or unknown inputs). In this paper, we present a systematic method that can exactly assign the eigenstructure with disturbance suppression and fault isolation capability. A desired eigenstructure for both fault isolation and disturbance suppression is obtained by an optimization method. For the dual purposes, terms for fault isolation and far disturbance suppression are included in the employed objective function for the optimization. The proposed scheme is applied to a simple example to confirm the usefulness of the method.

Mechanical Properties of Fault Rocks in Korea

  • Seo, Yong-Seok;Yun, Hyun-Seok;Ban, Jae-Doo;Lee, Chung-Ki
    • 지질공학
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    • 제26권4호
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    • pp.571-581
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    • 2016
  • To understand the mechanical properties of fault rocks, data from 584 in situ and laboratory tests on fault rocks from 33 tunnels were analyzed. The unit weights of the fault rocks range from 17.3 to $28.2kN/m^3$ and the cohesion and friction angles vary from 5 to 260 kPa and $14.7^{\circ}$ to $44.0^{\circ}$, respectively. The modulus of deformation and elasticity were generally < 200 MPa. In most cases, the uniaxial compressive strength was < 0.5 MPa, and Poisson's ratios were mainly 0.20-0.35. The mechanical properties of individual rock types were analyzed using box plots, revealing that the cohesion values and friction angles of shale and phyllite have relatively wide inter-quartile ranges and that the modulus of deformation and elasticity of shale have the lowest values of all rock types. In the analysis of mechanical properties by components of fault rocks, the largest values were shown in damage zones of individual rock types.

Torque Ripple Suppression Method for BLDCM Drive Based on Four-Switch Three-Phase Inverter

  • Pan, Lei;Sun, Hexu;Wang, Beibei;Su, Gang;Wang, Xiuli;Peng, Guili
    • Journal of Power Electronics
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    • 제15권4호
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    • pp.974-986
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    • 2015
  • A novel inverter fault-tolerant control scheme is proposed to drive brushless DC motor. A fault-tolerant inverter and its three fault-tolerant schemes (i.e., phase A fault-tolerant, phase B fault-tolerant, and phase C fault-tolerant) are analyzed. Eight voltage vectors are summarized and a voltage vector selection table is used in the control scheme to improve the midpoint current of the split capacitors. A stator flux observer is proposed. The observer can improve flux estimation, which does not require any speed adaptation mechanism and is immune to speed estimation error. Global stability of the flux observer is guaranteed by the Lyapunov stability analysis. A novel stator resistance estimator is incorporated into the sensorless drive to compensate for the effects of stator resistance variation. DC offset effects are mitigated by introducing an integral component in the observer gains. Finally, a control system based on the control scheme is established. Simulation and experiment results show that the method is correct and feasible.