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도시철도차량 차축의 경량화를 위한 EN 규격 기반의 차축 응력 평가
한순우(SoonWoo Han),정현승(HyunSeung Jung) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
Stress analysis of urban railway axle, especially K-EMU, is discussed in this work to design lightweight hollow axle. Railway axle is one of the heaviest parts in railway car system and weight reducing of an axle should be considered in designing lightweight railway car system. EN standard, EN 13103 is referred to calculate stress of a T car axle of K-EMU and the process of stress analysis based on the EN standard is explained. It is verified that maximum stress of K-EMU axle is far below the maximum permissible strength of railway axles. The stress of a hollow axle having similar outer dimension and material with a T car axle of K-EMU is estimated and shows satisfactory result.
문성인,강토,한순우,Moon, Seongin,Kang, To,Han, Soonwoo 한국압력기기공학회 2018 한국압력기기공학회 논문집 Vol.14 No.1
For safe operation of nuclear power plants, a loose-part monitoring system (LPMS) is used to detect and locate loose-parts within the reactor coolant system, and to estimate their mass and damage potential. There are several methods to estimate mass, such as the center frequency method based on the Hertz's impact theory, a frequency ratio method and so on, but it is known that these methods cannot provide accurate information on impact response for identifying the impact source. Thanks to increasing computing power, finite element analysis (FEA) method recently become an available option to calculate reliably impact response behavior. In this paper, a finite element analysis model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, is validated by performing a series of impact tests and the corresponding finite element analyses for flat plate and shell structures. Also, a FEA-based metal sphere signal map is developed, and then blind tests are performed to verify the map. This study provides an accurate simulation method for predicting the metal impact behavior and for building a metal sphere signal map, which can be used to estimate the mass of loose-parts on site in nuclear power plants.
구조물 내 감육결함 탐지를 위한 유한요소해석 기반 유도초음파 모드 최적화
문성인(Seongin Moon),강토(To Kang),한순우(Soonwoo Han),전준영(Jun-Young Jeon),박규해(Gyuhae Park) 한국비파괴검사학회 2018 한국비파괴검사학회지 Vol.38 No.5
판형 구조물내에 존재하는 결함을 탐지하기 위한 레이저 영상화 기법은 최근 10여년간 꾸준히 연구되어 왔으며, 음향파수분광법(AWS: Acoustic Wavenumber Spectroscopy)은 그 대표적인 방법 중 하나이다. 본 논문에서는 유한요소해석(FEA: Finite Element Analysis) 기법을 사용하여 박판 구조물에서 감육결함 크기를 예측하기 위한 AWS의 성능을 기술하였다. FEA를 통해 단일주파수 가진에 대한 구조물의 정상상태응답을 계산하고, 파수 예측 정확도에 미치는 감육결함의 크기 효과를 평가하였다. A0 모드 유도초음파는 판 두께에 따라 파동의 속도가 변화하는 특성으로 인해 결함을 영상화하는데 널리 사용된다. 그러나 평판 두께가 상대적으로 클 경우에는 두께 변화에 대한 파동의 속도 변화율이 감소하기 때문에 상대적으로 얕은 감육결함을 검출하기에 적절하지 않다. 따라서, 본 논문에서는 가진 주파수와 유도초음파 모드를 최적화하는 방법을 제안하였으며, 그 방법의 유용성을 검증하였다. Laser imaging technology has been studied to detect defects in plate-like structures over ten years, and acoustic wavenumber spectroscopy (AWS) is one of the most promising methods. This paper describes the performance of AWS for estimating the size of a wall-thinning defect in thin-plate structures by using finite element analysis (FEA). The structure’s steady-state response to single-tone ultrasonic excitation is simulated using FEA, and the effect of the wall-thinning defect size on the wavenumber-estimation accuracy is investigated. The A0 guided wave mode has been widely used to observed defects owing to the characteristic that the wave speed increases with increasing plate thickness. However, it is not appropriate for detecting relatively shallow wall-thinning defects, because the rate of change in the wave speed variation with the thickness decreases with the increase in the plate thickness. To overcome this limitation, we propose a method to optimize the excitation frequency and the effective guided wave mode instead of utilizing the A0 mode. The results show that our proposed method is promising for the effective characterization of the size of shallow wall-thinning defects in plate-like structures.
레이져 바이브로미터 스캐너를 이용한 평판의 얕은 결함 측정
강토(To Kang),문성인(Seongin Moon),한순우(Soonwoo Han),전준영(Jun Young Jeon),박규해(Gyuhae Park) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
A scanning laser Doppler vibrometer (SLDV) is a promising method to visualize defects in plate like structures. Recently, Lamb wave-based SLDV using continuous excitation widely adopted in NDE applications. To visualize defects using Lamb wave-based SLDV, A<SUB>0</SUB> mode has been usually used due to its nature of wave speed varying according to the thickness and to easily generated attributes using PZT. However, rate of change of wave speed varying according to the thickness is little in thick materials. To resolve this problem, axisymmetric mode is selected due to high wavenumber sensitivity. To generate axisymmetric mode, IDT (Interdigital transducer) sensor is designed and fabricated based on wavenumber sensitivity calculation. To evaluate the capability of the IDT-based SLDV, a 6-mmthick plate (40 mm × 40 mm) with defects of different depths (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm) is used. It is demonstrated that the detectability of thin defects in a thick plate is improved compared to that when using the A<SUB>0</SUB> mode.
원전기기 금속이물질 충격현상 모사 및 빅데이터 생산을 위한 자동해석시스템 개발
문성인(Seongin Moon),강토(To Kang),한순우(Soonwoo Han) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
A loose-part monitoring system (LPMS) is used to detect loose-parts in the reactor coolant system in nuclear power plant. For identifying the impact source, it is important to provide accurate information on impact response. Recently, a model-based diagnostics emphasize the importance of a model describing the behaviors of a mechanical system or component. Also, thanks to increasing computing power, finite element analysis (FEA) method recently beaome an available option to calculate reliable impact response behavior. In this paper, a FEA model to simulate the propagation behavior of the bending wave, generated by a metal ball impact, is validated by performing impact tests and the corresponding finite element analyses for a flat plate and a downsized steam generator structure. A novel methodology based on FEA was proposed to estimate the mass and the impact location of a loose-part, and then the usefulness of the methodology was validated through a series of FEAs. Also, an automated impact analysis system for FEA-based big data construction was developed. It is expected that the proposed methodology and the big data can be utilized in model-based diagnostics for estimation of impact parameters such mass, velocity and impact location of a loose-part in nuclear power plants.