전열관 비파괴검사를 위한 실린더형 자기카메라 개발

Metadata Downloads
Issued Date
The initiation and propagation of degradation, corrosion, and fatigue can directly damage megastructures such as nuclear/thermal power plants, aging aircraft, petrochemical structures, manned space stations, and rocket engines, as well as microstructures such as IC (Integrated Circuit) packages and VLSI (Very Large Scale Integration) chips. This can endanger human life and cause additional economic losses, environmental pollution, and a decrease in national status. If such damage is discovered early and steps are taken to repair or replace the damaged parts, the systems can be used safely until the end of the designed life cycle. In addition, life cycles can be extended by studying damage tolerance.
Damage initiation and propagation are classified as that occurring (1) in the manufacturing stage or (2) operating stage. The damage could be detected in a pre-service inspection (PSI) or in-service inspection (ISI), respectively, followed by recovery.
Nondestructive testing and evaluation (NDT&E), which investigates the existence, location, size, shape, and distribution of damage during the PSI and ISI, requires new technologies with higher speeds and smaller crack detection without needing to clean the specimen or make contact. NDT&E also requires a quantitative evaluation algorithm and database. Additionally, the ability to detect smaller cracks results in (1) inspection results with high reliability, (2) the detection of unexpected small damage, and (3) economic benefits resulting from the long time between inspections (reduction of fees, workers, and outage time during frequent periodic inspections).
Although eddy current testing (ECT) is used to evaluate the safety of megastructures such as nuclear and thermal power plants, aircraft, spacecraft, steel-manufactured items, automobiles, and ships, ECT has some disadvantages such as signal analysis difficulty and difficulty differentiating between cracks and volumetric flaws. In particular, a heat exchanger tube (HET) in a nuclear power plant consists of a paramagnetic or ferromagnetic material, or a mixture of the two, with constitutional changes. Thus, it is difficult to evaluate with ECT. In addition, ECT could misread a local magnetization area as a flaw, or attribute a large crack to local magnetization. Therefore, there is a need for imaging technology to obtain the leakage flux or eddy current distribution inside the HET.
In this research, a cylinder-type magnetic camera and two small-bore pipe specimens were manufactured. One of these specimens was made of a copper alloy (Cu 90%, Ni 10%) and the other was composed of austenite stainless steel (STS 304). Both specimens contained artificial flaws that were tested using the magnetic camera. The cylinder-type magnetic camera had a 32 × 32 Hall sensor array, high-pass filter (HPF) with a 284 Hz cutoff frequency, differential amplifier (60 dB), root-mean-square circuit, remotely controlled DC/AC power supply, switching circuit, and USB-type National Instruments data acquisition system (NI-DAQ). The eddy current distribution in a small-bore pipe was imaged using customized software. It also contained an automatic flaw detection and position detection system, and quantitative evaluation was possible using the software.
Alternative Title
Development of Cylinder-type Magnetic Camera for Nondestructive Testing of Heating Exchanger
Alternative Author(s)
Kang, Bugyun
조선대학교 대학원
일반대학원 제어계측공학
Awarded Date
Table Of Contents
제1장 서 론 1
제2장 이론적 고찰 11
제1절 와전류탐상 11
제2절 유한요소 수치해석 17
제3장 실린더형 자기카메라 검사 시스템 26
제1절 센서 배열 26
제2절 전원부 29
1. 원격제어 전원부 29
2. 스위칭 회로 32
제3절 신호처리부 37
제4절 소프트웨어 40
1. 운용소프트웨어 40
2. 해석소프트웨어 42
3. 자동평가 소프트웨어 45
제4장 실험 및 고찰 52
제1절 구리 합금(Cu 90%, Ni 10%) 전열관 52
1. 시험편 52
2. 스캔모드 실험결과 53
3. 실시간모드 실험결과 56
4. 정량평가 57
제2절 오스테나이트계 스테인리스강(STS 304) 전열관 59
1. 시험편 59
2. 실시간모드 실험결과 63
3. 정량평가 64
제5장 결 론 66
조선대학교 대학원
강부균. (2016). 전열관 비파괴검사를 위한 실린더형 자기카메라 개발.
Appears in Collections:
General Graduate School > 3. Theses(Master)
Authorize & License
  • AuthorizeOpen
  • Embargo2017-02-21
Files in This Item:

Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.