• Smart Structures and Systems
• /
• 제21권6호
• /
• pp.761-776
• /
• 2018

Guided wave testing is a reliable and safe method for pipeline inspection. In general, guided wave testing employs a circumferential array of piezoelectric transducers to clamp on the pipe circumference. The sensitivity of the operation depends on many factors, including transducer distribution across the circumferential array. This paper presents the sensitivity analysis of transducer array for the circumferential characteristics of guided waves in a pipe using finite element modelling and experimental studies. Various cases are investigated for the outputs of guided waves in the numerical simulations, including the number of transducers per array, transducer excitation variability and variations in transducer spacing. The effect of the dimensions of simulated notches in the pipe is also investigated for different arrangements of the transducer array. The results from the finite element numerical simulations are then compared with the related experimental results. Results show that the numerical outputs agree well with the experimental data, and the guided wave mode T(0,1) presents high sensitivity to the notch size in the circumferential direction, but low sensitivity to the notch size in the axial direction.

• 한국압력기기공학회 논문집
• /
• 제6권1호
• /
• pp.78-82
• /
• 2010

The feeder pipe of Main Primary Heat Transfer System in Wolsong Nuclear Power Plant was inspected by the Ultrasonic Phase Array technique in 2010. It is the first time to apply this method to the construction at Nuclear Power Plant in Korea. The time required for UT technique is less than RT method. The UT method doesn't need to evacuate personnel who works nearby inspecting area and doesn't need to wait developing of film. For these reasons, the UT method is the fastest method among the volumetric inspections. As a result of the examination, it became clear that main defect of the feeder pipe is the Lack of fusion in the welded area. Moreover, the rate of defect was reduced gradually as improvement of welder's skill. If welding machine has problem, the defect has tended to same pattern(occurred same position in the welding area) but these defects were founded without specific rules. For these reasons, the creation of defect is dependent on the skill of worker not on the automatic welding machine. This evaluation of defect signal and collecting data would be useful to further examination in ISI.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
• /
• pp.15.1-15.1
• /
• 2005

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 추계학술대회 논문집
• /
• pp.237-238
• /
• 2006

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.789-790
• /
• 2008

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.769-770
• /
• 2008

• Earthquakes and Structures
• /
• 제19권4호
• /
• pp.303-313
• /
• 2020

Spacious experimental and numerical investigation has been conducted by researchers to increase the ductility and energy dissipation of concentrically braced frames. One of the most widely used strategies for increasing ductility and energy dissiption, is the use of energy-absorbing systems. In this regard, the cyclic behavior of a chevron bracing frame system equipped with multi-pipe dampers (CBF-MPD) was investigated through finite element method. The purpose of this study was to evaluate and improve the behavior of the CBF using MPDs. Three-dimensional models of the chevron brace frame were developed via nonlinear finite element method using ABAQUS software. Finite element models included the chevron brace frame and the chevron brace frame equipped with multi-pipe dampers. The chevron brace frame model was selected as the base model for comparing and evaluating the effects of multi-tube dampers. Finite element models were then analyzed under cyclic loading and nonlinear static methods. Validation of the results of the finite element method was performed against the test results. In parametric studies, the influence of the diameter parameter to the thickness (D/t) ratio of the pipe dampers was investigated. The results indicated that the shear capacity of the pipe damper has a significant influence on determining the bracing behavior. Also, the results show that the corresponding displacement with the maximum force in the CBF-MPD compared to the CBF, increased by an average of 2.72 equal. Also, the proper choice for the dimensions of the pipe dampers increased the ductility and energy absorption of the chevron brace frame.

• 생물환경조절학회지
• /
• 제4권1호
• /
• pp.17-24
• /
• 1995

본 연구는 파이프하우스의 구조적 안전성을 검토하는데 필요한 기초자료를 구축하기 위하여 실시하였다. 지반에 매입된 파이프의 지점상태를 검토하여 적합한 구조해석 모델을 찾고, 파이프를 말뚝기초로 가정했을 때의 파이프의 지지력 및 인발 저항력을 구하기 위하여 모형 실험을 실시하였으며, 그 결과를 요약하면 다음과 같다. 1. 파이프하우스의 지점상태를 검토해본 결과 단동 하우스에서는 수평 및 연직하중 모두 고정으로, 연동하우스에서는 수평하중 재하시 힌지, 연직 하중 재하시 고정으로 해석하는 것이 실험치에 더 가까운 것으로 나타났다. 2. 지반에 매입된 파이프의 인발저항력은 파이프 직경 및 매입깊이에 따라 논의 연한지반에서는 35-54kg, 밭의 보통지반에서는 61-98kg, 단단한 지반에서는 108-120kg이상으로 나타났으며, 파이프와 흙사이의 주변마찰력은 1.51-4.76t/$m^2$정도의 범위를 보였다. 3. 파이프 직경 및 매입깊이에 따른 기초 지지력은 연한지반의 경우 35-76kg, 보통지반은 88-158kg, 단단한 지반은 131-305kg의 범위를 보였으며, 파이프의 선단지지력은 연한지반 0-22kg, 단단한 지반 22-140kg으로 나타났다. 4. 국내에서 많이 보급되어 있는 대표적인 파이프하우스의 경우, 적설심 30cm 까지는 파이프의 매입깊이가 30cm이면 지지력이 충분하지만 그 이상의 적설심에서는 지반의 종류에 따라 매입깊이를 증가시켜야 하고, 인발저항의 경우도 풍속 30㎧까지는 매입깊이 30cm이면 충분하지만 그 이상의 풍속에 대하여는 매입깊이를 증가시키거나 보강이 필요한 것으로 나타났다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2007년도 춘계학술대회A
• /
• pp.1813-1817
• /
• 2007

The present work presents plastic limit load solutions for piping branch junctions with local wall-thinning, based on detailed three-dimensional (3-D) and small strain FE limit analyses using elastic-perfectly plastic materials. Three types of loading are considered; internal pressure, in-plane bending on the branch pipe and in-plane bending on the run pipe. The wall-tinning located on variable area of the piping branch junction is considered. A wide range of piping branch junction and wall-thinning geometries are considered. Comparison of the proposed solutions with FE results shows good agreement

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회A
• /
• pp.299-304
• /
• 2008

This paper presents plastic limit loads of piping branch junctions with local wall thinning under combined pressure and in-plane bending, based on systematic three-dimensional finite element limit analyses using elastic-perfectly plastic materials. An ideal branch junction without weld or reinforcement around the intersection is considered with two locations of wall thinning; one in the run pipe, and the other in the branch pipe. Based on FE results, effects of thinning geometries on plastic limit moments are quantified and simple approximations of plastic limit loads are proposed.