• Title/Summary/Keyword: Weld Defects

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Development of Expert System for Diagnosis of Weld Defects (용접 결함 진단 전문가시스템의 개발)

  • 박주용
    • Journal of Advanced Marine Engineering and Technology
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    • v.20 no.1
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    • pp.13-23
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    • 1996
  • Weld defects degrade the strength and safety of astructure and are resulted from the various cases. The complexity of causal relation of weld defects requires an expert for the analysis of weld defects and the measures counter to them. An expert system has the intelligent functions such as the representation of knowledge and the inference. On this research, weld defect are systematically analysed and their causal model is developed. This information is saved to the knowledge base. The suitable inference algorithm for the diagnosis of weld defects is developed and realized with C++ programming.

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Construction of Through Transmission Scanning System for Weld Defects Detection of Rail Weld Zone (레일용접부의 용접결함검출을 위한 투과주사시스템의 구축)

  • Yun, In-Sik
    • Journal of the Korean Society of Safety
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    • v.20 no.1
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    • pp.30-35
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    • 2005
  • This study proposes construction of through transmission for weld defects detection of rail weld zone from ultrasonic signals. For these purposes, the ultrasonic signals for defects(porosity and crack) of weld zone in rails are acquired in the type of time series data and echo strength. 6 lines in the distance amplitude characteristics curve(DACC) indicated damage evaluation standard of weld zone in rails. The acquired ultrasonic signals agree flirty well with the mesured results of reference block and sensitivity block(defect location beam propagation distance, echo strength, etc). The proposed construction of through transmission in this study can be used for weld defects detection of rail weld zone.

A study on mathematical modeling and heat transfer analysis to predict weld bead geometry in horizontal fillet welding (수평필릿용접의 용접부 형상을 예측하기 위한 수학적 모델링 및 열전달 해석에 관한 연구)

  • 문형순;나석주
    • Journal of Welding and Joining
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    • v.14 no.6
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    • pp.58-67
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    • 1996
  • The horizontal filet welding is prevalently used in heavy and ship building industries to join the parts. The phenomena occurring in the horizonal fillet welding process are very complex and highly non-linear, so that its analysis is relatively difficult. Furthermore, various kinds of weld defect such as undercut, overlap, porosity. excess weld metal and incomplete penetration can be induced due to improper welding conditions. Among these defects, undercut, overlap and excess weld metal appear frequently in horizontal filet welding. To achieve a satisfactory weld bead geometry without weld defects, it is necessary to study the effect of welding conditions in the weld bead geometry. For analyzing the weld bead geometry with and without weld defects in horizontal fillet welding, a mathematical model was proposed in conjunction with a two-dimensional heat flow analysis adopted for computing the melting tone in . base metal. The reliability of the proposed model was evaluated through experiments. which showed that the proposed model was very effective for predicting the weld bead shape with or without weld defects in horizontal fillet welding.

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Fatigue Life Assessment of Steel Bridge Butt Joint Weld with Defects (강교량 맞대기용접 결함부의 피로수명 평가)

  • 백영남;장영권
    • Journal of Welding and Joining
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    • v.18 no.2
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    • pp.77-85
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    • 2000
  • There are many weld defects such as surface crack, lack of fusion, and incomplete penetration (IP) in the butt joint weld of existing steel bridges. The crack-like defects may significantly reduce the fatigue life of the structure. This paper presents the procedure and the results of the fatigue life assessment of the butt joints with weld defects in the existing steel girder bridge. The butt joint welds with incomplete penetration were instrumented with strain gages to determine the stress histogram under normal traffic. Based on the measured stress histogram the crack propagation analysis were performed for the fatigue life assessment. By using the suggested procedure and methodology, one can decide the time of periodic inspection and the necessity of repair of the butt joint welds with serious weld defects in the existing steel bridge.

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An Image Processing Algorithm for a Visual Weld Defects Detection on Weld Joint in Steel Structure (강구조물 용접이음부 외부결함의 자동검출 알고리즘)

  • Seo, Won Chan;Lee, Dong Uk
    • Journal of Korean Society of Steel Construction
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    • v.11 no.1
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    • pp.1-11
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    • 1999
  • The aim of this study is to construct a machine vision monitoring system for an automatic visual inspection of weld joint in steel structure. An image processing algorithm for a visual weld defects detection on weld bead is developed using the intensity image. An optic system for getting four intensity images was set as a fixed camera position and four different illumination directions. The input images were thresholded and segmented after a suitable preprocessing and the features of each region were defined and calculated. The features were used in the detection and the classification of the visual weld defects. It is confirmed that the developed algorithm can detect weld defects that could not be detected by previously developed techniques. The recognized results were evaluated and compared to expert inspectors' results.

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A study on the Estimate of Weld Bead Shape and the Compensation of Welding Parameters by Considering Weld Defects in Horizontal Fillet Welding (수평필릿용접시 용접부형상의 예측과 용접결함발생시 적절한 용접변수의 보상에 관한연구)

  • 김관형;이상배
    • Journal of the Korean Institute of Navigation
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    • v.23 no.4
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    • pp.105-114
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    • 1999
  • Generally, though we use the vision sensor or arc sensor in welding process, it is difficult to define the welding parameters which can be applied to the weld quality control. Especially, the important Parameters is Arc Voltage, Welding Current, Welding Speed in arc welding process and they affect the decision of weld bead shape, the stability of welding process and the decision of weld quality. Therefore, it is difficult to determine the unique relationship between the weld bead geometry and the combination of various welding condition. Due to the various difficulties as mentioned, we intend to use Fuzzy Logic and Neural Network to solve these problems. Therefore, the combination of Fuzzy Logic and Neural network has an effect on removing the weld defects, improving the weld quality and turning the desired weld bead shape. Finally, this system can be used under what kind of welding recess adequately and help us make an estimate of the weld bead shape and remove the weld defects.

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The Development of Automatic Inspection System for Flaw Detection in Welding Pipe (배관용접부 결함검사 자동화 시스템 개발)

  • Yoon Sung-Un;Song Kyung-Seok;Cha Yong-Hun;Kim Jae-Yeol
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.2
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    • pp.87-92
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    • 2006
  • This paper supplements shortcoming of radioactivity check by detecting defect of SWP weld zone using ultrasonic wave. Manufacture 2 stage robot detection systems that can follow weld bead of SWP by method to detect weld defects of SWP that shape of weld bead is complex for this as quantitative. Also, through signal processing ultrasonic wave defect signal system of GUI environment that can grasp easily existence availability of defect because do videotex compose. Ultrasonic wave signal of weld defects develops artificial intelligence style sightseeing system to enhance pattern recognition of weld defects and the classification rate using neural net. Classification of weld defects that do fan Planar defect and that do volume defect of by classify.

Monotoring Secheme of Laser Welding Interior Defects Using Neural Network (신경회로망을 이용한 레이저 용접 내부결함 모니터링 방법)

  • 손중수;이경돈;박상봉
    • Laser Solutions
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    • v.2 no.3
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    • pp.19-31
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    • 1999
  • This paper introduces the monitoring scheme of laser welding quality using neural network. The developed monitoring scheme detects light signal emitting from plasma formed above the weld pool with optic sensor and DSP-based signal processor, and analyzes to give a guidance about the weld quality. It can automatically detect defects of laser weld and further give an information about what kind of defects it is, specially partial penetration and porosity among the interior defects. Those could be detected only by naked eyes or X-ray after welding, which needs more processes and costs in mass production. The monitoring scheme extracts four feature vectors from signal processing results of optical measuring data. In order to classify pattern for extracted feature vectors and to decide defects, it uses single-layer neural network with perceptron learning. The monitoring result using only the first feature vector shows confidence rate in recognition of 90%($\pm$5) and decides whether normal status or defects status in real time.

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A Study on the Feature Extraction of Pattern Recognition for Weld Defects Evaluation of Titanium Weld Zone (티타늄 용접부의 용접결함평가를 위한 형상인식 특징추출에 관한 연구)

  • Yun, In-Sik
    • Journal of the Korean Society of Safety
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    • v.26 no.5
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    • pp.17-22
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    • 2011
  • This study proposes feature extraction method of pattern recognition by evaluation of weld defects in weld zone of titanium. For this purpose, analysis objectives in this study are features of attractor quadrant and fractal dimension. Trajectory changes in the attractor indicated a substantial difference in fractal characteristics resulting from distance shifts such as porosity of weld zone. These differences in characteristics of weld defects enables the evaluation of unique characteristics of defects in the weld zone. In quantitative fractal feature extraction, feature values of 0.87 and 1.00 in the case of part of 0.5 skip distance and 0.72 and 0.93 in the case of part of 1.0 skip distance were proposed on the basis of fractal dimensions. Attractor quadrant point, feature values of 1.322 and 1.172 in the case of ${\phi}1{\times}3mm$ porosity and 2.264 and 307 in the case of ${\phi}3{\times}3mm$ porosity were proposed on the basis of distribution value. The Proposed feature extraction of pattern recognition in this study can be used for safety evaluation of weld zone in titanium.

Study on the Simultaneous Control of the Seam tracking and Leg Length in a Horizontal Fillet Welding Part 1: Analysis and Measurement of the Weld Bend Geometry

  • Moon, H.S.;Na, S.J.
    • International Journal of Korean Welding Society
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    • v.1 no.1
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    • pp.23-30
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    • 2001
  • Among the various welding conditions, the welding current that is inversely proportional to the tip-to-work-piece distance is an essential parameter as to monitor the GMAW process and to implement the welding automation. Considering the weld pool surface geometry including weld defects, it should modify the signal processing method for automatic seam tracking in horizontal fillet welding. To meet the above necessities, a mathematical model related with the weld pool geometry was proposed as in a conjunction with the two-dimensional heat flow analysis of the horizontal fillet welding. The signal processing method based on the artificial neural network (Adaptive Resonance Theory) was proposed for discriminating the sound weld pool surface from that with the weld defects. The reliability of the numerical model and the signal processing method proposed were evaluated through the experiments of which showed that they are effective for predicting the weld bead shape with or without the weld defects in a horizontal fillet welding.

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