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defect inspection technologies for additive manufacturing

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International Journal of Extreme Manufacturing 2021年第2期3卷 23-43页

作者： Yao Chen Xing Peng Lingbao Kong Guangxi Dong Afaf Remani Richard Leach Shanghai Engineering Research Center of Ultra-precision Optical Manufacturing Department of Optical Science and EngineeringFudan UniversityShanghaiPeople’s Republic of China Manufacturing Metrology Team University of NottinghamNottinghamUnited Kingdom

Additive manufacturing(AM) technology is considered one of the most promising manufacturing technologies in the aerospace and defense industries. However, AM components are known to have various internal defects, such as powder agglomeration, balling, porosity,internal cracks and thermal/internal stress, which can significantly affect the quality, mechanical properties and safety of final parts. Therefore, defect inspection methods are important for reducing manufactured defects and improving the surface quality and mechanical properties of AM components. This paper describes defect inspection technologies and their applications in AM processes. The architecture of defects in AM processes is reviewed. Traditional defect detection technology and the surface defect detection methods based on deep learning are summarized, and future aspects are suggested.

关键词： additive manufacturing defect inspection machine learning deep learning neural network

Automatic defect inspection of Patterned FPC Board Based on 1-D Fourier Reconstruction

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Automatic Defect Inspection of Patterned FPC Board Based on ...

A new method for specular curved surface defect inspection based on reflected pattern integrity

第36届中国控制会议

作者： Juan Du Fang Chen Yue-Ming Hu School of Automation Science and Control Engineering South China University of Technology Engineering Research Centre for Precision Electronic Manufacturing Equipment of Ministry of Education South China University of Technology

ISBN: (纸本)9781538629185

In Recent years,flexible printed circuit boards（FPC） have been widely used in consumer electronic *** problem of automatic visual inspection of defects including pinholes,scratches and particles in FPC surfaces has been considered in this paper.A global 1-D Fourier based image reconstruction scheme that directly works on the 1-D line images instead of the traditional 2-D images is *** firstly eliminates the frequency components that represent the periodic pattern of a FPC line image in the 1-D Fourier spectrum,and then transforms the 1-D Fourier domain image to the 1-D spatial domain image based on the inverse Fourier *** Fourier reconstruction process can effectively remove the patterned background and distinctly preserve local anomalies in the resulting 1-D *** results on a number of microdefects embedded in FPC boards show that various ill-defined defects without designing and measuring the quantitative features of individual defect types can be reliably defected in this proposed method.

关键词： defect inspection FPC boards 1-D Fourier transforms Machine vision

来源： cnki会议评论

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Journal of Measurement Science and Instrumentation 2016年第3期7卷 221-228页

作者：姜美华付鲁华王仲宋宇航天津大学精密测试技术及仪器国家重点实验室天津300072

defect inspection of specular curved surface is a challenging job. Taking steel balls for example, a new method based on reflected pattern integrity recognition is put forward. The specular steel ball surface will totally reflect the patterns when it is placed inside a dome-shaped light source, whose inner wall is modified by patterns with certain regular. Distortion or intermittence of reflected pattern will occur at the defective part, which indicates the pattern has lost its integrity. Based on the integrity analysis of reflected pattern images？ surface defects can be revealed. In this paper, a set of concentric circles are used as the pattern and an image processing algorithm is customized to extract the surface defects. Results show that the proposed method is effective for the specular curved surface defect inspection

关键词： specularity curved surface defect inspection reflected pattern computer vision

Visual inspection of aircraft skin:Automated pixel-level defect detection by instance segmentation

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Chinese Journal of Aeronautics 2022年第10期35卷 254-264页

作者： Meng DING Boer WU Juan XU Abdul Nasser KASULE Hongfu ZUO College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 210016China Key Laboratory of Civil Aircraft Health Monitoring and Intelligent Maintenance of CAAC Nanjing 210016China

Skin defect inspection is one of the most significant tasks in the conventional process of aircraft *** paper proposes a vision-based method of pixel-level defect detection,which is based on the Mask Scoring ***,an attention mechanism and a feature fusion module are introduced,to improve feature ***,a new classifier head—consisting of four convolutional layers and a fully connected layer—is proposed,to reduce the influence of information around the area of the ***,to evaluate the proposed method,a dataset of aircraft skin defects was constructed,containing 276 images with a resolution of 960×720 *** results show that the proposed classifier head improves the detection and segmentation accuracy,for aircraft skin defect inspection,more effectively than the attention mechanism and feature fusion *** with the Mask R-CNN and Mask Scoring R-CNN,the proposed method increased the segmentation precision by approximately 21%and 19.59%,*** results demonstrate that the proposed method performs favorably against the other two methods of pixellevel aircraft skin defect detection.

关键词： Aircraft skin Automatic non-destructive testing defect inspection Instance segmentation Machine vision

inspection of pipeline girth welds with ultrasonic phased array technique

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High Technology Letters 2005年第3期11卷 240-244页

作者： Huang Jing（黄晶） Que Peiwen Jin Jianhua Institute of Automatic Detection Shanghai Jiaotong University Shanghai 200030 P.R. China

A novel automatic ultrasonic system used for the inspection of pipeline girth welds is developed, in which a linear phased array transducer using electronic scan is adopted. Optimal array parameters are determined based on a mathematical model of acoustic field for linear phased army derived from Huygens＇ principle. The testing method and the system structure are introduced. The experimental results show that the phased array transducer system has the same detectability as that of conventional ultrasonic transducer system, but the system architecture can be simplified greatly, and the testing flexibility and the testing speed can be improved greatly.

关键词： linear phased array transducer mathematical model of acoustic field pipeline girth welds defect inspection