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유도초음파를 활용한 격납건물 라이너 플레이트 상시감시 모니터링 검사를 위한 토모그래피 영상화
박준필,조윤호,Park, Junpil,Cho, Younho 한국압력기기공학회 2020 한국압력기기공학회 논문집 Vol.16 No.2
Large-scale industrial facility structures continue to deteriorate due to the effects of operating and environmental conditions. The problems of these industrial facilities are potentially causing economic losses, environmental pollution, casualties, and national losses. Accordingly, in order to prevent disaster accidents of large structures in advance, the necessity of diagnosing structures using non-destructive inspection techniques is being highlighted. The defect occurrence, location and defect type of the structure are important parameters for predicting the remaining life of the structure, so continuous defect observation is very important. Recently, many researchers have been actively researching real-time monitoring technology to solve these problems. Structure Health Monitoring Inspection is a technology that can identify and respond to the occurrence of defects in real time, but there is a limit to check the degree of defects and the direction of growth of defects. In order to compensate for the shortcomings of these technologies, the importance of defect imaging techniques is emerging, and in order to find defects in large structures, a method of inspecting a wide range using guided ultrasonic is effective. The work presented here introduces a calculation for the shape factor for evaluation of the damaged area, as well as a variable β parameter technique to correct a damaged shape. Also, we perform research in modeling simulation and an experiment for comparison with a suggested inspection method and verify its validity. The curved structure image obtained by the advanced RAPID algorithm showed a good match between the defect area and the shape.
3D 프린터 출력물의 적층 두께에 따른 초음파 속도 상관관계 연구
최선호(Sunho Choi),박준필(Junpil Park),이재선(Jaesun Lee) 한국비파괴검사학회 2021 한국비파괴검사학회지 Vol.41 No.2
3D 프린터는 소재를 겹겹이 쌓아 올려 적층하는 방식으로 기존의 공작기계와 같은 절삭 방식 대비 저렴한 비용과 시간으로 정교하고 복잡한 제품을 생산할 수 있다. 3D 프린터의 발전으로 생산 제조 방식에 새로운 패러다임을 제시했으나 적층 제조품에 대한 신뢰성 평가 방법과 기준이 명확하지 않다. 본 논문에서는 SLA(Stereo Lithography Apparatus) 방식을 이용하여 ABS Resin 소재로 적층 두께 및 적층 조건에 따른 초음파 전파 특성 평가를 위한 시험편을 제작하였다. 이를 바탕으로 크기가 다른 임의의 결함을 추가한 결함 시편을 제작하여 3D 프린터 출력물에 초음파 기법을 이용한 비파괴 평가와 적층 조건에 따른 상관 관계에 대해 연구하였다. 적층 두께 1 ~ 4 mm 까지는 초음파 전파 시간이 급격하게 변화하는 것을 확인하였으며, 적층두께 6mm 초과 영역에서는 초음파 전파 속도가 오차범위로 수렴하는 것을 확인할 수 있다. 이러한 결과를 바탕으로 적층제조품의 상태 및 신뢰성 확보를 통해 산업현장으로 확대 적용할 수 있을 것이다. 3D printing is a method of stacking materials in layers, enabling the production of sophisticated and complex products at a lower cost while consuming a smaller amount of time compared to cutting methods such as those that employ conventional machine tools. The development of 3D printers has suggested a new paradigm for production and manufacturing methods; however, the method and criteria for structural diagnosis for additive manufacturing are unclear. In this study, a test piece for the evaluation of ultrasonic propagation characteristics according to the lamination thickness and lamination conditions was fabricated with ABS resin using the stereolithography apparatus (SLA) method. Based on this, a defect specimen was prepared with additional defects of different sizes; non-destructive evaluation of the 3D printer output was performed using an ultrasonic technique, and its correlation with the stacking conditions was studied. It was confirmed that the ultrasonic propagation time rapidly changes up to a stacking thickness of 1 to 4 mm, and it can be seen that the ultrasonic propagation speed converges to an error range in the region where stacking thickness exceeds 6 mm. Based on these results, it will be possible to expand the application of 3D printing to industrial sites by securing the state and reliability of the laminated product.