Lamb파를 이용한 레이저 용접부의 비접촉 비파괴 검사

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),최철준(Choul-jun Choi) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.9

This paper aims to study that the defect exploration method to specimen's thickness, using an characteristic of an ultrasonic wave generating in ablation area and thermo elasticity area, has been applied to using a way of receiving it by Air-Coupled Transducer and transmitting it by an ultrasonic wave and a way of noncontact receiving and transmitting ultrasonic wave using a laser. The longitudinal, transverse waves have been used in 60㎜ thickness specimen and Lamb wave in 3㎜ to run artificial defect detection test. In this way, the usefulness of noncontact laser ultrasonic wave has been verified To confirm the possibility of implementation on natural defect existing at real welding part, thickness in 3㎜ SM45C and STS304 artificial defect specimen has been made and defect detection test using Lamb wave has been executed. Detected signal by signal treatment has been expressed in visual not RF signal. By doing so the convenience of defect detection has been attempted and the effectiveness of defect signal visualization using Lamb wave has been confirmed compare with defect image through SAT.

기계 구조물의 안정성 평가를 위한 레이저 초음파법 적용

김재열(jae-yeol Kim),송경석(kyung-seok Song),김창현(chang-hyun Kim),고명수(myung-soo Ko) 한국생산제조학회 2003 한국생산제조시스템학회 학술발표대회 논문집 Vol.2003 No.10

구조물의 비접촉 비파괴 검사를 위한 레이저 초음파법 적용

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),양동조(Dong-Jo Yang),김유홍(You-Hong Kim) 한국생산제조학회 2005 한국생산제조시스템학회 학술발표대회 논문집 Vol.2005 No.5

The defects evaluation of the interior and the surface would be considered as vital characteristics in predicting the total life span of the steel structure. More importantly, the understandings in the interior composite of welding zone and the notifications in the presence, the formation, and the positioning of the non-metallic inclusion are necessary as well, since there were signs of relatively high defect frequency presented in the welding zone. The ultrasonic testing is a highly recommended technique chosen from among other techniques because of variety of advantages in conducting the non-destructive testing for the welding zone. However, the ultrasonic testing had technical disadvantages referred as followings; the problems due to the couplant between the PZT and the specimen, the formations that were miniature and complex, the moving subject, and the high temperature surrounding the specimen. This research was conducted to resolve the technical disadvantages of the contact ultrasonic testing by studying the non-contact ultrasonic testing where the ultrasonic waves were transferred by the laser, and revealing the specimen defects at its interior part and its surface part. The ultimate goal of this research was to develop a non-destructive evaluation applying the laser manipulated ultrasonic method for the steel structure.

레이저 유도 초음파를 이용한 재료평가 및 비파괴 검사 시스템 개발에 관한 연구

김재열(Jeal-Yel Kim),송경석(Kyung-Seok Song),김창현(Chang-Hyun Kim),김유홍(Yoo-Hong Kim) 한국생산제조학회 2004 한국생산제조시스템학회 학술발표대회 논문집 Vol.2004 No.10

In the present study, a Nd;YAG Laser (pulse type) was used to emit ultrasonic signals to a test material. In addition, a total ultrasonic investigation system was designed by adopting a Fabry-Perot interferometer, which receives ultrasonic signals without any contact. For non-destructive test SM45C, which contains some flaws was used as a test material. Because it is easy to align light beam in receiver, and the length of the light beam does not change much even if convex mirror leans towards one side, confocal Fabry-Perot interferometer, which has stable frequency, and PI control are used to correct interfered and unstable signals from temperature, fluctuation and time shift of laser frequency. Stable signals are always obtained by the feedback of PI circuit signals in the confocal Fabry-Perot interferometer. The type, size and position of flaws inside the test material were examined by achieving the stabilization of an interferometer. This study presented a useful method, which could quantitatively investigate the fault of objects by using a Fabry-Perot interferometer.

마이켈슨 간섭계를 이용한 초정밀가공기의 나노변위 측정에 관한연구

박대광(Dae-Kwang Park),송경석(Kyung-seok Song),김재열(Jae-Yeol Kim),곽남수(Nam-su Kwak) 한국생산제조학회 2009 한국생산제조시스템학회 학술발표대회 논문집 Vol.2009 No.10

Generally, the development of a laser interferometer to measure micro displacement for a micro system. The fibre optic laser encoder system was designed such a way which enabled measurement for the displacement of the high precision and the positional control. The laser interferometer is able to measure micro displacement during a few Nano seconds of non-contact. In order to retrieve a correct displacement information, the fibre optic laser encoder system and the environmental compensation unit was capable of compensating for the air reflective index and the temperature. The measuring environment would largely affect the measuring results. The measuring environment mainly consisted of the vibration and the air drift, and the temperature. In order to evaluate the environmental effect, the deviation of the light interference signal was coincided with the temperature while the optical system was maintained stay put and the vibration and the air drift were in the shielded condition. This Paper focuses on the influence to the position information of the system under temperature variation and without/with considering environmental error compensation and stability of frequency in the laser encoder.

적외선 카메라를 이용한 용접부 안전성 평가에 관한 연구

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),최철준(Choul-Jun Choi),김훈조(Hoon-Jo Kim) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-

RT and UT are largely used as a non-destructive assessment of welding defects. RT shows difficulty in radioactive exposure and real-time detection. UT shows difficulty in quantitative detection of defects, and examination of a wide area in a short time. In order to settle the aforementioned disadvantages, many researchers try to find solution. In this paper, we apply a new examination method to verify the effectiveness in order to supplement the disadvantages of UT and RT, the existing non-destructive methods. The new method proposed in this paper is to use a difference in heat conductivity. If there is a discontinuous part, that is an internal defect, there is a difference in heat conductivity. Using this fact, it is possible to check the existence of an internal defect due to a temperature difference on the part with a defect and the part without a defect when the welded part is heated. The temperature difference on the surface indicated by the difference in heat conductivity can be checked for a wide area within a short time, by means of a thermal image camera thereby to settle the disadvantage of the conventional non-destructive inspection methods. The thermal image method, however, has a disadvantage in that thermal load must be given to the tested sample and it is difficult to quantify measured data. In order to overcome this disadvantage, we will describe preliminary test and the like for applying thermal load on the tested sample including a welding defect, photographing images by means of a thermal image camera, analyzing thermal images, and analyzing welding defects.

초음파 결함신호 영상화를 이용한 레이저 용접부 비파괴 평가

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),한재호(Jae-Ho Han),김훈조(Hun-Cho Kim) 한국생산제조학회 2006 한국생산제조시스템학회 학술발표대회 논문집 Vol.2006 No.5

This paper aims to study that the defect exploration method to specimen's thickness, using an characteristic of an ultrasonic wave generating in ablation area and thermo elasticity area, has been applied to using a way of receiving it by Air-Coupled Transducer and transmitting it by an ultrasonic wave and a way of noncontact receiving and transmitting ultrasonic wave using a laser. The longitudinal, transverse waves have been used in 60㎜ thickness specimen and Lamb wave in 3㎜ to run artificial defect detection test. In this way, the usefulness of noncontact laser ultrasonic wave has been verified. To confirm the possibility of implementation on natural defect existing at real welding part, thickness in 3㎜ SM45C and STS304 artificial defect specimen has been made and defect detection test using Lamb wave has been executed. Detected signal by signal treatment has been expressed in visual not RF signal. By doing so the convenience of defect detection has been attempted and the effectiveness of defect signal visualization using Lamb wave has been confirmed compare with defect image through SAT.

구조물의 비접촉 비파괴 검사를 위한 레이저 초음파법 적용

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),양동조(Dong-Jo Yang) 한국생산제조학회 2005 한국생산제조학회지 Vol.14 No.4

Measuring defects on the inside and on the surface of a steel structure is very important technology in order to predict the life span of the structure. In particular, a place with a high probability that it may contain defects is a welded part and it is very important to check defects in the part, absence/presence of non-uniform substances, its shape, and the location. Many non-destructive tests can be applied, but the ultrasonic flow detection test is widely used with some advantages. The ultrasonic flow detection test, however, cannot be applied when there is a problem by a contact medium between PZT and a specimen, in case of a small and complicated shape or a moving object or when the specimen is hot. In this study, to solve the problems of the contact ultrasonic flow detection test, the non-contact ultrasonic flow detection test for sending/receiving ultrasonic waves using lasers was described. I intended to develop a non-destructive detection system applying the laser application ultrasonic test to a steel structure by detecting the defects inside of and on the surface of the specimen.

마이켈슨 간섭계를 이용한 초정밀가공기의 나노변위 측정에 관한연구

박대광(Dae-Kwang Park),송경석(Kyung-seok Song),김재열(Jae-Yeol Kim),곽남수(Nam-su Kwak) 한국생산제조학회 2009 한국공작기계학회 추계학술대회논문집 Vol.2009 No.-

Generally, the development of a laser interferometer to measure micro displacement for a micro system. The fibre optic laser encoder system was designed such a way which enabled measurement for the displacement of the high precision and the positional control. The laser interferometer is able to measure micro displacement during a few Nano seconds of non-contact. In order to retrieve a correct displacement information, the fibre optic laser encoder system and the environmental compensation unit was capable of compensating for the air reflective index and the temperature. The measuring environment would largely affect the measuring results. The measuring environment mainly consisted of the vibration and the air drift, and the temperature. In order to evaluate the environmental effect, the deviation of the light interference signal was coincided with the temperature while the optical system was maintained stay put and the vibration and the air drift were in the shielded condition. This Paper focuses on the influence to the position information of the system under temperature variation and without/with considering environmental error compensation and stability of frequency in the laser encoder.

적외선 카메라를 이용한 용접부 안전성 평가에 관한 연구

김재열(Jae-Yeal Kim),송경석(Kyung-Seok Song),최철준(Choul-Jun Choi),김훈조(Hoon-Jo Kim) 한국생산제조학회 2006 한국생산제조시스템학회 학술발표대회 논문집 Vol.2006 No.5

RT and UT are largely used as a non-destructive assessment of welding defects. RT shows difficulty in radioactive exposure and real-time detection. UT shows difficulty in quantitative detection of defects, and examination of a wide area in a short time. In order to settle the aforementioned disadvantages, many researchers try to find solution. In this paper, we apply a new examination method to verify the effectiveness in order to supplement the disadvantages of UT and RT, the existing non-destructive methods. The new method proposed in this paper is to use a difference in heat conductivity. If there is a discontinuous part, that is an internal defect, there is a difference in heat conductivity. Using this fact, it is possible to check the existence of an internal defect due to a temperature difference on the part with a defect and the part without a defect when the welded part is heated. The temperature difference on the surface indicated by the difference in heat conductivity can be checked for a wide area within a short time, by means of a thermal image camera thereby to settle the disadvantage of the conventional non-destructive inspection methods. The thermal image method, however, has a disadvantage in that thermal load must be given to the tested sample and it is difficult to quantify measured data. In order to overcome this disadvantage, we will describe preliminary test and the like for applying thermal load on the tested sample including a welding defect, photographing images by means of a thermal image camera, analyzing thermal images, and analyzing welding defects.