접속부 형태와 재질에 따른 인공기저막의 진동거동 특성

김상원(Sang Won Kim),안상현(Sang Hyeon Ahn),박수아(Sua Park),정영도(Youngdo Jung),허신(Shin Hur),김완두(Wan Doo Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

In order to transmit the vibration of ossicle to the input port of totally implantable artificial cochlear, a fluid-filled interface of tube shape is required. In order to investigate the vibratory transfer characteristic according to the material and shape of interface oscillation behavior of an artificial bailar membrane was measured and compared. The interface and artificial cochlear package were filled with phosphate buffered saline solution. Vibration signal was appiled to the entrance of interface by using piezo actuator. Vibratory characteristic of artificial cochlear membrane was analyzed by using laser Doppler vibrometer. Experiments were carried out without any interface and with interfaces; straight metal tube, straight plastic tube and curved plastic tube. Experimental results show that the measured magnitude of membrane vibration decreased in the order of the cases without a tube, with a metal tube, and with a plastic tube. The experimental results with straight plastic tube and curved plastic tube were similar.

High-speed angular-scan pulse-echo ultrasonic propagation imager for in situ non-destructive evaluation

Syed H. Abbas,Jung-Ryul Lee 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.2

This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a 100 ⨯ 100 mm2 area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens. This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a 100 ⨯ 100 mm2 area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system cThis study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a 100 ⨯ 100 mm2 area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.an successfully visualize defects in the inspected specimens.

Three dimensional evaluation of aluminum plates with wall-thinning by full-field pulse-echo laser ultrasound

Hong, S.C.,Abetew, A.D.,Lee, J.R.,Ihn, J.B. Applied Science Publishers 2017 Optics and lasers in engineering Vol.99 No.-

We propose a full-field pulse-echo laser ultrasonic wave propagation imager (FF-PE-UPI) for the evaluation of structural defects. The FF-PE-UPI consists of a Q-switched laser for the generation of thermoelastic waves, a laser Doppler vibrometer (LDV) for sensing, and a two-axis translation stage for raster scanning of the combined generation and sensing laser beams. A-scan, B-scan, and C-scan data representations are used for the evaluation of structural defects. Three specimens were tested: a 4-mm aluminum plate with an area of 50% thickness reduction, a 6-mm aluminum plate with an area of 25% thickness reduction, and an 8-mm aluminum plate with engraved letters. The damages on the tested specimens were successfully visualized.

레이저 가진 및 레이저 도플러 진동계 센싱 기반 레이저 C-scan 시스템 개발

홍승찬,이정률 제어로봇시스템학회 2014 제어로봇시스템학회 각 지부별 자료집 Vol.2014 No.12

C-scan, which is representative inspection using ultrasonic testing, shows precise result of visualizing defects in structure. However, conventional C-scanners have some drawbacks to inspect structures such as unexpected damages during contact inspection, restriction of approach on immersion technique. Recently, laser ultrasonic based nondestructive evaluation (NDE) techniques are being increasingly used. In this study, development of fully non-contact laser C-scan system using Q-switched laser (QL) and laser Doppler vibrometer (LDV) is conducted. In addition, damage visualization algorithms are developed to visualize defects that occur in various structure. Based on laser C-scan system, aluminum plate and pipe structures including artificial defects are inspected and visualized.

액체거동의 비접촉 다점측정을 위한 레이저진동계와 갈바노미터스캐너 계측시스템

김준희,신윤수,민경원 한국전산구조공학회 2018 한국전산구조공학회논문집 Vol.31 No.5

슬로싱과 같은 액체의 동적 거동을 측정하고 제어하는 연구가 다양한 공학분야에서 활발히 진행중이다. 건축공학분야에서 도 건축물의 풍진동을 저감시키는 동조액체감쇠기의 연구에 액제 진동이 측정되고 있다. 본 논문에서는 기존 파고 측정 센서의 한계를 극복하기 위하여 레이저 장비 중 LDV와 스캐닝 장비 중 갈바노미터스캐너를 이용하여 동조액체감쇠기 내의 액체 진동을 측정하는 방법을 제안하고 검증하였다. LDV가 속도와 변위를 측정하는 원리를 기술하였고 갈바노미터스캐너의 구동 원리에 따라 LDV의 단일 포인트로 다점측정이 가능한 시스템을 구성하였다. 동조 액체감쇠기의 4점 액체 진동을 측정하여 각 점의 시간 영역 데이터를 기존에 사용하던 비디오 센싱 데이터와 비교하였고 파형 분석을 통해 진행파와 정상파를 구별할 수 있음을 확인하였다. 또한 측정 딜레이가 있는 데이터를 상호 상관을 취하여 특이값 분해를 하고 이론 및 비디오 센싱 결과와 일치하는 고유진동수와 모드형상을 도출하였다. Researches regarding measurement and control of the dynamic behavior of liquid such as sloshing have been actively on undertaken in various engineering fields. Liquid vibration is being measured in the study of tuned liquid dampers(TLDs), which attenuates wind motion of buildings even in building structures. To overcome the limitations of existing wave height measurement sensors, a method of measuring liquid vibration in a TLD using a laser Doppler vibrometer(LDV) and galvanometer scanner is proposed in this paper: the principle of measuring speed and displacement is discussed; a system of multi-point measurement with a single point of LDV according to the operating principles of the galvanometer scanner is established. 4-point liquid vibration on the TLD is measured, and the time domain data of each point is compared with the conventional video sensing data. It was confirmed that the waveform is transformed into the traveling wave and the standing wave. In addition, the data with measurement delay are cross-correlated to perform singular value decomposition. The natural frequencies and mode shapes are compared using theoretical and video sensing results.

High-speed angular-scan pulse-echo ultrasonic propagation imager for in situ non-destructive evaluation

Abbas, Syed H.,Lee, Jung-Ryul Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.22 No.2

This study examines a non-contact laser scanning-based ultrasound system, called an angular scan pulse-echo ultrasonic propagation imager (A-PE-UPI), that uses coincided laser beams for ultrasonic sensing and generation. A laser Doppler vibrometer is used for sensing, while a diode pumped solid state (DPSS) Q-switched laser is used for generation of thermoelastic waves. A high-speed raster scanning of up to 10-kHz is achieved using a galvano-motorized mirror scanner that allows for coincided sensing and for the generation beam to perform two-dimensional scanning without causing any harm to the surface under inspection. This process allows for the visualization of longitudinal wave propagation through-the-thickness. A pulse-echo ultrasonic wave propagation imaging algorithm (PE-UWPI) is used for on-the-fly damage visualization of the structure. The presented system is very effective for high-speed, localized, non-contact, and non-destructive inspection of aerospace structures. The system is tested on an aluminum honeycomb sandwich with disbonds and a carbon fiber-reinforced plastic (CFRP) honeycomb sandwich with a layer overlap. Inspection is performed at a 10-kHz scanning speed that takes 16 seconds to scan a $100{\times}100mm^2$ area with a scan interval of 0.25 mm. Finally, a comparison is presented between angular-scanning and a linear-scanning-based pulse-echo UPI system. The results show that the proposed system can successfully visualize defects in the inspected specimens.

[Original Paper] Development of An Automated Scanning Laser Doppler Vibrometer For Measurements of In-Plane Structural Vibration

Hyun-Gwon Kil(길현권) 한국소음진동공학회 1997 소음 진동 Vol.7 No.2

레이저진동계를 사용한 동조액체댐퍼의 액체 진동 측정

신윤수,민경원,김준희 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.6

In this study, dynamic vertical displacement of liquid in the tuned liquid column damper(TLCD) is measured by a laser Doppler vibrometer(LDV) to overcome limitations of existing sensors and to leverage noncontact sensing. Addressing advantages of noncontact measurements, operational principles of the LDV to measure velocity and displacement of a target object in motion is explained. The feasibility of application of the LDV to measurement of liquid motion in the TLCD is experimentally explored. A series of shake table tests with the TLCD are performed to determine requirements of application of the LDV. Based on the experimental results, it is proved that the LDV works under the condition of adding dye to the liquid by increasing the intensity of reflected laser and thus validity is verified by comparison with a conventional wave height meter.

레이져 바이브로미터 스캐너를 이용한 평판의 얕은 결함 측정

강토(To Kang),문성인(Seongin Moon),한순우(Soonwoo Han),전준영(Jun Young Jeon),박규해(Gyuhae Park) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

A scanning laser Doppler vibrometer (SLDV) is a promising method to visualize defects in plate like structures. Recently, Lamb wave-based SLDV using continuous excitation widely adopted in NDE applications. To visualize defects using Lamb wave-based SLDV, A<SUB>0</SUB> mode has been usually used due to its nature of wave speed varying according to the thickness and to easily generated attributes using PZT. However, rate of change of wave speed varying according to the thickness is little in thick materials. To resolve this problem, axisymmetric mode is selected due to high wavenumber sensitivity. To generate axisymmetric mode, IDT (Interdigital transducer) sensor is designed and fabricated based on wavenumber sensitivity calculation. To evaluate the capability of the IDT-based SLDV, a 6-mmthick plate (40 mm × 40 mm) with defects of different depths (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm) is used. It is demonstrated that the detectability of thin defects in a thick plate is improved compared to that when using the A<SUB>0</SUB> mode.

ESPI에 의한 레이저용접 조건에 따른 진동 특성 분석

김경석,정현철,백상규,이유황,유득남 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-

This paper describes the variations of resonance frequencies and vibration mode shapes of laser welded cold rolled carbon steel plate(SCPI) induced by thermal loading during laser welding processing. The characteristics of those are analyzed with stroboscopic ESPI. Electronic speckle pattern interferometry (ESPI) that the electronic processes were added to SPI is one of the very powerful method in the experimental vibration analysis field. Stroboscopic ESPI to make it reliable are compared with theory and experimental method: Finite Element Method(FEM) and Scanning Laser Doppler Vibrometer(SLDV). The results of stroboscopic ESPI are well agreed with SLDV and also the comparison with theory give good agrement within 5%.