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충격하중을 받은 CFRP 적층판의 손상거동과 잔류굽힘피로강도
임광희,양인영,Im, Kwang-Hee,Yang, In-Young 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6
In this paper, static and fatigue bending strengths of CFRP(carbon fiber reinforced plastic laminates having impact damage(FOD) are evaluated. Composite laminates used for this experiment are CF/EPOXY and CF/PEEK orthotropy laminated plates, which have two-interfaces[${0^0}_4{90^0}_4}$]$_sym$. A steel ball launched by the air gun colides against CFRP laminates to generate impact damages. The damage growth during bending fatigue test is observed by the scanning acoustic microscope(SAM). When the impacted side is compressed, the residual fatigue bending strength of CF/PEEK specimen P is greater that that of CF/EPOXY SPECIMEN B. On the other hand, when the impacted side is in tension, the residual fatigue bending strength of CF/PEEK speicemen P is smaller than that of CF/EPOXY specimen B. In the case of impacted-side compression, fracture is proposed from the transverse crack generated near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-b delamination in the case of impacted-side tension.
자동차용 볼트의 검사를 위한 시뮬레이션에 기반한 ECT 센서 설계 및 실험적특성
임광희(Kwang-Hee Im),이슬기(Seul-Gi Lee),김학준(Hak-Joon Kim),송성진(Sung-Jin Song),우용득(Yong-Deuck Woo),나승우(Seung-Woo Ra),이형호(Hyung-Ho Lee) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.3
Oil filters for vehicular parts are used under high and low temperatures as the engine is cooled, and defects can be generated with repeated changes in the operating environment and with changes in the shape, such as very high internal losses for the bolts. Visually checking for defects inside a bolt is impossible. Nondestructive evaluation methods such as eddy current testing (ECT) are recommended as a more effective way to examine inside a bolt and detect surface defects in a short amount of time. In this study, the fit bobbin coil eddy current probe was applied to checking the bolts. The bolt parameters were calculated by using a COMSOL analysis program to obtain parameters for professional interior design and fault diagnosis.
임광희(Kwang-Hee Im),정종안(Jong-An Jeong),David K. Hsu,이길성(Kil-Sung Lee) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.1
A study of terahertz waves (T-ray) was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The to-be-used systems were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both turbine blades of wind energy (non-conducting polymeric composites) and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. This was demonstrated in CFRP (Carbon fiber reinforced plastics) laminates. Refractive index (n) was defined as one of mechanical properties; so a method was solved in order solve the “n” in the material with the cut parts of the turbine blades of wind energy. The defects and anomalies investigated by terahertz radiation were foreign material inclusions and simulated disband. Especially, it is found that the T-ray went through the turbine blade with greater thickness (about 90mm).
임광희(Kwang-Hee Im),김지훈(Ji-Hoon Kim),David K. Hsu 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.2
A study of terahertz waves was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The terahertz systems were consisted of time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both non-conducting polymeric composites and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. The CFRP (Carbon fiber reinforced plastics) laminates were utilized for confirming the experimentation in the terahertz NDE. In carbon composites the penetration of terahertz waves is quite limited and the detection of flaws is strongly affected by the angle between the electric field direction of the terahertz waves and the intervening fiber directions. A refractive index (n) was defined as one of mechanical properties; so a method was obtained in order solve the “n” in the material with non-conductivity. The usefulness and limitations of terahertz radiation are investigated for the NDE of FRP composites.
One-Sided Nondestructive Evaluation of CFRP Composites By Using Ultrasonic Sound
Kwang-Hee Im(임광희),Gui-Lin Zhang(장계림),Sung-Rok Choi(최성록),Chang-Hee Ye(예창희),Je-Sung Ryu(류제성),Soo-Hwan Lim(임수환),Min-Gui Han(한민규),David K. Hsu 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.1
It is well known that stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences their properties. Ultrasonic NDE of composite laminates is often based on the backwall echoes of the sample. A pair of such transducers was mounted in a holder in a nose-to-nose fashion to be used as a scanning probe on composites. Miniature potted angle beam transducers were used ( Rayleigh waves in steel) on solid laminates of composites. Experiments were performed to understand the behavior of the transducers and the nature of the waves generated in the composite (mode, wave speed, angle of refraction). C-scan images of flaws and impact damage were then produced by combining the pitch-catch probe with a portable manual scanner known as the Generic Scanner (”GenScan”). The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to fiber orientation of the CFRP composites, including low level porosity, ply waviness, and cracks. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with numerical results and one-side ultrasonic measurement might be very useful to detect the defects.
첨단 NDE 기법을 이용한 풍력터빈 블레이드의 페인팅 두께 모니터링 평가기법
임광희(Kwang-Hee Im),장계림(Gue-Lin Zhang),김우진(Woo-Jin Kim),정예원(Ye-Won Jeong),조철현(Chul-Hyun Cho),김선규(Sun-Kyu Kim),조영태(Young-Tae Cho),우용득(Yong-Deuck Woo) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The composite materials are being utilized on the various areas. Here, the paint used for wind blades was experimentally analyzed which data agreed with known data. Using these characterized material properties, the characteristics were successfully demonstrated through NDE behavior propagating through the painting materials to acquire the refractive index. Both ultrasonic and T-ray techniques were used to analyze the thickness of paint on the GFRP (Glass fiber reinforcement plastics) composites. The non-destructive evaluation (NDE) technique has been established for measuring the thickness. Good results have been obtained in tests on the thickness of the standard painted samples.