• Title/Summary/Keyword: Laminate Thickness

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Study on Out-of-plane Properties and Failure Behavior of Aircraft Wing Unit Structures (항공기 날개 부분 단위구조체의 면 외 방향 물성 및 파손거동에 관한 연구)

  • Yoon, Chang-Mo;Lee, Dong-Woo;Byun, Joon-Hyung;Tran, Thanh Mai Nguyen;Song, Jung-il
    • Composites Research
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    • v.35 no.2
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    • pp.106-114
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    • 2022
  • Carbon fiber-reinforced plastic, well known high specific strength and high specific stiffness, have been widely used in the aircraft industry. Mostly the CFRP structure is fabricated by lamination of carbon fiber or carbon prepreg, which has major disadvantage called delamination. Delamination is usually produced due to absence of the through-thickness direction fiber. In this study, three-dimensional carbon preform woven in three directions is used for fabrication of aircraft wing unit structure, a part of repeated structure in aircraft wing. The unit structure include skin, stringer and rib were prepared by resin transfer molding method. After, the 3D structure was compared with laminate structure through compression test. The results show that 3D structure is not only effective to prevent delamination but improved the mechanical strength. Therefore, the 3d preform structure is expected to be used in various fields requiring delamination prevention, especially in the aircraft industry.

Development and Evaluation of Large Scale Composite Lattice Structures (대형 복합재 격자구조체 개발 및 평가)

  • Kim, Donggeon;Doh, Youngdae;Kim, Gensang;Kim, Myungjoo;Lee, Sangwoo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.6
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    • pp.74-86
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    • 2021
  • The composite lattice structure is a structure that supports the required load with the minimum weight and thickness. Composite lattice structure is manufactured by the filament winding process using impregnating high-strength carbon fiber with an epoxy resin. Filament winding process can laminate and manufacture only structurally necessary parts, composite lattice structure can be applied to aircraft fuselages, satellite and launch vehicles, and guided weapons to maximize weight reduction. In this paper, the development and evaluation of the composite lattice structure corresponding to the entire process from design, analysis, fabrication, and evaluation of large-scale cylindrical and conical composites lattice structure were performed. To be applicable to actual projectiles and guided weapons, we developed a cylindrical lattice structure with a diameter of 2,600 mm and a length of 2,000 mm, and a conical lattice structure with an upper diameter of 1,300 mm, a lower diameter of 2,500 mm, and a length of 900 mm. The performance of the developed composite lattice structure was evaluated through a load test.

Comparison of the degree of conversion of light-cured resin cement in regard to porcelain laminate thickness, light source and curing time using FT-IR (도재 라미네이트 두께와 광원 및 광조사 시간에 따른 광중합형 레진 시멘트의 FT-IR을 이용한 중합도 비교)

  • Yuh, Chi-Sung;Kim, Jee-Hwan;Kim, Sun-Jai;Lee, Yong-Keun;Shim, June-Sung
    • The Journal of Korean Academy of Prosthodontics
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    • v.47 no.4
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    • pp.416-423
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    • 2009
  • Statement of problem: The degree of light attenuation at the time of cementation of the PLV restoration depends on characteristics such as thickness, opacity and shade of the restorations, which interfere with light transmittance and, as a result, may decrease the total energy reaching the luting cement. Purpose: The purpose of this study was to compare the degree of conversion of light-cured resin cements measuring by FT-IR in regard to different thickness, light devices and curing time. Material and methods: In the control group, a clear slide glass (1.0 mm) was positioned between the light cured resin cement and light source. The specimens of ceramics were made with IPS Empress Esthetic. The ceramics were fabricated with varying thicknesses-0.5, 1.0, 1.5 mm with shade ETC1. Rely $X^{TM}$ Veneer with shade A3, light-cured resin cement, was used. Light-activation was conducted through the ceramic using a quartz tungsten halogen curing unit, a light emitting diode curing unit and a plasma arc curing unit. The degree of conversion of the light-cured resin cement was evaluated using FT-IR and OMNIC. One-way ANOVA and Tukey HSD test were used for statistical analysis ($\alpha$< .05). Results: The degree of conversion (DC) of photopolymerization using QTH and LED was higher than results of using PAC in the control group. After polymerization using QTH and LED, the DC results from the different ceramic thickness- 0.5 mm, 1.0 mm, 1.5 mm- did not show a significant difference when compared with those of control group. However, the DC for polymerization using PAC in the 1.5mm ceramic group showed significantly lower DC than those of the control group and 0.5 mm ceramic group (P<.05). At 80s and 160s, the DC of light-cured resin cement beneath 1.0 mm ceramic using LED was significantly higher than at 20s (P<.05). Conclusion: Within the limitation of this study, when adhering PLV to porcelain with a thickness between 0.5-1.5 mm, the use of PAC curing units were not considered however, light cured resin cements were effective when cured for over 40 seconds with QTH or LED curing units. Also, when curing the light cured resin cements with LED, the degree of polymerization was not proportional with the curing time. Curing exceeding a certain curing time, did not significantly affect the degree of polymerization.

Design and Performance Evaluation of Two-Layered Microwave Absorbers(Dielectric/Magnetic) for Wide Oblique Incidence Angles Used for ITS (ITS용 2층형 전파 흡수체(유전체/자성체) 설계 및 경사 입사 흡수 특성 해석)

  • Kim, Jae-Woong;Kim, Sung-Soo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.11
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    • pp.1217-1223
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    • 2007
  • Advanced microwave absorbers for wide oblique incidence angles are required in many applications including wireless communication or vehicle identification in ITS(Intelligent Transport System) where 5.8 GHz DSRC(Dedicated Short Range Communication) system is applied. In this study, two-layered microwave absorber(with a laminate structure of dielectric/magnetic composites) has been designed for the achievement of low reflection coefficient over wide incidence angles at 5.8 GHz. Iron flake particles are used as the filler in the absorbing layer, and the magnetic composite sheet exhibits high magnetic loss due to ferromagnetic resonance in gigahertz frequencies. The surface layer of low dielectric constant containing small amount of carbon black is used as the impedance transformer. On the basis of transmission line theory, the reflection loss has been calculated for the two-layer structure with variation of incident angles for both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations. At the optimum thickness of the composite layers, a low value of reflection loss(less than -10 dB) has been predicted for wide incidence angles up to $55^{\circ}$ which is in good agreement with the measured value determined by free-space measurement.

Static and Fatigue Characteristics of Urethane Foam Cored Sandwich Structures (우레탄 폼 코아 샌드위치 구조물의 정적 및 피로 특성)

  • 김재훈;이영신;박병준;김덕회;김영기
    • Composites Research
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    • v.12 no.6
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    • pp.74-82
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    • 1999
  • The static and fatigue characteristics of polyurethane foam cored sandwich structures are investigated. Three types of the specimens with the glass fabric faces and the polyurethane foam core are used; non-stitched. stitched, and stiffened sandwich specimen. Especially additional structural reinforcements with the twisted polyester and glass fiber for thickness direction are made to stitched sandwich structure panel to minimize the delamination of structure which is stitched the upper and lower faces through the core and the resin is impregnated Into stitched fiber with the characteristics of low viscosity of resin at resin flow temperature and cured together with during the curing process. Bending strength of stitched specimen which is 50 mm $50{\times}50{\;}mm$ pitched is improved by 50 % as com-pared with non-stitched specimen and stiffened specimen is improved 10 times more than non-stitched structure. After fatigue testing of $10^6$cycles by 20% of ultimate load under monotonic load, the bending fatigue strength of non-stitched specimen is decreased by 27% of monotonic bending strength, 39% for stitched structure and 20% for stiffened specimen. To verify the aging effect of polyurethane form core, Ultrasonic C-scanning equipment is used to detect the damage of skin laminate alone after fatigue test. From results of UT C-scan images, there is no defect that can be damaged occurred during fatigue test. It is concluded that the decrease of bending strength for foam cored sandwich specimen is caused by the decrease of stiffness due to the aging of polyurethane foam core during fatigue cycles.

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Study of adhesion properties of flexible copper clad laminate having various thickness of Cr seed layer under constant temperature and humidity condition (항온항습 조건하에서 Ni/Cr 층의 두께에 따른 FCCL의 접합 신뢰성 평가)

  • Choi, Jung-Hyun;Noh, Bo-In;Yoon, Jeong-Won;Kim, Yong-Il;Jung, Seung-Boo
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.80-80
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    • 2010
  • 전자제품의 소형화, 경량화, 고집적화가 심화됨에 따라 전자제품을 구성하는 회로의 미세화 또한 요구되고 있다. 이러한 요구는 경성회로기판 (rigid printed circuit board, RPCB) 뿐만 아니라 연성회로기판 (flexible printed circuit board, FPCB) 에도 적용되고 있으며 이에 대한 많은 연구 또한 이루어지고 있다. 연성회로기판은 일반적으로 절연층을 이루는 폴리이미드 (polyimide, PI)와 전도층을 이루는 구리로 이루어져 있다. 폴리이미드는 뛰어난 열적 화학적 안정성, 우수한 기계적 특성, 연속공정이 가능한 장점을 가지고 있으나, 고온다습한 환경하에서 높은 흡습성으로 인해 전도층을 이루는 구리와의 접합특성이 저하되는 단점 또한 가지고 있다. 또한 전도층을 이루는 구리는 고온다습한 환경하에서 산화 발생이 용이하기 때문에 접합특성의 감소를 야기할 수 있다. 따라서 본 연구에서는 고온다습한 조건하에서 sputtering and plating 공정을 통해 순수 Cr seed layer를 가지는 연성회로기판의 seed layer의 두께와 시효시간의 변화로 인해 발생하는 접합특성의 변화를 관찰하고 분석하였다. 본 연구에서는 두께 $25{\mu}m$의 일본 Kadena사(社)에서 제작된 폴리이미드 상에 sputtering 공정을 통해 순수 Cr으로 이루어진 각각 두께 100, 200, $300{\AA}$의 seed layer를 형성한 후 전해도금법을 이용, 두께 $8{\mu}m$의 구리 전도층을 형성한 시료를 사용하였다. 제작된 시료는 고온다습한 환경하에서의 접합 특성의 변화를 관찰하기 위하여 $85^{\circ}C$/85%RH 항온항습 조건하에서 각각 24, 72, 120, 168시간 동안 시효처리 한 후, Interconnections Packaging Circuitry (IPC) 규격에 의거하여 접합강도를 측정하였다. 시료의 전도층은 폭 3.2mm 길이 230mm의 패턴을 가지도록, 절연층은 폭 10mm, 길이 230mm으로 구성되었으며 이를 50.8mm/min의 박리 속도로 각 시편당 8회의 $90^{\circ}$ peel test를 실시하였다. 파면의 형상과 화학적 조성을 분석하기 위해 SEM (Scanning electron microscope)과 EDS (Energy-dispersive X-ray spectroscopy)를 사용하였으며, 파면의 조도 측정을 위해 AFM (Atomic force microscope)을 사용하였다. 또한 계면의 화학적 결합상태를 분석하기 위해 XPS (X-ray photoelectron spectroscopy)를 통해 파면을 관찰 분석하였다.

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Adhesion reliability of flexible copper clad laminate under constant temperature and humidity condition by thickness of Ni/Cr seed layer (항온항습 조건하에서 Ni/Cr 층의 두께에 따른 FCCL의 접합 신뢰성 평가)

  • Choi, Jung-Hyun;Noh, Bo-In;Yoon, Jeong-Won;Yoon, Jae-Hyun;Choi, Don-Hyun;Kim, Yong-Il;Jung, Seong-Boo
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.75-75
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    • 2009
  • 연성회로기판은 일반적으로 절연체를 이루는 폴리이미드와 전도체를 이루는 구리로 구성되어 있다. 폴리이미드는 뛰어난 열적 화학적 안정성, 기계적 특성, 공정성 등의 장점으로 인해 연성회로기판의 절연체로서 제안되었지만 전도체를 이루는 구리와의 접합 특성이 우수하지 않기 때문에 많은 연구가 현재까지 진행되고 있고, 그 결과 연성회로기판의 접합 특성에 많은 개선이 이루어짐과 동시에 다양한 공정 방법이 제안되고 있다. 하지만 고온다습한 환경에서 사용될 경우 폴리이미드의 높은 흡습성과, 구리와 seed layer의 산화 문제로 인해 접합 특성이 저하된다는 단점 또한 가지고 있다. 따라서 본 연구를 통해 고온다습한 조건하에서 seed layer가 80Ni/20Cr 합금으로 구성된 연성회로기판의 seed layer의 두께와 시효시간으로 인해 발생하는 접합 신뢰성의 차이를 관찰하였다. 본 연구에서는 두께 $25{\mu}m$의 폴리이미드 위에 각각 100, 200, $300{\AA}$ 두께의 80Ni/20Cr의 합금 조성을 가지는 seed layer를 스퍼터링 공정을 통해 형성한 후 전해도금법을 이용하여 $8{\mu}m$ 두께의 구리 전도층을 형성하였다. 접합 특성 평가를 위해 ICP 규격에 따라 전도층 패턴을 폭 3.2mm, 길이 230mm로 시편을 제작하여 50.8mm/min의 이송 속도로 각 시편당 8회의 $90^{\circ}$ peel test를 실시하였다. 또한 $85^{\circ}C$/85% 항온항습 조건하에서 각각 24, 72, 120, 168시간 동안 시효 처리 후 같은 방법으로 연성회로기판의 접합 특성을 평가하였다. 파면의 형상과 조성을 분석하기 위해 SEM (Scanning electron microscope)과 EDS (Energy-dispersive X-ray spectroscopy)를 사용하였으며, 파면의 조도 측정을 위해 AFM (Atomic force microscope)을 사용하였다. 또한 파면의 잔여물 분석을 위해 EPMA (Energy probe microanalysis)를 사용하였고 계면의 화학적 결합상태를 분석하기 위해 XPS (X-ray photoelectron spectroscopy)를 통해 파면을 분석하였다.

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Jangdo(Small Ornamental Knives) manufacturing process and restoration research using Odong Inlay application (오동상감(烏銅象嵌)기법을 활용한 장도(粧刀)의 제작기술 및 복원연구)

  • Yun, Yong Hyun;Cho, Nam Chul;Jeong, Yeong Sang;Jang, Chu Nam
    • Korean Journal of Heritage: History & Science
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    • v.49 no.2
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    • pp.172-189
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    • 2016
  • In this research, literature research on the Odong material, mixture ratio, casting method and casting facility was conducted on contemporary documents, such as Cheongong Geamul. Also, a long sword was produced using the Odong inlay technique. The sword reproduction steps were as follows; Odong alloying, silver soldering alloying, Odong plate and Silver plate production, hilt and sheath production, metal frame and decorative elements, such as a Dugup (metal frame), production, Odong inlay assembly and final assembly. For the Odong alloy production, the mixture ratio of the true Odong, which has copper and gold ratio of 20:1, was used. This is traditional ratio for high quality product according to $17^{th}$ century metallurgy instruction manual. The silver soldering alloy was produced with silver and brass(Cu 7 : Zn 3) ratio of 5:1 for inlay purpose and 5:2 ratio for simple welding purpose. The true Odong alloy laminated with silver plate was used to produce hilt and sheath. The alloy went through annealing and forging steps to make it into 0.6 mm thick plate and its backing layer, which is a silver plate, had the matching thickness. After the two plates were adhered, the laminated plate went through annealing, forging, engraving, silver inlaying, shaping, silver welding, finishing and polishing steps. During the Odong colouring process, its red surface turns black by induced corrosion and different hues can be achieved depending on its quality. To accomplish the silver inlay Odong techniques, a Hanji saturated with thirty day old urine is wrapped around a hilt and sheath material, then it is left at warm room temperature for two to three hours. The Odong's surface will turn black when silver inlay remains unchanged. Various scientific analysis were conducted to study composition of recreated Odong panel, silver soldering, silver plate and the colouring agent on Odong's surface. The recreated Odong had average out at Cu 95.57 wt% Au 4.16wt% and Cu 98.04 wt% Au 1.95wt%, when documented ratio in the old record is Cu 95wt% and Au 5wt%. The recreated Odong was prone to surface breakage during manufacturing process unlike material made with composition ratio written in the old record. On the silver plate of the silver and Odong laminate, 100wt% Ag was detected and between the two layers Cu, Ag and Au were detected. This proves that the adhesion between the two layers was successfully achieved. The silver soldering had varied composition of Ag depending on the location. This shows uneven composition of the silver welding. A large quantities of S, that was not initially present, was detected on the surface of the black Odong. This indicates that presence of S has influence on Odong colour. Additional study on the chromaticity, additional chemical compounds and its restoration are needed for the further understanding of the origin of Odong colour. The result of Odong alloy testing and recreation, Odong silver inlay long sword production, scientific analysis of the Odong black colouring agent will form an important foundation of knowledge for conservation of Odong artifact.