• Textile Coloration and Finishing
• /
• v.11 no.1
• /
• pp.42-47
• /
• 1999

본 연구는 노멕스 직물과 일반 방염직물의 쾌적성에 영향을 주는 중요한 인자를 찾기 위하여 직물의 열적 성질과 역학 성질에 관하여 연구한 것이다. 사용된 직물은 재해를 일으킬 수 있는 환경에서 방호용 의복으로 사용되는 노멕스 직물이 주를 이루며, 비교를 위하여 방염직물과 쾌적성이 좋은 일반직물을 포함시켰다. 직물의 물리적 성질과 열 특성을 측정하였으며, 역학 성질을 측정하여 노멕스 직물과 다른 직물을 서로 비교 분석하였다. 노멕스 직물은 파이버 자체가 뻣뻣하기 때문에 쾌적성을 향상시키기 위해서는 소프트감을 높이는 것이 중요한 요소라는 것을 확인할 수 있었다. 같은 노멕스 직물이라도 쾌적성 면에서 서로 차이를 보여주므로 직물의 구조적 성질이 직물을 구성하고 있는 파이버 성질보다 쾌적성에 더 영향을 미치는 것을 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.12
• /
• pp.1931-1936
• /
• 2010

In Korean tilting trains, honeycomb composite panels are used for high speed and light weight. The side wall of a tilting train consists of an aluminum honeycomb coated with carbon-fiber-reinforced epoxy skin and a nomex honeycomb panel as the main structure, with glass wool inserted between the panels. In this study, based on ASTM E2249-02, we measure the intensity sound transmission loss (TL) of the honeycomb composite panels. Using mass law deviation (MLD), we estimate the sound insulation performance of the honeycomb composite panels in terms of their weight and explore the feasibility of substituting a conventional corrugated steel panel. The transmission-loss data of the honeycomb composite panels obtained in the study will be used to establish noise-reduction measures for train compartments.

• Composites Research
• /
• v.24 no.1
• /
• pp.17-23
• /
• 2011

The failure of composite sandwich joints was experimentally investigated. A total of 30 joint specimens of 5 different types were tested with various fastening methods and core materials. In the NomexTM core sandwich joints, the core shear buckling was commonly observed in all the specimens which was followed by the slope change of the load-displacement curve. After the shear buckling, however, the joints carried additional loads of 50~200% over the buckling loads and then finally failed in the upper face breakage. The joints of PMI foam core showed the shear failure of the core instead of shear buckling and experienced the sharp drop of the carried load. Considering the failure modes, while both the core and face properties are important in the $Nomex^{TM}$ core joints, core shear strength seems to be the critical factor for the foam core joints.

• Fashion & Textile Research Journal
• /
• v.21 no.5
• /
• pp.606-617
• /
• 2019

The present study newly developed a firefighters' protective jacket and pants using a Nomex honeycomb structured layer (HPC) in cases of being exposed to flashover or flameover. This study evaluated the protective and comfort functions of an HPC compared to the current KFI firefighters' protective clothing (FPC). The results are as follows. First, thermal protective performance (TPP) of fabric layers was 2.75 times greater for HPC than FPC at $125kW/m^2$. Second, the predicted second and third degree burn areas were smaller for HPC than FPC when using a flame manikin. Third, thermal insulation using a thermal manikin was 0.2 clo greater for HPC than FPC. Fourth, there were no marked differences in maximal performance, mobility, and microclimate temperature/humidity between FPC and HPC through human wear trials. The thermal insulation of HPC was higher than that of FPC; however, any negative effect of HPC thermal insulation on the comfort functions for firefighters was not found. In conclusion, the newly-developed HPC provided more protection in reducing burn injuries from $125kW/m^2$, while no negative impact on maximal performance, mobility and thermal comfort functions of firefighters, which is appropriate for quick-evasive tactics at the flashover, flameover or back draft fires.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.195-198
• /
• 2000

Microstrip antenna for SAR applications is designed with microwave composite laminates and Nomex honeycomb cores, which becomes an aircraft's structural panel. This study demonstrated fabrication, design procedures and structural and electrical performances of complex antenna system presented. For validating structural rigidity, 3-point bending test is performed, and simulation results for the complex antenna array are compared with measurements for its electrical performance. The results show that this antenna system can be applied in dual polarized synthetic aperture radar and has a good flexural stiffness with comparison of previous sandwich constructions.

• Composites Research
• /
• v.16 no.4
• /
• pp.59-65
• /
• 2003

FEM analysis of the smart skin structure, and application of the sandwich structures investigated. The honeycomb manufactures only provide stillness of thickness direction and transverse shear modulus. Although these are dominant mechanical properties. the other mechanical properties are needed in FEM analysis. Hence, this work shows procedures of obtaining those mechanical properties. Honeycomb material was assumed to be ar, isotropic material and properties are estimated by its dominant honeycomb properties. The other honeycomb properties are then obtained by mechanical properties of Nomex. Buckling test and three point bending test were simulated by ABAQUS. Both the shell and solid element models were used. The results were compared with experimental results and analytical approaches. They showed good agreements. This study shows a guideline of FEM analysis of smart skin structure using commercial a FEM package.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.1
• /
• pp.115-126
• /
• 2001

In this paper, through a series of comparative experiments, effects of two different cure processing methods, cocure and precure, on the mechanical properties of honeycomb core materials for aircraft applications are considered. Mass of moisture accumulated into the closed cells of the sandwich panel specimen from the measured mass of moisture diffused to the full saturation state into the elements(skin, adhesive layer, Nomex honeycomb), consisting the honeycomb sandwich specimen has been calculated. Water reservoir of 70$\^{C}$ was used to have specimens absorb moisture to see the influence of moisture absorbed into sandwich panel on its mechanical properties. For the repair condition holding for 2 hours at 177$\^{C}$(350℉) temperature, a pressure due to the vapor expansion in each cell of the sandwich panel, which may result in the local separation of the interface between laminated skin and the surface of the honeycomb, has been estimated by vapor pressure-temperature relation from the thermodynamic steam table and compared to the pressure from the ideal gas state equation. The bonding strengths of the laminated skins on the flat surface of the Nomex honeycomb have been compared by the flatwise tension test and climbing drum peel test performed at room temperature for dry, wet and wet-repair specimens, respectively.

• Composites Research
• /
• v.14 no.6
• /
• pp.1-8
• /
• 2001

In this paper, the sandwich panel composites consisting of core material and face sheet were studied to evaluate the mechanical properties, noise level and fire resistance including flammability, smoke, and toxicity. Four types of sandwich panel were prepared using various kinds of panel and honeycomb materials. It was observed that Al honeycomb/Al skin composite materials had the excellent flatwise tensile strength and edgewise compressive strength compared with other types of composites. The flatwise compressive strength and flexural strength of Nomex honeycomb/Al skin composite were higher than those of other composites. PMI form/Al skin composite showed the higher core shear strength and facing bending strength. From the experimental results of flame resistance tests, it can be said that the phenol based skin composite has the excellent flame retardation properties, which are similar to those of the commercial skin composites.

• Composites Research
• /
• v.27 no.2
• /
• pp.77-81
• /
• 2014

In this study, it was performed damage assessment and repair of small scale aircraft adopted on composite. This aircraft adopted the sandwich structure to skin of wing. This study aims to investigate the residual strength of sandwich composites with nomex honeycomb core and carbon fiber face sheets after the open hole damage by the experimental investigation. The 4-point bending tests were used to find the bending strength, and the open hole was applied to introduce the simulated damage on the specimen. The bending strength test results after open hole were compared with the results of no damaged specimen test. In addition, The damaged composite structure was repaired using external patch repair method after removing damaged area. After that, this study presents comparison results of the experimental investigation between the damaged and the repaired specimen. It was found that the bending strength of repaired specimen was recovered up to 95% of undamaged specimen.

• Composites Research
• /
• v.20 no.5
• /
• pp.26-33
• /
• 2007

Pull-out and shear strengths of insert Joints of sandwich structure were investigated by experiment. Specimens were prepared by cocuring of nomex honeycomb core and carbon-epoxy composite face using an adhesive FM73. A total of 75 specimens with 10 different types depending on the core height and density, face thickness, and loading direction were tested. In the test under pull-out loading, although both the core height and density affect the failure loads, the effect of cell density is more serious. Dominant factor fur failure loads of the joints under shear loading is face thickness and the effect of core height is negligible. In the joint with same dimension, failure loads vary depending on the potted area of the core, particularly in the pull-out test.