Ultra-lightweight fiber-reinforced envelope material for high-altitude airship

2021 ◽  
pp. 1-7
Author(s):  
Rahul Vallabh ◽  
Ang Li ◽  
Philip D. Bradford ◽  
David Kim ◽  
Abdel-Fattah M. Seyam
Keyword(s):  
High Altitude ◽  
Fiber Reinforced ◽  
Envelope Material

Natural Aging Mechanics Characteristics on Fiber Reinforced High Altitude Airship Envelope Composite

2014 ◽  
Vol 1049-1050 ◽  
pp. 73-76 ◽  
Author(s):  
Yun Chao Gu ◽  
Long Bin Liu ◽  
Shuai Cao ◽  
Hou Di Xiao ◽  
Ming Yun Lv
Keyword(s):  
Mechanical Properties ◽  
High Altitude ◽  
Fracture Strength ◽  
Mechanical Load ◽  
Natural Aging ◽  
Physical And Mechanical Properties ◽  
Natural Light ◽  
Fiber Reinforced ◽  
Breaking Elongation ◽  
Envelope Material

For High altitude airship (HAA) with long time affected by space harsh environment, due to the occurrence of natural light radiation aging physical and mechanical properties, fiber-reinforced airship envelope material results in degradation of the mechanical load performance, even causing damage to the balloon airship. Based on the ground aging simulation of the airship envelope material under the natural light, the morphology of airship envelope material in the natural aging process can be observed and the specimen comparison test is carried on for its fracture strength and breaking elongation to qualify its mechanical properties. The specimens with the axial angle of 0°and 90°were respectively tested to get its mechanical properties and the comparative analysis on degradation of fracture strength and breaking elongation before and after its 720h aging is developed too. The test results shows that the mechanical properties of different specimens decrease, wherein the maximum degradation is 0° specimens and that of 90°specimens t is not very significant weakening. Natural aging characteristics of airship envelope material provide support for the design and improvement of anti-aging properties of the airship envelope material.

Study on Fiber-Reinforced Laminated Composite Textile Tearing Behavior and Strength Prediction

2014 ◽  
Vol 651-653 ◽  
pp. 1370-1373
Author(s):  
Yun Chao Gu ◽  
Long Bin Liu ◽  
Shuai Cao ◽  
Hou Di Xiao ◽  
Ming Yun Lv
Keyword(s):  
Engineering Application ◽  
Laminated Composite ◽  
Initial Crack ◽  
Strength Prediction ◽  
Deformation Analysis ◽  
Fiber Reinforced ◽  
Mechanics Performance ◽  
Envelope Material ◽  
Safety And Stability ◽  
Tearing Strength

The tearing behavior of fiber-reinforced laminated composite textile plays the key role in the decision of mechanics performance of high altitude airship envelop material, even directly deciding its safety and stability. This paper, based on typical woven fabricated fiber yarns’ characteristics of geometry and mechanics, adopts Euler-displacement deformation analysis to explore yarn bundles deformation effects on tearing behavior and strength of envelope material with prefabricated damage and crack. Also, models with prefabricated crack with different size and textile density are respectively built to find factors that affect tearing behavior and strength of envelope material. From tests, it can be observed that the built models for predicting its tearing strength are in conformity with the experimental data. Nonlinear relationship is reflected between the initial crack width or yarn bundles density with tearing strength. Conclusively, the methods and models adopted in this paper provide an effective and innovative mind on tearing behavior and strength of fiber reinforced envelope material and make the foundation for its engineering application.

Analysis and retardation of helium permeation for high altitude airship envelope material

2019 ◽  
Author(s):  
Durga Vasudevan ◽  
Hariharan Mohan ◽  
Saarang Gaggar ◽  
Ramesh Burela Gupta
Keyword(s):  
High Altitude ◽  
Envelope Material

Study on Crack Tearing Propagation of High Altitude Airship Envelope Composite Material

2014 ◽  
Vol 1049-1050 ◽  
pp. 81-84
Author(s):  
Shuai Cao ◽  
Yun Chao Gu ◽  
Hou Di Xiao ◽  
Pan Pan Mi
Keyword(s):  
High Altitude ◽  
Laminated Composite ◽  
Space Environment ◽  
Main Bearing ◽  
Program Language ◽  
Envelope Material ◽  
High Space ◽  
Comparative Results ◽  
Elastic And Plastic Deformation ◽  
Bearing Part

High altitude airship (HAA) envelope material is vulnerable to be damaged and become failure with the long floating time in the space while withstanding severe and bad high space environment. HAA envelopee is composed of fabric laminated composite and the fabric yarn bundles are the main part to bear outer loads. Also the main bearing part is woven by Kevlar filaments and it is valid to analyze its mesomechanical properties as two-dimensional textile material. On the basis of yarn bundles mechanics, the paper considers the elastic and plastic deformation and collides among the bundles for its analysis. And the mesomechanic model is built to explore mechanisms on tearing propagation of pre-notched envelopee material samples. The results from the model computed by program language Matlab are compared with the test data for the same model. The comparative results are almost line with what the engineering requires.

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

1967 ◽  
Vol 25 ◽  
pp. 366-367
Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
High Altitude ◽  
Amyl Acetate ◽  
Temperature Variations ◽  
Film Forming ◽  
Film Specimen ◽  
Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

Characterization of interfaces in CVD-coated nicalon fiber-reinforced SiC

1989 ◽  
Vol 47 ◽  
pp. 556-557
Author(s):  
K.L. More ◽  
R.A. Lowden
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Chemical Vapor ◽  
Chemical Vapor Infiltration ◽  
Frictional Stress ◽  
Fiber Reinforced ◽  
Pull Out ◽  
Carbon Coated ◽  
Fiber Matrix

The mechanical properties of fiber-reinforced composites are directly related to the nature of the fiber-matrix bond. Fracture toughness is improved when debonding, crack deflection, and fiber pull-out occur which in turn depend on a weak interfacial bond. The interfacial characteristics of fiber-reinforced ceramics can be altered by applying thin coatings to the fibers prior to composite fabrication. In a previous study, Lowden and co-workers coated Nicalon fibers (Nippon Carbon Company) with silicon and carbon prior to chemical vapor infiltration with SiC and determined the influence of interfacial frictional stress on fracture phenomena. They found that the silicon-coated Nicalon fiber-reinforced SiC had low flexure strengths and brittle fracture whereas the composites containing carbon coated fibers exhibited improved strength and fracture toughness. In this study, coatings of boron or BN were applied to Nicalon fibers via chemical vapor deposition (CVD) and the fibers were subsequently incorporated in a SiC matrix. The fiber-matrix interfaces were characterized using transmission and scanning electron microscopy (TEM and SEM). Mechanical properties were determined and compared to those obtained for uncoated Nicalon fiber-reinforced SiC.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

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