Cryogenic Interlaminar Properties of PBO Fiber/Epoxy Composites

2011 ◽  
Vol 391-392 ◽  
pp. 1445-1449
Author(s):  
Chun Hua Zhang ◽  
Shi Lin Luan ◽  
Xiu Song Qian ◽  
Bao Hua Sun ◽  
Wen Sheng Zhang
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Liquid Nitrogen Temperature ◽  
Epoxy Composites ◽  
Bending Test ◽  
Test Results ◽  
Sem Images ◽  
Three Point Bending ◽  
Pbo Fiber ◽  
Interlaminar Shear

The influences of low temperature on the interlaminar properties for PBO fiber/epoxy composites have been studied at liquid nitrogen temperature (77 K) in terms of three point bending test. Results showed that the interlaminar shear strength at 77 K were significantly higher than those at room temperature (RT). For the analysis of the test results, the tensile behaviors of epoxy resin at both room temperature and liquid nitrogen temperature were investigated. The interface between fiber and matrix was observed using SEM images.

Experimental study on the mechanical behavior and microstructural assessment of Kevlar/epoxy composites at liquid nitrogen temperature

2014 ◽  
Vol 23 (3-4) ◽  
pp. 95-100 ◽  
Author(s):  
Sanghamitra Sethi ◽  
Bankim Chandra Ray
Keyword(s):  
Mechanical Behavior ◽  
Liquid Nitrogen ◽  
Failure Modes ◽  
Progressive Failure ◽  
Liquid Nitrogen Temperature ◽  
Woven Fabric ◽  
Epoxy Composites ◽  
Interlaminar Shear ◽  
Three Point Bend Test ◽  
Point Bend

AbstractThe present investigation emphasized the understanding of the mechanical behavior and progressive failure modes of Kevlar/epoxy-reinforced laminated composites subjected to a three-point bend test at liquid nitrogen (LN2) temperature (77 K). The tests were conducted on the woven fabric laminates with different loading speeds and characterized by scanning electron microscopy (SEM). The effect of LN2 temperature on the interlaminar shear strength (ILSS) of Kevlar/epoxy composites with various loading speeds was observed. The results indicate that the values of ILSS were increased at higher crosshead speeds compared to ambient temperature. The fibrillation progression and matrix failure (riverline marking) was observed by SEM. A change in crosshead speed may result in the variation of failure modes.

Experimental and Numerical Investigation of Critical Buckle Load of Composite Specimens

2015 ◽  
Vol 732 ◽  
pp. 85-90
Author(s):  
Lukáš Bek ◽  
Radek Kottner ◽  
Jan Krystek ◽  
Tomáš Kroupa
Keyword(s):  
Static Analysis ◽  
Glass Fibre ◽  
Large Deformations ◽  
Bending Test ◽  
Test Results ◽  
Beam Test ◽  
Three Point Bending ◽  
Box Beams ◽  
Buckle Beam ◽  
Thin Walled

Different carbon and glass fibre strips were subjected to the double clamp buckle beam test. Furthermore, thin-walled glass fibre box-beams were subjected to the three-point bending test. Results of experiments were compared to different numerical simulations using buckling analysis or static analysis considering large deformations.

The Bending Strength of Brittle Materials and the Characteristics of the Elastic Wave Signal by Vickers Indentation

2004 ◽  
Vol 261-263 ◽  
pp. 1635-1640 ◽  
Author(s):  
Seok Hwan Ahn ◽  
Ki Woo Nam ◽  
Kotoji Ando
Keyword(s):  
Elastic Wave ◽  
Room Temperature ◽  
Bending Strength ◽  
Brittle Materials ◽  
Bending Test ◽  
Vickers Indentation ◽  
Three Point Bending ◽  
Wave Signal ◽  
Wave Detector ◽  
Fracture Wave

Four kinds of brittle materials were used to evaluate the bending strength under three-point bending and the characteristics of the elastic wave signal by Vickers indentation. The bending test was carried out under room temperature and high temperature. A crack was made at the tension side of the specimen with a Vickers indenter to investigate fracture strength. Fracture wave detector was used to evaluate characteristics of waveform and frequency of the elastic wave signal.

Research on DC Breakdown and Flashover Characteristics of PI with Different Temperature

2016 ◽  
Vol 709 ◽  
pp. 11-14
Author(s):  
Tian Ye Niu ◽  
Jia Xin Wu ◽  
Ying Wen Li ◽  
Dong Sheng Xu ◽  
Lu Li ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Rapid Development ◽  
Liquid Nitrogen Temperature ◽  
Power Equipment ◽  
Electrical Characteristics ◽  
Cryogenic Temperatures ◽  
Insulating Materials ◽  
Dielectric Performance ◽  
Working Performance

The electrical characteristics of insulating materials play a key role on the working performance and operation reliability of power equipment. With the rapid development of superconducting technology in recent years,the working temperature of high temperature superconducting power equipment can be controlled around the liquid nitrogen temperature. Due to its excellent dielectric performance and mechanical properties, polyimide have been widely used in power equipment at room temperature. However, polyimide, as a kind of cryogenic insulating materials, is rarely reported at present. Therefore, the study of the insulating characteristics of polyimide at the cryogenic temperatures is of great significance. The DC breakdown property and flashover performance of polyimide are tested around room temperature (300K) and liquid nitrogen temperature (78K). The results show that temperature has some effects on the DC breakdown property and flashover performance of polyimide.

Application of interference fits on cylindrical monochromator crystals to overcome clamping and cooling deformations

2019 ◽  
Vol 26 (2) ◽  
pp. 382-385
Author(s):  
Joshua Stimson ◽  
Michael Ward ◽  
John Sutter ◽  
Sofia Diaz-Moreno ◽  
Simon Alcock ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
Silicon Crystal ◽  
Liquid Nitrogen Temperature ◽  
Cryogenic Cooling ◽  
Element Analysis ◽  
Thermal Interface ◽  
Macro Scale ◽  
Order Of Magnitude

In order to provide adequate cryogenic cooling of both existing and next-generation crystal monochromators, a new approach to produce an optimum thermal interface between the first crystal and its copper heat exchanger is proposed. This will ensure that the increased heat load deposited by higher X-ray powers can be properly dissipated. Utilizing a cylindrical silicon crystal, a tubular copper heat exchanger and by exploiting the differing thermal and mechanical properties of the two, a very good thermal interface was achieved at liquid-nitrogen temperatures. The surface flatness of the diffracting plane at one end of the cylindrical crystal was measured at room temperature while unconstrained. The crystal was then placed into the copper heat exchanger, a slide fit at room temperature, and then cooled to liquid-nitrogen temperature. At −200°C the slide fit became an interference fit. This room-temperature `loose' fit was modelled using finite-element analysis to obtain the desired fit at cryogenic temperatures by prescribing the fit at room temperature. Under these conditions, the diffraction surface was measured for distortion due to thermal and mechanical clamping forces. The total deformation was measured to be 30 nm, an order of magnitude improvement over deformation caused by cooling alone with the original side-clamped design this concept method is set to replace. This new methodology also has the advantage that it is repeatable and does not require macro-scale tools to acquire a nanometre-accuracy mounting.

Study of Electrical Properties of Ge-Nanocrystalline Films Deposited by Cluster-Beam Evaporation Technique

1998 ◽  
Vol 536 ◽  
Author(s):  
Souri Banedjee ◽  
H. Ono ◽  
S. Nozaki ◽  
H. Morisaki
Keyword(s):  
Electrical Properties ◽  
Liquid Nitrogen ◽  
Coulomb Blockade ◽  
Room Temperature ◽  
Liquid Nitrogen Temperature ◽  
Cluster Beam ◽  
Nanocrystalline Films ◽  
Current Voltage ◽  
Evaporation Technique

AbstractRoom temperature current-voltage (I-V) characteristics were studied across the thickness of the Ge nanocrystalline films, prepared by the cluster beam evaporation technique. The films thus prepared are deposited either at room temperature (Ge-RT) or at liquid nitrogen temperature (Ge-LNT). Ge-LNT nanofilm is subjected to oxidation while Ge-RT did not get oxidized. Steps were observed in the I-V characteristics of the thin Ge- LNT samples suggesting the Coulomb Blockade effect.

Effect of Rolling Temperature on Microstructure and Mechanical Properties of Cryorolled Al-Mg-Si Alloy Reinforced with 3wt% TiB2 In Situ Composite

2012 ◽  
Vol 584 ◽  
pp. 556-560 ◽  
Author(s):  
B. Gopi ◽  
N. Naga Krishna ◽  
K. Sivaprasad ◽  
K. Venkateswarlu
Keyword(s):  
Mechanical Properties ◽  
Liquid Nitrogen ◽  
Room Temperature ◽  
True Strain ◽  
Liquid Nitrogen Temperature ◽  
Tensile Tests ◽  
Rolling Temperature ◽  
Rolled Sample ◽  
Peak Broadening

The present work investigates the effect of rolling temperature on the mechanical properties and microstructural evolution of an Al-Mg-Si alloy with 3wt% TiB2 in-situ composite that was fabricated by stir casting route. The composite was rolled to a true strain of ≈0.7 at three different temperatures viz; room temperature (RT), liquid propanol (LP) and liquid nitrogen (LN) temperatures. Tensile tests revealed that the samples rolled at liquid nitrogen temperature exhibited improved properties compared to the samples rolled at other two temperatures. A tensile strength and ductility of 291 MPa and 8% respectively were exhibited by the liquid nitrogen rolled sample. The strength is observed to be ≈12% higher and ductility is ≈60% more when compared to the room temperature rolled sample. X ray diffraction peaks indicated that rolled samples exhibited considerable increase in peak broadening compared to the unrolled one, which is attributed to the increase of the lattice strain due to distortion and the decrease in grain size of the material. The enhanced mechanical properties of the liquid nitrogen rolled samples were attributed to the combined effect of grain refinement and accumulation of higher dislocation density.

Complementary Use of Inductive Test and Bending Test for the Characterization of SFRC

2014 ◽  
Vol 580-583 ◽  
pp. 2213-2219 ◽  
Author(s):  
Lin Liao ◽  
Sergio Cavalaro ◽  
Albert de la Fuente ◽  
Antonio Aguado
Keyword(s):  
Steel Fibre ◽  
Fibre Orientation ◽  
Bending Test ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Flexural Behaviour ◽  
Steel Fibre Reinforced Concrete ◽  
Three Point Bending ◽  
Experimental Campaign

Many researches have been conducted in past decades for promoting the application of steel fibre reinforced concrete (SFRC), either conventional or self-compacting. However, the differences of post-crack behaviour and the properties of these two types of concrete remains unclear. The objective of this paper is to analyse such differences in terms of flexural behaviour, fibre orientation and contribution as well as the fibre content. For that, an extensive experimental campaign was carried out. In total 3 mixes of self-compacting and 3 mixes with traditional concrete were produced with the nominal fibre contents of 30kg/m3, 45kg/m3 and 60kg/m3. In each series, specimens were produces and characterized by three point bending test (code EN 14651) and inductive test. The results illustrate how fibre orientation and distribution justify the differences in the mechanical behaviour of the materials and the scatter of the bending test results.

Chemically disordered Ni3Al synthesized by high vacuum evaporation

1991 ◽  
Vol 6 (10) ◽  
pp. 2019-2021 ◽  
Author(s):  
S.R. Harris ◽  
D.H. Pearson ◽  
C.M. Garland ◽  
B. Fultz
Keyword(s):  
Liquid Nitrogen ◽  
Room Temperature ◽  
Single Phase ◽  
High Vacuum ◽  
Liquid Nitrogen Temperature ◽  
Vacuum Evaporation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Average Grain Size

Films of chemically disordered fcc Ni3Al were synthesized by the vacuum evaporation of Ni3Al onto room temperature and liquid nitrogen temperature substrates. X-ray diffractometry and transmission electron microscopy showed the material to be single phase with an average grain size of about 4 nm. The formation of the equilibrium L12 ordered phase occurred simultaneously with grain growth at temperatures above 350°C. Differential scanning calorimetry provided ordering enthalpies of 7 kJ/mole and 9 kJ/mole for material evaporated onto room temperature and liquid nitrogen temperature substrates, respectively.

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