scholarly journals Impact Sensitivity and Ignition Mechanisms of Nanoaluminum-poly(perfluorinated methacrylate) Nanocomposites

MRS Advances ◽  
2018 ◽  
Vol 3 (17) ◽  
pp. 887-903
Author(s):  
Lauren A. Morris ◽  
Darla Graff Thompson ◽  
Racci DeLuca ◽  
Ian Shelburne ◽  
I. Emre Gunduz ◽  
...  
Keyword(s):  
Impact Testing ◽  
Energy Output ◽  
Initiation Mechanism ◽  
Pinch Point ◽  
Bomb Calorimetry ◽  
Gas Gun ◽  
Velocity Threshold ◽  
Higher Power ◽  
Ignition Mechanism ◽  
The Impact

ABSTRACTNanoenergetic composites are of overwhelming interest to the Department of Defense because of the higher power output and the ability to finely tune the ignition thresholds of these composites. Recently, several variants of a nanoaluminum-poly(perfluorinated methacrylate) (AlFA) have been synthesized and optimized for a variety of applications including reactive warhead liners and bullet spotters. While conventional techniques such as thermal analysis and bomb calorimetry can be used to characterize the reaction mechanism and energy output of AlFA composites, characterizing their dynamic behaviour is more challenging. Bullet spotter applications require a material to be impact sensitive at very low velocities, yet be adequately insensitive. Several live-fire tests were conducted which revealed the AlFA50 material reacted consistently upon target impact at high velocities, but unreliably at very low velocities. In an effort to better understand the fundamental impact ignition mechanism and to determine the impact velocity threshold of AlFA50 a series of Taylor gas gun experiments were conducted. It was determined that the light-initiation mechanism was consistent with a pinch mechanism, and that the ignition velocity threshold was near 74 m/s. Based on these results, it was hypothesized that the addition of a filler material could be used to sensitize the AlFA50, and that Asay shear impact testing could be used to determine a more optimal shape of such inclusions. Experiments performed using the Asay shear impact test setup confirmed the pinch ignition mechanism, but observations also revealed that the size of the pinch point was important. Finally, it was shown that the addition of large glass beads (> 1mm in diameter) was effective at sensitizing the AlFA50 material at high and low velocities, with ignition observed at impact velocities as low as 35 m/s.

scholarly journals Simulation of 2-Coil and 4-Coil Magnetic Resonance Wearable WPT Systems

Proceedings ◽  
2021 ◽  
Vol 68 (1) ◽  
pp. 13
Author(s):  
Yixuan Sun ◽  
Stephen Beeby
Keyword(s):  
Power Efficiency ◽  
Power Transmission ◽  
Rotation Angle ◽  
Wireless Power ◽  
Peak Efficiency ◽  
Frequency Splitting ◽  
At Resonance ◽  
Higher Power ◽  
The Impact ◽  
Proper Frequency

This paper presents the COMSOL simulations of magnetically coupled resonant wireless power transfer (WPT), using simplified coil models for embroidered planar two-coil and four-coil systems. The power transmission of both systems is studied and compared by varying the separation, rotation angle and misalignment distance at resonance (5 MHz). The frequency splitting occurs at short separations from both the two-coil and four-coil systems, resulting in lower power transmission. Therefore, the systems are driven from 4 MHz to 6 MHz to analyze the impact of frequency splitting at close separations. The results show that both systems had a peak efficiency over 90% after tuning to the proper frequency to overcome the frequency splitting phenomenon at close separations below 10 cm. The four-coil design achieved higher power efficiency at separations over 10 cm. The power efficiency of both systems decreased linearly when the axial misalignment was over 4 cm or the misalignment angle between receiver and transmitter was over 45 degrees.

Alfa fibers for Cereplast bio-composites reinforcement: Effects of chemical and biological treatments on the mechanical properties

2021 ◽  
pp. 096739112110060
Author(s):  
Mouna Werchefani ◽  
Catherine Lacoste ◽  
Hafedh Belguith ◽  
Chedly Bradai
Keyword(s):  
Charpy Impact ◽  
Impact Testing ◽  
Hot Water ◽  
Cellulose Content ◽  
Twin Screw ◽  
Electron Microscopy Analysis ◽  
Alfa Fibers ◽  
Charpy Impact Testing ◽  
Water Treatments ◽  
The Impact

The present work is a comparative study of the impact of Alfa fiber modifications on the Cereplast composites mechanical behavior. Various treatments have been employed, including mechanical, soda, saltwater-retting, hot-water treatments and enzymatic treatment using xylanase. Chemical and morphological analyses were carried out in order to determine the changes of the biochemical composition and the dimensions of fibers. Cereplast composites reinforced with Alfa fibers were fabricated using a twin-screw extrusion followed by an injection molding technique with a fiber load of 20 wt. %. Resulting materials were assessed by means of tensile, flexural and Charpy impact testing. Scanning Electron Microscopy analysis was carried out to investigate the interfacial properties of the composites. The results have shown a significant enhancement of mechanical strengths and rigidities for the xylanase-treated fiber composites, owing to the increase of cellulose content, the enhancement of defibrillation level and the improvement of matrix-fiber adhesion. The data proved that the technology of enzymes can be used as a powerful and eco-friendly approach to modify fiber surfaces and to increase their potential of reinforcement.

Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials

MRS Bulletin ◽  
2010 ◽  
Vol 35 (1) ◽  
pp. 41-47 ◽  
Author(s):  
E. Grossman ◽  
I. Gouzman ◽  
R. Verker
Keyword(s):  
Space Debris ◽  
Synergistic Effects ◽  
Degradation Mechanism ◽  
Space Environment ◽  
Materials Properties ◽  
Gas Gun ◽  
Naturally Occurring ◽  
Space Activity ◽  
The Impact ◽  
Debris Impact

AbstractIn the last 40 years, the increased space activity created a new form of space environment of hypervelocity objects—space debris—that have no functional use. The space debris, together with naturally occurring ultrahigh velocity meteoroids, presents a significant hazard to spacecraft. Collision with space debris or meteoroids might result in disfunction of external units such as solar cells, affecting materials properties, contaminating optical devices, or destroying satellites. The collision normally results in the formation of additional debris, increasing the hazard for future missions. The hypervelocity debris effect is studied by retrieving materials from space or by using ground simulation facilities. Simulation facilities, which include the light gas gun and Laser Driven Flyer methods, are used for studying the materials degradation due to debris impact. The impact effect could be accelerated when occurring simultaneously with other space environment components, such as atomic oxygen, ultraviolet, or x-ray radiation. Understanding the degradation mechanism might help in developing materials that will withstand the increasing hazard from the space debris, allowing for longer space missions. The large increase in space debris population and the associated risk to space activity requires significant measures to mitigate this hazard. Most current efforts are being devoted to prevention of collisions by keeping track of the larger debris and avoiding formation of new debris.

scholarly journals Effects of temperature and impactor nose diameter on the impact behavior of PA6 and PP thermoplastic composites

2018 ◽  
Vol 51 (1) ◽  
pp. 64-74 ◽  
Author(s):  
Akar Dogan ◽  
Yusuf Arman
Keyword(s):  
Load Capacity ◽  
Testing Machine ◽  
Polyamide 6 ◽  
Impact Testing ◽  
Impact Behavior ◽  
Thermoplastic Composites ◽  
Test Machine ◽  
Effects Of Temperature ◽  
Impact Energies ◽  
The Impact

In this study, the effects of temperature and impactor nose diameter on the impact behavior of woven glass-reinforced polyamide 6 (PA6) and polypropylene (PP) thermoplastic composites were investigated experimentally. Impact energies are chosen as 10, 30, 50, 70, 90, 110, 130, and 170 J. The thickness of composite materials is 4 mm. Impact tests were performed using a drop weight impact testing machine, CEAST-Fractovis Plus, and the load capacity of test machine is 22 kN. Hemispherical impactor nose diameter of 12, 7, and 20 mm were used as an impactor. The tests are conducted at room temperature (20°C and 75°C). As a result, the PP composites of the same thickness absorbed more energy than PA6 composites. The amount of absorbed energy of PP and PA6 composites decreased with temperature.

On the impact testing of cyclotrimethylene trinitramine crystals with different internal qualities

2008 ◽  
Vol 103 (9) ◽  
pp. 093517 ◽  
Author(s):  
R. H. B. Bouma ◽  
A. G. Boluijt ◽  
H. J. Verbeek ◽  
A. E. D. M. van der Heijden
Keyword(s):  
Impact Testing ◽  
Cyclotrimethylene Trinitramine ◽  
The Impact

Dynamic effects in the impact testing of brittle materials

1975 ◽  
Vol 10 (4) ◽  
pp. 621-632 ◽  
Author(s):  
P. W. McMillan ◽  
J. R. Tesh
Keyword(s):  
Brittle Materials ◽  
Impact Testing ◽  
Dynamic Effects ◽  
The Impact

Low Velocity Impact Resistance of CPVC Pipes Exposed to Natural Outdoor Weathering Conditions

2012 ◽  
Vol 445 ◽  
pp. 959-964
Author(s):  
Z. Khan ◽  
Necar Merah ◽  
A. Bazoune ◽  
S. Furquan
Keyword(s):  
Impact Resistance ◽  
Outdoor Exposure ◽  
Impact Testing ◽  
Low Velocity Impact ◽  
Pipe Material ◽  
Low Velocity ◽  
Impact Energies ◽  
The Impact ◽  
Impact Events ◽  
Outdoor Weathering

Low velocity drop weight impact testing of CPVC pipes was conducted on 160 mm long pipe sections obtained from 4-inch (100 mm) diameter schedule 80 pipes. Impact test were carried out for the base (as received) pipes and after their exposure to out door natural weathering conditions in Dhahran, Saudi Arabia. The results of the impact testing on the natural (outdoor exposure) broadly suggest that the natural outdoor exposures produce no change in the impact resistance of CPVC pipe material for the impact events carrying low incident energies of 10 and 20J. At the impact energies of 35 and 50J the natural outdoor exposures appear to cause appreciable degradation in the impact resistance of the CPVC pipe material. This degradation is noted only for the longer exposure periods of 12 and 18 months.

Low Velocity and Compression-After-Impact Response of Pin-Reinforced Sandwich Composites

1999 ◽  
Author(s):  
Uday K. Vaidya ◽  
Mohan V. Kamath ◽  
Mahesh V. Hosur ◽  
Anwarul Haque ◽  
Shaik Jeelani
Keyword(s):  
Impact Testing ◽  
Low Velocity Impact ◽  
Sandwich Composites ◽  
Low Velocity ◽  
Static Compression ◽  
Velocity Impact ◽  
Transverse Stiffness ◽  
Impact Studies ◽  
Compression After Impact ◽  
The Impact

Abstract In the current work, sandwich composite structures with innovative constructions referred to as Z-pins, or truss core pins are investigated, in conjunction with traditional honeycomb and foam core sandwich constructions, such that they exhibit enhanced transverse stiffness, high damage resistance and furthermore, damage tolerance to impact. While the investigations pertaining to low velocity impact have appeared recently in Vaidya et al. 1999, the current paper deals with compression-after-impact studies conducted to evaluate the residual properties of sandwich composites “with” and “without” reinforced foam cores. The resulting sandwich composites have been investigated for their low velocity (< 5 m/sec) impact loading response using instrumented impact testing at energy levels ranging from 5 J to 50 J impact energy. The transverse stiffness of the cores and their composites has also been evaluated through static compression studies. Compression-after-impact studies were then performed on the sandwich composites with traditional and pin-reinforcement cores. Supporting vibration studies have been conducted to assess the changes in stiffness of the samples as a result of the impact damage. The focus of this paper is on the compression-after-impact (CAI) response and vibration studies with accompanying discussion pertaining to the low velocity impact.

scholarly journals The Effect of Layers and Bullet Type on Impact Properties of Glass Fibre Reinforced Polymer (GFRP) Using a Single Stage Gas Gun (SSGG)

2014 ◽  
Vol 564 ◽  
pp. 428-433 ◽  
Author(s):  
S.N.A. Safri ◽  
Mohamed Thariq Hameed Sultan ◽  
N. Razali ◽  
Shahnor Basri ◽  
Noorfaizal Yidris ◽  
...  
Keyword(s):  
Impact Energy ◽  
Glass Fibre ◽  
Impact Test ◽  
Single Stage ◽  
Gas Gun ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced ◽  
The Impact

The purpose of this work is to study the best number of layer with the higher impact energy using Glass Fibre Reinforced Polymer (GFRP). The number of layers used in this study was 25, 33, 41, and 49. The impact test was performed using Single Stage Gas Gun (SSGG) for each layers given above with different bullets such as blunt, hemispherical and conical bullets. The gas gun pressure was set to 5, 10, 15 and 20 bar. All of the signals captured from the impact test were recorded using a ballistic data acquisition system. The correlation between the impact energy in terms of number of layer and type of bullet from this test are presented and discussed. It can be summarise that as the number of layer increases, impact energy also increases. In addition, from the results, it was observed that by using different types of bullets (blunt, hemispherical, conical), there is only a slight difference in values of energy absorbed by the specimen.

Effect of Hydrogen Content on Impact Property of A357 Alloy

2011 ◽  
Vol 704-705 ◽  
pp. 1201-1204 ◽  
Author(s):  
Yang Li ◽  
Zheng Bing Xu ◽  
Jian Min Zeng
Keyword(s):  
Crack Propagation ◽  
Hydrogen Content ◽  
Impact Test ◽  
Testing Machine ◽  
Initial Crack ◽  
Impact Testing ◽  
Total Absorption ◽  
A357 Alloy ◽  
Absorption Energy ◽  
The Impact

The impact specimens with different hydrogen contents were solution treated at 540±3°C for 12h; water quenched at 60-100°C; and aged at 165±1°C for 6h. The impact test was carried out at Roell450 pendulum impact testing machine. The impact test results show that the impact energy has strong relation with the hydrogen content. The total absorption energy increases with the increasing of hydrogen content. The crack propagation energy Avp and present larger proportion than the initial crack energy Avi in the total absorption energy Av. The number of the pinholes increases and the pinholes turn from smaller irregular ones into sub-circular shape ones. The specimen with irregular sub-circular pinholes has larger KI, and has more crack propagation resistance.

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