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RISS 인기검색어
- 검색키워드
- 저자 : Abrar H. Baluch (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Effect of velocity variation on carbon/epoxy composite damage behavior
Baluch, Abrar H,Kim, Chun Gon SAGE Publications 2016 Journal of composite materials Vol.50 No.15
<P>In this paper, the damage mechanism for carbon fiber-reinforced polymers composites was studied from low- to high-velocity impact for different velocity ranges. Initially, the composites were manufactured by using CU125NS prepreg in quasi-isotropic 16 layers pattern [0/+/- 45/90](2s) in autoclave by adopting standard procedures. Specimens were also exposed to the simulated LEO environment and 0.42% total mass loss occurred due to out-gassing. Afterwards, the specimens were impacted with Al2017-T4 spherical projectiles of 5.56mm in diameter, 0.25g in weight for different velocities ranging from 500m/s to 2200m/s. With the impact velocity increase, the energy absorption was found to increase in the composite specimens, while the ratio of energy absorbed to total impact energy remains the same on average. Mainly, the fiber breakage and matrix fracture play a critical role in energy absorption, but delamination contribution also found increasing trend with the increase of impactor velocity. Afterwards, C-SCAN analyses were conducted to investigate the damage patterns, and it was found that the damage area increased with higher velocities. The delamination contribution increased on average by 12.7% for the velocity range of 2200m/s in comparison to that for 502m/s. On the basis of these findings, it was concluded that the contribution of fiber breakage, matrix fracture and delamination towards the damage mechanism of composites is greater for higher velocities.</P>
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Behavior of composite structures orientations towards their failure and damage
Baluch, Abrar H,Kim, CG SAGE Publications 2015 Journal of composite materials Vol.49 No.29
<P>In this paper, carbon/epoxy composites were employed as a potential candidate for spacecraft structural shielding along with the new concept of geometric configurations according to the threat severity to maximize the impactor energy absorption to improve performance. Carbon/epoxy composites of quasi-isotropic 16 layers [0/ ± 45/90]<SUB>2s</SUB> were manufactured using an autoclave, and the specimens were exposed to a low Earth orbit environment, which produced an average total mass loss of 0.42%, mainly due to outgassing. Al2017-T4 spherical projectiles with a diameter of 5.56 mm weight of 0.25 g were used as the impactor in the velocity range of 1500 ± 500 m/s. Earlier experimentations showed the superiority of obliquity towards energy absorption for single bumpers. Double bumpers with one 45° obliquity at 100 mm standoff absorbed 14% more specific energy than double bumpers with one at 30°; both of them were found to be superior to normal–normal bumpers by 40% and 30% on average, respectively. By CSCAN, it was also found that oblique impact on the first bumper resulted in less damage on the rear bumper and resulted in the superiority of the proposed geometric configurations, which enabled enhanced protection and designs according to threat severity.</P>
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High Velocity Impact Characteristics of Shear Thickening Fluid Impregnated Kevlar Fabric
Park, Yurim,Baluch, Abrar H.,Kim, YunHo,Kim, Chun-Gon The Korean Society for Aeronautical and Space Scie 2013 International Journal of Aeronautical and Space Sc Vol.14 No.2
The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 km/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 nm diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.
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High Velocity Impact Characteristics of Shear Thickening Fluid Impregnated Kevlar Fabric
Yurim Park,Abrar H. Baluch,YunHo Kim,Chun-Gon Kim 한국항공우주학회 2013 International Journal of Aeronautical and Space Sc Vol.14 No.2
The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 ㎞/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 ㎚ diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.
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Sathish Kumar, Sarath Kumar,Jurado-Manriquez, Edwin Antonio,Kim, YunHo,Choi, Chunghyeon,Baluch, Abrar H.,Kim, Chun-Gon Elsevier 2018 COMPOSITE STRUCTURES -BARKING THEN OXFORD- Vol.188 No.-
<P><B>Abstract</B></P> <P>This paper deals with how the use of Polybenzimidazole (PBI) as a film coating over conventional composite designs could help improve the hypervelocity impact ballistic performance of the system. PBI coated composite samples were studied for resistance to Low Earth Orbit environment conditions like high vacuum, thermal cycling, Atomic Oxygen and Ultraviolet Radiation in a simulation facility. It was observed that the PBI coated composites reduced mass loss and surface erosion compared to the non-coated samples after LEO exposure. Hypervelocity impact experiments were conducted on the PBI coated composites for impact velocities between 2.5 to 3 km/s. The experiments showed that the PBI film coating significantly increased the energy absorption of the composite system. The effect of thickness increase as a result of the film application on energy absorption was also found to be negligible confirming the effectiveness of PBI coating as a hypervelocity shield.</P>
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