• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.527-532
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• 2000

The armor composite material targets such as aramid FRMLs with different type and ply number of face material and different type of back-up material, were studied to determine ballistic impact resistance and dynamic failure behavior during ballistic impact. Ballistic impact resistance is determined by $\textrm{V}_{50}$ ballistic limit, a statical velocity with 50% probability for complete penetration, test method. Also dynamic failure behaviors are respectfully observed that result from $\textrm{V}_{50}$ tests. $\textrm{V}_{50}$ tests with $0^{\circ}$ obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during high velocity impact tests. As a result, ballistic impact resistance of anodized Al 5052-H34 alloy(2 ply) is better than that of anodized Al 5052-H34 alloy(1 ply), but Titanium alloy showed the similar ballistic impact resistance. In the face material, ballistic impact resistance of titanium alloy is better than that of anodized Al 5052-H34 alloy. In the back-up material, ballistic impact resistance of T750 type aramid fiber is better than that of CT709 type aramid fiber.

• International Journal of Safety
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• v.4 no.2
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• pp.6-11
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• 2005

The goals of the paper are to understand the impact damage behavior and identify the effect of surface protective materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types, which are with and without surface protective material. The visualization for impact damage by two different impactors is made by metallurgical microscope. Based on the impact force history and damage, the impact resistance parameters were employed,rod its validity in identifying the damage resistance of filament wound composite pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the surface protective material were evaluated quantitatively

• Structural Engineering and Mechanics
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• v.32 no.5
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• pp.685-699
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• 2009

Current research and development of high performance concrete, together with study of phenomena that are pertinent to impact resistance, have lead to a new generation of barriers with improved properties to resist impact loads. The paper reviews major properties and mechanisms that affect impact resistance of concrete barriers as per criteria that characterize the resistance. These criteria are the perforation limit, penetration depth and the amount of front and rear face damage. From the long-known, single strength parameter that used to represent the barriers' impact resistance, more of the concrete mix ingredients are now considered to be effective in determining it. It is shown that the size and hardness of the aggregates, use of steel fibers and micro-silica have different effects on performance under impact and on the resistance. Additional pertinent phenomena, such as the rate and size effects, confinement and local versus global response, are pointed out with their reference to possible future developments in the design of impact resisting concrete barriers.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.453-456
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• 2009

Impact resistance of shape memory alloy hybrid composite(SMAHC) plates were experimentally investigated. Shape memory alloy(SMA) have large failure strain and failure stress and can absorb large strain energies through phase transformation. SMA wires were embedded in composite plates to improve their weak impact resistance. Tensile tests of SMA wires were performed at various temperature to investigate their thermo-mechanical properties. Low-Velocity impact tests of several types of composite plates with SMA/Al/Fe were performed. Embedding SMA wires was most effective to improve impact resistance of composite plates. The effects of SMA position on impact resistance were also investigated.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.57
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• pp.243-282
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• 2013

This study aims to develop the research model about the factors that have impact on uTradeHub users' acceptance and resistance to innovation. The followings show the research hypotheses and the results of test. i) The result of H1 empirical analysis confirmed that relative advantage and task adaptedness of e-Trade have more impact on acceptance of innovation than on resistance to it. And also perceived risk and complicity of e-Trade have more impact on resistance of innovation than on acceptance to it. ii) The result of H2 analysis confirmed that the characteristics of foreign trading companies (support by CEO and IT infra maturity) has more impact on acceptance of innovation than on resistance to it. iii) The result of H3 analysis confirmed that characteristics of uTradeHub user' resistance has more impact on resistance of innovation than on acceptance to it. And also, it was confirmed that acceptance of innovation has more impact on the diffusion of e-Trade than resistance to innovation. iv) The result of H4 analysis confirmed that the difference of the degree and factors that has impact on the user's resistance and acceptance by adoption stage of e-Trade. This study has significance in that it arranges the concept and stages of e-Trade systematically and, unlike other studies, it goes beyond the acceptance and diffusion of e-Trade to the inclusion of resistance together in the model.

• Steel and Composite Structures
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• v.44 no.1
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• pp.105-117
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• 2022

Impact resistance efficiency of the newly designed sandwich beam with a laterally arched core as bio-inspired by the woodpecker is numerically investigated. The principal components of the beam comprise a dual-core system sandwiched by the top and bottom laminated CFRP skins. Different materials, including hot melt adhesive, high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS), epoxy resin (EPON862), aluminum (Al6061), and mild carbon steel (AISI1018), are considered for the side-arched core layer of the beam for impact efficiency assessment. The aluminum honeycomb takes the role of the second core. Contact force, stress, damage formation, and impact energy for beams equipped with different materials are examined. A diversity in performance superiority is noticed in each of these indicators for different core materials. Therefore, for overall performance appraisal, the impact resistance efficiency index, which covers several chief impact performance parameters, of each sandwich beam is computed and compared. The impact resistance efficiency index of the structure equipped with the AISI1018 core is found to be the highest, about 3-10 times greater than other specimens, thus demonstrating its efficacy as the optimal material for the bio-inspired dual-core sandwich beam system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.145-146
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• 2023

In this study, the effect of hybrid fiber reinforcement on the residual strength and impact resistance of high-strength cementitious composites exposed to high temperatures was investigated. A cementitious composites was manufactured in which 0.15 vol% of polypropylene fiber (PP) and 1.0 vol% of smooth steel fiber (SSF) were double-mixed, and a residual strength test was conducted while thermal stress was applied by heating test, and then a high-velocity impact test was performed. In the case of general cementitious composites, the rear surface is damaged due to explosion and low tensile strength during high temperature or impact, while hybrid fiber reinforced cementitious composites can repeatedly absorb and distribute stress until multiple fibers are damaged to suppress the propagation of impact and resistance to explosion. Therefore, this study analyzed the residual strength of cementitious composites exposed to high temperatures depending on whether hybrid fibers were mixed or not, and collected research data on fracture behavior through high-speed impact tests to evaluate impact resistance and mechanical properties.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.14-19
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• 2005

One area in which composites have been used rather extensively is for fabricating pressure vessel. These structures can be readily manufactured by filament winding, which is, as far as composite fabrication techniques are concerned, a relatively inexpensive method for producing composite structures. Unfortunately, the higher strength material and fabrication costs are not the only disadvantages of fiber-reinforced polymer composites when they are compared to metals. Additionally, these materials tend to exhibit brittle behavior. This is of particular concern when they are subjected to a low-velocity impact during routine handling a significant amount of structural damage can be introduced into the composites. The goals of this paper are to understand the impact damage behavior and identify the effect of surface coating materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types with and without surface protective material. The visualization for impact damage is made by metallurgical microscope. Based on the impact force history and damage, the resistance parameters were employed and its validity in identifying the damage resistance of pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the protective material were evaluated quantitatively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.8 s.239
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• pp.1109-1117
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• 2005

To identify damage that develops in filament wound composite pressure vessels subjected to low velocity impact, a series of impact tests was performed on specimens cutting from the full scale pressure vessel. The resulting damages by the three different impactors were assessed by the scanning acoustic and metallurgical microscope. Based on the impact force history and damage, the resistance parameters were proposed and its validity in identifying the damage resistance of CFRP pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the impactor shape were estimated quantitatively.

• Earthquakes and Structures
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• v.17 no.6
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• pp.567-575
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• 2019

In order to investigate the dynamic impact resistance of steel fiber reinforced full light-weight concretes, we implemented drop weight impact test on a total of 6 reinforced beams with 0, 1 and 2%, steel fiber volume fraction. The purpose of this test was to determine the failure modes of beams under different impact energies. Then, we compared and analyzed the time-history curves of impact force, midspan displacement and reinforcement strain. The obtained results indicated that the deformations of samples and their steel fibers were proportional to impact energy, impact force, and impact time. Within reasonable ranges of parameter values, the effects of impact size and impact time were similar for all volumetric contents of steel fibers, but they significantly affected the crack propagation mechanism and damage characteristics of samples. Increase of the volumetric contents of steel fibers not only effectively reduced the midspan displacement and reinforcement strain of concrete samples, but also inhibited crack initiation and propagation such that cracks were concentrated in the midspan areas of beams and the frequency of cracks at supports was reduced. As a result, the tensile strength and impact resistance of full light-weight concrete beams were significantly improved.