• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.1
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• pp.64-70
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• 2009

This study is to analyze the impact of automotive body with computer simulation. The total deformation, equivalent strain and strain and principal stress are analyzed respectively in case of front, rear and side impacts. The maximum total deformation of side impact is more than 6 times as large as that of rear impact. The maximum equivalent strain or stress of side impact is more than 4 times as large as that of rear impact. These deformation, strain and stress of front impact are a little more than those of rear impact. The maximum principal stress of side impact is more than 4.5 times as large as that of rear impact. This stress of front impact is a little more than that of rear impact.

• Structural Engineering and Mechanics
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• v.27 no.4
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• pp.409-424
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• 2007

In this paper, an identification method of impact force is proposed for composite structures. In this method, the relation between force histories and strain responses is first formulated. The transfer matrix, which relates the strain responses of sensors and impact force information, is constructed from the finite element method (FEM). Based on this relation, an optimization model to minimize the difference between the measured strain responses and numerically evaluated strain responses is built up to obtain the impact force history. The identification of force history is performed by a modified least-squares method that imposes the penalty on the first-order derivative of the force history. Moreover, from the relation of strain responses and force history, an error vector indicating the force location is defined and used for the force location identification. The above theory has also been extended into the cases when using acceleration information instead of strain information. The validity of the present method has been verified through two experimental examples. The obtained results demonstrate that the present approach works very well, even when the internal damages in composites happen due to impact events. Moreover, this method can be used for the real-time health monitoring of composite structures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.8 no.2
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• pp.69-75
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• 2009

This study is analyzed by impact simulation according to material property at terminal case of hand phone. Maximum equivalent stress or strain at plastic is 40 times as great as that at magnesium alloy. And the next greatest stress or strain is shown at aluminium alloy. The value of maximum equivalent stress is shown as 6.5 Mpa in case of plastic, magnesium alloy and aluminium alloy. Maximum shear strain at plastic is 40 times as great as that at magnesium alloy. And the next greatest strain is shown at aluminium alloy. The value of deformation or strain at magnesium alloy and aluminium alloy is not different.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.158-159
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• 2017

In this study, it evaluate the strain properties of fiber reinforced concrete and fiber reinforced cement composite. The types of fiber are Hooked steel fiber and it was mixed 0.5, 1.0 vol.% in concrete and 1.0, 2.0 vol.% in cement composites. The impact test was conducted by using a projectile (diameter: 25mm, velocity: 170m/s) and strain properties on the rear side of each specimen was evaluated by strain gage. After the impact test, fracture grade, fracture depth was evaluated.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.304-309
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• 2000

Strain gage method is used to evaluate the mode I dynamic stress intensity factor of marging steel(18Ni) and titanium alloy(Ti-6A1-4V). To decide the best strain gage position on specimen, static fracture toughness test was performed. Then instrumented charpy impact test and dynamic tensile test was performed by using strain gage method for evlauating dynamic stress intensity factor. Strain gage signals on the crack tip region are used to calculate the stress intensity factors. It is found that strain gage method is more useful than method by using load which is obtained from impact tup to assess dynamic characteristics such as dynamic stress intensity factor.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.611-616
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• 2020

Polycarbonate (PC) materials having electrical insulation properties, are thermoplastic material and are easily processed, have excellent strength and heat resistance characteristics, and also have transparent and hard characteristics. In this study, we tried to derive the ε-N curve of strain-life, which shows the relationship between the strain characteristics and the life of the material when repeated impact loads are applied to the PC plastic material. As the impact load increased to 3.0kg, 4.0kg, 5.0kg, and 6.0kg, the strain also increased linearly to 0.033, 0.041, 0.046, and 0.055. At 3.0kg of mass impact, the test piece broke with 12000 impact cycles, 8400 times at 3.5kg, 7400 times at 4.0kg, 6600 times at 4.5kg, 4700 times at 5.0kg, 3000 times at 5.5kg, and 1000 times at 6.0kg. The number of fractures exponentially decreased as the load gradually increased. Using these results, an ε-N curve for PC plastic was derived.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.4
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• pp.21-27
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• 2007

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. Therefore the prediction of impact energy in design process is very helpful to the most of breaker manufacturers. In this study, we carried on modeling and simulation of a hydraulic breaker to predict impact energy via commercial CAE software. The modeling and simulation of a hydraulic breaker was achieved with two parts. One is a hydraulic circuit analysis part via AMESim and the other is impact strain analysis part via ANSYS.

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.1931-1939
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• 1993

The wave propagation characteristics of laminated composites subjected to a transverse high-velocity impact of a steel ball is investigated. For this purpose, high-velocity impact experiments were conducted to obtain the strain response histories, and a finite element analysis based on the higher-order shear deformation theory in conjunction with the static contact law is used. Test materials for investigation are glass/epoxy laminated composite materials with $[0^{\circ}/45^{\circ}/0^{\circ}/-45^{\circ}]_{2s}$ and $[90^{\circ}/-45^{\circ}/90^{\circ}-45^{\circ}/90^{\circ}]_{2s}$ stacking sequences. As a result, the strain responses obtained from the experiments represented the wave propagation characteristics in the transversely impact, also the wave propagation velocities obtained from high-velocity impact experiments and wave propagation theory agree well.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.139-144
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• 2004

Dynamic crack initiation in ductile steel is investigated by means of impact loaded 3 point bend(PB) specimens. Results from non-viscoplastic and viscoplastic materials are compared. Their materials are applied with various impact velocities and static strain rates. The specimen has the size 320${\times}$750 mm with a thickness of 10 mm. A modified 3PB specimen design with reduced width at the ends has been developed in order to avoid the initial compressive load of the crack tip and also to avoid the uncertain boundary conditions at the impact heads. Numerical simulations are made by using the FEM code ABAQUS. Therefore, their results are plotted by shapes of the von Mises plastic stress and equivalent plastic strain of the specimens applied by various impact velocities.