• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.48-56
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• 2003

This paper investigates the collapse characteristics of CF/Epoxy composite tubes subjected to axial loads as changing interlaminar number and outer ply orientation angle. The tubes are aften used for automobiles, aerospace vehicles, trains, ships, and elevators. We have performed static and dynamic impact collapse tests by a way of building impact test machine with vertical air compression. It is fanad that CF/Epoxy tube of the 6 interlaminar number (C-type) with 90$^{\circ}$ outer orientation angle and trigger absorbed more energy than the other tubes (A. B and D-types). Also collapse mode depended upon outer orientation angle of CF/Epoxy tubes and loading type as well； typical collapse modes of CF/Epoxy tubes are wedged, splayed and fragmentcl.

• Structural Engineering and Mechanics
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• v.12 no.2
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• pp.157-168
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• 2001

In this paper, experimental investigation into the behavior of reinforced concrete (RC) columns tested under large lateral displacement with four different types of loading arrangements is presented. Each loading arrangement has a different system for controlling the consistency of the loading condition. One of the loading arrangements used three units of link mechanism to control the parallelism of the top and bottom stub of column during testing, and the remaining employed eight hydraulic jacks for the same purpose. The loading systems condition used in this investigation were similar to the actual case in a moment-resisting frame where the tested column was displaced in a double curvature. Ten model column specimens, divided into four series were prepared. Two columns were tested monotonically until collapse, and unless failure took place at an earlier stage of loading, the remaining eight columns were tested under cyclic loading. Test results indicated that the proposed system to keep the top and bottom stubs parallel during testing performed well.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.78-78
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• Journal of Welding and Joining
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• v.20 no.6
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• pp.802-808
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.110-113
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• 2004

Aluminum and CFRP tube is light-weight material representatively but collapse mechanism is different under axial loading. Aluminum tube absorbs energy by stable plastic deformation under axialloading. While CFRP(Carbon Fiber Reinforced Plastics)tube absorb synergy by unstable brittle failure but its specific strength and stiffness is higher than that of aluminum tube. In this study, for complement of detect and synergy effect by combination with the advantages of each member, the axialcollapsetests were performed for combined aluminum CFRP tubes which are composed of aluminum tubes wrapped with CFRP out side aluminum square tubes. Collapsecharacteristics were analyzed for combined square tubes which have different CFRP orientation angle and thickness. Test results were compared with that of aluminum tubes and CFRP tubes.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.1-14
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• 1997

In this paper, collapse test of thin-walled structural member widely used for automobiles is carried out under static compression load to observe the effects of cross- sectional shape and material on the energy absorbing capacity in the viewpoint of cras- hworthiness. Specimens tested consist of two sorts(Aluminium, CFRP) and configur- ations(Circular, Square) with variation in thickness. Also, comparisons of Al circular and square specimens are made to find the influence of difference in shape on the energy absorbing capability according as the thickness of specimen varies.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.83-86
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• 2005

The front-end side members of automobiles, such as the hat-shaped section member, absorb most of the energy during the front-end collision. The side members absorb more energy in collision if they have higher strength and stiffness, and stable folding capacity (local buckling). Using the above characteristics on energy absorption, vehicle should be designed light-weight to improve fuel combustion ratio and reduce exhaust gas. Because of their specific strength and stiffness, CFRP are currently being considered for many structural (aerospace vehicle, automobiles, trains and ships) applications due to their potential for reducing structural weight. Although CFRP members exhibit collapse modes that are significantly different from the collapse modes of metallic materials, numerous studies have shown that CFRP members can be efficient energy absorbing materials. In this study, the CFRP side members were manufactured using a uni-directional prepreg sheet of carbon/Epoxy and axial static collapse tests were performed for the members. The collapse mode and the energy absorption capability of the members were analyzed under the static load.

• Earthquakes and Structures
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• v.14 no.4
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• pp.349-360
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• 2018

Reinforced concrete (RC) moment frames supported on two ground levels have been widely constructed in mountainous areas with medium to high seismicity in China. In order to investigate the seismic collapse behavior and risk, a scaled frame model was tested under constant axial load and reversed cyclic lateral load. Test results show that the failure can be induced by the development of story yielding at the first story above the upper ground. The strong column and weak beam mechanism can be well realized at stories below the upper ground. Numerical analysis model was developed and calibrated with the test results. Three pairs of six case study buildings considering various structural configurations were designed and analyzed, showing similar dynamic characteristics between frames on two ground levels and flat ground of each pair. Incremental dynamic analyses (IDA) were then conducted to obtain the seismic collapse fragility curves and collapse margin ratios of nine analysis cases designated based on the case study buildings, considering amplification of earthquake effect and strengthening measures. Analysis results indicate that the seismic collapse safety is mainly determined by the stories above the upper ground. The most probable collapse mechanism may be induced by the story yielding of the bottom story on the upper ground level. The use of tie beam and column strengthening can effectively enhance the seismic collapse safety of frames on two ground levels.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.6
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• pp.114-120
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• 2006

Front-end side members of vehicles are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was undertaken to analyze the energy absorption characteristics of spot welded hat and double hat-shaped section members under the axial collapse. The experiments were performed with respect to the various collapse velocities. It was expected that para-closed sections would show collapse characteristics which be quite different from those of perfectly closed sections. The collapse velocities were selected as follows: the velocities in the hat-shaped section members were 0.00017m/sec, 0.017m/sec, 4.7m/sec, 6.5m/sec, 6.8m/sec, 7.2m/sec, and 7.3m/sec those in the double hat-shaped section members were 0.00017m/sec, 0.017m/sec, 6.5m/sec, 6.8m/sec, 7.2m/sec 7.3m/sec, and 7.9m/sec. In the program system presented in this study, an explicit finite element code, LS-DYNA3D, is adopted for simulating complicated collapse behavior of the hat and double hat-shaped section members under the same condition of the collapse test. The validity of simulation was confirmed by the comparison between the simulation result and the collapse experiment.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.3
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• pp.118-126
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• 1993

Static and dynamic crushing behaviors of composite box tube show the difference with those of metal tube. This paper investigates the characteristics of static and dynamic crushing test which were conducted to characterize the energy absorption and collapse mode of composite box tubes. Sixteen kinds of tube specimens were fabricated from[0/90] woven Glass/Epoxy fabric and autoclave cured. Axial crushing tests were performed using Instron and Dynatup Impact Tester. It is shown that collapse mode and energy absorption capacity can vary according to the aspect ratio, length, loading rate, lay-up direction of fabric, and trigger geometry of the composite box tube.