Woo-Chae Hwang

Collapse behavior evaluation of hybrid thin-walled member by stacking condition

Abstract The recent trend of vehicle design aims at crash safety and environmentally-friendly aspect. For the crash safety aspect, the energy absorbing members should absorb collision energy sufficiently but for the environmentally-friendly aspect, the vehicle structure must be light weight in order to improve the fuel efficiency and reduce the tail gas emission. Therefore, the light weight of vehicle must be achieved in a securing safety status of crash. An aluminum or carbon fiber reinforced plastics (CFRP) is representative one of the light-weight materials. Based on the respective collapse behavior of aluminum and CFRP member, the collapse behavior of hybrid thin-walled member was evaluated. The hybrid members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, the effects of the stacking condition on the collapse behavior evaluation of the hybrid thin-walled member were tested. The collapse mode and energy absorption capability of the hybrid thin-walled member were analyzed with the change of the fiber orientation angle and interface number.

Optimal crashworthiness design of CFRP hat shaped section member under axial impact

Abstract The designing of vehicles should be more concerned with the aspect of securing safety performance, while reducing the weight of vehicle structural members should also be taken into consideration. Carbon fibre reinforced plastics (CFRPs) of the advanced composite materials as structural materials for vehicles have a wide application in lightweight structural materials of air planes, ships and automobiles because of their high strength and stiffness. The objective of this study is to investigate the energy absorption characteristics of CFRP hat shaped section members under the axial impact collapse test. The CFRP side members were made of 8‐ply unidirectional prepreg sheets stacked at different angles (±15°, ±45°, 90°, 0°/90° and 90°/0°, where 0° direction coincides with the axis of the member) and interface numbers (2, 3, 4, 6 and 7). The axial impact collapse tests were carried out for each section member. The collapse mode and the energy absorption characteristics of each member were analysed.

Impact characteristics of double-hat cross-section carbon fibre reinforced plastic members for optimal crashworthiness design

Abstract The global demand for reduction in the weight of automobiles has led many countries to focus on the development of hybrid, eco-friendly and electric cars. A reduction in the weight of materials can both increase fuel efficiency and maximise automobile performance. In this study, carbon fibre reinforced plastic members with double-hat cross-sections were manufactured. Impact crushing tests were performed with changes in the stacking conditions such as variations of stacking angles and interface numbers. The impact crushing mode and absorbed energy were quantitatively analysed according to the changes in the stacking conditions. This analysis was performed to obtain design data that can be applied in the development of optimum lightweight members for automobiles.

Crushing behavior of lightmass structural member

Carbon fiber reinforced plastic (CFRP) of the advanced composite materials is widely used in lightmass structural materials of air planes, ship and automobiles because of high strength and stiffness. In this study, experimental investigation was performed for each specimen. The square section members consist of aluminum, CFRP and hybrid (aluminum/CFRP) member, and hat-shaped section members consist of CFRP and hybrid (aluminum/CFRP) members specimen. Based on the collapse characteristics of aluminum square section member, the collapse characteristics and energy absorption capability of hat-shaped section members were analyzed. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed. In the lightmass design aspect, the collapse characteristics and energy absorption capability of the members were compared.

Impact characteristics of carbon fibre reinforced plastics structural members according to the variation of stacking conditions

Abstract Circular and square carbon fibre reinforced plastics members were made of eight-ply unidirectional prepreg sheets stacked at different angles based on the collapse characteristics of circular carbon fibre reinforced plastics members. In this study, the impact energy at the crosshead speeds of 5·52, 5·14 and 4·57 m s−1 were 611·52, 529·2 and 419·44 J (in circular members), and 2·16, 1·85 and 1·67 m s−1 were 372·4, 274·4 and 223·44 J (in square members). The purpose was to experimentally examine absorption behaviour and strength depending on changes in the stacking configuration when circular and square carbon fibre reinforced plastics members with different stacking configurations were exposed to separate impact velocities. The impact characteristics were also considered.

Energy absorption characteristics of lightweight structural member by stacking conditions

The recent trend in vehicle design is aimed at improving crash safety and environmental-friendliness. To solve these issues, the needs for lighter vehicle to limit exhaust gas and improve fuel economy has been requested for environmental-friendliness. Automobile design should be made for reduced weight once the safety of vehicle is maintained. In this study, composite structural members were manufactured using carbon fiber reinforced plastic (CFRP) which are representative lightweight structural materials. Carbon fiber has been researched as alternative to metals for lightweight vehicle and better fuel economy. CFRP is an anisotropic material which is the most widely adapted lightweight structural member because of their inherent design flexibility and high specific strength and stiffness. Also, variation of CFRP interface number is important to increase the energy absorption capacity. In this study, one type of circular shaped composite tube was used, combined with reinforcing foam. The stacking condition was selected to investigate the effect of the fiber orientation angle and interface number. The crashworthy behavior of circular composite material tubes subjected to static axial compression under same conditions is reported. The axial static collapse tests were carried out for each section member. The collapse modes and the energy absorption capability of the members were analyzed.

A study on collapse behavior and energy absorption capability of Al/CFRP hybrid structural member

In vehicle industry, the design of vehicle should be inclined towards the safety performance aspect, at the same time; it also should have weight loss of a vehicles structural member. In this study, experimental investigations are performed for Al/CFRP Hybrid structural members. They are cured by heating to the appropriate curing temperature (130°C) by means of a heater at the vacuum bag of the autoclave. Because the CFRP is an anisotropic material whose mechanical properties, such as strength and elasticity, change with its stacking condition, special attention was given to the effects of the stacking condition on the collapse behavior evaluation of the Al/CFRP Hybrid structural members. The collapse mode and energy absorption capability of the Al/CFRP Hybrid structural members was analyzed with change of the fiber orientation. The stacking condition were selected to investigate the effect of the fiber orientation angle (±15°, ±45°, 90°, 0°/90°and 90°/0° where 0°direction coincides with axis of the member)on the energy absorption of the Al/CFRP Hybrid structural members. The collapse mode and energy absorption capability of Al/CFRP Hybrid structural members was analyzed with change of the fiber orientation of CFRP.

Axial collapse characteristics of CFRP composites with stacking conditions under the hygrothermal

CFRP composite material has superior specific strength and rigidity compared to metallic material, and is widely adopted in the various fields. Exceptional corrosion resistance enables the acceptance in maritime structural members such as ship and oildrilling machineries. However, CFRP composite material has the weakness in hygrothermal environment and crash environment. Especially, moisture ingress into composite material under hygrothermal environment can change molecule arrangement and chemical properties. In addition, interface characteristics and component material properties can be degraded. An experimental investigation was carried out to study the crash evaluations of CFRP composites to dynamic crushing by impact loading. We have made a collapse experiment to research into the difference of absorbed energy and deformation mode between moisture absorbed specimen and non-moisture absorbed specimen. As a result, the effect of moisture absorption and impact loads of approximately 30~50% reduction in strength are shown.