Ju-Ho Choi

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.

Energy absorption comparison of CFRP tube under humid conditions

Abstract The various parts used in the manufacture of automotives involve a range of different materials. There is now greater emphasis on vehicle safety and, in order to improve this, it is necessary to increase impact absorption capability. Recent research has focused on the suitability of carbon fibre reinforced plastic (CFRP) because of its strength and light weight. It has many advantages but there are also some disadvantages. The performance of CFRP is poor in a hygrothermal environment. Giving CFRP circular members on constant temperature and humidity hinders any impact on the number of interfaces being checked. Specimens for each condition are compared based on change of energy absorption and water absorption rate. We have carried out a static collapse experiment to study the difference of energy absorption and impact modes.

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.

Impact characteristics of CFRP structure member according to variation of stacking condition and impact energy

Abstract Carbon fibre reinforced plastic (CFRP) circular and square members were made of eight-ply unidirectional prepreg sheets stacked at different angles (0/90 and 90/0°, where 0° direction coincides with the axis of the member) and interface numbers (2, 4 and 6) based on the collapse characteristics of the CFRP circular member. In this study, the impact energies at the crosshead speeds of 5·52, 5·14 and 4·57 m s−1 are 611·52, 529·2 and 419·44 J (at circular members), the impact energies at the crosshead speeds of 2·16, 1·85 and 1·67 m s−1 are 372·4, 274·4 and 223·44 J (at square members). The purpose is to examine experimentally the absorption behaviour and strength evaluation, depending on changes in the stacking configuration when the CFRP circular member with different stacking configuration is exposed to separate impact velocity in addition to considering the impact characteristics.

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.