Goichi Ben

Examination of heat resistant tensile properties and molding conditions of green composites composed of kenaf fibers and PLA resin

Disposing of conventional fiber-reinforced polymers (FRPs) poses an environmentally challenging problem. Disposal of FRPs by combustion discharges carbon dioxide in the air because the resin of FRPs is made of fossil fuel. When they are disposed of in the ground, FRPs remain semi-permanently without decomposing. In response to these problems, green composites are now being developed and are extensively studied as a material that produces a lower environmental burden. In this paper, green composites using kenaf fiber yarn bundles and PLA (poly(lactic acid)) are fabricated and their tensile properties are evaluated in the experiment. The tensile Youngs modulus of all of the laminations is larger than that of PLA alone and the tensile strength of some laminations is larger than that of PLA alone. In particular, the value of UD composite of 0° shows double the tensile strength of PLA alone. Furthermore, the molding conditions for fabricating with a hot press are investigated and the heat resistant tensile properties of green composites are also reported.

Fabrication method and compressive properties of CFRP isogrid cylindrical shells

Since isogrid structures are composed of triangular grid stiffeners and a surface skin, they have a high specific strength and stiffness. These structures are now being mainly used for aerospace applications. In order to produce a metal isogrid cylindrical shell, most of the thick metal plates must be cut off while the remaining thin surface skins with the stiffeners and both ends of the skins are welded to each other. This process needs a long lead time and a high cost, and unstable behaviors are observed in the joint parts. On the other hand, carbon fiber reinforced plastics (CFRP) isogrid cylindrical shells can be fabricated with an integral method by using a filament winding apparatus. In this study, a fabrication method of the CFRP isogrid cylindrical shells is proposed and their compressive tests are carried out to investigate the reinforcement effect of the grids on the CFRP isogrid cylindrical shells. Furthermore, the results of the static compressive tests are compared with numerical ones obtained by finite element method (FEM).

Impact strength and response behaviour of CFRP guarder belt for side collision of automobiles

In automobiles, carbon fibre reinforced plastic (CFRP) has a possibility of weight reduction in automotive structures which can contribute to improve mileage and then to reduce carbon dioxide. On the other hand, the safety of collision should also be made clear in the case of employing CFRP in automotive structures. In this paper, the CFRP guarder belt equipped in the automotive door is developed and examined by an experiment and a numerical analysis for replacing the conventional steel door guarder beam. In the numerical analysis, a commercial FEM solver (ANSYS) was employed and the laminated shell element was used in the CFRP guarder belts. The contact element between the impactor and the upper surface of CFRP guarder belt, and between the supporters and the inner surface of the belt was No. 173 with the target element No. 170. The experimental relation of impact load to displacement for CFRP guarder belt agreed considerably with that of the numerical result. After the comparison of both the results it has been found that the numerical method developed here is quite useful for estimating the impact behaviour of the CFRP guarder belt.

Evaluation of quasi-isotropic plate and cylindrical shell fabricated with green composite sheets

Conventional fiber reinforced plastics (FRPs) have some problems in the case of disposal. Their combustion disposal discharges the carbon dioxide in the air because resins of FRPs are made of fossil fuel. In the case of disposal into the ground, these FRPs remain semi-permanently without decomposing. Therefore, green composites are now developed and are studied as one of less the environmental burden materials. In this study, two kinds of continuous green composite sheets, which were composed of Kenaf fibers or Linen fibers as reinforcement and biodegradable poly butylene succinate (PBS) resin as a matrix, were fabricated with a pultrusion molding. Since the PBS resin is a thermoplastic resin, the PBS/KENAF or PBS/LINEN composite sheets can be treated as intermediate materials such as Carbon Fiber Reinforced Plastic prepregs. In order to apply the PBS/KENAF or PBS/LINEN composite sheets to structural components, quasi-isotropic plates and cylindrical shells were fabricated and evaluated.

Development and Evaluation of Mechanical Properties for Kenaf Fibers/PLA Composites

A new type of composite used biodegradable resins and natural fibers is now being developed and this new type of composites is designated as a green composite. This paper presents a fabrication method and mechanical properties of the green composite used Kenaf fibers as the reinforcement and PLA as the matrix. In order to obtain the higher tensile strength, various kind of surface treatments were executed on the Kenaf fiber and some parameters were changed during the process of fabrication. Then, these effects on the strength of green composite are also reported.

Pultrusion techniques and evaluations of sandwich beam using phenolic foam composite

Phenolic resin has the excellent properties of fire resistance, low smoke production during burning, and a good balance between its cost and mechanical properties compared with other types of resin used in fire-resistant polymers (FRPs). If phenolic resin can be employed as a matrix of FRP, such FRP can have a higher fire safety factor which will be a desirable property in the structures of vessels and railway carriages. However, for the case of the resole type of phenolic resin, water formed from the condensation reaction remains in the matrix, and this water evaporates resulting in the formation of voids during the curing process. In order to develop a new type of phenolic composite that can overcome this weakness, we used a foam type of phenolic resin and glass fibers as the matrix and the reinforcement, respectively. We, then, developed a new pultrusion technique for the new phenolic foam composite and examined its mechanical properties and thermal conductivity.In this paper, we report a new technique to mold not only a phenolic foam composite but also a sandwich beam in which the phenolic foam composite as a core and a thin phenolic FRP layer as a faceplate are used. We also investigated the compressive strength and elastic modulus under high temperatures and compared the result with that at room temperature. Finally, we show that the compressive properties of the phenolic foam composite and the sandwich beam are stable at higher temperatures.

Effects of Temperature on Mode II Fracture Toughness of Multidirectional CFRP Laminates

End notched flexure (ENF) tests were performed to investigate the effects of temperature and fiber orientation on Mode II interlaminar fracture behavior, GIIC (GII at the crack initiation), of carbon fiber-reinforced epoxy composites, T800H/#3631. The values of GIIC for three kinds of laminates, [012//012], [22.5/-22.5/08/-22.5/22.5//-22.5/22.5/08/22.5/-22.5] and [45/-45/08/-45/45//-45/45/08/45/-45], with a pre-cracked interface, that is // in each laminate, were obtained at three temperatures, i.e. -100°C, 25°C and 150°C. It is shown that GIIC is obviously affected by the temperature and fiber orientation. The scanning electron microscope (SEM) observation was also carried out to investigate the fracture surface. SEM analysis suggested that the decreased Mode II interlaminar fracture toughness for all kinds of specimens at high temperature could be attributed to temperature-induced matrix property change or fiber-matrix interfacial weakening.

Evaluation of new GFRTP and CFRTP using epsilon caprolactam as matrix fabricated with VaRTM

Abstract Thermoplastic resins used as a matrix of fiber reinforced thermoplastics (FRTPs) are composed of high polymers that remain highly viscous even at a higher temperature than their melting points. As a result, they need an even higher temperature, a higher pressure and a longer processing time to allow them to bond with fibers that require large and specialized equipment. In contrast, fiber-reinforced thermoset plastics (FRPs) can be easily molded owing to the use of lower viscosity liquid resin as the matrix using simpler devices. In this paper, a new fabrication method of FRTPs using in situ polymerizable ε caprolactam as the matrix is presented. This method uses vacuum-assisted resin transfer molding without the need for large and specialized equipment. The ε-caprolactam molecules were converted from their monomer form into a polyamide 6 resin, with ring-opening polymerization of ε-caprolactam during the molding process at a lower temperature than its melting temperature. The two kinds of FRTPs obtained using ε-caprolactam as the matrix had neither voids nor unfilled parts because ε-caprolactam had a very low viscosity before the polymerization. These FRTPs not only exhibit superior bending properties but also are suitable for high-speed molding, namely, within a few minutes of process time.

Development of Simulation Technology for Impact Behavior of CFRP/Al Alloy Hybrid Beams in Side Collision of Automobiles

Carbon fiber reinforced plastic (CFRP) laminates are used in various industrial fields because they have excellent properties in their specific strength and specific stiffness. The CFRP has a potential of weight reduction in the automotive structure, which can contribute to the improvement of mileage as well as the reduction of carbon dioxide. On the other hand, the safety issue in case of collision should be also clarified when employing the CFRP as automotive structures. In this paper, hybrid beams which consisted of an Al alloy beam and a CFRP laminate were examined by both experiments and numerical analyses as candidates to replace the conventional steel door guarder beam used inside the automotive door. The experimental relations of impact loading to the displacement for the Al beams with different thicknesses, widths and types of CFRP showed good agreement with those from numerical results. In order to increase the impact energy absorption, other hybrid beams were devised and calculations performed by using the same parameters in the same numerical method and their results also agreed with those of experiments executed after the calculation. These facts show that the numerical method developed here can be generally used for estimating the impact behavior of CFRP/Al hybrid beams. Furthermore, a suggestion for how to install the hybrid beam to automotive doors was proposed by the numerical method. As a result, the effectiveness of our simulation technology is demonstrated here.

Development and Impact Behaviors of AL Door Guarder Beam Reinforced with CFRP for Side Collision of Automobiles

Carbon fiber reinforced plastic (CFRP) laminates are used in the wide field, because they have excellent properties of a specific strength and of a specific stiffness. The CFRP has a possibility of weight reduction automotive structures which can contribute to improve mileage and then to reduce Carbon dioxide. On the other hand, the safety of collision should be also made clear in the case of employing the CFRP to automotive structures. In this paper, the Al guarder beam reinforced with the CFRP is examined by an experiment and by a numerical analysis for replacing it to the conventional steel door guarder beam equipped in the automotive door. The experimental relations of impact load to displacement for the Al guarder beams with the different thickness of CFRP showed the good agreement with those of numerical results. From the comparison of these results, the numerical method developed here is quite useful for estimating the impact behaviors of Al guarder beam with CFRP layer.