Key Engineering Materials Vols. 334-335

Abstract: To enhance dispersion stability of magnetorheological (MR) fluids, hybrid magnetic particles of carbonyl iron (CI)/ poly(vinyl butyral) (PVB) with core/shell microstrcutre (CI-PVB) were prepared, since pure magnetic CI based MR fluid systems show severe sedimentation of the CI particles due to the large density mismatch with the carrier liquid and difficulties in redispersion after caking. The composite particles of CI-PVB have a lower density than that of the pure CI particles, while exhibiting almost original magnetic property of the CI. Both CI and CI-PVB particles were dispersed in mineral oil (20 vol%) and their MR characteristics were examined via a rotational rheometer with a magnetic field supplier. Various characterizations of the CI-PVB particles were performed via SEM, TEM and FT-IR. Both yield stress and flow curve of shear stress as a function of shear rate of the MR fluids were investigated under applied magnetic field strengths.

Abstract: 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.

Abstract: In this work, flux method is used to control the surface morphologies and crystal structures of the fine K2Ti6O13 fibers. When K2CO3 as a flux is added into fine K2Ti6O13 fibers and heated at 1100oC for 2h, the crystal of fibers are transformed to K2Ti4O9 and K2Ti2O5, however, the resulting fibers have no significant change in morphologies. On the other hand, when KCl is used as flux (15wt%) and heated at 1200oC for 2h, the diameters of the resulting fibers become about 2 micron without any change of the crystal structure.

Abstract: In the present investigation, mold filling process of resin injection/compression molding (RI/CM) is compared with resin transfer molding (RTM) for simple mold geometry. To do this, analytical solutions are obtained for RI/CM in unidirectional flow. Based on the analytical solutions, flow front progression and pressure distribution are compared with RTM at different fiber content. The results indicate that the RI/CM reduces the mold filling time significantly, particularly for composite parts with higher fiber content.

Abstract: The estimation method of the damping properties for woven composites has proposed. The proposed method has been applied to the plain woven composites. From these results, it is recognized that the computational damping properties have agreed with the experimental ones. Next, the effect of angle of fiber bundle on material damping of plain woven composites has investigated. The results show that the damping ratio is highest at angle of 45 degree.

Abstract: Numerical simulation for unidirectional hoop composite laminates under flexural loads was finished. The change of tensile and compressive stresses, the position of local crush and delamination and stiffness degradation were analyzed with parametric program compiled by APDL language in ANSYS. The results showed that composite laminate could bear the load continually after local crush and delamination. Displacements of calculated result with stiffness degradation model matched test results well.

Abstract: Biodegradable composites made from bagasse fiber and biodegradable resin were prepared and the biodegradation were investigated by the soil burial test in terms of the effects of fiber content, alkali treatment to bagasse fiber and different soil. The biodegradable resin showed some extent biodegradation. The addition of bagasse fiber caused the acceleration of weight loss of the fiber reinforced composites in comparison with the neat biodegradable resin. The weight loss of the composites increased with the increase in the fiber content, which could attribute to the preferential degradation of bagasse fiber and the resin around the fiber. However there was no significant difference in weight loss between untreated and alkali treated fiber composites. Furthermore, it is noted that the weight loss drastically increased in the case of the composites buried in the microorganism enriched soil. This results from the increase of bacteria and fungi in soil. The photographs and SEM micrographs showed the degradation of the resin and the composites.

Abstract: The general aim of this work is to provide a numerical tool devoted to the description of thermosetting matrix properties evolutions all over the cure. The study is related to quality of cure and residual stress state topics, especially for thick matrix. A formulation as simple as possible of some important basic couplings that occur during the cure of a class of structural thermosetting matrix is proposed. A methodology of linking thermal, diffusion and mechanical phenomena together is presented. First FEM results of cure simulation are presented and compared with experimental data of the cure.

Abstract: A unique melt spinning equipment for E-glass is compatibly combined with a melt spinning extruder to manufacture commingled yarns. The in-situ commingling enables to combine homogeneously both glass and polypropylene filament arrays in one processing step and without fibre damage compared to commingling by air texturing. Best composite performance is achieved with a sizing for glass fibres consisting of aminosilane and maleic anhydride grafted polypropylene film former, which enable a good strand integrity with the polypropylene yarn. The results of fundamental research on variation of technological processing conditions like diameter ratios, draw ratios, variation of cooling conditions and arrangements of intermingling are reported for glass fibre/polypropylene systems.