The present study aims at obtaining fundamental design data for improved joint configurations of secondary bonded joints of sandwich constructions for FRP ships. Non.crimp knitted glass fabrics based on infusion molding methods are adopted in construction of FRP ships to substitute conventional woven rovings and chopped strand mats based on hand lay.up molding methods. Joint configurations of stepped lap, single strap and single scarf are comparatively evaluated in terms of joint efficiency. It was experimentally demonstrated that a high joint efficiency larger than90%was achieved on modified stepped lap joints by means of changing two.axial into four.axial fabric with same glass weight since tensile strength of glass reinforcements is better balanced to shear strength of resin matrix.

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It is generally known that the bending resistance of composite film, which consists of organic composition and filler, decreases as the amount and particle size of added filler increases. However, the precise relation between bending resistance(cycles at break in bending test : Bc)and filler has not been clearly known. For this reason, we examined the influence of filler on the Bc of composite film. As a result, we found that there was a linear relationship between the Bc and the specific surface area unit weight of filler in composite film(Sunit).Furthermore, the Bc value of unknown composite film(X)is able to be obtained from the breaking elongation of bulk film(X without filler)and Sunit of X from the linear relationship of the prediction relation. Finally, we verified the usefulness of the prediction relation with the composite film of different organic composition.

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A new manufacturing process was employed for the EMI Shielding film applied to plasma display panel which is one of thin type display and the resin to be applied to the process were developed. The metallic foil pattern should be formed on the resin film with high accuracy in this manufacturing process. It is cleared that the developed resin satisfies this function and keeps stable optical properties so that the cloudiness and discoloration do not occurred. This paper is concerned with the basic design technique for the developed resin.

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Tensile and four-point bending tests on porous ceramics are carried out and their fracture properties are investigated. A formula model was devised and FEM model analysis was carried out in order to simulate the fracture properties. The results obtained are summarized as follows. (1) Experimental results show non.liner deformation during the loading process that is not observed in monolithic ceramics. (2) The fracture model in which porous ceramics is regarded as mixture elements of ceramics and pores is proposed, and this model can simulate well experimental results. (3) FEM models show that the nominal fracture stress for a model with small cross sectional area is smaller than that with larger one. (4) FEM models using pore elements could simulate dispersion of strength that is strongly affected by distribution of pore elements.

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Silicon oxycarbide (SiOC) ceramics are expected as one of the oxidation resistant matrices for ceramic matrix composites. In the present study, silicon oxycarbide ceramics were synthesized through the Sol-Gel route with low environmental impact. The gels were synthesized from ethylalcohol, methyltriethoxysilane (MTES), hydrochloric acid (HCl) and purified water (H2O), and they were pyrolyzed at 1000, 1500 and 1700oC. The structures of gels after heat treatment were analyzed by X-ray diffraction (XRD). XRD results indicated that 硫-SiC was obtained in the present method and crystallization was increased with increasing heat treatment temperature, whereas the number of cracks also increased with increasing heat treatment temperature. For this reason, heat treatment temperature for fabricating composites was decided as 1000oC. Oxidation tests at 1150oC resulted in no weight change in fabricated composites. In order to weaken the fiber/ matrix interfacial shear strength, carbon was coated on the fiber surfaces with epoxy resin acetone solutions. Tensile strength of unidirectional bundle composites with 20% epoxy content solutions became four times as large as that of the specimen without solution. Tensile strength of textile composites also became three times. However tensile strength after oxidation was very low. The silica formation strengthened the fiber/ matrix interfacial shear strength, which result in the reduction of tensile strength.

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This study focused on the skin layers as an improvement of strength, and examined the generation method of skin layers and its effect on mechanical properties such as strength and rigidity of foamed plastics. Concretely, polystyrene resin (PS), polycarbonate resin (PC), and polyvinylchloride resin (PVC) were used and the generation of the skin layers was tried to these resins under various foaming conditions in the batch type foaming process. The obtained foamed plastics with skin layers were carried out three-point bending test and the effect of the skin layers on the strength characteristic was investigated. Consequently, the followings have been clarified. (1) The thickness of the skin layers can be controlled by change of the dispersing time after the blowing agent was saturated and foam temperature and it can be enlarged by lowering the foam temperature, and lengthening the dispersing time. (2) Though the specific strength of foamed plastics without skin layers decreases in from 20% to 30% compared with that of unfoamed plastics, by adding the skin layers, specific strength equal with unfoamed plastics can be obtained. And, the thickness of skin layers contributes to the strength improvement with from 7% to 8% of the thickness of specimen. (3) Though the specific rigidity of foamed plastics without skin layers decreases in from 40% to 50% compared with that of unfoamed plastics, it improves with an increase in the skin layers. And specific rigidity can be maintained with 70% to 80% of unfoamed plastics by adding the skin layers of from 7% to 8% of the thickness of specimen.

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In this study, the unidirectional fiber-reinforced polymer model composites were prepared by controlling the geometric fiber arrangement uniformly and nonuniformly using 20 carbon fibers and epoxy resin. The effects of nonuniform fiber arrangement on the macroscopic fracture properties and mesoscopic fracture process were investigated based on the results of the tensile test and fracture surface observation for the prepared model composites. While the difference in fracture load was scarcely induced by the difference in fiber arrangement uniformity, the matrix cracking morphology was affected by fiber arrangement uniformity. The effect of fiber arrangement uniformity on the fracture process was discussed from the mesomechanical viewpoint.

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Analytical discussion for establishing an failure criterion on fiber/matrix interface by using cruciform specimen method is presented. By changing cruciform angle in which fiber embedded along, interfacial failures in various stress ratio of tensile and shear could be obtained experimentally. In order to establish the interfacial failure criterion in mixed mode, it is necessary to comprehend the relationship between experimental results and initiation location of the interfacial failure which is also dominated by the interfacial failure criterion itself. This relationship is complicated and is desired to be clarified analytically in advance of the experiments. In the present work, interfacial stress distributions are first analyzed by finite element method. And then the logic to obtain the interfacial failure criterion from the experiments is described.

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The structural analysis of textile composites is very difficult because of the complex woven structure. Therefore, various know-how and tools for the analysis have been accumulated to date. In this study, two micromechanical models based on equivalent inclusion method and predictive software tools for the mechanical properties of textile composites have been developed. The inclusion model using Mori-Tanaka method and selfconsistent method are fast and good overall accuracy in the low to mid volume fraction range. However, they lose some micro structural information as yarn segment positions and are not considered in the micromechanics analysis. The inclusion element model can take into account positional information of yarn segments. We consider that it is a very useful model which covers the weakness of the inclusion model. If we can use these resources widely and openly, we will be able to receive considerable benefits in the CAE field of composite materials. Today, the Internet becomes widely used, and the Web technology has been also matured. Consequently, a Java-based internet CAE system has been creatively built using applet and servlet. The developed system is not only easy to use through the Internet by Web browser, but also is not dependent on specific computer environment by Java language and the peripheral technologies.

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