It is needed for the application of advanced composite materials to light weight structures in industrial or public use that cost reduction, good conformability and anti-delamination are to be established in their fabrication. In this article, various kinds of textile preforms for composites that possess three dimensional fiber orientation and net shape are reviewed, categorizing the preforms by structural dimension and orientating axial numbers. Textile composites are applicable to mass production of light weight structures which satisfy any definite requirement, by establishing the textile preforming process and the following process for consolidation of textile reinforcement and matrix resin.

抄録全体を表示

Thermal properties of carbon fiber reinforced carbon matrix, C/C, composites were determined in the temperature range between 20℃ and 2000℃. As thermal properties, specific heat, thermal conductivity, thermal diffusivity, coefficient of thermal expansion, and emissivity were evaluated as a function of temperature. Three kinds of laminate type C/C composites, unidirectional, cross-ply, and quasi-isotropic, were examined. In addition to representation to temperature dependence of above-mentioned thermal properties, comparison was made between measured thermal properties with theoretical predic tions. Main difficulty in the prediction of the thermal properties were to simulate complex microstructures of the C/C composites, i. e., porous structure and dispersed transverse cracks. As far as thermal conductivity and coefficient of thermal expansion were concerned, it was shown that the Eshelby model was effective and gave reasonable prediction, because of its versatility to simulate the complex microstructure.

抄録全体を表示

The viscoelasticity of a composite material is influenced especially by the strength of adhesive bonding between resin and fiber. The viscoelastic properties are investigated from the viewpoint of interfacial properties of composites. A significant concept named 'balance stress', which reflects viscoelastic properties of a composite, is introduced. While balance stress indicates the strength of adhesive bonding in the interface, interfacial bonding is evaluated strength creep behavior of the material, analysed with a three element model of the material into viscoelastic coefficients. On the other hand, the three viscoelastic coefficients have strong relation to fatigue process of a composite material, reflecting fatigue damage. Some experimental results for composites are shown and discussed on the basis of viscoelastic properties. The viscoelasticcoefficients proved to be a helpful measure to estimate both interfacial properties and fatigue damages of composite material.

抄録全体を表示

Fracture mechanism of hydrogen embrittlement has not been clarified yet, in spite of a lot of studies One of the reasons is due to difficulty of catching directly the evidence of hydrogen. Then, atomic computer simulation is expected to answer this problem. A review of atomistic computer simulation and of results of hydrogen embrittlement is presented A. question whether hydrogen embrittlement is caused by lattice decohesion or enhancement of plastic deformation due to hydrogen is also discussed.

抄録全体を表示

Fracture surface of amorphous polymer such as epoxy resin, which is remained by stable growth of crack from a sharp and smooth initial crack under viscoelastic environment of mechanical behaviors, is at a glance covered with featureless fine river-stream pattern. The energy absorption by a crack accompanied by this type of fracture surface is so low that the most dangerous circumstances arise occasionally in actual situation in the industrial design. Since the current type of fractography techniques can not reveal the features of structure and morphology of fracture surface of this type in detail, a computer-aided fractgraphy technique that can be applicable to extremely smooth fracture surface of amorphous polymer has to be newly developed. At first, the authors apply several types of texture analysis to the case of epoxy resin, such as the analyses of frequency, run length, and the extrema, then discuss on the usefulness of the method for understanding the feature of disperse pattern of fracture surface image. Also, quantitative analysis is examined on fracture surfaces produced by a steady crack growth.

抄録全体を表示

This paper presents the design method of materials composed of some ingredients by using neural network. In a field of synthetic material design, it is possible to find the elastic properties of synthetic materials from distribution ratio of ingredients using Finite Element Method. But in practice it is largely wanted to find distribution ratio of ingredients from the properties of synthetic materials. Up to now, a trial-and-error technique to do that have been used. Therefore it is required a great deal of labor to find distribution ratio of ingredients. In this paper, the neural network system for material design, that if only the properties of synthetic material are input to the system, distribution ratio of ingredients can be output automatically, is proposed. From the numerical examples of simple material design, it is shown that the proposed method is much available.

抄録全体を表示

We have proposed two methods to improve structural reliability of brittle materials. One of them is a simple evaluation of strength distribution using a simultanious loading of many test pieces. The other is to establish a wise (Ken）material with self-diagnosing function. Concernig to the later concept, we have developed carbon-fiber-glass-fiber-reinforced plastic composite (CFGFRP), in which fatal fracture can be foreseen by monitaring the electrical resistance during and after straining. The resistance change of this composite is statistically interpreted using the fracture mode in the simultanious loading system. The resistance change of the CFGFRP is found to be statistically reliable and reproductive.

抄録全体を表示

This paper presents fracture toughnesses of 2-D carbon-carbon composites using compact tension specimens. Purpose of this study to evaluate the fracture toughness of the C/C composite based on a linear fracture mechanics. The crack growth resistance curves are obtained using a compliance matching method. As a result, the R-curves of the C/C composite are characterized by a rapid increase in the crack growth resistance at the initial stage and a distinct in the final stage. It is found that fracture toughness in the C/C composite is greatly influenced by a crack front region which is formed by a micro-crak and /or an interfacial delamination. In order to explain the unloading and the reloading stage of the load-displacement curves, a fracture model in the C/C composite is proposed.

抄録全体を表示

In this paper, experimental evaluation of thermal residual stress in 90°ply in CFRP cross- ply laminates was conducted. Temperature dependence of thermal expansion conefficient and Young's modulus was measured. Furthermore, deflection of unsymmetric cross-ply laminates was measured as a function of temperature to determine stress-free temperature and thermal residual stress (ply separation method). Thermal residual stress calculated by using the thermal expansion coefficient and Young' modulus was compared with the value obtained by the ply separation method.

抄録全体を表示

Cold forged products obtained from preliminarily rolled rods of HDPE, PP, POM, ABS and PVC were studied on their elastic and thermal recovery, and secular chnge of dimension. The optimum amount of reduction of area in rolling, and effect of heat treatment, were made clear in order to attain the best qualities of cold forged products. The cold forged products obtained from preliminarily rolled rod was found to have extremely good dimensional stability by heat treatment in boiling water bath. This cold forging process was applied to make small machine parts such as knob, and good results were obtained.

抄録全体を表示