The technique of ultrasonic welding has been successfully applied to amorphous alloys, which can be welded to some amorphous alloys and to other metallic materials such as aluminium and copper etc. Those welding techniques can be considered for possible application where the welding is achieved either at a low temperature or by a short welding time of a thin surface layer followed by ultrasonic welding. The short time heating at the interfaces during the welding process has no effect on the crystallization of amorphous alloy. The weldability of such a materials must be strongly limited by the low thermal stability of amorphous state. Additional studies on the welding mechanism and on the weldability of amorphous alloys to various materials are in progress.

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This paper describes a study of application LCA (Life Cycle Analysis/Assessment） concept on polymer based composite materials. Composite materials are considered that they are not environmental conscious materials because of their difficulty in recycling. However, they can be used for a long time compared with conventional materials. In addition, they can bring high fuel efficiency by reducing weight of products. Therefore, environmental load of materials should be evaluated all through lifetime period and applying LCA to composite materials is important to develop environmental conscious composites. In this paper, first, application LCA to CFRP is mentioned. And to evaluate environmental load per unit performance, the calculation system for selecting materials according to mechanical properties using WWW is introduced. Finally, sensitivity analysis examples for polymer data are presented and difference of importance among inventory data is discussed.

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This paper describes an investigation of a critical parameter establishment for initiation and propagation of debonding crack at fiber-matrix interface of PMC. FEM analysis is carried out based on the single-fiber composite pull-out test by using the axisymmetric cylindrical pull-out model, and investigate the complex stress intensity factor and the variation of energy release rate G according to the progress of interfacial debonding crack. Thermally induced stress due to thermal expansion mismatch at fiber-matrix interface and a work hardening property of the matrix are also considered in FEM. As a result of FEM analysis, it becomes clear that the maximum of total energy release rate G_total originates from interference of a quickly increasing G₂ (shear part）and a sharply decreasing G₁ (normal part）at the very short interface crack length. This proposed method contributes to the understanding of the fiber pull-out process and provides a tool for the analysis of experimental results towards a fracture mechanics criterion of the debonding crack at the fiber-matrix interface.

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Matrix cracking behavior in thermally-cycled interlaminar-toughened CFRP cross-ply laminates under static tensile loading is investigated experimentally. Tensile tests are performed after thermal cycling between -70℃ and 150℃. Transverse matrix crack density is measured as a function of the laminate strain. The effect of the number of thermal cycles on matrix cracking is observed experimentally. The experimental results are compared with analytical predictions based on a two-dimensional elastic analysis considering the effect of thermal residual stresses. It is found that the effect of thermal cycles on matrix crack behavior can be characterized as change in the critical values for transverse cracking.

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Tension, creep and low cycle fatigue tests were carried out on smooth specimens of polycarbonate at room temperature at strain rate of the order of 10-4/s. Our attention was focussed on the yield behavior of polycarbanate under quasi-static load conditions. The necking and cold-drawing behavior is observed commonly in individual tests. The experiment shows that the creep failure and the low cycle fatigue failure are governed by the tensile properties. On the basis of the yield behavior in tension of polycarbonate, the experimental results of creep and low cycle fatigue tests can be explained, and the limiting condition for creep failure is determined.

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The authors derived the method to obtain length distribution of visible part of fibers in transplanted matrix. The position and direction of the fibers in a high volume fraction composite are affected by adjacent fibers. In view of the fact, the authors assumed that fibers are coupled in the composite. Some useful results were obtained by numerical calculations. The direction distribution of the visible parts is unaffected by the distance between the coupled fibers, although the average length of the visible part decreases with the increasing distance.

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The laser Raman and the FT-infrared microspectroscopic analyses were applied to evaluate the interfacial degradation behavior in a model composite of aramid fiber (Kevlar49) and unsaturated polyester (UP） in water at 30 and 90℃. The residual tensile stress, which was preliminarily introduced into the embedded fiber by removing the static tension after curing the specimen, was measured by the laser Raman technique. The progress of interfacial degradation was monitored from the variation in the residual stress. The quantity and the structure of absorbed water in the matrix very near the interface were analysed by the infrared spectra for the thin film speciemn, in which the fiber was not subjected to pre-tension during the cure. The residual tensile stress in the fiber was monotonously decreased in hot water at 90℃, although the stress reduction at early stage was mainly caused by the relaxation of elastic modulus of matrix resin. In water at 30℃ the residual stress remained the initial value for long time above 1000h. At early stage of immersion the isolated water was mainly observed, and then the amount of clustered water was increased with increasing time, particularly at 90℃. It remains to be elucidated which type of water more strongly contributes to the interfacial degradation.

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A prediction method of fatigue strength of polymer composites for an arbitrary frequency, stress ratio, and temperature is proposed. The method is based upon the four hypotheses, (A）failure mechanism for CSR (constant strain-rate）, creep, and fatigue failure is the same, (B）the same time-temperature superposition principle holds for all failure strengths, (C）linear cumulative damage law is applicable for specimen failure under nondecreasing stress process, and (D）fatigue strength shows linear dependence upon stress ratio. Flexural CSR, creep, and fatigue strengths of satin-woven CFRP laminates were measured at various loading rates and temperatures. The validity of hypotheses B, C, D, and the applicability of this prediction method were experimentally confirmed by creep tests and fatigue tests of different conditions of loading rate and temperature. It was also confirmed that the hypothesis A is not necessarily always for this prediction method through discussions.

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Inflatable space structures are expected to be a promising candidate for future large scale space structures because of the lightness and compactness of the volume at the launch stage. In this paper plausibility of a inflation structure was examined utilizing the expansion force of foam materials for the inflation thrust. As a trial inflatable space structure, an sandwich-structured extension mast was chosen, i.e., made of foam materials covered with an aluminum sheet or a carbon fiber cloth, due to the simple extension mechanism. As the first report of the inflation structures, this paper describes forming behavior of urethane foam in a tube and mechanical properties of processed foam rods. The discussion was at first done with respect to the effect of tube geometry on the expansion behavior. Compressive modulus and strength were then examined. Various phenomena appearing in the forming process were pointed out and their influence to the compressive modulus and the strength were studied by use of Gibson and Ashby model.

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Propagation of indentation fracture was firstly monitored on α-SiC ceramics through a current drop accompanied by the decrease in current conduction area. The current decrease ratio before and after indentation during the constant voltage application was proportional to the crack area formed. However, during the indentation, the current anomalously increased even though the indentation crack propagated. This phenomena is probably due to the piezoresistance effect which has already been reported in SiC single crystal. When bending stress was applied to α-SiC ceramics, the current increase ratio was proportional to the bending strain. A fracture foreseeing system is proposed for α-SiC ceramics in which initial crack monitoring without stress application and bending strain monitoring utilizing the piezoresistance effect are combined.

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Films have been often resin-bonded to base plates for electronic parts requiring various high quality-functions. If these parts should be fatigue-fractured, the expected function would no longer be performed. It is necessary, therefore, to clear an important factor controlling the fatigue fracture of these parts. In this work, as the model specimens, the commercial grade iron films with the thickness of 100μm were bonded to the steel base plate by diffusion, or by using cyanoacrylate and epoxy resins. In the fatigue testing results obtained using these specimens, including the film thickness of 50 μm bonded with epoxy resin, there was a tendency for the adhesive resin layer to fracture readily at the initial fatigue stage but to protect a damage caused in the base plate during fatigue, thus resulting in the increase of the fatigue lives of the film-bonded plates. This tendency was extremely strong for the fllm-bonded plate with compressive residual stresses on the film subjected to the shrinkage deformation of epoxy adhesive resin, in the solidification during a cooling process.

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A new method for determining fringe order and the principal direction of birefringence from a single image combining an elliptically polarized white light and color image processing for practical photoviscoelastic analysis is developed. To determine fringe order, a data-base-search approach based on the primary color analysis is employed. After determining fringe order, the principal direction of birefringence is obtained by solving a non-linear equation. The successful applications of the method to photoelastic and photoviscoelastic analyses are shown. It is emphasized that the proposed method can be applicable to time-varying phenomena since multiple exposures are not necessary for sufficient data acquisition to complete stress analysis.

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In the recent situation where the application areas to the elastomers (rubber-like elastic materials）is increasingly expanded and their more frequent utilization is found out, demands are growing for their more information on strength, fracture characteristics, wear resistance and fatigue resistance. As many studies have already been conducted on their tensile strengths and tensile energies, no study has at present been found out on their fracture characteristics nevertheless its undoubted importance. Under such aspect, a fundamental research is executed in the present paper on three types of the elastomer materials comprising, polyurethane rubber, using the fine dot methods to clarify characteristics and the materials evaluations of the elastomer materials and obtain their deformation behaviors and fracture processes. This paper, however, discusses that the crack opening displacement can be an important parameter for quantitative evaluation of strength characteristics of the elastomers.

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