This investigation demonstrates that scanning tunneling microscoky (STM) and stomic force microscopy (AFM) are capable of performing in-situ nanoscopic visualization of initiation and growth processes of localized corrosion in aqueous solutions. We discuss advantage and disadvantage of STM and AFM for in-situ visualization in aqueous solutions: an AFM is more suitable compared with an STM for in-situ visualization of localized corrosion damage, from the standpoints of scanning speed, stability and capability of imaging non-conducting surface of corrosion products. The nanoscopic initiation and growth mechanisms of localized corrosion of pitting corrosion, intergranular corrosion and stress corrosion crack of an austenitic stainless steel and 7XXX series aluminum alloys are dincussed based upon nanoscopic in-situ visualization by using STM/AFM.

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Researches on the hydrogen embrittlement of Ni and Ni based alloys in which phase transformation does not occur are reviewed. Characteristics of hydrogen diffusion, influence of hydrogen on the flow stress and the fracture mechanism of hydrogen embrittlement are discussed. Plastic deformation seems to play an important role in hydrogen embrittlement of Ni and Ni alloys in comparison with that of iron and steels. In spite of many efforts, however, the fracture mechanism of hydrogen embrittlement has been under the discussion. Then, different approaches may be needed.

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The computational simulation method of micro-mechanical behavior in metal matrix composites containing short fibers is studied to predict the macroscopic nonlinear stress-strain relationship of the metal matrix composites. Three-dimensional nonlinear finite element analysis is developed for two kinds of periodic array of the fiber distributions. Then, we also take account of the residual stresses in the composites, which are due to the difference of thermal expansion coefficients of fiber and metal matrix. After the validity of the computational simulation method is examined with the experimental results of a SiC particle reinforced 6061 aluminum alloy composite, the effects of the arrangement, volume fraction and aspect ratio of fibers, and the residual stresses on the macroscopic stress-strain relationship of a SiC whisker reinforced 6061 aluminum alloy composite at room temperature are clarified quantitatively.

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Delamination is one of the most critical failure modes in a laminated composite structure. In order to improve the interlaminar fracture toughness, the concept of “interlayer” has been applied to the thermoset composite materials. In the present paper, the static interlaminar fracture characteristics of the interlayer toughened carbon/epoxy, T800H/3900-2, was examined and compared with those of a thermoplastic composite, APC2, as a reference. Fracture region transition, which is deflection of crack path from interlayer to intralaminar, is observed in the static Mode Ⅰ interlaminar crack growth of T800H/3900-2. Mode Ⅰ interlaminar fracture toughness, G _IR, during the propagation decreases in relation to the decrease of the interlayer fracture surface area. Mode Ⅱ crack growth resistance curve (R-curve) was obtained under the constant CSD rate by applying the stabilized ENF test. The remarkable fracture region transition is not observed in the Mode Ⅱ R-curve of T800H/3900-2, and the toughened carbon/epoxy composite exhibits excellent crack growth resistance under Mode Ⅱ loading.

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In this study, the evaluation method of fracture toughness values in the stable fracture process of Sheet Molding Compounds: SMC has been researched by the experimental fracture mechanical methods for an elastic-plastic material using a compact type test piece. The length of the stable crack growth is measured by the colored method by ink. Fracture toughness value is evaluated by J-value calculated by Rice's method. The stable fracture process is shown by R-curve. The value of J_in that is a fracture toughness value at the point of stable crack initiation is decided by the results. Furthermore, the stable fracture process has been evaluated by the diameter of the damage zone at notch tip. The damage zone is obtained by the development of surface cracks. It is found that the diameter depends on the change of the fracture toughness values and the stable crack growth and also this relation is confirmed in the case of corrosion condition.

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Coefficients of thermal expansion (CTEs) of ZrO₂ particle/Al₂O₃ and ZrO₂ particle /SiC whisker/Al₂O₃ composites were experimentally ditermined in the temperature range of room temperature to 1200K. In order to examine capability of CTE design of ceramic matrix composites, CTEs of constituent materials (monolithic ceramics) were also axamined. Temperature dependence and relative magnitude of CTEs for the monolithic ceramics were shown to be easily understood from the viewpoint of the relation of Grüeizen. Using the low of mixture based on the equivalent inclusion method, it was demonstrated that accurate design of CTE can be made, provided that temperature dependency and magnitude of CTE of SiC whisker is assumed to be smaller tcan that of the bulk SiC. This CTE behavior of SiC whisker was shown to be reasonable from the viewpoint of Grueisen relation and Ruffa's theory, because the theory leads to low CTE and slow and gradual increase of CTE with temperature when elastic modulus and thus the Debye temperature are becomes higher.

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The establishment of a dynamical procedure to develop suitable theoretical models and the production of new data and knowledge for the purpose of materials design are set as the final target of developing a computerized materials data system on high-Tc superconducting materials. Suitable data formats are proposed and required functions of data ananlysis are developed for this purpose with flexibility for continuously data updating. A series of case studies are carried out to demonstrate the efficiency of the proposed data processing method and the validation of a developed theoretical model that reflects the energy-level structure of carrier holes. The calculations of the Madelung potentials for the high-Tc superconducting cuprates are taken as the first step of developing this theoretical model. The case studies using the developed model confirm the important role that hole transfer plays in determining the superconducting properties of yttrium superconducting cuprates, and also show a direction of materials developments effectively.

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It is well known that photoviscoelastic technique can be used as an experimental technique for viscoelastic stress and strain analysis. However, this technique is far too complicated, because the transient birefringence and temperature should be continuously measured over the period of the loading process in order to determine the transient stress and strain. The uncertainty of the reliability of the numerical solution of viscoelastic stress analysis still exists essentially, because the analytical conditions employed for numerical calculation, such as material parameters, configuration and boundary conditions and others, should be numerically modeled. In this paper, an approach to experimental and numerical hybrid analysis of the stress and strain in a viscoelasic body, which is straightforward and reliable, is proposed. In this analysis, the experimental birefringence measured easily at arbitrary time is compared with that numerically calculated for the purpose of assuring the reliability of the numerical results. The effectiveness of the proposed method is assessed by a specific example, in which the thermal stress generated in a rectangular epoxy beam subjected to rapid cooling is analyzed by this hybrid method.

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This paper is concerned with the prediction of a long term creep deformation of epoxy resins used as matrix resins for CFRP. Short term creep compliances for epoxy resins were measured at various temperatures. Long term creep compliance predicted by applying the modified reciprocation law of time and temperature to these short term creep compliance at various temperatures is fairly well agreed with that directly measured by long term creep test at a constant temperature. Furthermore, it is found that the modified reciprocation law is applicable in a limmited temperature range.

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