General reliability analysis and strength reliability of ceramics are reviewed. The general statistical theory of brittle fracture derived by the authors involves 3 random variables, namely, fracture stress, fracture location and flaw-orientation angle, which is based on the fracture statistics and fracture mechanics. Using this theory, we can analyze or estimate various fracture-related properties of ceramics, for instance, strength distribution, distribution of fracture location, flaw-size distribution of fracture origin, flaw-orientation angle distribution of fracture origin, fatigue-life-time distribution for individual cause of fracture. Further, theory of Non-destructive inspection and theory of surface strengthening of ceramics are derived using flaw-size distribution function of fracture origin. The significance of the information related to fracture is pointed out with some theoretical and numerical examples.

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It has been suspected that nanoindentation results are often influenced by residual stresses existing in material surface layer. In this work, the influence of residual stress on nanoindentation tests has been studied experimentally. Steel specimens are electrochemically polished to reduce mechanical working layer, and specimens whose surfaces have different residual stresses from -20 to -200MPa are prepared. Indentation results with those specimens shows that compressive residual stresses makes indentation hardness higher.

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It is very important to determine the Yield stress in materials science and its related fields. In particular, there are growing demands for such determinations in the Micro Electro Mechanical Systems (MEMS). In this work, a nanoindentation technique with a spherical tip has been applied to the Yield stress determination for a low carbon steel surface. It has been found that the estimated stress-strain relations are almost agree with those measured by tensile tests when the influence of the residual stress of the specimen surface is taken into account.

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Moire method was introduced by Weller in 1948 and has been improved by many researchers. The classical Moire method, referred to as geometric or coarse Moire has been widely used in experimental stress and strain analysis. Therefore authors have developed an electron Moire method which can be detected the micro-deformation of the specimen. The model grids for this method were fabricated by an electron beam lithography and photo-lithography. Recently, femtosecond laser exposure has been used for fabricate micro-size devices which size is a few micro-meters. In this study, a model grid for an electron Moire method and a scanning laser Moire method were fabricated by a femtosecond laser exposure systems. These model grids were tried to be used for observation of the micro Moire fringe.

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Recently, UV chain curing polymers (CCP), which can cure thick and opaque FRP by applying a UV light to a revealed part of the FRP, have been developed. In the present paper, a refractive index measurement by an embedded optical fiber was applied to monitor chain cure reaction of CCP-based GFRP and CFRP. From the results, it was found that the chain cure reaction of the CCP-based FRP could be monitored by the refractive index measurement method. It also appeared that curing behaviors of temperature and DOC of CCP-based GFRP and CFRP during the chain cure reaction were remarkably different from the behavior of CCP resin.

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This paper reports a new fabrication process for micro composite structure by combination of nano plastic forming, coating and polishing technologies. The nano plastic forming is possible to fabricate smaller structures on the surface of various materials than 1μm without using lithography process. The fabricates small structures are filled with metallic material by using coating technology, and excessive coated layer is removed by polishing. This process is tested on various kinds of micro composite structures.

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Actuators are being found in increasingly various fields and in many applications. And it is one of the most important parts for machines because it determines its performance. In electromagnetic actuators, the performance of coils is very important. In order to obtain narrow width coil lines, the LIGA process can be used to fabricate nano- and micro-scale structure. In this research, we have fabricated microcoil with high aspect ratio coil lines. By using the LIGA process, a coil consisting of 10μm lines and spaces with an aspect ratio of about 5 can be manufactured. For current paths of microcoil, we succeeded a void-free electroplating method to form into narrow pitch coil lines. It is expected that microcoil with high aspect ratio can deliver high performance in spite of miniature size.

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Nickel electroforming is used as a fabrication technology of micro metal mold including LIGA process. However, neither the strength nor peelability of electroformed nickel is enough. There are several methods to improve strength of the metal mold-alloying, and using additive composition of electroplating bath, for example. In this research, we improved the hardness of the metal mold by electroforming on hard and thin nickel electroplating. We used sodium allylsulfonate as an additive for hard nickel electroplating. The hardness was approximately 600Hv and kept the property after annealing of temperature 250℃. Finally, we fabricated nickel mold has micro pattern and the thickness of 4mm.

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Diamond-like carbon (DLC) film was deposited on Si(100) substrate by a focused ion-beam chemical vapor deposition (FIB-CVD) method to investigate microstructure of a DLC/Si interface. The microstructure was analyzed by high-resolution transmission electron microscopy (HRTEM) equipped with energy dispersion microscopy (EDS). Bright field images showed that a transition layer existed at the DLC/Si interface. From EDS analysis, it was found that the transition layer consisted of both C and Si atoms, and has a thickness of around 100nm. HRTEM images and convergence beam electron diffraction patterns revealed that the transition layer was structurally divided three layers, i.e. amorphous, clustered and crystalline Si-C layers.

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This report deals with the precision grinding of micro fresnel shape with many micro grooves and precision molding of micro glass fresnel lenses. Fresnel lenses are useful for the next generation type of optical devices because of its thin structure and excellent optical characteristics. In the conventional method, the lens materials were restricted to plastics, because the cutting tool was a single crystal diamond and the mold material was restricted to a soft metal such as copper or electroless deposited nickel-phosphorous (Ni-P) alloy. In this study, a new grinding method and a new sharp edge truing method were developed and the molds of glassy carbon for IR lenses were ground in trial and a ultra precision glass lenses were molded.

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In this paper, in order to investigate the validity of the tightening control by an acoustic emis-sion (AE) method, tightening tests were conducted under actual conditions and both tightening accuracy and variations compared with those by conventional control methods. The results showed that the AE method was more effective for plastic-region bolt tightening control than conventional ones. A new system for controlling plastic-region bolt tightening by AE method was developed.

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Guided waves propagating in the circumferential direction of a pipe (Circumferential guided waves: CGWs) have been in the spotlight as one of the improved method for a small defect detection. While an inspection area of the CGW is restricted in the circumferential area, the sensitivity for a small defect is high due to the high frequency (0.5-5MHz) used. In this paper, wide range selective generation of the CGW are proposed by using tone-burst signals with several center-frequencies. Generated CGWs are verified with time-frequency analyses in comparison to the theoretical dispersion relations.

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We have proposed a new ultrasonic method for measuring internal temperature distribution of heated materials. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis method using a finite difference model has been developed to determine one-dimensional temperature distribution in a heated plate. To demonstrate the practical feasibility of the developed method, a steel plate of 30mm thickness is heated by contacting with molten aluminum at 700℃ and ultrasonic pulse-echo measurements are then performed for the steel during heating. The internal temperature distribution and its transit variation determined ultrasonically agree well with those obtained using thermocouples installed in the steel.

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In many fields of engineering, there are growing demands for measuring surface temperature distribution of heated materials. In this work, application of laser ultrasound technique to non-contact surface temperature measurements of heated materials has been studied. A thick aluminum plate is heated and the surface acoustic wave and surface temperature are continuously monitored using a laser ultrasound system and an infrared camera, respectively. The temperature dependence of the surface wave velocity of the aluminum is then determined. It has been found that the temperature dependence is almost linear in the temperature range up to 230℃. This result could be used for ultrasonic measurements of surface temperature distribution of heated materials.

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A microstructural study was performed on transient liquid phase (TLP) bonded Waspaloy superalloy with a Ni-Cr-B filler. The applicability of a diffusion model to determine the time required for complete isothermal solidification (tf) was investigated. Over the temperature range of 1065-1110℃ experimental observations of tf were in reasonable agreement with tf values predicted by the diffusion model. However, a notable deviation was observed in joints prepared between 1175 and 1225℃ in that the rate of isothermal solidification was reduced at these temperatures resulting in the formation of a centerline eutectic-type microconstituent, which in contrast, was prevented from forming after holding the brazing assembly for an equivalent bonding time at a lower temperature of 1145℃.

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The braze pressure welding (BPW) of the austenitic stainless pipe is conducted under the various joining condition with various filler metal; two Fe-based filler metals, four Ni-based filler metals and their mixture are used. With CR3B Fe-based filler metal, the metallographic observation and the elemental analysis reveal the formation of sound joint. This joint has the enough tensile strength demanded for the commercial standard. The distribution of Cr around the joint interface is not uniform, which might lower the corrosion resistance. The mixture of filler metals forms the residual layer in the joint interface which weakens the joint. The higher joining pressure and the uniformity of the temperature distribution around the joint interface contribute to the formation of sound joint. The usage of Fe-based filler metal with richer Cr and Mo as minor element and the higher joining pressure is considered to provide the better condition.

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