We have successfully developed a time-resolved imaging method based on photoelasticity technique, which make it possible to directly and dynamically obtain the images of laser induced transient stress field. Using this method, the effects of sacrificial coatings on laser induced stress wave can be visualized. Our results prove black paint coating has been able to significantly enhance the laser induced stress wave. In an attempt to reach quantitative analysis of laser induced stress form photoelasticity images, simulation based on FEM has also been carried out.

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Closed-cell porous aluminum is a multifunctional material with both lightweight and high energy absorption properties. These properties are considered to be governed by morphology of pores of porous aluminum. In this study, compression test was conducted in the X-ray CT system and deformation process of pores was nondestructively observed during compression. It was shown that deformation process of individual pore can be observed in this system.

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The ultra-thin palladium membrane was diffusion-bonded with the austenitic stainless steel SUS304 disks at various temperature and with the bonding time of 1,800s under the pressure of 0.2 MPa. The cross sections of the joined interface were examined using FE-SEM. The element distribution showed that the counter diffusion between the Pd membrane and SUS304 austenitic stainless steel was not occurred apparently at the bonding temperature of 1,000℃. But at 1,100℃, the counter diffusion made the Pd membrane totally change into the intermetallic compound. According to the results, the nominal diffusion coefficient of Pd/SUS304 was obtained.

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Porous aluminum is a lightweight material with high energy absorption properties. In this study, porous aluminum / dense steel sandwich panel was fabricated by friction stir processing (FSP) route. It is expected that both mixing a blowing agent into aluminum and bonding the aluminum precursor to dense steel plate can be conducted simultaneously by FSP. It was shown that sandwich panel which had high interface strength with porosity of approximately 90% was successfully fabricated at a holding temperature of 1003 K and at a holding time of 14 min 30 sec.

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Recently, porous aluminum has attracted special interest as a new functional material. However, the application of porous aluminum remains limited due to high-cost fabrication and low productivity. To overcome these problems, the authors proposed a new fabrication method by using friction stir processing (i. e. FSP route precursor method). In this study, at first, the precursors of ADC12 and A1050 are fabricated by FSP route individually and those precursors are welded by friction stir welding (FSW). Moreover, by foaming the welded precursor, ADC12-A1050 porous aluminum is manufactured. Based on the cross-sectional images of the porous aluminum, porosity and pore structures are examined. Although ADC12-A1050 bonded precursor begins to foam from the part of ADC12, ADC12-A1050 porous aluminum with high porosity and high circularity can be manufactured under proper forming conditions.

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The joining phenomena during the friction process of pure titanium (Ti) and pure copper (OFC) friction welding was investigated. When the joint was made at a friction pressure of 60MPa or lower, the OFC side was deformed from both weld faying surfaces contacting. Then, the joint generated the sparkle from the Ti side with increasing friction time. The peripheral portion of the Ti side was heavily deformed and intensely upset when it had the sparkle. On the other hand, the joint did not have the sparkle of the Ti side when it was made at a friction pressure of 75MPa or higher. The deformation of the OFC side was large and intensely upset. The fact that the joining phenomena had dissimilarity was due to the difference of the yield strength at the temperature in the friction process.

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It was investigated that effect of the thermal history during the braze-pressure-welding process for the austenitic stainless steel to its sensitization property. The SUS304 austenitic stainless steel pipes were joined using the braze-pressure-welding method with the induction heating. The cleaning metal, or insert metal, was the Fe-base alloy (Fe(Bal.)-20Cr-l0Ni-3Si- 2.5B-1Mo). For the cross section samples of the pipe wall with various distance from the joint interface, the degree of the sensitization was measured using the EPR method. The grain size of the samples was also measured to modify the degree of the sensitization. The value of the sensitization was high at the vicinity of the joint interface, but it dropped with the distance. It was shown that the severe sensitization did not occur by the BPW process.

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There are difficulties to obtain the sound joint by brazing of the carbon-fiber-reinforced carbon (CFC) composites and refractory metals. Those difficulties are caused by the CFC composites' strong anisotropy in mechanical properties, especially in the thermal expansion coefficient. In this research, the proper orientation of CFC composites to the brazing interface is investigated. A cross-ply laminate CFC composites plate was cut with various angles to the fiber direction. Their end faces were perpendicular to the laminate direction. The end face was brazed to pure titanium disk in the vacuum. The active brazing filler of Ag-32.25Cu-1.75Ti (Cusil-ABA[○!R], Wesgo Metals) was used. The brazing temperature was at 830℃, and the keeping time was 300s. For the brazed joint, the tensile joint strength and the shear joint strength were measured. When the angle of fiber direction and the brazing interface was 45℃, the joint tensile joint strength reached to the maximum value. So did the shear strength of the brazed joint.

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Gas shield arc welding is widely used as a high deposition rate welding process with a shielding gas to prevent an oxidation of welding metal. In this research, a welding system which is possible to maintain strength of joint in the automatic welding by detecting the position of welding wire tip and the welding line was constructed. In order to increase the reliability of the system, an image processing algorithm which can decrease the influence of spatters during the welding and increase the percentage of the welding line detection was discussed. In order to confirm the validity of the system, the constructed system was applied to the welding control experiments.

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Carbon fiber reinforced plastics (CFRP) has a great potential application in aircraft fuselage due to their high specific stiffness and specific strength. It is crucial to coat the CFRP surface with a high conductivity metal in order to reduce the effect of lightning strike on the aircraft. Thermal spray process can be used to produce coating on CFRP substrate. However, the volume resistivity of thermal sprayed coating is higher than that of its bulk metal. Moreover, the coating obtained is porous and has high oxidation content. The cold spray process is an attractive method to make a dense and tight coating without any detrimental effects acquired from the high temperature process. On this study, aluminium coating was successfully cold sprayed onto CFRP substrate with interlayer coating processed by plasma spray. The volume resistivity of coating was significantly lower than coating produced by plasma spray process

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Powder Jet Deposition (PJD) technique was applied to the formation of a ceramic coatings in atmosphere and at room temperature. In additional benefits, the PJD is very simple and compact because small solid particles impinge on substrate by a splay nozzle. Therefore, it is possible to apply the PJD to the creating and repairing ceramic coatings for large and complex structures like engines of next generation space plane etc. The aim of this study is to optimize of the spray parameters of condition of aluminum titanate ceramic coatings on several substrates by the PJD technique and to clarify the mechanism of ceramics deposition. In the case of oxide ceramic coatings, lower particle velocity was better for the deposition in this study. The optimized spraying pressure, which can obtain the thickest deposition, is approximately 0.05MPa. In this case, the particle velocity was measured in approximately 90m/s by high-speed camera.

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From April 2009 to March 2011 we are progressing the "Research committee for construction of modeling, analyzing, evaluation CAE systems on joint structures". This committee is consisted of following three subcommittees. (1)Bolted joint structures, (2) Adhesive joints and (3) Fretting fatigue. Now these subcommittees have given many results, so we will make an interim report taking advantage of this conference.

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The wear process in a bridge typed fretting fatigue testing under a partial and gross slip conditions was analyzed using finite element method. The property of wear dispersed energy within one cycle loading was elucidated on the relationship of local contact pressure and also relative slip. The behaviors of the contact pressure on fretting surface and tangential stress which change with fretting number of cycles were clarified. Fatigue life evaluation parameters, i.e., SWT (Smith-Watson-Topper) and equivalent stress in modified Goodman's diagram, were analyzed under contact wear process, and the relationships between those parameters at fretting fatigue limits and the wear volume and elastic-plastic deformation were discussed.

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In the present study fretting fatigue behavior of 304 austenitic stainless steel has been investigated by carrying out fretting fatigue tests using 304 austenitic stainless steel specimens with two different heat treatment conditions (as received and sensitized condition) under three different contact pressures using bridge type 304 austenitic stainless steel contact pads. Finite element analysis was performed to evaluate the tangential stress range and compressive stress range at the contact edge. Tangential stress range - compressive stress range diagram has been constructed at various fretting fatigue lives. Tangential stress range -Compressive stress range diagram of 304 stainless steel has been compared with the generalized tangential stress range -compressive stress range diagram obtained for trbine steel and automotive steel.

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Application to the bolt is advance the expansion of the use of the titanium system materials. Therefore, the bolt made of the titanium alloy that it is low cost and the friction characteristic is more excellent is developed. In this report, to apply the titanium alloy newly developed to the bolt, a tightening and impact strength characteristic are examined. And performance as the bolted joints was examined.

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In transverse fatigue of a bolted joint, the apparent fatigue limits (the highest amplitude of transverse vibration force which can be applied to the bolted joint without generating fatigue) vary according to the bolt tightening conditions even if the bolt size and the property class are the same. Hence, it is necessary to develop a guideline to safety and appropriately design bolted joints under transverse vibration. In this study, a method to predict the apparent fatigue limit of the bolted joint using the fatigue limit of a bolt material has been developed.

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I perform the fatigue life evaluation of the stress concentration to own the stress singular place by Manson - Coffin low with a plasticity strain range, but, as for the evaluation, it is difficult. Therefore I introduce it because I inspected the validity from the breakdown test result of the torque limiter whether I can evaluate it by binding fatigue and Critical Distance at the time of the destruction and relations of the stress value at that time together by a straight line as one approach for a high cycle.

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In the recent years, researches on the natural fiber reinforced composites have been increasing. They are also expected as alternatives materials for traditional composites. Although natural fiber has many advantages, use of animal-based natural fibers such as silk fiber (SF) in a biocomposite material has been rarely reported. Therefore, the silk fiber reinforced poly(butylene succinate) (PBS) biodegradable composite was investigated in the present study. The mechanical properties of silk fiber reinforced PBS biodegradable composites (SF/PBS) were studied. The tensile tests of the long fiber unidirectional PBS biodegradable composites and cross-ply laminate with different fiber surface treatments were carried out. It was found that the experimental results showed that Young's modulus and the tensile strength of SF/PBS composite are the highest when using fibers with sericin removal. In analysis, Young's modulus in unidirectional composite is predictable by the rules of mixture. In addition, Young's modulus and Poisson's ratio in cross-ply laminate are predictable by the laminate theory.

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In predicting the mechanical properties in fiber reinforced composite materials, it is very important to evaluate the mechanical properties in reinforcing fibers. However, it is not very easy because of the small diameter of fibers. It is known that carbon fibers have anisotropy and the mechanical property is assumed to be orthotropic or transversely isotropic. However, few examples of direct measurements of the anisotropic elastic constants of carbon fiber are seen. In the present study, we made an attempt to evaluate the elastic constants in a carbon fiber as a transversely isotropic material. If we assume that a carbon fiber is a transversely isotropic material, there are five independent elastic constants, that is, axial Young's modulus, the axial Poisson's ratio, the transverse Young's modulus, the transverse Poisson's ratio and the axial shear modulus. In the first place we tried to evaluate the axial shear modulus by torsion test.

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