In this study, mechanical behaviors and strength of 3-D woven heat resistant composite with optical fiber for compressive load are experimentally investigated. The maximum fracture stresses for three types of specimen that have different optical fiber orientation are evaluated by static compression test. This report shows the effect of Z-directional yarn in 3-D composite on compressive strength by comparing with the results for 2-D composite specimen.

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The calcium phosphate including Hydroxapatite (Ca_<10>(PO_4)_6(OH)_2 : referred to as Hap) utilizes as a biomaterial, because that resembles the principal ingredient of the tooth and bone and have superior biocompatibilty. Through coating calcium phosphate on metallic biomaterial such as the commercially titanium, the biocompatible character can be given to the material together with its mechanical strength. Some trials have been conducted for applying these coated materials to the artificial bone and so on. In this study, the optimum condition of the Hap films formation by electrochemical method was investigated by employing QCM (Quartz Crystal Microbalance), FE-SEM and EDX. Adhesive strength of coated HAp films evaluated by the scratch test. Also, biocompatible character was examine by immersion text into quasi-human body fluid.

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Rotating bending fatigue tests were carried out on specimens of ferrite-pearlitic cast irons and pearlitic ductile cast irons with a shot-peening (SP) treatment. It has been reported that sites of the fatigue crack initiation are transferred from the surface to subsurface in the range of longer life region over (10)^7 cycles. So the initiation and the propagation behaviors of the surface fatigue cracks with the compressive residual induced by the SP treatment and also the subsurface fatigue crack were investigated by the detailed observations of the specimen surface and the fracture surface. As a result, the non-propagating surface cracks under the influence of the SP treatments were observed. And the flat area of subsurface fatigue cracks similar to the fish-eye region increased with decreasing of the stress amplitude.

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Though the platinum is one of the representative precious metals, the platinum has been used as an industrial use material of the crucible for the glass melt recently. In this study, the fatigue reliability at elevated temperature of platinum alloy which was the industrial use material demonstratively was examined by the elucidation of fracture mechanism. Main results were follow; (1) S-N characteristics of the PtRh alloy was almost arranged in the straight line. And, the (10)^7 -fatigue strength was 30Mpa. (2) From the fractography using SEM, it was indicated that fatigue fracture mechanism was similar to the static destruction in the high stress side, on the other hand, it was effected by creep in the low stress side.

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It is well known that fiber reinforced metal (FRM) plate warps under thermal load, if the internal fiber distribution within the matrix is biased. In this paper, a simple 1-dimensional model is established to analyze the thermal deformation of unidirectional metal matrix composite (UD-MMC) thin plate. Based on the assumptions that the plate is experiencing pure bending deformation, closed-form expressions of the plate's normal strain and bending curvature are deduced from force and moment equilibrium equation. Two examples, one-ply-fiber and four-ply-fiber lay-ups are analyzed, leading to the explicit relationship between curvature and plate parameters. The four-ply-fiber case agrees well with the full 3-D FEM simulations, proving the appropriateness of the present model. This analysis, with simplicity and relative considerable accuracy, can be applied in the design of the thermal-deformation based actuators.

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With good high-temperature resistance, high specific stiffness and strength, metal matrix composites (MMCs) are used in aerospace structures. As part of the research project to evaluate MMCs' strength at elevated temperature, tensile tests of SiC fiber (Nippon Carbon's HI-(NICALON)^<TM>) reinforced pure aluminum (1090) were performed, in order to measure the material's strength from room temperature to elevated temperature up to 500℃. The measured data, as well as those collected from literature, show that the material's strength decreases linearly with the increase of temperature.

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Nb-Ti filament embedded in composite exhibit uniform elongation or multiple necking when the composites are elonged beyond the strain at which the filaments tested alone start to neck and fail. In the present study, deformation behavior of Nb-Ti filaments in composite wires with different copper ratios was analyzed using finite element analysis. The initial roughness of 1.0% and 0.5% was given to this model to initiate multiple necking. At a copper ratio of 0 and 1 (V_f=1 and 0.5), the reduction of cross-section at the initial roughness of only 1.0% is remarkable. On the other hand at a copper ratio of more than 1,the reduction of cross-section at the initial roughness of 0.5% also fallowed. Thus multiple necking of Nb-Ti filaments was successfully reproduced in this analysis.

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In the strain wave gearing, the flexspline is a thin-wall cylinder with external teeth, the circular spline is a rigid ring with internal teeth, and the wave generator is an oval bearing. The main purpose of this study is the numerical evaluation of the stress in the flexspline which is the key element for the motion transmission in this components. When the flexspline is deformed into an elliptical shape by repeated load from the wave generator, the fatigue strength at the root of the tooth in the flexspline is a serious problem. The cup type strain wave gearing is modeled for FEM analysis. In the three dimensional field, the work ball of bearing and the oil film are modeled. And 16 nodes element is used as the contact element to consider the contact problem between the teeth of flexspline and circular spline. Deformation shape of the flexspline, various stress distribution at the root of tooth in the flexspline, and load of the bearing ball are calculated. The results show good agreement with experimental measurement qualitatively and quantitatively.

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A design support CAE system was developed to reduce production cost, weight, and design time of box structures. This system assists users in optimizing box structures using a genetic algorithm. This optimum method can construct new structures by exchanging parts in box structure for different shape parts in part database. We applied this system to optimum problems of stiffeners forming box structure and researched the convergence performance.

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In accordance with the resent wide spread of mobile type electronics equipment, such as note-size mobile computers, mobile telephones and wireless remote controllers, the requirements for the reliability improvements of these equipment for severe environmental conditions such as temperature, humidity, water, pressure vibration and impact become high. One of the effective method for these requirements is the packing of these electronics equipment in the environmental protection case. In this paper we introduce the development of impact load protection case especially for mobile computers. To determine the optimum design parameters of each components, the ROBUST design method is used. And using these impact protection case the impact acceleration acting on the mobile computers decrease to about 1/3 compared with that without protection case.

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A method is proposed for estimating the sizes of surface cracks in magnetic materials. The method is based on applying magnetic field, determining leakage magnetic field, in the vicinity of a crack, by moving Hall element on the surface of the material along one or two scanning lines crossing the crack, and measuring the corresponding Hall voltage distribution. A dipole model of a crack is utilized, in which a surface crack is considered as being full with magnetic dipoles aligned parallel to the applied field, and whose density varies linearly along the depth of the crack. The crack sizes and the parameters of the distribution of magnetic dipoles along the crack depth are computed by crack inversion, which represents a regression for the Hall voltage distribution. Hall voltage distributions are measured on ferromagnetic steel samples containing one artificial surface crack. Some crack inversions are performed for estimating the maximum crack depth and the crack width of cracks with rectangular, and isosceles triangular cross-sections along the long crack axis. The fast and accurate estimation of the maximum crack depth, and the crack width by such crack inversions could be important for pipeline inspection. Another crack inversions are performed for determining the cross-section along the long axis of the investigated cracks, and the results are satisfactorily.

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An experimental study was carried out with the aim of development of a friction coefficient reduction and fatigue reliability for Mg alloy by surface modification that DLC film products by ion source sputtering. Especially, it was examined in detail from the meso structure scale for the effect on Mg alloy which DLC film cause. The main results obtained are as follows : (1) Production of DLC film could success by sputtering Si as intermediate layer. As results showed that friction coefficient of DLC film reduced up to 1/3. (2) The precipitate of Mg_<17>Al_<12> grow the DLC film material according to heat treatment effect with the ion sputter, and the propagation of crack was arrested by this precipitate. (3) Fatigue reliability evaluation by 「S-N globe」, it is insufficient. Because the crack of DLC film material propagate difference of the general surface modification material from the surface.

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DLC Thin films were coated on PC (Polycarbonate) to improve tribological properties (Friction coefficient, Wear). The influence of processing methods on friction and wear properties was experimentally carried out. DLC thin films for PC were coated with the following two different methods (1) DLC thin film deposited with plasma-chemical vapor deposition (P-CVD/DLC/PC). (2) DLC thin film deposited with ionic vapor deposition (IVD/DLC/PC). As the results, the friction and wear evaluation shows that DLC coated PC (P-CVD/DLC/PC, IVD/DLC/PC) markedly reduce the friction coefficient and wear compared to Virgin materials (Uncoated PC). Especially, the friction and wear properties of IVD/DLC/PC were more excellent than that of P-CVD/DLC/PC.

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The friction and fatigue property of Al-Si sintered alloy which modified by Diamond like carbon (DLC) coating an Fine particle bombarding treatment (FPB) were investigated. The main results obtained are as follows : (1) The friction coefficient of DLC coating material was remarkably lower than that of virgin material. In FPB treated material, little adhesion and wear existed. (2) The fatigue strength of DLC coating and FPB treated material were improved. Improvement of fatigue strength in DLC coating material was mainly attributed to long crack in the surface. This crack growth direction was along the surface. On the other hand, in FPB treated material, flat region existed in the fracture origin.

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The failure behaviour around a crack tip in adhesive joint is important in relation to the structural integrity of adhesive structures. The bond thickness is one of the important design parameters in adhesive structures. In this study, we investigate the bond thickness effect on the fracture toughness of adhesive joint using rubber-modified epoxy resin from the viewpoint of microstructure. The shapes of dispersed rubber particles in adhesive layers of damaged and undamaged specimens are observed by an optical microscope. As a result, damage zones along interfaces between an adhesive layer and two adherends influence the fracture toughness of an adhesive joint which has a thin bond thickness

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Uniaxial tension tests were performed on fine-grain Al-Mg alloy (5083-O) sheets at various forming speeds (5.6×(10)^<-5>S^<-1> to 5.3×(10)^<-1>S^<-1>) at elevated temperatures (473 &acd; 623K). From the tests, it was found that the tensile flow stress is strongly influenced by forming speed and temperature. In order to describe such rate-and temperature-dependent stress-strain responses, a viscoplastic constitutive model is presented. In the mode, we assume that the viscoplastic strain rate consists of two components due to the grain-boundary sliding superplasticity and the ordinary viscoplasticity. The predicted stress-strain responses by this constitutive model are in good agreement with the corresponding experimental results.

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This paper presents a procedure for numerical quantifying the probability of brittle failures in steels controlled by size distribution of initiated microcracks. It shows how the fracture probability varies with the stress intensity factor, the temperature, and with the deformation characteristics of steel. The application of the proposed method on Ni-Cr steel demonstrated very good agreement of predicted temperature dependence of scatter in fracture toughness with experimental results. Controlling micromechanism of initiation and propagation of brittle fracture and its stages were identified from results of fractography analysis. Newly, using two ways the characteristic distance as the radial distance from the crack tip where the microcrack initiation is most probable has been calculated in dependence on temperature.

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We have calculated the higher order Mode-I stress fields associated with the acceleration (or deceleration) of a crack. As we calculate the fields, we find that the work of Freund and Roskis, is not complete because the 1-st order stress fields at the tip of a crack diverges as the velocity of a crack approaches to zero. We have resolved this problem and numerically found that the hoop stress at the crack-tip shows an interesting differences for the accelerating and decelerating phase of a crack.

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