CFRP laminate is very sensitive to the impact. Even a low impact creates a delamination and results in the deterioration of the structural reliability. In our previous study, electric resistance change method (ERCM) and two-stage electric potential change method (two-stage EPCM) are proposed to monitor the delamination in the CFRP laminate. ERCM is suited to be applied to the part of the structure where the high accuracy of estimation is required. On the other hand, two-stage EPCM is suited to be applied to the large structure or the part which required rapid monitoring. In this paper, asymmetrical dual charge EPCM is newly introduced. The method can reduce the number of electric charges compare to the ERCM and show fine estimation throughout the object although two-stage EPCM shows poor performance near the center of the charged electrodes. The proposed method is, therefore, to be a standard of the delamination monitoring methods which utilize the electrical property of CFRP laminate. FEM analyses and experiments are conducted in this paper. As a result, the applicability of the method to the practical use is confirmed.

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This paper studies method of quantitative crack monitoring based on the in-situ Eddy Current Monitoring (ECM) system. The capability of the ECM system in monitoring fatigue crack propagation is discussed along with the crack growth simulation. The fatigue tests for two austenitic stainless steel specimens were conducted, one has a V-notch and the other has a semi-elliptic slit. Their crack propagation was nonitored by means of eddy current testing (ECT) at room temperature. The numerical simulation of crack propagation by using stress intensity factor and a diagram of fatigue crack propagation velocity was carried out to derive mesh models for ECM signal calculation. Comparisons between experimental and numerical ECM signals reveal that this system is capable of quantitatively monitoring the crack growth process.

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LTI was added to blends of PLA and PCL to improve the immiscibility of the two different kinds of biodegradable polymers. Fracture properties of PLA/PCL and PLA/PCL +LTI were evaluated and compared to assess the effect of LTI additive on the fracture behavior. Both the J-integral at initiation, J_in, and the total fracture energy, J_f, were improved effectively due to LTI addition. Fracture surfaces were also examined using SEM to characterize fracture mechanism. It was confirmed that the size of PCL spherulites became smaller by adding LTI, and therefore void formation was inhibited, resulting in the improvement of the fracture properties.

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Ultrasonic health monitoring of structures under realistic operating conditions is very difficult because ultrasonic waves are influenced by not only structural defects but also environmental disturbances. In this investigation, we examined the method of ultrasonic spectroscopy to classify the signal changes as “structural” or “experimental”. Using aluminum plates, the ultrasonic propagation characteristics against the growth of defects (fatigue crack, slit and drilled hole) and the change in the environment disturbances (water drop, temperature and load) was investigated. The frequency dependency of both propagation delays and amplitudes of tone-burst waves were different from each other for defects and environmental disturbances, and it was found that defects could be distinguished from the environmental disturbances by monitoring the delay-amplitude plot lines of the tone-burst waves with increasing frequency.

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The effects of 125°C holding time on static strength of package solder ball and impact strength of package solder ball have been investigated for BGA-IC package with Pb-free solder or Pb solder. A solder ball failure can be divided into ductile failure of solder ball and interface failure between a copper and intermetallic compound. Results shows that aging time increases the ductile strength of solder ball in a package and decrease the interface strength of package. The impact strength of solder ball in a BGA package can be predicted from the static strength of solder ball. The predicted impact strength of solder ball was compared with the actual impact strength of solder ball. It shows good correlation.

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We developed a method to evaluate the life of the wiring in non-solder mask defined (NSMD) solder joint pads in an LSI package. Generally, in a thermal cycling test, a package with NSMD pads has a longer life than a package with conventional pads. However, the load on the wiring in the pad in package with NSMD pads is greater than that in a package with conventional pads, so the joints with the NSMD pads may become disconnected due to failure of the wiring, not the solder. A method is thus needed to evaluate the life of the wiring. We have developed a method to measure the fatigue strength of the wiring, and we have developed a method to evaluate the life of the wiring by the finite element method. The life of the wiring in the pad is predicted by the analyzed plastic strain in the wiring and the measured fatigue strength data.

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This paper considered stress analysis of a circular cylinder in pressing fit process. The pressing fit experiment was conducted, the strain of the center part of circular cylinder was measured, and the stress was calculated. As a result, the load has increased while pressing fit process. And the load of a circular cylinder with roulette has decreased greatly. At first the compression stress increases in pressing fit process and the stress decreases in pressing about the half of specimens. When the ratio of contact area increases, the compression stress increases. Stress analysis of a circular cylinder in pressing fit process by three-dimensional elasticity theory and finite element methods (FEM). In three-dimensional elasticity theory, stress solution was given using Boussinesq-Dougall displacement function. And stress was calculated by Dini transformation and Fourier transformation. In FEM, stress was calculated using MARC. The analytical results agree with experimental data.

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This paper presents a method for global or quasi-optimum for the discrete and continuous design variables, based on Branching Generalized Random Tunneling Algorithm (BGRTA). By treating the discrete design variables as penalty function, the augmented objective function is constructed. As a result, all design variables can be treated as the continuous design variables. The augmented objective function becomes non-convex, and has many local minima. That is, finding optimum of discrete design variables is transformed into finding global optimum of this augmented objective function. Then BGRTA is applied to this augmented objective function, subject to the behavior and side constraints. We also propose the new update scheme of penalty parameter for the penalty function of discrete design variables in this paper. The proposed update scheme of penalty parameter utilizes the information of the penalty function of discrete design variables. By utilizing the characteristics of BGRTA, some optima are obtained. The validity of the proposed method is examined through typical benchmark problems.

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Treatment of contact between a sheet and tools is one of the most difficult problems to deal with in finite-element simulations of the sheet metal forming processes. In order to obtain more accurate tool models without increasing the number of elements, this paper describes new formulations for contact problems using local interpolation proposed by Nagata for tool surfaces. A contact search algorithm between the sheet nodes and the interpolated tool surfaces and the consistent tangent stiffness matrix for the sliding nodes were developed. The developed algorithms were introduced into the static-explicit elastoplastic finite-element method code STAMP3D. Simulations of a square cup drawing process with a very coarsely discretized punch model were carried out. The simulated results showed that the proposed algorithms gave the proper deformation process, thus demonstrating the validity of the proposed formulations.

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The purpose of this research is to develop a method to perform a finite-element analysis (FEA) coupling diffusion of water and structure (deformation) on electro-active polymer (EAP) such as Nafion 117 electrified in the water. In the resent report, some experiments were carried out to find properties of Nafion 117 that will be used in the FEA. First, the experiments in which wet Nafion 117 was electrified in the distilled water were performed to examine relations between voltage, current and deformation. Then the volume content of water on Nafion 117, coefficient of linear expansion and specific volume were determined measuring the volume and mass of test pieces of dried and wet Nafion 117. Then the experiment on free vibration of a cantilever of wet Nafion 117 in the distrilled water and the FEA following the experiment were carried out in order to find Young's modulus of the wet Nafion 117. The coefficients, α and β of Rayleigh were also found by comparing the experimental results and the calculated ones.

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Ni-Ti alloy, one of well-known shape memory alloys, attracts attention by their functional advantages in thin films or their nanostructures. Stress induced martensitic transformation (SIMT) is recognized as a principal deformation mechanism, while its atomistic view on nucleation or prematensitic transformation is left unrevealed. Therefore, we computationally investigate microscopic mechanism of SIMT in Ni-Ti alloy using molecular dynamics simulation (MDS) with embedded atom metod (EAM) potential function. The Ni-Ti simulation model consisted of 19 404 atoms and surrounded by free surfaces is subjected to loading and unloading with appropriate structural relaxations. To identifying crystalline phase changes from B 2 (parent) to B 19' (martensite) in the alloy under loading, we monitor lattice parameters, ratio of two lattice parameters, and their angles from instantaneous atomic positions. We define the martensite phase by specifying possible combination of the parameters according to literatures. In loading process, with rapid stress descent, the MDS model deforms and shows maximal ratio of martensite phase. We find that there are two major paths of atomic configurational change from B 2 to B 19' in these martensite structures and there is also another kind of long-range atomic migration whose distance is larger than single lattice constant. The separation into these multiple paths is caused by discrepancy in angles between interatomic connecting line in unitcell and the tensile direction. It is also find that each paths have characteristic activation energies during configurational change (i.e. during phase transformation). It is ensured that SIMT is microscopically constructed by various types of structural changes and their energetics.

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This paper discusses a displacement control problem in a two-layered composite disk consisting of a transversely isotropic structural layer onto which a piezoceramic layer of crystal class 6 mm is perfectly bonded. It is considered that some electrodes are concentrically arranged on the top surface of the disk. When an axisymmetric heating temperature acts on the bottom surface of the disk, the thermally induced displacement distribution on the bottom surface is controlled by applying a stepwise electric potential distribution to the top surface. The voltage which could be applied to each electrode is determined by optimization so that the displacement over the bottom surface of the disk has a desired distribution.

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A stochastic temperature solution is derived for the heat conduction problem in a nonhomogeneous plate with random thermal conductivity by perturbation method and Laplace transform. The nonhomogeneous plate, which has exponential variations in the thermal conductivity and mechanical properties through the plate thickness, is heated by a prescribed deterministic temperature on the one surface. The stochastic thermal stress problem in the nonhomogeneous plate with the random thermal conductivity or random coefficient of linear thermal expansion is analyzed thorough the use of thermal stress expression reported by one of present authors. Numerical results for the standard deviation of thermal stress are presented for the case that the randomness in the thermal conductivity and coefficient of linear thermal expansion is assumed to follow a uniform probability distribution.

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Osteoporosis is serious medical issue to be solved in aging society. There are no less than 10 million osteoporosis patients in Japan. Osteoporosis causes frequently bone compressive fracture in lower vertebrae. It is important to estimate a fracture risk and provide adequate treatment in early stage of osteoporosis. However, bone mineral density is quantified by Dual Energy X-ray Absorptiometry (DEXA) in current clinical diagnosis of osteoporosis, mechanical factor such as bone strength, which is essential to evaluate bone fracture risk, is not considered. In this study, we evaluated the fracture risk of osteoporosis patient's vertebrae by patient-specific finite-element (FE) analysis in static loading condition. We used “Mechanical Finder (RCCM, Co., LTD.)” that was computer software for bone strength analysis considering individual bone shape and density distribution based on Computer Tomography (CT) images. Furthermore, we also tried to evaluate the fracture risk by dynamic FE analysis to reflect more severe loading conditions. Availability of dynamic analysis was investigated in comparison with the results of the static analysis. At last, efficiency of proposed mechanical evaluation method for vertebral osteoporosis was discussed.

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When the plasma is first applied and hydrophilic monomers are next graft-polymerized to the surface of cloth, the cloth comes to breathe moisture and control offensive odor simultaneously. The objectives of the present study are to manufacture an intelligent comfortable wear which can absorb the sweat and the odor from human body promptly, and can disperse it quickly to outside environment. First, the atmospheric nonthermal plasma graft polymerization apparatus was improved to treat a wear directly. Using this apparatus, it was succeeded to manufacture functional wears having hydrophilic property in the outer side and hydrophobic property in the inner side simultaneously. The performances of moisture breathe and odor control properties were evaluated for the treated clothes and manufactured wears. It was confirmed that water vapor and ammonia could be effectively removed from human body.

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Through the X-ray method, synthetic remarkable effect of surface hardening due to highspeed submerged water-jet-peening and the corresponding mechanism is quantitatively investigated, for two cases with and without carburizing upon the tooth gear surface manufactured by SCr420H steel, when the jet is accompanied by uniformly large bubble cloud. Clearly, the effect is remarkably improved by such carburizing quenching.

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