One of the blades that are widely used for cutting of paperboard in paperboard converting industry is called ‘double structure blade’. Other than a hardened center bevel cutting tip, this blade has a soft tapered bottom for pressure adjustment. This paper reports on pressure balance characteristics of this blade under a quasi-static reciprocal loading condition in small number of cutting using a crank type press machine that has four load cells mounted under its cutting table. From this research, the following results were observed: (1) The four load cells force difference method was proposed in order to evaluate pressure unbalance of a blade under reciprocal loading condition. (2) A plastic deformation has occurred on the blade bottom tip at a certain applied force and has resulted in reducing the crank machine force balance. (3) In any number of cutting, the first cutting was found to have the biggest load cell force different (max-min) before stabilizing in the subsequent cutting. (4) The blade bottom tip pressure has decreased at certain applied forces caused by upsetting and lateral bending deformation of the bottom tip. (5) The blade crushed tip thickness tangency measured along its cutting line has showed reducing at a certain high applied forces caused by the cutting tip hazard layer and the bottom tip plastic crushing.

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In the present paper, the dent and its recovery phenomena of spherical shells due to compression by a moving rigid plate are investigated using the finite element method. The numerical results show that there are two different kinds of dents generated in the compression of spherical shells: one, called R-dent, can be completely recovered by unloading, and the other, called S-dent, are always remain after unloading, and that there are two different types of spherical shells, S-type and R-type, dependent on the possibility of the existence of R-dent. A classification chart of types is produced for various combinations of dimensions and material properties of spherical shells. Furthermore, it is revealed that the classification of types is possible by comparing the critical angle φ_c, which prescribes the classification of dents, with the angle φ_b when the buckling occurs.

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Air plasma sprayed thermal barrier coatings (APSed TBCs) exhibit splat microstructure formed by thin layers of lamellae (splats), and also include many interlamellar pores and voids. These microstructural features are primarily responsible for the low stiffness commonly exhibited by such coatings. The splat microstructure thus has an important influence on resistance to fractures, such as delamination, because thermal stress in coatings depends on its stiffness. Previous investigations have revealed that the mechanical properties of ceramic top coatings, such as stiffness and fracture toughness, vary not only with the thermal spray process but also with thermal exposure. In the present study, the correlation between the mechanical properties and splat microstructure of an APSed TBC is studied using the simple sintering model and numerical simulation (distinct element method). Numerical simulation results clarified that the mechanical properties of an APSed TBC were controlled by the splat microstructure, which varied depending on the sintering mechanism. The variation of mechanical properties in the APSed TBCs with thermal exposure can be predicted using the method proposed here.

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We have investigated the usability of the spectral element method in ab-initio electron structure calculations on the basis of norm-conserving pseudopotential method. The spectral element method as a variant of the finite element method employs a Gauss-Lobatto-Legendre polynomial as a shape function. Using higher-order shape function, we obtain rapid convergence of the error in the total energy with respect to the number of degrees of freedom. This property significantly reduces the computational cost when one performs the highly accurate calculation. In the spectral element method positions of quadrature points are chosen so that some matrices turn to be diagonal matrix and sparse matrix. This also reduces the computational task required in the density functional calculation.

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Dispersion curves and wave structures for a railway rail were obtained with a semi-analytical finite element method. Since one portion of many modes obtained by the calculation are suitable modes for guided wave inspection, which are non-dispersive long propagating modes, dominant modes were obtained from wave structure data for the three sections of rail cross-section, head, web and bottom and for x, y and z directions. As a result, suitable modes for guided wave inspection are limited to A₀, SH and Rayleigh-like modes vibrating locally at these sections.

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This paper proposes a finite element procedure for the simulations of material nonlinearity so-called domain switching in polycrystalline ferroelectric/ferroelastic bodies. Conventional FEM, which has been used for linear piezoelectric analyses, is not appropriate for solving the nonlinear problem from thermodynamic viewpoint because it corresponds to finding a saddle point of functional. Therefore, we use a recently proposed alternative FEM that corresponds to finding local minimum points of functional. In the alternative FEM, both mechanical displacement and vector potential for electric displacement instead of scalar potential are chosen as unknown variables. As a constitutive law in each crystal, we adopt a class of Landau's potential energy models, which is a popular phenomenological description for phase transitions in solid-state physics. Because the processes of the nonlinear behavior are essentially dynamic phenomena and the total potential of the system may have local minimum solutions, we employ a dynamic formulation for the nonlinear analyses with the consideration of Debye-type dielectric relaxation and mechanical wave propagation. Numerical examples of a two-dimensional polycrystalline ferroelectric model are shown and the results can qualitatively predict ferroelectric behaviors such as hysteresis curves and butterfly curves.

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Time-dependent fracture mechanics parameter (C^*) has been used to characterize the crack growth behavior of Sn-Pb eutectic solder (63Sn-37Pb) from crack growth (CG) tests under cyclic loading with various hold times (5, 20, 30, 50, 100 seconds), low cycle fatigue (LCF) tests under various frequencies (10^-3-10^-1 Hz), and creep crack growth (CCG) test. The results showed that CG, LCF, and CCG processes of Sn-Pb eutectic solder were dominated by time-dependent mechanism, and C^*-parameter could be successfully correlated with their crack growth rates, i.e. the plots of C^*- da/dt located within a scatter band with an exponent of 1. Although crack growth behavior was essentially time-dependent, crack growth mechanism was varied between under short hold time and long hold time. SEM observations of the longitudinal sections of CG specimens revealed that cracks under short hold time conditions propagated in transgranular manner through the Sn-Pb colonies, while those under long hold time conditions propagated in intergranular manner around the Sn-Pb colony boundaries.

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Investigation of microstructural changes in pure commercial-grade iron caused by fine particle peening (FPP) treatment was undertaken by detailed observation using field emission-scanning electron microscopy (FE-SEM) and measurement of the X-ray diffraction peak full width at half maximum (FWHM). The effect of pre-FPP treatment on the oxygen diffusion process within iron is also discussed. FPP treatment produced stratification patterns with many dislocations and grain boundaries on the treated surface. This unique microstructure strongly affected the diffusion capacity, so that thicker oxygen-concentrated layers were observed on pre-FPP/oxygen diffusion-treated surfaces.

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The microstructure of Ti-6Al-4V alloy treated with Fine Particle Peening (FPP) was studied. The influence of different peening times, particle supply rates, and particle sizes on the microstructure was especially investigated. FPP treatment using steel particles created a modified microstructure with a lamellar feature beside the treated surface. The modified structure showed higher hardness comparing to the interior region and it was accompanied by Fe elements transferred from particles. Energy Dispersive X-ray Spectroscopy (EDS) analyses revealed that the amount of transferring Fe elements was increased as peening times and/or particle supply rates were increased. Fe transfer was also accelerated by FPP treatment using smaller particles. The reasons for this behavior were as follows: (1) plastic deformation induced by collisions of particles was effectively accumulated with an increase of peening time and particle supply rate, and (2) plastic deformation induced by collisions of particles became more severe as particle size decreased. The accumulation and severity of plastic deformation strongly affected the formation of the modified microstructure enriched with transferred elements.

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The interaction of dislocations with a static mode I crack is studied by large scale molecular dynamics simulations. The model consists of a blunted [001](110) crack in nickel, to which after relaxation at K < K_Ic the displacement field of a dislocation is added. The response of the system is monitored during its evolution in the micro-canonical ensemble. The simulations allowed to identify different characteristic processes during the interaction of the impinging dislocation with the crack. In particular, stimulated dislocation emission and cross slip processes are observed to be important for the development of a plastic zone.

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Ab initio density functional theory (DFT) calculations have been performed to examine various factors which may influence the ideal strength, namely multiaxial loading condition and structure with low symmetry. First, the effect of normal stress on the ideal shear strength (ISS) in covalent crystals, Si, C, Ge and SiC, was evaluated. It was found that the response of ISS to normal stress differs depending on the material, while in metals the trend is unchanged. Obtained ISS as a function of normal stress is useful to understand criteria of dislocation nucleation in a pristine crystal because local lattices at the nucleation site undergo superimposed stress components in experiment. Secondly the ideal tensile strength of silicon surface was evaluated to examine how atomistic-level structure affects the mechanical property. The theoretical tensile strength of Si nanofilms with (100) surface, which is flat with dimer-row structures, shows only small reduction even though the thickness is down to 1 nm, meaning that the flat surface possesses high strength.

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