Electronic items, Automotive crash is a non-repeatable phenomenon, and we are hard to measure qualification for a single crash test. Today there are some softwares, like PAMCRASH or LS-DYNA to simulate them. But the simulations are very hard to generate whole model and may generate different results even on the same machine and same applications is executed. In this paper, authors are developing the SPH((Smooth Particle Hydrodynamics) particle models of the whole electronic items model and studying impact analysis of them. Of course, the pre-impact velocity, elastic-plastic deformation of the electronic items and automotives are the important information produced during the crash accidents. Authors described the possibility of SPH particle method to simulate electronic items dropping or car-crash and provide hints to get more safety and stable electronic items or car model.

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A coupling analysis of DEM and SPH has been developed for 3-dimensional powder packing process. The powder materials in compression are initially modeled by DEM and after the time when the material is fully compressed SPH has been applied to obtain the stress and strain distributions in a product. The GPU has been utilized to decrease the computing time. It has been cleared that this method is valuable for the analysis of 3-dimensional powder-packing analysis.

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Although the MPS (Moving Particle Simulation) method has been expected to prevail in wide industrial applications, the numerical instability of pressure remains a serious problem. This paper shows that the modification in a Poisson equation using hybrid source terms and the optimization of those parameters reduce the instability. At the same time, this optimization method is effective to prevent the volume compression of the MPS particles, which has the trade-off against the stability.

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A previous research made an integral mathematical contribution for obtaining local function interpolation using neighboring nodal values of the solution function. Subsequent researchers developed mesh-free methods for FEM. This principle can also be used to obtain discrete differential operators on irregular nodes. They may be successfully applied to Finite Difference Method (FDM), Moving Particle Semi-implicit (MPS) method and Random Collocation Method (RCM). In this paper, we obtain discrete differential operators on irregular nodes and successfully apply them to solve differential equations using the RCM.

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In the time-domain BEM with Haar wavelets for 2-D diffusion problems, the relation between the number of non-zero entries of the coefficient matrices and the degree of freedom(DOF) N is theoretically investigated using the information on the size and the arrangement of the support of the basis functions. The coefficient matrices are compressed using the Beylkin-type level-independent truncation scheme with a DOF-independent prescribed threshold value A. The number of non-zero entries of the matrix G^<(L,p)> and H^<(L,p)> (1 &le; p &le; L, L: current time step), N(G^<(L,p)>) and N(H^<(L,p)>), increases in proportion to the factors log N, N^<1/2>, N and N log N, except for the behavior in the smaller DOF range where N(G^<(L,p)>) and N^(H<(L,p)>) 〜 O(N^2).

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In this study, the elastic-viscoplastic properties of ultra-fine plate-fin structures with offset in the direction of flow channel are investigated using the elastic-viscoplastic simulation procedure based on the time-dependent homogenization theory. By employing a novel boundary condition for boundary value problems, a cuboidal unit cell defined for an ultra-fine plate-fin structure with no offset can be also used as the analysis domain for the homogenization analysis of plate-fin structures with offset. The elastic-viscoplastic behavior of ultra-fine offset plate-fin structures made of Ni-based alloy under uniaxial tension at high temperature is analyzed using the present method. It is shown that the offset can affect elastic-viscoplastic properties of ultra-fine plate-fin structures, such as macroscopic stress-strain relations and distributions of microscopic equivalent stress.

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In this study, the distributions of microscopic stresses at a free edge of a cross-ply carbon fiber-reinforced plastic (CFRP) laminate are analyzed three-dimensionally based on a homogenization theory. For this, the mathematical homogenization theory for elastic materials is reconstructed for CFRP laminates with free edges using a traction free boundary condition. This theory is then applied to the analysis of microscopic stress distributions at a free edge of a cross-ply CFRP laminate subjected to in-plane uniaxial tension. It is shown that microscopic in-plane shear stresses noticeably occur at the interlaminar area between 0°- and 90°- plies, especially around the free edge.

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Slip deformation in composite bi-crystal models subjected to tensile load is investigated by a finite element crystal plasticity analysis code. Accumulation of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs) are studied in detail. Results of the analysis show non-uniform deformation and the high density of GNDs accumulated in the form of band in parallel to grain boundary plane. Mechanism of non-uniform deformation and accumulation of GNDs in the form of band is discussed from the viewpoint of the effect of elastic incompatibility of composite materials. Mechanism of dislocation pattern formation is discussed from the viewpoint of imaginary disclination type deformation field with pair body interaction.

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The paper motivates to propose a model of evaluating the transformation plasticity, TP, coefficient by numerical calculation since identification of the coefficient so far needs complicated and time consuming experiments. A parallely connected two bar model consisted of mother and new phases is proposed: Tensile stress occurs in mother phase with larger thermal expansion coefficient in the course of cooling phase transformation, while compressive stress takes place in new phase with smaller coefficient. A tensile external stress even lower than yield stress is accelerated by the initial tensile stress in mother phase easily reaches yielding followed by plastic deformation. Simple thermo-elastic-plastic theory is employed to numerically calculate the rate and the current value of stress and strain in both phases depending on the amount of externally applied stress by use of material parameters for stress-strain relation and phase transformation kinetics characterized to material focused. Deviation of induced strain subjected to external stress from that of zero stress is now regarded as TP strain, and the TP coefficient is obtained by the TP strain derided by the external stress.

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In the previous paper, dependence of the driving force of the deformation localization on the physical mechanisms of the elastic stiffness degradation caused by the plastic deformation, which is closely related to changes of ultrasonic wave velocities due to the plastic deformation, was examined in detail. Successively, the new model for ductile fracture initiation was proposed based on the new concept, i.e., ductile fracture initiation is caused by the jump of wave velocity along the intersected crossing line between two different stationary discontinuity bands characterized by vanishing velocity of an acceleration wave. The micro-crack nucleation caused by the jump of the velocity along intersected crossing line between the two discontinuity bands was verified theoretically by the shock wave theory and analyzed numerically using the theory of ultrasonic wave velocity under the plastic deformation proposed by the author. In the present paper, ductile fracture progress of FCC single crystals under plastic buckling is simulated using the finite element crystal plasticity model (FEPM) with built in proposed criteria, and then crystal orientation effect on plastic buckling progress of the single crystals is examined.

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This paper describes the polycrystal viscoelastic analyses of a modified 9Cr-1Mo steel at 550℃ in air by using an FEM program newly developed by the present authors. The analyses used a 2D polycrystal model of the high Cr steel having different aggregates of crystal orientations. The results were compared with an experimental creep deformation vs. time curves obtained by the creep tests of the high Cr steel at 550℃ in air. It was shown that the analyses successfully reproduced the creep curve which agreed well with the experimental one. It was also implied that the creep curve, especially at the final stage of the creep process, can be largely affected by the crystal orientation of the material.

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