The present paper proposes an integral equation formulation for static bending and its implementation of stiffened-anisotropic plates using boundary element method. For an eccentrically stiffened plate, in-plane and out-of-plane deformations are coupled. It implies that the bending and plane-stress deformation of the elastic plate should be considered together with tensile, bending and twisting deformation of the stiffener. In this paper, three components of interactive force and two components of interactive moment between the plate and stiffener are treated as line distributed unknown loads. The numerical results obtained by the computer code developed in this study are discussed, whereby the versatility of the proposed method of analysis is demonstrated.

View full abstract

In this paper, some novel transformations based on sinh and tan functions. These transformations are shown that they improve dramatically the shape of the integrand to more tractable one and very accurate integration results are obtained by using only the standard Gaussian quadrature. The effectiveness of the proposed transformations for nearly singular kernels with various orders are demonstrated through some numerical results.

View full abstract

This paper describes the Trefftz solution of the boudnary value problem governed with the three-dimensional Poisson equation. The inhomogeneous term of the governing equation is approximated with the polynomial function in the orthogonal coordinates in order to derive the particular solution related to the term. The solution of the problem is approximated with the superposition of the homogeneous solution of Laplace equation and the derived particular solutions with unknowns. Unknown parameters are determined so that the approximate function satisfies the boundary conditions by means of the collocation method.

View full abstract

A body force distribution method is presented for the two-dimensional elasticity problems of an infinite plate subjected to harmonic vibration loads by applying a fundamental solution in elastodynamics. The fundamental solution used here is defined as a steady-state solution for a harmonic vibration body force acting at a point in an infinite elastic plate. As an illustrative exampe of the method of solution, we consider an infinite elastic plate with a circular hole subjected to harmonic vibration pressures. The principle of the method of solution is to distribute body forces so as to satisfy boundary conditions on the circular hole. The problem is formulated by an integral equation with unknown body forces. Numerical results are shown.

View full abstract

The unique thermal properties of carbon nanotubes (CNT) may offer tremendous opportunities for the development of fundamentally new composite materials. Numerical simulation of the thermal behavior of the CNT-based composites turns out to be of extremely large computational scale. Simple computations have revealed a phenomenon that temperatures within the CNT are almost uniform, which has its origin in the huge difference of heat conductivity between the CNT and the host polymer. Based on this observation, a simplified approach is proposed, which dramatically reduces the computational scale. Numerical examples demonstrate the efficiency and sufficient accuracy of the simplified approach.

View full abstract

In the course of steel development, heterogeneity at various scales has been elaborately controlled in order to realize superior characteristics at macro scale Since the development of sheet steels for automotive-body parts shifted its focus from ferritic mild steels to high-strength steels, the steel industry requires more powerful tools than the conventional crystal plasticity which can only take crystallographic textures into account. Unfortunately, the present effort on the development of multiscale plasticity does not sufficiently apply the industrial knowledge on mechanical metallurgy. In this report, the significance of the heterogeneity control is reviewed with several examples and some prospects for multiscale plasticity are discussed from the industrial points of view.

View full abstract

When one wants to buy an industrial product such as a car or a home electric product, it is the common rule that he requests the document for the quality assurance attached to the product. It is the age now when the trial production and the following experiments are replaced by the virtual numerical simulation, therefore, the quality assurance of computing is a very important subject.

View full abstract

Flow-fields around basic SSTO-rocket configurations are numerically simulated by the Navier-Stokes computations. The study starts with the simulations of the Apollo-type configuration, in which the simulated results are comparing with NASA's experiments and the capability of CFD approach is discussed. Computed aerodynamic coefficients of Apollo configuration agree well with the experiments at subsonic, transonic and supersonic regime at all angles of attack. Dependencies of the computed results on the grid resolution is investigated.

View full abstract

LES/RANS hybrid, LES and MILES simulations are applied to an axi-symmetric base flow for the supersonic flows at high Reynolds number. The idea of LES/RANS hybrid methodology is that RANS model is used in the boundary layer because of its low computational costs than LES, and LES is used in massively separated regions where unsteady flow structures are correctly captured. The subgrid-scale stresses are computed using the compressible form of Smagorinsky's model. Baldwin-Lomax model is applied to the RANS region. The LES/RANS hybrid simulations accurately capture the physics of turbulent flows. The reverse flow behind the base shows satisfactory agreement with the experimental data. The base pressure distributions, which is the primary parameter from the engineering interest, is in good agreement with the experimental results.

View full abstract

In this paper, a prediction method of aerodynamic coefficients called 'Wake Integration Method' was discussed based on CFD simulations. Compared with traditional 'Surface Integration Method', the advantages of this method are the improvement of the accuracy of drag prediction and the drag decomposition capability to wave, viscous, and induced drag. This method was applied to unstructured grid inviscid simulations. It was confirmed that the good agreement with other prediction method about lift coefficient and induced drag terms. As concerns the profile (wave) drag term, it was seen to be affected by numerical effect.

View full abstract