L. M. Hsiung, D. H. Lassila¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 185-191, 2002, DOI:10.3970/cmes.2002.003.185

Abstract Initial dislocation structures in as-annealed high-purity Mo single crystals, and deformation substructures of the crystals compressed at room temperature under different strain rates have been examined and studied in order to elucidate the physical mechanisms of dislocation multiplication and motion in the early stages of plastic deformation. The initial dislocation density was measured to be in a range of 10⁶ ~ 10⁷ cm⁻². More importantly numerous grown-in superjogs were observed along screw dislocation lines. After testing in compression, dislocation density (mainly screw dislocations) increased to 10⁷ ~ 10⁸ cm⁻². Besides, the formation of dislocation dipoles (debris) due to More >

L. Gaul, M. Fischer¹, U. Nackenhorst²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 815-824, 2002, DOI:10.3970/cmes.2002.003.815

Abstract A sequential FEM--BEM approach is employed to calculate the dynamic behavior and sound radiation of rotating wheels. The equations of motion for the wheel are developed in the frame of an Arbitrary Eulerian Lagrangian description with a time-independent formulation for steady state rolling and a spatial description of vibrations. The noise radiation caused by the vibration modes is computed by the symmetric hybrid boundary element method. More >

G.D. Hatzigeorgiou¹, D.E. Beskos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 791-802, 2002, DOI:10.3970/cmes.2002.003.791

Abstract This paper presents a general boundary element methodology for the dynamic analysis of three-dimensional inelastic solids and structures. Inelasticity is simulated with the aid of the continuum damage theory. The elastostatic fundamental solution is employed in the integral formulation of the problem and this creates in addition to the surface integrals, volume integrals due to inertia and inelasticity. Thus an interior discretization in addition to the usual surface discretization is necessary. Isoparametric linear quadrilateral elements are used for the surface discretization and isoparametric linear hexahedra for the interior discretization. Advanced numerical integration techniques for singular More >

R. C. Batra¹, H.-K. Ching¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 717-730, 2002, DOI:10.3970/cmes.2002.003.717

Abstract The Meshless Local Petrov-Galerkin (MLPG) method is used to analyze transient deformations near either a crack or a notch tip in a linear elastic plate. The local weak formulation of equations governing elastodynamic deformations is derived. It results in a system of coupled ordinary differential equations which are integrated with respect to time by a Newmark family of methods. Essential boundary conditions are imposed by the penalty method. The accuracy of the MLPG solution is established by comparing computed results for one-dimensional wave propagation in a rod with the analytical solution of the problem. Results… More >

Jin Yeon Cho¹, Seung Jo Kim²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 687-698, 2002, DOI:10.3970/cmes.2002.003.687

Abstract In this work, an explicit solution procedure for the recently developed discontinuous time integration method is proposed in order to reduce the computational cost while maintaining the desirable numerical characteristics of the discontinuous time integration method. In the present explicit solution procedure, a two-stage correction algorithm is devised to obtain the solution at the next time step without any matrix factorization. To observe the numerical characteristics of the proposed explicit solution procedure, stability and convergence analyses are performed. From the stability analysis, it is observed that the proposed algorithm gives a larger critical time step More >

D.W. Brenner, O.A. Shenderova, D.A. Areshkin, J.D. Schall¹, S.-J. V. Frankland²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.5, pp. 643-674, 2002, DOI:10.3970/cmes.2002.003.643

Abstract The derivation of a bond-order potential energy function and a self-consistent tight-binding scheme is presented, followed by a survey of the application of these methods to calculating properties of carbon nanostructures. The modeling studies discussed include properties of functionalized and kinked carbon nanotubes, Raman shifts for hydrogen stored in nanotubes, nanotubes in a composite, properties of nanotubes in applied potential (electrical) fields, and structures and properties of nanocones, nanodiamond clusters and rods, and hybrid diamond-nanotube structures. More >

J.Y. Jang¹, M.M. Khonsari²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.4, pp. 455-464, 2002, DOI:10.3970/cmes.2002.003.455

Abstract Thermohydrodynamic analysis of journal bearings lubricated with multigrade oils is presented. Design charts are presented that enable one to readily estimate the bearing maximum temperature and the shaft temperature using a series of dimensionless parameters introduced in this paper. More >

Yuanzhong Hu¹, Yuchuan Liu, Hui Wang

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.4, pp. 447-454, 2002, DOI:10.3970/cmes.2002.003.447

Abstract Scuffing, a major cause of failure in automobile engines, is considered as a dynamic process in this study. Local adhesions may occur randomly in lubricated contacts due to the existence of asperity contact and breakdown of lubricating films. Scuffing would take place if the local events develop rapidly into a large-scale plastic deformation and catastrophic failure. A system dynamic model established in the present paper allows one to predict dynamic behavior of a tribological system through numerical solutions of a group of differential equations. Results show that a transition to adhesion begins when the surface More >

George D. Manolis¹, Stavros Pavlou²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 399-416, 2002, DOI:10.3970/cmes.2002.003.399

Abstract A free-space Green's function for problems involving time-harmonic elastic waves in variable density materials under plane strain conditions is developed herein by means of Hormander's method in the context of matrix algebra formalism. The challenge when solving problems involving inhomogenous media is that the coefficients appearing in the governing equations of motion are position-dependent. Furthermore, an additional difficulty stems from the fact that these governing equations are vectorial, which implies that coordinate transformation techniques that have been successful with scalar waves can no longer be used. Thus, the present work aims at establishing the necessary More >

Ch. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 381-398, 2002, DOI:10.3970/cmes.2002.003.381

Abstract A 2-D time-domain boundary integral equation method (BIEM) for transient dynamic analysis of cracked orthotropic solids is presented in this paper. A finite crack in an unbounded orthotropic solid subjected to an impact loading is considered. Hypersingular time-domain traction boundary integral equations (BIEs) are applied in the analysis. A time-stepping scheme is developed for solving the hypersingular time-domain traction BIEs. The scheme uses a convolution quadrature formula for temporal and a Galerkin method for spatial discretizations. Numerical examples are given to show that the presented time-domain BIEM is highly efficient and accurate. More >