G. Dziatkiewicz¹ and P. Fedelinski¹

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.1, pp. 35-46, 2007, DOI:10.3970/cmes.2007.017.035

Abstract The aim of the present work is to show the formulation and application of the dual reciprocity boundary element method (BEM) to free vibrations of two-dimensional piezoelectric structures. The piezoelectric materials are modelled as homogenous, linear -- elastic, transversal isotropic and dielectric. Displacements and electric potentials are treated as generalized displacements and tractions and electric charge flux densities are treated as generalized tractions. The static fundamental solutions, which are required in the proposed approach, are derived using the Stroh formalism. The domain inertial integral is transformed to the equivalent boundary integral using the dual reciprocity More >

D. Soares Jr.^1,2, W.J. Mansur¹, D.L. Lima³

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.1, pp. 19-34, 2007, DOI:10.3970/cmes.2007.017.019

Abstract The present paper discussion is concerned with the development of robust and efficient algorithms to model propagation of interacting acoustic and elastic waves. The paper considers acoustic-elastic, acoustic-acoustic and elastic-elastic partitioned analyses of coupled systems; however, the focus here is the acoustic-elastic coupling considering finite elements and the acoustic-acoustic coupling considering finite elements and finite differences (other coupling procedures can be implemented analogously). One important feature of the algorithms presented is that they allow considering different time-steps for different sub-domains; so it is possible to substantially improve efficiency, accuracy and stability of the central difference More >

T. Fujimoto¹ and T. Nishioka¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 91-102, 2006, DOI:10.3970/cmes.2006.011.091

Abstract In the dynamic fracture of metallic material, some cracks propagate with the incidence of plastic deformation, and distinct plastic strain remains near the post-propagation area. In order to elucidate these dynamic nonlinear fracture processes, the moving finite element method is developed for nonlinear crack propagation. The T* integral is used as the parameter to estimate crack tip condition. First, the effect of material viscosity and crack propagation velocity have been discussed based on the numerical results for fracture under pure mode I high speed loading. Under mixed mode loading, numerical simulations for fracture path prediction More >

K. Yashiro¹, Y. Nakashima¹, Y. Tomita¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 73-80, 2006, DOI:10.3970/cmes.2006.011.073

Abstract A simple back force model is proposed for a dislocation cutting into γ' precipitate, taking the work formaking and recovering an anti-phase boundary (APB) into account. The first dislocation, or a leading partial of a superdislocation, is acted upon by a back force whose magnitude is equal to the APB energy. The second dislocation, or a trailing partial of a superdislocation, is attracted by the APB with a force of the same magnitude. The model is encoded in the 3D discrete dislocation dynamics (DDD) code and applied to the cutting behavior of dislocations at a… More >

T. Yoda¹, N. Kodama²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 1-8, 2006, DOI:10.3970/cmes.2006.011.001

Abstract A nonlinear dynamic response analysis of a box section steel rigid frame under seismic action is proposed on the basis of a beam model. The average stress-strain relation of the beam model can be formulated for transverse stiffener spacing, in which stress-strain relation after local buckling is assumed. As a result of the present study, the maximum lateral displacements and the residual displacements of a box section steel rigid frame were well estimated by the proposed beam element model that considers the deterioration effect due to local buckling. More >

Wenzhong Tang¹, Suresh G. Advani¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.2, pp. 165-176, 2005, DOI:10.3970/cmes.2005.008.165

Abstract An optimization method is proposed to simulate the motion of long flexible fibers in shear flow. The fiber is modeled as spheres connected by massless rigid rods and ball-socket joints. The optimization method is mathematically justified and used to obtain the position of a fiber at the next time step from its current position. Results for a single fiber in simple shear flow agree well with those reported in the literature. The usefulness of the method is demonstrated by simulating the motion of two interactive fibers subjected to shear flow field, and by studying the More >

D. Soares Jr.¹, W.J. Mansur^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.2, pp. 153-164, 2005, DOI:10.3970/cmes.2005.008.153

Abstract A coupling procedure is described to perform time-domain numerical analyses of dynamic fluid-structure interaction. The fluid sub-domains, where acoustic waves propagate, are modeled by the Boundary Element Method (BEM), which is quite suitable to deal with linear homogeneous unbounded domain problems. The Finite Element Method (FEM), on the other hand, models the structure sub-domains, adopting a time marching scheme based on implicit Green's functions. The BEM/FEM coupling algorithm here developed is very efficient, eliminating the drawbacks of standard and iterative coupling procedures. Stability and accuracy features are improved by the adoption of different time steps More >

Toshihisa Nishioka ¹,

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.3, pp. 209-216, 2005, DOI:10.3970/cmes.2005.010.209

Abstract Recent Advances in Numerical Simulation Technologies for Various Dynamic Fracture Phenomena are summarized. First, the basic concepts of fracture simulations are explained together with pertinent simulation results. Next, Examples of dynamic fracture simulations are presented. More >

R. Matsumoto, M. Nakagaki

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.3, pp. 187-198, 2005, DOI:10.3970/cmes.2005.010.187

Abstract Large-scale molecular dynamics simulations of tensile deformation of amorphous metals containing a nano-crystalline particle were performed in order to clarify the effects of particle size and crystal volume fraction on the deformation mechanism and strength. It became clear that particle size has very little effect, while crystal volume fraction has a substantial influence. Elastic modulus and flow stress intensify as crystal volume fraction increases. Furthermore, the stress in the crystal phase continues to increase, even after yielding in the amorphous phase. Consequently, work-hardening effects appear, preventing localization of plastic deformation. Thus, the dispersed nano-crystalline particles… More >

R.L. Huston¹, C.-Q. Liu²

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 143-152, 2005, DOI:10.3970/cmes.2005.010.143

Abstract This paper presents a summary of recent developments in computational methods for multibody dynamics analyses. The developments are presented within the context of an automated numerical analysis. The intent of the paper is to provide a basis for the easy development of computational algorithms. The principal concepts discussed are: differentiation algorithms, partial velocities and partial angular velocities, generalized speeds, Euler parameters, Kane's equations, orthogonal complement arrays, lower body arrays and accuracy testing functions. More >