A. Frangi¹, L. Ghezzi, P. Faure-Ragani²

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 41-48, 2006, DOI:10.3970/cmes.2006.015.041

Abstract Three dimensional magneto-mechanical problems at low frequency are addressed by means of a coupled fast Boundary Element - Finite Element approach with total scalar potential and focusing especially on the issue of global force calculation on movable ferromagnetic parts. The differentiation of co-energy in this framework and the use of Maxwell tensor are critically discussed and the intrinsic links are put in evidence. Three examples of academic and industrial applications are employed for validation. More >

P. Fedelinski¹, R. Gorski¹

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 31-40, 2006, DOI:10.3970/cmes.2006.015.031

Abstract The aim of the present work is to analyze and optimize plates in plane strain or stress with stiffeners subjected to dynamic loads. The reinforced structures are analyzed using the coupled boundary and finite element method. The plates are modeled using the dual reciprocity boundary element method (DR-BEM) and the stiffeners using the finite element method (FEM). The matrix equations of motion are formulated for the plate and stiffeners. The equations are coupled using conditions of compatibility of displacements and equilibrium of tractions along the interfaces between the plate and stiffeners. The final set of equations of motion is solved… More >

A. Milazzo¹, I. Benedetti², C. Orlando³

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 17-30, 2006, DOI:10.3970/cmes.2006.015.017

Abstract A boundary integral formulation and its numerical implementation are presented for the analysis of magneto electro elastic media. The problem is formulated by using a suitable set of generalized variables, namely the generalized displacements, which are comprised of mechanical displacements and electric and magnetic scalar potentials, and generalized tractions, that is mechanical tractions, electric displacement and magnetic induction. The governing boundary integral equation is obtained by generalizing the reciprocity theorem to the magneto electro elasticity. The fundamental solutions are calculated through a modified Lekhnitskii's approach, reformulated in terms of generalized magneto-electro-elastic displacements. To assess the reliability and effectiveness of the… More >

S. N. Atluri¹, H. T. Liu², Z. D. Han²

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 1-16, 2006, DOI:10.3970/cmes.2006.015.001

Abstract The Finite Difference Method (FDM), within the framework of the Meshless Local Petrov-Galerkin (MLPG) approach, is proposed in this paper for solving solid mechanics problems. A "mixed'' interpolation scheme is adopted in the present implementation: the displacements, displacement gradients, and stresses are interpolated independently using identical MLS shape functions. The system of algebraic equations for the problem is obtained by enforcing the momentum balance laws at the nodal points. The divergence of the stress tensor is established through the generalized finite difference method, using the scattered nodal values and a truncated Taylor expansion. The traction boundary conditions are imposed in… More >

R. Springhetti¹, G. Novati¹, M. Margonari²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 67-80, 2006, DOI:10.3970/cmes.2006.013.067

Abstract With reference to potential and elastostatic problems, a BEM-FEM coupling procedure, based on the symmetric Galerkin version of the BEM, is developed; the continuity conditions at the interface of the BE and FE subdomains are enforced in weak form; the global linear system is characterized by a symmetric coefficient matrix. The procedure is numerically tested with reference first to 2D potential problems and successively to 3D elastoplastic problems (with plastic strains confined to the FE subdomain). More >

F. Aymerich¹, M. Serra²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 49-66, 2006, DOI:10.3970/cmes.2006.013.049

Abstract The study reported in this paper explores the potential of Ant Colony Optimization (ACO) metaheuristic for stacking sequence optimization of composite laminates. ACO is a recently proposed population-based search approach able to deal with a wide range of optimization problems, especially of a combinatorial nature, and inspired by the natural foraging behavior of ant colonies. ACO search processes, in which the activities of real ants are simulated by means of artificial agents that communicate and cooperate through the modification of the local environment, were implemented in a specifically developed numerical algorithm aimed at the lay-up optimization (based on a strain… More >

R. Vignjevic¹, T. De Vuyst², J. C. Campbell¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 35-48, 2006, DOI:10.3970/cmes.2006.013.035

Abstract An approach to the treatment of contact problems involving frictionless sliding and separation under large deformations in meshless methods is proposed. The method is specially suited for non-structured spatial discretisation. The contact conditions are imposed using a contact potential for particles in contact. Inter-penetration is checked as a part of the neighbourhood search. In the case of conventional SPH contact conditions are enforced on the boundary layer 2h thick while in the case of the normalized SPH contact conditions are enforced for the particles lying on the contact surface. The implementation of the penalty based contact algorithm for the explicit… More >

P.M. Baiz¹, M.H. Aliabadi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 19-34, 2006, DOI:10.3970/cmes.2006.013.019

Abstract In this paper the linear buckling problem of elastic shallow shells by a shear deformable shell theory is presented. The boundary domain integral equations are obtained by coupling two dimensional plane stress elasticity with boundary element formulation of Reissner plate bending. The buckling problem is formulated as a standard eigenvalue problem, in order to obtain directly critical loads and buckling modes as part of the solution. The boundary is discretised into quadratic isoparametric elements while in the domain quadratic quadrilateral cells are used. Several examples of cylindrical shallow shells (curved plates) with different dimensions and boundary conditions are analysed. The… More >

Luigi Morino¹, Giovanni Bernardini¹, Franco Mastroddi²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 1-18, 2006, DOI:10.3970/cmes.2006.013.001

Abstract The paper presents an overview of recent work by the authors and their collaborators on multi--disciplinary optimization for conceptual design, based on the integrated modeling of structures, aerodynamics, and aeroelasticity. The motivation for the work is the design of innovative aircraft configurations, and is therefore first--principles based, since in this case the designer cannot rely upon past experience. The algorithms used and the philosophy behind the choices are discussed. 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 >