J. Sladek¹, V. Sladek, Ch.Zhang²

Structural Durability & Health Monitoring, Vol.1, No.2, pp. 131-144, 2005, DOI:10.3970/sdhm.2005.001.131

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed for crack analysis in two-dimensional (2-d), anisotropic and linear elastic solids with continuously varying material properties. Both quasi-static and transient elastodynamic problems are considered. For time-dependent problems, the Laplace-transform technique is utilized. A unit step function is used as the test function in the local weak-form. It is leading to local boundary integral equations (LBIEs) involving only a domain-integral in the case of transient dynamic problems. The analyzed domain is divided into small subdomains with a circular shape. The moving least-squares (MLS) method is More >

Y.C. Shiah¹, T.L. Guao¹, C.L. Tan²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 321-338, 2005, DOI:10.3970/cmes.2005.007.321

Abstract It is well known in elastic stress analysis using the boundary element method (BEM) that an additional volume integral appears in the basic form of the boundary integral equation if thermal effects are considered. In order to restore this general numerical tool as a truly boundary solution technique, it is perhaps most desirable to transform this volume integral exactly into boundary ones. For general 2D anisotropic thermo-elastostatics without heat sources, this was only achieved very recently. The presence of concentrated heat sources in the domain, however, leads to singularities at these points that pose additional More >

J. Sladek¹, V. Sladek¹, S.N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 477-490, 2004, DOI:10.3970/cmes.2004.006.477

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed for solution of static and elastodynamic problems in a homogeneous anisotropic medium. The Heaviside step function is used as the test functions in the local weak form. It is leading to derive local boundary integral equations (LBIEs). For transient elastodynamic problems the Laplace transfor technique is applied and the LBIEs are given in the Laplace transform domain. The analyzed domain is covered by small subdomains with a simple geometry such as circles in 2-d problems. The final form of local integral equations has a More >

K. Woo¹, H. Igawa², C.H. Jenkins³

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 397-408, 2004, DOI:10.3970/cmes.2004.006.397

Abstract This paper presents the development and evaluation of a wrinkling analysis procedure for anisotropic membranes. The procedure is based on a penalty-parameter modified material model and a non-linear root finding to simulate the uni-axial stress state. The procedure was implemented in the ABAQUS finite element code as a user subroutine, and then applied to annular and square membranes. The wrinkle problems were also solved by shell element post-buckling analysis and the results were compared. The effect of anisotropy and unsymmetric loading on the wrinkling behavior was investigated. More >

J. Sladek¹, V. Sladek¹, S.N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.3, pp. 309-318, 2004, DOI:10.3970/cmes.2004.006.309

Abstract Meshless methods based on the local Petrov-Galerkin approach are proposed for solution of steady and transient heat conduction problem in a continuously nonhomogeneous anisotropic medium. Fundamental solution of the governing partial differential equations and the Heaviside step function are used as the test functions in the local weak form. It is leading to derive local boundary integral equations which are given in the Laplace transform domain. The analyzed domain is covered by small subdomains with a simple geometry. To eliminate the number of unknowns on artificial boundaries of subdomains the modified fundamental solution and/or the More >

P. Vena¹, R. Contro

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 497-506, 2003, DOI:10.3970/cmes.2003.004.497

Abstract The adoption of artificial ligaments in current surgery is still characterised by a low success rate due to the fact that mechanical properties of the biomedical devices are such that a biomechanical compatibility is not fully satisfied. A durable artificial ligament should exhibit stiffness as well as strength properties which are such that a full articulation functionality is guaranteed. To this purpose, reliable numerical methods able to predict the mechanical behaviour of such devices both in the elastic and in inelastic range until complete rupture, could be used for designing of devices with tailored mechanical More >

Wolfgang Brocks¹, Weidong Qi²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.3, pp. 313-320, 2002, DOI:10.3970/cmes.2002.003.313

Abstract Results of a numerical study of creep damage development and its effect on the deformation behavior in the Ni-based superalloy IN 738 LC at 850 °C are reported. A continuum damage mechanics based anisotropic damage model has been coupled with the unified model of Chaboche, and is used for the present study. Numerical computations are performed on a plate containing a circular hole under tension. They show that the applied damage model does not cause damage localization and no significant mesh-dependence of the results are observed. More >

M. Kögl, L. Gaul²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 27-44, 2000, DOI:10.3970/cmes.2000.001.479

Abstract A Boundary Element formulation is presented for the solution of three-dimensional problems of anisotropic elastodynamics. Due to the complexity of the dynamic fundamental solutions for anisotropic materials and the resulting high computational costs, the approach at hand uses the fundamental solution of the static operator. This leads to a domain integral in the representation formula which contains the inertia term. The domain integral can be transformed to the boundary using the Dual Reciprocity Method. This results in a system of ordinary differential equations in time with time-independent matrices. Several general questions concerning the anisotropic solutions, More >

R. Mustata¹, S. D. Harris², L. Elliott¹, D. Lesnic¹, D. B. Ingham¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 107-116, 2000, DOI:10.3970/cmes.2000.001.409

Abstract An inverse boundary element method is developed to characterise the components of the hydraulic conductivity tensor K of anisotropic materials. Surface measurements at exposed boundaries serve as additional input to a Genetic Algorithm (GA) using a modified least squares functional that minimises the difference between observed and BEM-predicted boundary pressure and/or hydraulic flux measurements under current hydraulic conductivity tensor component estimates. More >

Y.C. Shiah¹, C.L. Tan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 91-99, 2000, DOI:10.3970/cmes.2000.001.393

Abstract In the direct formulation of the boundary element method (BEM), a volume integral arises in the resulting integral equation if thermal effects are present. The steps to transform this volume integral into boundary ones in an exact analytical manner are reviewed in this paper for two- dimensional anisotropic thermoelasticity. The general applicability of the BEM algorithm for fracture mechanics applications is demonstrated by three crack problems with slanted cracks. The numerical results of the stress intensity factors are presented and compared with those obtained using superposition. More >