E. Ferretti¹, E. Casadio, A. Di Leo¹

CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.3, pp. 163-190, 2008, DOI:10.3970/cmes.2008.030.163

Abstract In this study, the Cell Method (CM) is applied in order to investigate the failure mechanisms of masonry walls under shear force. The direction of propagation is computed step-wise by the code, and the domain is updated by means of a propagation technique of intra-element nodal relaxation with re-meshing. The crack extension condition is studied in the Mohr/Coulomb plane, using the criterion of Leon. The main advantage of using the CM for numerical analyses of masonry is that the mortar, the bricks and the interfaces between mortar and bricks can be modeled without any need to use homogenization techniques, simply… More >

P.H. Wen¹, M.H. Aliabadi², Y.W. Liu³

CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.3, pp. 133-148, 2008, DOI:10.3970/cmes.2008.030.133

Abstract Based on the variation of potential energy, the element-free Galerkin method (MFGM) has been investigated for structures with crack on the basis of radial base function interpolation. An enriched radial base function is introduced to capture the singularities of stress at the crack tips. The advantages of the finite element method are remained in this method and there is a significant improvement of accuracy, particularly for the crack problems of fracture mechanics. The applications of the element-free Galerkin method with enriched radial base function to two-dimensional fracture mechanics in functionally graded materials have been presented and comparisons have been made… More >

S.S. Xu, Y. Dong, Y. Zhang

CMES-Computer Modeling in Engineering & Sciences, Vol.30, No.1, pp. 17-26, 2008, DOI:10.3970/cmes.2008.030.017

Abstract A meshless method for arbitrary crack growths is presented. The new method is based on a local partition of unity by introducing additional degrees of freedom that determine the opening of the crack. The crack is modeled with overlapping crack segments located at the nodes. The crack segments are rotated at directional changes of the principal tensile stress such that smearing of the crack is avoided. Such smearing occurs in fixed crack method probably because of inaccurate stress state around the crack tip when the crack propagates. The key feature of our method is that it does not require algorithms… More >

Q. Ma¹, C. Levy², M. Perl³

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.2, pp. 95-110, 2008, DOI:10.3970/cmes.2008.029.095

Abstract Networks of radial and longitudinally-coplanar, internal, surface cracks are typical in rifled, autofrettaged, gun barrels. In two previous papers, the separate effects of large arrays of either radial or longitudinally-coplanar semi-elliptical, internal, surface cracks in a thick-walled, cylindrical, pressure vessel under both ideal and realistic autofrettage were studied. When pressure is considered solely, radial crack density and longitudinal crack spacing were found to have opposing effects on the prevailing stress intensity factor, K_IP. Furthermore, the addition of the negative stress intensity factor (SIF), K_IA, resulting from the residual stress field due to autofrettage, whether ideal or realistic, tended to decrease… More >

G.F. Karlis¹, S.V. Tsinopoulos², D. Polyzos³, D.E. Beskos⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.3, pp. 189-208, 2008, DOI:10.3970/cmes.2008.026.189

Abstract A boundary element method, suitable for solving two and three dimensional gradient elastic fracture mechanics problems under static loading, is presented. A simple gradient elastic theory (a simplied version of Mindlin's Form-II general theory of gradient elasticity) is employed and the static gradient elastic fundamental solution is used to construct the boundary integral representation of the problem with the aid of a reciprocal integral identity. In addition to a boundary integral representation for the displacement, a boundary integral representation for its normal derivative is also necessary for the complete formulation of a well-posed problem. Surface quadratic line and quadrilateral boundary… More >

L.K. Keppas¹, G.I. Giannopoulos¹, N.K. Anifantis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 181-196, 2008, DOI:10.3970/cmes.2008.025.181

Abstract In the present paper a boundary element procedure is formulated to treat two-dimensional time dependent thermo-elastic contact problems incorporating thermal resistance along the contacting surfaces. The existence of pressure-dependent thermal contact leads to coupling of temperature and stress fields. Therefore, the inherent non-linearity of the problem demands simultaneous treating of both thermal and mechanical boundary integral equations while iterative procedures are introduced to ensure equilibrium of mechanical and thermal contact conditions at each step of the process. The transient behavior of interfacial cracks in bimaterial solids when undergo thermal shock in the presence of partial crack closure and thermal contact… More >

A.N. Guz¹, V.V. Zozulya²

CMES-Computer Modeling in Engineering & Sciences, Vol.22, No.2, pp. 119-128, 2007, DOI:10.3970/cmes.2007.022.119

Abstract The frictional contact interaction of the edges of a finite plane crack is studied for the case of normal incidence of a harmonic SH-shear wave which produces antiplane deformation. The forces of contact interaction and displacement discontinuity are analyzed. Influence of the wave frequency on the stress intensity factor for different coefficients of friction is studied here. More >

A.N. Guz¹, O.V. Menshykov^1,2, V.V. Zozulya³, I.A. Guz²

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.3, pp. 205-214, 2007, DOI:10.3970/cmes.2007.017.205

Abstract The contact interaction of opposite faces of an elliptical crack is studied for the case of a normal time-harmonic shear wave loading. The distribution of stress intensity factors (shear modes II and III) as functions of the wave number and the friction coefficient is investigated. The results are compared with those obtained for an elliptical crack without allowance for the contact interaction. 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 are demonstrated for various crack… More >

M. Perl¹, C. Levy ², V. Rallabhandy ²

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 37-48, 2006, DOI:10.3970/cmes.2006.011.037

Abstract The Bauschinger Effect (BE) impact on K_IN– the combined, Mode I, 3-D Stress Intensity Factor (SIF) distributions for arrays of radial, internal, surface cracks emanating from the bore of a fully or partially autofrettaged thick-walled cylinder is investigated. A in-depth comparison between the combined SIFs for a “realistic” - Bauschinger Effect Dependent Autofrettage (BEDA) and those for an “ideal” - Bauschinger Effect Independent Autofrettage (BEIA) is performed. The 3- D finite element (FE) analysis is performed employing the submodeling technique and singular elements along the crack front. Both autofrettage residual stress fields, BEDA and BEIA, are simulated using an equivalent… More >