Abdulnaser M. Alshoaibi^1,2, M. S. A. Hadi², A. K. Ariffin²

Structural Durability & Health Monitoring, Vol.3, No.1, pp. 15-28, 2007, DOI:10.3970/sdhm.2007.003.015

Abstract An adaptive finite element method is employed to analyze two-dimensional linear elastic fracture problems. The mesh is generated by the advancing front method and the norm stress error is taken as a posteriori error estimator for the h-type adaptive refinement. The stress intensity factors are estimated by a displacement extrapolation technique. The near crack tip displacements used are obtained from specific nodes of natural six-noded quarter-point elements which are generated around the crack tip defined by the user. The crack growth and its direction are determined by the calculated stress intensity factors as the maximum circumference More >

Waruna Seneviratne¹, John Tomblin², Suranga Gunawardana³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 81-86, 2007, DOI:10.3970/icces.2007.004.081

Abstract An experimental study was conducted to investigate the use of fracture mechanics to predict failure initiation of adhesive joints. Most practical plane fracture problems are mixed mode and failure initiation of adhesive joints is a result of such conditions. It is widely accepted that a useful method for characterizing the toughness of bonded joints is to measure the fracture toughness; energy per unit area needed to produce failure. For a given adhesive, mode mixity has a dependency towards fracture toughness and fracture toughness is directly associated with stress. Main goal in this investigation was to… More >

E. Schnack¹, A. Dimitrov², F.-G. Buchholz³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.4, pp. 139-146, 2007, DOI:10.3970/icces.2007.001.139

Abstract In fracture mechanics, we have to discuss corner and edge singularities for two- and three-dimensional problems in isotropic and layered anisotropic continua. To say something about the behavior of crack propagation starting from corners and edges, we need the information about stress asymptotics in the vicinity of three-dimensional corner points. Thus, in this paper we can study two aspects: the interface crack in layered unisotropic materials with re-entrant corners and surface cracks for the homogeneous isotropic continua. To study the effect of geometrical singularities on the stress intensity factors, we have to define generalized stress… More >

Milazzo A.¹, aimo A.¹, Orl,o C.¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.2, pp. 69-74, 2007, DOI:10.3970/icces.2007.001.069

Abstract In this paper a Hierarchical approach for the analysis of advanced aerospace structures is presented. The proposed Global/Local model uses two kind of numerical methods for the different steps of analysis. In particular the first step of the Hierarchical procedure is performed by the Finite Element code Patran/NastranTM, while the local analysis is performed by using a Boundary Element code based on the multidomain anisotropic technique. The accuracy and the effectiveness of the model have been demonstrated analysing classical stress concentration problems. Then the procedure has been used to analyze more complex structure among which More >

J.A. Sanz, M. Solis, J. Dominguez¹

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.3, pp. 215-230, 2007, DOI:10.3970/cmes.2007.017.215

Abstract A general mixed boundary element formulation for three-dimensional piezoelectric fracture mechanics problems is presented in this paper. The numerical procedure is based on the extended displacement and traction integral equations for external and crack boundaries, respectively. Integrals with strongly singular and hypersingular kernels appearing in the formulation are analytically transformed into weakly singular and regular integrals. Quadratic boundary elements and quarter-point boundary elements are implemented in a direct way in a computer code. Electric and stress intensity factors are directly computed from nodal values at quarter-point elements. Crack problems in 3D piezoelectric bounded and unbounded 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 >

S. Hagihara¹, M. Tsunori², T. Ikeda³, N. Miyazaki³

CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.2, pp. 63-72, 2007, DOI:10.3970/cmes.2007.017.063

Abstract The element-free Galerkin (EFG) method is applied to the calculation of elastic-plastic fracture mechanics parameters such as the J-integral and T*-integral. The fields of displacement, strain and stress for a crack problem are obtained using the elastic-plastic EFG method. Then the elastic-plastic fracture mechanics parameters J-integral and T*-integral are calculated from path and domain integrals. In the finite element analysis, paths for the path integral and domains for the domain integral are selected depending on finite element mesh division. On the other hand, they can be arbitrarily selected in the EFG method, and we can… More >

G. Davì¹, A. Milazzo¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 177-182, 2006, DOI:10.3970/sdhm.2006.002.177

Abstract An alternative single domain boundary element formulation and its numerical implementation are presented for the analysis of two-dimensional cracked bodies. The problem is formulated employing the classical displacement boundary integral representation and a novel integral equation based on the stress or Airy's function. This integral equation written on the crack provides the relations needed to determine the problem solution in the framework of linear elastic fracture mechanics. Results are presented for typical problems in terms of stress intensity factors and they show the accuracy and efficiency of the approach. More >

L. Susmel^1,2, D. Taylor²

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 91-108, 2006, DOI:10.3970/sdhm.2006.002.091

Abstract This paper reports on an attempt to systematically re-interpret the conventional multiaxial fatigue criteria in terms of the Theory of Critical Distances: in the present study the criteria proposed by Crossland, Dang Van, Papadopoulos, Matake, McDiarmid, respectively, and the so-called Modified W\"{o}hler Curve Method were considered. The procedure devised to re-interpret the above methods in terms of the Theory of Critical Distances was based on the following two assumptions: (i) the critical distance is a material constant to be determined under fully-reversed uniaxial fatigue loading; (ii) the presence of non-zero mean stresses as well as… More >

L.S. Miers¹, J.C.F. Telles²

CMES-Computer Modeling in Engineering & Sciences, Vol.14, No.3, pp. 161-170, 2006, DOI:10.3970/cmes.2006.014.161

Abstract This work aims at extending the concept of the Numerical Green's Function (NGF), well known from boundary element applications to fracture mechanics, to the Local Boundary Integral Equation (LBIE) context. As a "companion" solution, the NGF is used to remove the integrals over the crack boundary and is introduced only for source points whose support touches or contains the crack. The results obtained with the coupling of NGF-LBIE in previous potential discontinuity Laplace's equation problems and the authors' experience in NGF-BEM fracture mechanics were the motivation for this development. More >