I. Benedetti¹, A. Milazzo¹, M.H. Aliabadi²

Structural Durability & Health Monitoring, Vol.5, No.3, pp. 251-274, 2009, DOI:10.3970/sdhm.2009.005.251

Abstract In this work a three-dimensional BEM model is used for the analysis of structures with cracks and surface bonded piezoelectric PZT patches used as strain sensors. The cracked structure is modelled by the dual boundary element method, which allows for accurate and reliable crack analysis, while the piezoelectric patch is analyzed by a finite element state-space approach, that embodies both the full electro-mechanical coupling and the suitable sensor's boundary conditions. The model is used to investigate the strain-transfer mechanism from an host elastic structure to the piezoelectric layer, taking into account the effect of the adhesive layer, as well as… More >

J. Useche, P. Sollero, E.L. Albuquerque¹, L. Palermo²

Structural Durability & Health Monitoring, Vol.4, No.2, pp. 107-116, 2008, DOI:10.3970/sdhm.2008.004.107

Abstract The fracture analysis of cracked thick plates repaired with adhesively bonded composite patches using a boundary element formulation is presented. The shear deformable cracked isotropic plate was modeled using the dual boundary method. In order to model the repair, a three parameter boundary element formulation was established. This formulation is based on Kirchhoff's theory for symmetric layer composite plates and considers the transversal deflection and two in-plane rotations. Interaction forces and moments between the cracked plate and the composite repair were modeled as distributed loading, and discretized using continuous and semi-discontinuous domain cells. Coupling equations, based on kinematic compatibility and… More >

S.P.L. Leme¹, M.H. Aliabadi², L.M. Bezerra¹, P.W. Partridge¹

Structural Durability & Health Monitoring, Vol.3, No.3, pp. 121-132, 2007, DOI:10.3970/sdhm.2007.003.121

Abstract The coupled electromechanical behaviour of a thin piezoceramic sensor bonded to a stiffened panel subjected to membrane mechanical loadings is examined. The sensor is characterised by an electrostatic line model bonded to a damaged panel modelled by the dual boundary element method. Numerical results obtained demonstrate that the proposed method is capable of modelling changes in the signal output due to presence of cracks. Also presented is a numerical model for detecting fatigue crack growth in a stiffened panel using piezoceramic sensors. More >

C.P. Providakis¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 249-254, 2006, DOI:10.3970/sdhm.2006.002.249

Abstract This paper explores the concept of strain energy density rate in relation to the crack initiation in fracture analysis problems arising in creeping cracked structural components. The analysis of the components is performed by using the boundary element methodology in association with the employment of singular boundary elements for the modeling of the crack tip region. The deformation of the material is assumed to be described by an elastic power law creep model. The strain energy density rate theory is applied to determine the direction of the crack initiation for a center cracked plate in tension which is subjected to… More >

P.D. Shah¹, Ch. Song², C.L. Tan¹, X. Wang¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 225-238, 2006, DOI:10.3970/sdhm.2006.002.225

Abstract Numerical T-stress solutions in two dimensional anisotropic cracked bodies are very scarce in the literature. Schemes to evaluate this fracture parameter in anisotropy have been reported only fairly recently. Among them are those developed in conjunction with two different computational techniques, namely, the Boundary Element Method (BEM) and the Scaled Boundary Finite-Element Method (SBFEM). This paper provides a review of the respective schemes using these techniques and demonstrates their efficacy with three examples. These examples, which are of engineering importance, involve cracks lying in a homogeneous medium as well as at the interface between dissimilar media. The numerical T-stress solutions… More >

E.J. Sapountzakis¹, V.G. Mokos¹

Structural Durability & Health Monitoring, Vol.2, No.4, pp. 207-224, 2006, DOI:10.3970/sdhm.2006.002.207

Abstract In this paper a boundary element method is developed for the second-order analysis of frames consisting of composite beams of arbitrary constant cross section, taking into account shear deformation effect. The composite beam consists of materials in contact, each of which can surround a finite number of inclusions. The materials have different elasticity and shear moduli with same Poisson's ratio and are firmly bonded together. Each beam is subjected in an arbitrarily concentrated or distributed variable axial loading, while the shear loading is applied at the shear center of the cross section, avoiding in this way the induction of a… 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. Palermo Jr.¹, L.P.C.P.F. Almeida², P.C. Gonçalves³

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 123-130, 2006, DOI:10.3970/sdhm.2006.002.123

Abstract The kernels of integrands are usually differentiated to obtain the general boundary integral equation (BIE) for stresses and its corresponding traction equation. An alternative BIE for stresses can be obtained when the tangential differential operator is introduced in problems using Kelvin type fundamental solutions. The order of the singularity is reduced with this strategy and the Cauchy principal value sense or the first order regularization can be used in the resultant BIE. The dual boundary element formulation with the BIE for tractions using the tangential differential operator is analyzed in the present study. Shape functions with same expressions for conformal… More >

S. N. Atluri¹

Structural Durability & Health Monitoring, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/sdhm.2005.001.001

Abstract The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack growth models are used to… More >

Y.C. Shiah¹, Y.M. Lee², Chi-Chang Wang²

CMC-Computers, Materials & Continua, Vol.33, No.3, pp. 229-255, 2013, DOI:10.3970/cmc.2013.033.229

Abstract In this paper, the boundary integrals for treating 3D field problems are fully regularized for planar elements by the technique of integration by parts (IBP). As has been well documented in open literatures, these integrals appear to be strongly singular and hyper-singular for the associated fundamental solutions. In the past, the IBP approach has only been applied to regularize the integrals for 2D problems. The present work shows that the IBP can also be further extended to treat 3D problems, where two variables of the local coordinates are involved. The presented formulations are fully explicit and also, most importantly, very… More >