V. Mallardo, C. Alessandri¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 165-176, 2006, DOI:10.3970/sdhm.2006.002.165

Abstract The formation of cracks and their propagation in brittle materials has been intensively studied in the last years. The main difficulty is related to the theoretical and numerical possibility to follow the development of regions of highly localised strains. The nonlinear phenomenon is physically different from the one which occurs in ductile materials: it starts with a narrow fracture process zone containing a large number of distributed microcracks which could lead to the formation of macrocracks and eventually to rupture. In the present paper, a simple nonlocal damage model is coupled to the crack analysis in order to describe the… More >

D. Benasciutti¹, R. Tovo¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 149-164, 2006, DOI:10.3970/sdhm.2006.002.149

Abstract The probability density functions used to characterize the distribution of fatigue cycles in random loads are usually defined over an infinite domain. This means that they give a non-zero probability to count cycles with an infinitely large peak or valley, which however seems of less physical sense. Moreover, practically all the methods existing in the literature completely neglect the negative effect on fatigue strength produced by fatigue cycles with positive mean values. With theses premises, this work tries to further extending the probabilistic theory used by the frequency-domain methods by addressing to distinct problems. First, it tries to include in… More >

RamanaM. Pidaparti¹

Structural Durability & Health Monitoring, Vol.2, No.3, pp. 131-148, 2006, DOI:10.3970/sdhm.2006.002.131

Abstract This paper provides an overview of the computational intelligence methods developed for the structural integrity assessment of aging aircraft structures. Computational intelligence techniques reviewed include artificial neural networks, inverse neural network mapping, wavelet based image processing methods, genetic algorithms, spectral element methods, and particle swarm optimization. Multi-site damage, corrosion, and corrosion-fatigue damage in aging aircraft is specifically discussed. Results obtained from selected computational intelligence methods are presented and compared to the existing alternate solutions and experimental data. The results presented illustrate the applicability of computational intelligence methods for assessing the structural integrity of aging aircraft structures and materials. 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 >

P. Bocchini, C. Gentilini, F. Ubertini, E. Viola¹

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 109-122, 2006, DOI:10.3970/sdhm.2006.002.109

Abstract This paper provides a simple and reliable method for the probabilistic characterization of the linear elastic response of frame structures with edge cracks of uncertain depth and location. A statistical analysis of the structural response allows consideration of the reliability of the investigated structure. A numerical example provides an indication of the performance of the approach proposed. 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 of non-zero out-of-phase loading has… More >

L. Nobile¹, C. Carloni¹

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 83-90, 2006, DOI:10.3970/sdhm.2006.002.083

Abstract The analysis of buckling of elastic columns is one of the first problem in structural engineering that was historically solved. Critical loads of perfect columns with various end restrains have been derived. Nevertheless, the perfect column is an idealized model. In reality, unavoidable imperfections should be considered. Solutions for transversal disturbing load, crookedness or load eccentricity have been proposed. Another frequent imperfection to be taken into account is the weakness at an interior location due to a partial edge crack. In this paper the influence of this type of imperfection on the critical load is analyzed. The case of the… More >

M. M. Rahman¹, A.K. Ariffin, N. Jamaludin, C. H. C. Haron

Structural Durability & Health Monitoring, Vol.2, No.2, pp. 69-82, 2006, DOI:10.3970/sdhm.2006.002.069

Abstract This paper describes finite element based vibration fatigue analysis techniques to predict fatigue life using the narrow band frequency response approach. The life prediction results are useful for improving the component design at a very early development stage. The approach is found to be suitable for periodic loading but requires very large time records to accurately describe random loading processes. The focus of this paper is to investigate the effects of surface treatments on the fatigue life of the components of free piston linear engine. The finite element modeling and frequency response analysis have been performed using a computer-aided design… More >

A. Soprano¹, F. Caputo¹

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 51-68, 2006, DOI:10.3970/sdhm.2006.002.051

Abstract This work describes the results of the experience acquired by the authors during their participation to some among the European research programs with the aim to develop a probabilistic risk assessment procedure to analyse the spreading of fatigue-induced damage in typical aeronautical components. The several steps of the procedure are pointed out, and especially the modelling of the damage evolutionary process; the initiation and the transitional probabilities, which characterize the passage from one damage level to a higher one, are fully characterized and their dependence from time and from the damage state of surrounding zones illustrated by various example results. More >

G. Milani¹, T. Rotunno², E. Sacco³, A. Tralli^1,4

Structural Durability & Health Monitoring, Vol.2, No.1, pp. 29-50, 2006, DOI:10.3970/sdhm.2006.002.029

Abstract Aim of the present work is the evaluation of the ultimate load bearing capacity of masonry panels reinforced with FRP strips. The investigation is developed performing both experimental and numerical studies. In particular, several panels subjected to different loading conditions are tested in the Tests Laboratory of the University of Florence (Italy). Then, numerical models based on combined homogenization and limit analysis techniques are proposed. The results obtained by numerical simulations are compared with experimental data. The good agreement obtained shows that the proposed numerical model can be applied for the evaluation of the ultimate load bearing capacity of reinforced… More >