A. Ramachandra Murthy¹, Nagesh R. Iyer¹, B.K. Raghu Prasad²

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.6, pp. 459-480, 2012, DOI:10.3970/cmes.2012.089.459

Abstract This paper presents the details of crack growth study and remaining life assessment of concrete specimens made up of high strength concrete (HSC, HSC1) and ultra high strength concrete (UHSC). Flexural fatigue tests have been conducted on HSC, HSC1 and UHSC beams under constant amplitude loading with a stress ratio of 0.2. It is observed from the studies that (i) the failure patterns of HSC1 and UHSC beams indicate their ductility as the member was intact till the crack propagated up to 90% of the beam depth and (ii) the remaining life decreases with increase… More >

Leiting Dong^1,2, Satya N. Atluri²

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.5, pp. 417-458, 2012, DOI:10.3970/cmes.2012.089.417

Abstract Two-dimensional weakly-singular Symmetric Galerkin Boundary Elements (SGBEMs) are developed, following the work of [Han and Atluri (2003)], using non-hypersingular integral equations for tractions. Specifically, the present 2D SGBEM is used to compute the stress intensity factors for arbitrary-shaped line cracks, including embedded, edge, branching, and intersecting cracks. The computed stress intensity factors show high accuracy, even with very coarse meshes. The non-collinear mixed-mode fatigue growth analysis of cracks requires a very minimal effort¡ªsimply extending the cracks by adding an element to each crack tip, in the direction of the crack-growth as determined by a physics-based… More >

Ramamurty Raju P.¹, Rajesh S.¹, Satyanarayana B.², Ramji K.³

Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 139-152, 2011, DOI:10.3970/sdhm.2011.007.139

Abstract This paper presents the details of method of sample size determination to estimate the characteristic fatigue life of aluminum alloy, A356.2-T6. The characteristic fatigue life of the alloy has been estimated by assuming log normal distribution model. A step wise procedure is outlined to determine the number of specimens required at predetermined stress amplitude to estimate the fatigue life with an acceptable error at 50% probability and various confidence levels, 90%, 95% and 99%. Maximum percentage of errors has also been calculated for the above probability and confidence levels. Details of generation of S-N curve More >

C. Braccesi¹, F. Cianetti^1,2

Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 83-118, 2011, DOI:10.3970/sdhm.2011.007.083

Abstract In this paper the problem of the correct evaluation of the stress state of mechanical components of non linear systems in the frequency domain was analysed. This is one of the most important steps in the frequency domain evaluation of the fatigue behaviour of components submitted to random loads. A new methodology to obtain an accurate representation in frequency domain of the non-linear behaviour of the system as well as of the stress state of the components both in terms of power spectral density (PSD) function and of frequency response function (FRF) was proposed and More >

Dennis Bäcker¹, Andreas Ricoeur², Meinhard Kuna¹

Structural Durability & Health Monitoring, Vol.7, No.1&2, pp. 1-22, 2011, DOI:10.3970/sdhm.2011.007.001

Abstract A new sensor concept for monitoring fatigue crack growth in technical structures is presented. It allows the in-situ determination of the position of the crack tip as well as the fracture mechanical quantities. The required data are obtained from a piezoelectric polymer film, which is attached to the surface of the monitored structure. The stress intensity factors and the crack tip position are calculated from electrical potentials obtained from a sensor array by solving the non-linear inverse problem. More >

A. Lanciotti, L. Lazzeri¹, C. Polese², C. Rodopoulos³, P. Moreira^4,5, A. Brot⁶, G. Wang⁷, L. Velterop⁸, G. Biallas⁹, J. Klement

Structural Durability & Health Monitoring, Vol.7, No.3, pp. 211-230, 2011, DOI:10.3970/sdhm.2011.007.211

Abstract An experimental activity was performed to collect test data on the fatigue crack propagation in various types of specimens, within the DaToN research project, partly funded by the EU in the FP6 programme. Only one general configuration was used, i.e. flat panels with two blade stringers, with different options for the manufacturing processes, that could be integral or welded. The purpose of this test activity was to obtain useful results for the validation and calibration of prediction methodologies, also developed in the same DaToN research project. A wide experimental programme was defined and performed by More >

S.M.O. Tavares¹, S.M. Häusler², P.M. Baiz³, P.M.S.T. de Castro¹, P. Horst² , M.H. Aliabadi³

Structural Durability & Health Monitoring, Vol.7, No.3, pp. 191-210, 2011, DOI:10.3970/sdhm.2011.007.191

Abstract This article is the second part of a two parts paper which presents, compares and discusses the different crack growth simulation models which were introduced for fatigue crack growth assessment during the DaToN project. In the first part, different simulation approaches were applied to determine a calibration of the stress intensity factors as a function of the crack length for a two stiffeners panel with a central crack. Due to the residual stress field promoted by the different manufacturing processes, its influence was included in the numerical models to determine the stress intensity factors. In… More >

S.M. Häusler¹, P.M. Baiz², S.M.O. Tavares³, A. Brot⁴, P. Horst¹, M.H. Aliabadi², P.M.S.T. de Castro³, Y. Peleg-Wolfin⁴

Structural Durability & Health Monitoring, Vol.7, No.3, pp. 163-190, 2011, DOI:10.3970/sdhm.2011.007.163

Abstract This article represents the first part of a two-part article which presents, compares and discusses the different crack growth simulation models which were introduced for fatigue crack growth assessment during the DaToN project. The project was funded by the EC within the 6th framework program and was specifically devoted to investigate innovative manufacturing techniques for metallic structures with special focus on the effects of residual stresses on the fatigue crack growth and residual strength behaviour. Within this first part the different simulation approaches, including the residual stress modelling approaches will be introduced and stress intensity… More >

N. Yan, N. Kawagoishi, Y. Maeda, Q. Chen

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 103-104, 2011, DOI:10.3970/icces.2011.017.103

Abstract Fatigue tests under rotating bending and ultrasonic loading were carried out using plain specimens with different grain sizes of Ni-base super alloy, Inconel 718, in order to investigate the effects of grain size and loading frequency on fatigue properties. Fatigue strength was increased with decreasing in grain size under both tests. Moreover, the fatigue strength under ultrasonic loading was higher than that under rotating bending. The resistance to crack initiation was larger in smaller grain sized alloy under both tests, and larger under ultrasonic loading than under rotating bending. Effects of loading frequency and grain… More >

Youshi Hong, Chengqi Sun, Aiguo Zhao

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 91-92, 2011, DOI:10.3970/icces.2011.016.091

Abstract The researches on the behavior of very-high-cycle fatigue (VHCF) for high strength steels have become a new branch in the field of metal fatigue since 1980s. The characteristics of crack initiation and propagation for high strength steels in VHCF regime differ from those in low cycle and high cycle fatigue regimes. One of the most distinct phenomena for VHCF regime is the interior or subsurface crack initiation at inclusions or at other inhomogeneities. In fact, the period of crack initiation and early growth dominates the fatigue life, which is extremely evident for the fatigue process… More >