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Abstract: The objective of this paper is to develop a probabilistic model for a stiffened panel subjected to correlated growth of cracks in the stiffener and plate elements. The geometry functions of the correlated cracks in the plate and in the stiffener are defined based on the stress intensity factors calculated by finite element analysis. A validation of the stress intensity factor and the geometry function calculation has been performed for an isolated crack in a plate with a central/edge through thickness crack. The Paris–Erdogan law is used to predict the crack propagation. Monte Carlo simulation is employed to define the statistical descriptors of the crack growth in the stiffened panel under different correlation functions and a probabilistic model of crack size as a function of time are presented adopting a truncated normal distribution to describe the probability density function of the crack size in the plate and in the stiffener. A procedure for the development of a probabilistic crack growth model for a stiffened panel has been proposed, allowing for the existence of multiple cracks both in the stiffeners and in the plate and accounting for the correlation between them. The developed probabilistic model may be used for fatigue crack growth analysis and is suitable for reliability assessment of a stiffened panel subjected to correlated crack growth. [Copyright &y& Elsevier]

Abstract: In this paper creep crack growth behaviour of P92 welds at 923K are presented. Creep crack growth behaviour for P92 welds are discussed with C * parameter. Creep crack growth behaviour of P92 welds has been compared with that of P91 welds with C * parameter. NSW and NSW–MOD model were compared with the experimental creep crack growth data. Plane strain NSW model significantly overestimates the crack growth rate, and plane stress NSW model underestimates it. Whilst, NSW–MOD model for plane stress and plane strain conditions gives lower and upper bound of the experimental data, respectively. FE analysis of creep crack growth has been conducted. Constrain effect for welded joints has been examined with C * line integrals of C(T) specimens. As a result, constant C * value using the material data of welded joint gives 10 times lower than that of only HAZ property. Whilst, the predicted CCG rates for welded joint are 10 times higher than those for only HAZ properties. Compared with predicted CCG rate from FE analysis and the experimental CCG rate, it can be suggested that creep crack growth tests for lower load level or for large specimen should be conducted, otherwise the experimental data should give unconservative estimation for components operated in long years. [ABSTRACT FROM AUTHOR]

Abstract: This paper deals with the development of a continuum inelasticity–damage-based model. The aim is to describe the behavior of plain and reinforced concrete under monotonic and cyclic loading. We consider that inelasticity is due to micro-crack openings, and that the material recovers its original elastic modulus when all micro-cracks are closed. We make the hypothesis that the displacement field, due to micro-crack openings, remains consistent with a strain called Unitary Crack Opening. The damage is described by a simple scalar which is taken as a multiplier of the Unitary Crack Opening tensor. Hence, the crack closure effects are directly described, the material recovers its original elasticity when micro-cracks are closed. Damage variable multiplied by the Unitary Crack Opening tensor gives a good description of anisotropy. Nonlinearity occurs when both damage and Unitary Crack Opening strains exist. Firstly, the thermodynamic and mathematical basis of the model are explored. Elementary tests are firstly considered for validation. Furthermore, the single edge notched beam and a beam subjected to cyclic loading are tested. [Copyright &y& Elsevier]