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In the present paper, mathematical models are proposed in order to analyze the strength of pinloaded lugs with semi-elliptical crack and through-the-thickness crack. The crack growth investigation of considered crack configurations tackles…
Crack closure concept has been widely used to explain different issues of fatigue crack propagation. However, different authors have questioned the relevance of crack closure and have proposed alternative concepts. The main objective here…
Fatigue surface crack growth and the in-plane and out-of-plane constraint effects are studied through experiments and computations for aluminium alloy D16T. Subjects for studies are cruciform specimens under different biaxial loading and…
In the current work an experimental study of the crack tip opening displacement (CTOD) is performed to evaluate the ability of this parameter to characterise fatigue crack growth. A methodology is developed to measure and to analyse the…
This study compares both uniaxial and multiaxial variable amplitude experimental crack growth data for naturally initiated fatigue cracks in tubular specimens of 2024-T3 aluminum alloy to predictions based on two state-of-the-art analysis…
This work is aimed at reproducing numerically a campaign of experimental tests performed for the development of reinforced panels, typically found in aircraft fuselage. The bonded reinforcements can significantly reduce the rate of fatigue…
The paper deals with the Stress Intensity Factor assessment of cracks at the intersection of holes loaded by internal pressure. Triangular flaws are considered at the intersection of two holes inside a specific specimen. The research…
The goal of the authors’ investigations was determination of the fatigue crack growth in fragments of steel structures (of the puddled steel) and its cyclic behavior. Tested steel elements coming from the turn of the 19th and 20th were…
In this study, multiple and non-planar crack propagation analyses are performed using Fracture and Crack Propagation Analysis System (FCPAS). In an effort to apply and validate FCPAS procedures for multiple and non-planar crack propagation…
This paper is devoted to the analysis of the load path effect on I+II+III mixed mode fatigue crack propagation in a 316L stainless steel. Experiments were conducted in mode I+II and in mode I+II+III. The same maximum, minimum and mean…
In this work it is proposed a methodology for the evaluation of plasticity-induced crack shielding from the analysis of the crack tip displacements fields measured by digital image correlation. This methodology is based on the evaluation…
A four-parameters model for interpolation of fatigue crack growth data is presented. It has been validated by means of both data produced by the Authors and data collected from Literature. The proposed model is an enhanced version of a…
Crack initiation and propagation have been investigated on the polymeric material ABS (Acrylonitrile Butadiene Styrene), under ultrasonic fatigue testing. Three controlled actions were implemented in order to carry out fatigue tests at…
The crack growth behavior in 2324-T39 aluminium alloy was experimentally investigated. Two types of crack branching were observed. The mechanism of an uncommon crack branching which results from the link up of secondary crack with the main…
The linear elastic analysis of cracked bodies is a Twentieth Century development, with the first papers appearing in 1907, but it was not until the introduction of the stress intensity factor concept in 1957 that widespread application to…
The present paper describes a novel experimental technique recently presented that allows one to study interactions between the crack and microstructural barriers with an unprecedented level of ease and detail. The method consists in…
The peculiar geometrical shape and working conditions of crankshafts make fatigue becoming responsible for most of the failure cases in such components. Therefore, improvement of crankshaft performance requires enhancing its fatigue life.…
The fivefold symmetric modular stellarator Wendelstein 7-X (W7-X) is currently under construction in Greifswald, Germany. The superconducting coils of the magnet system are bolted onto a central support ring and interconnected with five…
The paper analyses previously reported work, which uses digital image correlation to measure fatigue crack closure. As well as determining crack opening loads, the information on crack shape may be used to estimate the stress intensity…
In rolling contact fatigue (RCF), cracks usually initiate from inclusions beneath the surface and propagate to the contact surface. In the present study, synchrotron radiation computed laminography (SRCL) imaging was performed to observe…
The initial crack path is analysed in a fretting fatigue test with cylindrical contact, where there is a stress gradient and a multiaxial and non-proportional stress state. For this, a cylindrical pad is pressed, with a constant normal…
In this paper we investigated the influence of consecutive dynamic and gigacycle fatigue loads on the lifetime of aluminum-magnesium alloy AlMg6. Preloading of samples was achieved during dynamic tensile tests in the split-Hopkinson bar…
We predict the fatigue life of a planar tubular truss when geometrical parameters, material properties, and live loads are non-deterministic. A multi-level calculation uncertainty quantification framework code was designed to aggregate the…
The current work presents a novel methodology for the experimental quantification of the crack tip plastic zone during fatigue crack growth. This methodology is based on the application of yield criteria to estimate the area and the shape…
In Portugal there is a number of old metallic riveted railway and highway bridges that were erected by the end of the 19th century and beginning of the 20th century, and are still in operation, requiring inspections and remediation…
In this work, the orientation and propagation of cracks in fretting fatigue problems is analyzed numerically using the finite element method (FEM) and the extended finite element method (X-FEM). The analysis is performed by means of a 2D…
Semi–empirical notch sensitivity factors q have been widely used to properly account for notch effects in fatigue design for a long time. However, the intrinsically empirical nature of this old concept can be avoided by modeling it using…
The current work presents an experimental study on the use of the crack tip opening displacement (CTOD) to evaluate its ability to characterise fatigue crack growth. A methodology is developed to measure and to analyse the CTOD from…
The behavior of short cracks that depart from elastoplastic notch tips is modeled to estimate the stresses required to initiate and to propagate cracks in notched structural components, and to evaluate the size of tolerable crack-like…
A Multi-Site Damage (MSD) crack growth simulation is presented, carried out by means of Dual Boundary Element Method (DBEM), in a two-dimensional analysis of a cracked butt-joint made of aluminium 2024 T3. An equivalent crack length is…
The initiation and propagation of fatigue cracks during cyclic torsion loading was studied in a cast Al alloy (A357) with a relatively large (~500 ?m) grain size. 2D observations, revealed that multi site crack initiation occur on the…
In this study, a generalized Barenblatt and Botvina dimensional analysis approach to fatigue crack growth is proposed in order to highlight and explain the deviations from the classical power-law equations used to characterize the fatigue…
The advances in the use of thermoelastic stress analysis (TSA) for fracture mechanics assessment are reviewed. The development of techniques to determine stress intensity factor is presented followed by the application of these techniques…
This paper presents an application of the boundary element method to the analysis of crack growth problems in linear elastic fracture mechanics and the correlation of results with experimental data. The methodology consists of computing…
The question about the existence of a correlation between the parameters C and m of the Paris’ law is re-examined in this paper. According to dimensional analysis and incomplete self-similarity concepts applied to the linear range of…
During a ferry flight, in a standard operation condition and at cruising level, a military cargo experienced a double hydraulic system failure due to a structural damage of the dual booster actuator. The booster actuator is the main…
The paper investigates the fatigue crack growth in typical bridge weldments by means of numerical analysis. The extended finite element (XFEM) method is coupled with the low-cycle fatigue (LCF) approach in ABAQUS, and parametric analyses…
Most mechanical components experience multi-axial cyclic loading conditions during service. Experimental analysis of fatigue cracks under such conditions is not easy and most works tend to focus more on the simpler but less realistic case…
Blades of combustion turbines are extremely loaded turbojet elements, which transmit operative energy onto a rotor. Experiences of many years indicate, that cracks initiation and propagation in the blades during the operation time can…
The variation of crack shape factor (a/c) during propagation has an important role on calculation of the stress intensity factor (SIF), where imprecise estimation of this latter can lead us to an inaccurate prediction of failure…
The present work aims at developing a new approach towards the analysis of the crack path through the access to the information from the infrared (IR) video imaging of the steady fatigue crack growth. We first test some commonly available…
Power plant piping system subjected to many cyclic loading conditions leads to fatigue loading and thereby crack initiation in the piping system. Demonstrating Leak-Before-Break (LBB) in the design stage itself plays an important role in…
Over the years several design philosophies to fatigue developed in order to combine structural safety and economy to manufacturing and operating aircraft process. The safe-life approach, which consists of designing and manufacturing a safe…
In this study a procedure to stress intensity factors calculation for imitation models made of titanium alloy is described. In service fatigue cracks are detected in a disk and blade “dovetail type” attachment. On the base of this…
This work is devoted to the comparative analysis of three techniques for measurement of energy dissipation in metals under fatigue crack propagation: original contact heat flux sensor, post-processing of the infrared thermography data and…
This paper deals with the fatigue assessment of cast steel defects in terms of macroscopic shrinkage porosity. Within preliminary studies, a generalized Kitagawa diagram GKD was established by numerical analyses of V-notched specimens with…
A three-parameters model for the interpolation of fatigue crack propagation data is proposed. It has been validated by a Literature data set obtained by testing 180 M(T) specimens under three different loading levels. In details, it is…
