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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…
The crack growth behavior of the aluminum alloy 6061 T651 was investigated using cruciform specimens with a measurement area of 120 x 120 x 2 mm3 with two center crack configurations of the starting notch parallel to one of the loading…
The CJP model of crack tip stresses is a modified version of the Williams crack tip stress field which takes account of simplified stress distributions that arise from the presence of a zone of plastic deformation associated with the crack…
It is generally accepted that fatigue crack growth is retarded after an overload, which has been explained either by plasticity-induced crack closure or near-tip residual stress. However, any interpretation of overload effect is…
In many engineering applications special requirements are directed to a material's fracture behavior and the prediction of crack paths. Especially if the material exhibits anisotropic elastic properties or fracture toughnesses, e.g. in…
While it is well known that fatigue crack growth in metals that display confined slip, such as high strength aluminium alloys, develop crack paths that are responsive to the loading direction and the local microstructural orientation, it…
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…
The fatigue crack propagation is one of the major problems and of the real concern in the evaluation of the structural integrity of components. This is due to the fact that once a fatigue crack has been detected it is also known its effect…
Aeroengine manufacturers have to demonstrate that critical components such as turbine disks, made of DA Inconel 718, meet the certification requirements in term of fatigue crack growth. In order to be more representative of the in service…
Crack closure influences fatigue crack growth rate and must be included in the design of components. Plasticity induced crack closure is intimately linked with the crack tip plastic deformation, which becomes residual as the crack…
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…
Fully automatic fatigue crack growth simulation system is developed using S-version FEM (SFEM). This system is extended to fracture in heterogeneous material. In the heterogeneous material, crack tip stress field becomes mixed mode…
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…
In the present work finite element method has been employed to study the interaction of multiple cracks in a finite rectangular plate of unit thickness with cracks on the same side under uniaxial loading conditions. The variation of the…
A class of fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and local strain-life damage models have been proposed in literature. The fatigue crack growth is regarded as a process of…
Near tip full-field strains in a growing fatigue crack have been studied in situ using the Digital Image Correlation (DIC) technique in a compact tension specimen of stainless steel 316L under tension-tension cyclic loading. An error…
Fatigue crack growth (FCG) is associated with irreversible and non-linear processes happening at the crack tip. This explains different problems observed in the use of da/dN-?K curves, namely the inability to explain stress ratio and load…
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…
An inhomogeneous distribution of non-metallic inclusions can result from the steel casting process. The aim of the present study was to investigate the damaging effect of an inhomogeneous distribution of nonmetallic inclusions on the crack…
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…
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 concept of the average stress has been employed to propose the maximum average tangential stress (MATS) criterion for predicting the direction of fracture angle. This criterion states that a crack grows when the maximum average…
The weight function method provides a powerful and reliable tool for the determination of the stress intensity factor around the crack tip in a linearly elastic cracked solid subjected to arbitrary loading conditions. However, it is…
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…
The premature contact of crack surfaces attributable to the near-tip plastic deformations under cyclic loading, which is commonly referred to as plasticity induced crack closure (PICC), has long been focused as supposedly controlling…
Crack tip stress-induced phase transformation mechanisms in nickel-titanium alloys (NiTi) were analyzed by Digital Image Correlation (DIC), under fatigue loads. In particular, Single Edge Crack (SEC) specimens, obtained from a commercial…
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…
The aim of the paper is to estimate a value of the critical applied stress for a crack initiation from a sharp V-notch tip. The classical approach of the linear elastic fracture mechanics (LELM) was generalized, because the stress…
Due to the peculiar graphite elements shape, obtained by means of a chemical composition control (mainly small addition of elements like Mg, Ca or Ce), Ductile Cast Irons (DCIs) are able to offer the good castability of gray irons with the…
In order to study the growth mechanism of fatigue cracks in ultrafine grained copper, stress controlled fatigue tests of round-bar specimens with a small blind hole as a crack starter were conducted. The hole was drilled on the surface…
The concept of ratchetting strain as a crack driving force in controlling crack growth has previously been explored at Portsmouth using numerical approaches for nickel-based superalloys. In this paper, we report the first experimental…
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 this study, the influence of a material’s plastic properties on the crack tip fields and dislocation density behavior is analytically and numerically analyzed using the conventional mechanism-based strain-gradient plasticity (CMSGP)…
New experimental technique for a determination of the stress intensity factor (SIF) and T-stress values is developed and verified. The approach assumes combining the crack compliance method and optical interferometric measurements of local…
Fatigue crack initiation and propagation involve plastic strains that require some work to be done on the material. Most of this irreversible energy is dissipated as heat and consequently the material temperature increases. The heat being…
In stress analysis of cracked plates, alongside the stress intensity factor which quantifies the singular stress component perpendicular to the crack plane, the role played in crack growth by the constant term parallel to the crack plane…
The work is devoted to experimental investigation of the laser shock peening (LSP) effect on fatigue crack propagation rate and heat dissipation at the crack tip in specimens made of titanium alloy Grade 2 with a stress concentrator. It is…
The hydrogen effect on the fracture toughness and fatigue crack growth behaviour in the martensitic high strength steel is investigated. The secondary ion mass spectrometry method has been employed to analyse the distribution of hydrogen…
In this work, the use of circumferentially cracked bar (CCB) sample to determine material fracture toughness in the upper shelf regime for carbon steels has been investigated. Since high fracture toughness materials are known to exhibit…
Highly deformable materials (elastomers, gels, biological tissues, etc.) are ubiquitous in nature as well as in technology. The understanding of their flaw sensitivity is crucial to ensure a desired safety level. Fracture failure in soft…
Fatigue crack growth (FCG) is linked to irreversible and non-linear processes happening at the crack tip, which explains different problems observed in the use of da/dN-DK curves. The replacement of DK by non-linear crack tip parameters…
The torsional fatigue behaviour of circumferentially notched specimens made of austenitic stainless steel, SUS316L, and carbon steel, SGV410, characterized by different notch root radii has been recently investigated by Tanaka. In that…
This paper analyzes the effects of crack tip plastic strains and compressive residual stresses, created by fatigue pre-cracking, on environmentally assisted cracking of pearlitic steel subjected to localized anodic dissolution and hydrogen…
In the last two decades, visual image techniques such as Digital Image Correlation (DIC) enabled to experimentally determine the crack tip displacement and strain fields at small scales. The displacements are tracked during loading, and…
This work is devoted to the development of an experimental method for studying the energy balance during cyclic deformation and fracture. The studies were conducted on 304 stainless steel AISE and titanium alloy OT4-0 samples. The…
For various configurations examined in a series of fatigue experiments on thin-walled tubes under tension and torsion, the experimental results – crack path, crack growth life, near crack tip deformations, and crack closure – are measured…
Looking at the long-time behaviour of a dam, it is necessary to assume that the water can penetrate a possible crack washing away some components of the concrete. This type of corrosion reduces the tensile strength and fracture energy of…
This work presents an in-situ characterisation of crack-tip strain fields following an overload by means of synchrotron X-ray diffraction. The study is made on very fine grained bainitic steel, thus allowing a very high resolution so that…
According to Gradient Mechanics (GM), stress fields have to be determined by directly incorporating into the stress analysis a length scale which that takes into account the material microstructural features. This peculiar modus operandi…
In this paper Digital Image Correlation (DIC) is used to study the evolution of the plastic zone close to a crack tip. A modified CT-specimen was used in order to fulfill the plane stress condition. The strain field around the crack tip…
