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The focus of manufacturing is more and more on innovative and application-oriented products considering lightweight construction. Hence, especially functional graded materials come to the fore. Due to the application-matched functional…
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…
A three-dimensional crack propagation simulation is performed by the Dual Boundary Element Method (DBEM). The Stress Intensity Factors (SIFs) along the front of a semi elliptical crack, initiated from the external surface of a hollow axle…
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…
Additive layer manufacturing has recently gained a lot of interest due to the feasibility of producing metallic components directly from a computer-aided design file of the part. Selective laser melting, one of the main additive layer…
The influence of fiber orientation on the crack propagation behavior was studied with single edgenotched specimens which were cut from an injection-molded plate of short-fiber reinforced plastics of polyphenylenesulphide (PPS) reinforced…
The investigation of fatigue strength of lotus-type structure with nodular cast iron as a base material using computational model is analysed in present study. The irregular pores distribution in transversal and longitudinal direction…
The aim of this paper is to calculate how the surface crack front and the dimensionless compliance evolve in cracked cylindrical bars subjected to cyclic tension or bending with different initial crack geometries (crack depths and aspect…
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…
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…
Fretting fatigue experiments aim to represent industrial problems and most of them endure variable loading. Being able to assess lifetime of assemblies, especially for low propagation rate conditions, is essential as experimental…
In this paper, crack propagation in Advanced Gas-cooled Reactor (AGR) graphite bricks with ageing properties is studied using the eXtended Finite Element Method (X-FEM). A parametric study for crack propagation, including the influence of…
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…
Crack propagation in gears is a problem related not only to the life of the components, but also to the concept of failsafe design. Fail safe design means to design a component in order that, if a failure occurs, this may cause a “safe…
The subject for studies is an aluminium cylindrical hollow specimen with external axial and part circumferential semi-elliptical surface crack undergoing fatigue loads. Both the optical microscope measurements and the crack opening…
During the last years many researchers put so much effort to design layered structures combining different materials in order to improve low fracture toughness and mechanical reliability of the ceramics. It has been proven, that an…
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…
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…
While a long stable crack propagation phase was observed during experiments of complex welded components, very conservative assessments of the fatigue life were achieved in the past. The difference was explained by the stress gradient…
Considerations are made for the fracture morphology and its evolution in relation to the brittle fracture along butt-weld, where crack path stability may play important roles in various aspects. Analyses of a kinked and curved crack are…
Titanium alloy (Ti-6Al-4V) having a bimodal “harmonic structure”, which consists of coarsegrained structure surrounded by a network structure of fine grains, was fabricated by mechanical milling (MM) and spark plasma sintering (SPS) to…
Thin rimmed and webbed gears are used in particular applications to reduce systems weight. This kind of gears need an accurate and fail safe design. As a matter of fact, a possible failure, due to bending fatigue, consists in crack…
The simulation of critical and subcritical crack propagation in heterogeneous materials is not a simple problem in computational mechanics. These topics can be studied with different theoretical tools. In the crack propagation problem it…
In this paper a methodology for evaluating crack initiation under biaxial conditions is presented. The methodology consists of evaluating the crack length automatically with digital processing of highmagnification images of the crack. The…
Crack trajectories under different loading conditions and material microstructural features play animportant role when the conditions of crack initiation and crack growth under fatigue loading have to beevaluated. Unavoidable…
Crack propagation simulation began with the development of the finite element method; the analyses were conducted to obtain a basic understanding of the crack growth. Today structural and materials engineers develop structures and…
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…
In this work different strategies to estimate crack path for cylindrical contacts under fretting conditions are carried out. The main goal is to propose and to evaluate methodologies not only to estimate the direction of crack initiation…
Multiaxial fatigue behavior is an important topic in critical structural components. In the present study the biaxial-planar fatigue behavior of a powder metallurgical TRIP steel (Transformation Induced Plasticity) was studied by taking…
The presented work introduces a numerical parametric study on the crack propagation direction under mixed-mode conditions (mode I + II). It is conducted for the geometry of an eccentric asymmetric fourpoint bending of a single edge notched…
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…
Brittle fracture in carbon steel has a serious impact on the safety of steel structures. Thus, technology that arrests crack propagation is the final line of protection for such structures. It is such an important issue that conditions…
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 objective of the present paper is to clarify the effect of defect length in depth direction on rolling contact fatigue (RCF) crack propagation in high strength steel. RCF test and synchrotron radiation micro computed tomography (SR…
Steel fiber reinforced concrete is potentially very promising material with unique properties, which currently is widely used in some applications, such as floors and concrete pavements. However, lack of robust and reliable models of fiber…
The paper contains plane strain analysis of uniformly stretched plate working in creep condition. The plate contains initial defects in forms of central and/or edge cracks working in mode I. These cracks are modelled by attributing…
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…
Considerable efforts have been made over the last decades to improve performance of spring steels, which would increase the service time of springs and also allow vehicles weight reduction. There are different possibilities of improving…
During fatigue crack propagation experiments with constant force as well as constant stress intensity lock in thermography and heat flow measurements with a new developed peltier sensor have been performed. With lock in thermography space…
This work presents a review of crack propagation simulation models considering plane stress and plane strain conditions. It is presented also a chronological different methodologies used to perform the crack advance by finite element…
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…
Fatigue considerations often distinguish between fatigue crack nucleation and fatigue crack propagation. The current work presents a modeling approach utilizing one Fatigue Damage Indicator to treat both in a unified way. The approach 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…
Engine components are usually subject to complex loading patterns such as mixed-mode Low Cycle Fatigue Loading due to maneuvering. In practice, this LCF Loading has to be superimposed by High Cyclic Fatigue Loading caused by vibrations.…
This paper deals with the fatigue crack propagation behavior of rolled AZ31B magnesium alloy (grain size: approximately 40 ?m). Fatigue crack propagation tests were performed on single edge notched tension specimens at a stress ratio of R…
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…
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…
There is an ever increasing need for accurate understanding of the fatigue crack growth behaviour in major engineering materials and components. With the move towards more complex, probabilistic assessments, the traditional ‘safe’ or…
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…
