MODELLING OF STRESS GRADIENT EFFECT ON FATIGUE LIFE USING WEIBULL BASED DISTRIBUTION FUNCTION

In the present paper, a new approach is developed in order to take into account the stress gradient effect on fatigue life of structural components. The proposed approach is based on the weakest link concept in which the shape coefficient of the Weibull distribution becomes a function of a local damage parameter. The function simulates the experimentally observed relationship between the shape of the fatigue life distribution and the stress level. Such an approach allows one to calculate the global probability distribution of the fatigue life for notched structural components in a wide range of fatigue life regime: 104-107 cycles typically. For comparison purposes, the approach is applied to calculate the number of cycles to crack initiation of structural elements under three probability levels: 5%, 63% and 95%. The calculated lifetimes are compared with the lifetimes obtained from experiments performed on notched cruciform specimens and notched round specimens subjected to constant amplitude loading

Non-local energy based fatigue life calculation method under multiaxial variable amplitude loadings

Reliable design of industrial components against high cycle multiaxial fatigue requires a model capable of predicting both stress gradient and load type effects. Indeed, taking into account gradient effects is of prior importance for the applicability of fatigue models to real structures. In this paper, a fatigue life assessment method is proposed for proportional and non-proportional multiaxial variable amplitude loadings in the range 104 –107 cycles. This method derives from the fatigue criterion initially proposed by Palin-Luc and Lasserre (1998) [2] and revisited by Banvillet et al. (2003) [16] for multiaxial constant amplitude loading. The new proposal consists of a complete reformulation and extension of the previ- ously cited energy based fatigue strength criteria. It includes two major improvements of the existing criteria. The first one consists in a fatigue criterion for multiaxial variable amplitude loadings while only constant amplitude loadings were considered in the above cited works. The second one is an extension to an incremental fatigue life assessment method for proportional and non-proportional multiaxial variable amplitude loadings. No cycle counting technique is needed whatever the variable amplitude load- ings type considered (uniaxial or multiaxial). The predictions of the method for constant and variable amplitude multiaxial loadings are compared with experimental results on specimens from literature and from new experiments on a ferrito-perlitic steel. The above mentioned method has been implemented as a post-processor of a finite element software. An application to a railway wheel is finally presented.Thèse CIFRE avec la SNCF, contrat direct ARTS / SNC

Elastic–Plastic Transition in Iron: Structural and Thermodynamic Features

The structural and thermodynamic features of the elastic–plastic transition in armco iron and its plastic deformation are studied. Energy storage in iron is shown to have a nonlinear character and be accompanied by wavelike heat dissipation. To describe the energy balance in the plastically deformed metal, a theoretical model is proposed based on a statistical description of the evolution of an ensemble of typical mesodefects (microshears). Moreover, a procedure is developed to experimentally determine the dependence of the potential of the medium on the mesodefect density using infrared scanning data.This work was supported in part by the Russian Foundation for Basic Research, project nos. 05-08- 33652, 07-08-96001, and 07-01-0-96004

Scaling Invariance of Fatigue Crack Growth in Gigacycle Loading Regime

The role of the collective behavior of defect ensembles at the crack tip and the laws of fatigue crack propagation in R4 high strength steel have been studied under conditions of symmetric tension–compression gigacycle loading at 20 kHz. At every stage of the fatigue crack growth, replicas from the sample side surface were taken and studied by the method of three dimensional relief profilometry (using NewView interferometer profilometer) so as to study the scaling invariant laws of defect related structure evolution.This study was supported in part by the Russian Foundation for Basic Research, Project nos. 08-01-00699, 09-01-92005-NNS_a, and 09-01-92441-KE-

Tom Palin: the tent

The Tent resides within a series of small-scale oil paintings on wood that have occupied me for the past five years. Completed in 2013, it formed part of the Royal Academy Summer Exhibition in 2015, where it hung in the landscape room in Burlington House, curated by Jock McFadyen. For this and a companion piece – The Hill – I was the recipient of a British Institution Award. The Tent was loaned to Dean Clough, from a private collection. The paintings in this series are landscapes, and share a concern for a singular location or place, at once familiar or commonplace. The image-aspect of a painting resides within a surface, and its accessibility – outward facing, static and open – acts as the way in. Only then, when an acquaintance has been made can a painting begin its work. This work can be seen as a drawing together and disclosure of painterly possibilities, residual references and processes of making: as duration, intimation and desire. For it is in being a painting that a painting keeps itself busy, and, in being The Tent, such busyness is – as is the case with all paintings – necessarily circumscribed. The painting is small, rough, shiny and framed; its image of tent and cloud fashioned from not inscribed upon its surface, fusing form and content together. This continues an ongoing investigation into the origins and destinations of paintings (the making and receiving aspects). The context is landscape painting, and discourses to do with place and facture within both Romantic and formalist traditions. I draw from memory, allowing the material, manual aspects of the work to inaugur, extend and fashion the stuff of paint into a formal configuration…into a representation of sorts. This arrangement of brush marks of colour and tone takes up where memory falters or fabricates, continuing a journey of its own as the processes of painting evolve. At points in time the relationship between leader and follower – between memory and the possibilities set in motion by the image – reverses, leaving me in some doubt as to the identity of the author of the final arrangement

Pleasure islands

Pleasure Islands is series of collaborative exhibitions that seeks to gather together new works from a diverse collection of early and mid-career painters. Each iteration of Pleasure Islands builds upon previous connections, both painterly and in terms of curatorial strategies, and extends new invitations, pursuing a shifting, dynamic and open conversation about the role and viability of painting today. The First exhibition featured works by 11 artists: Robin Megannity, Louise Giovanelli, Brian Moutford, Dylan Thomas, Tom Farthing, Jane Hayes Greenwood, Tal Regev, Tom Palin, Donal Moloney, Peter Daviz and Tom Howse, and took place in Artwork Atelier, Salford. The second show contained the work of 11 artists, and took place in 3Space, Manchester, later the same year. This exhibition was set to a specially created audio score by Alexander Roberts, a.k.a. Kepier Widow. Conceived as a sound track, recordings of the space were manipulated, and the data processed in response to the environment. Participating artists were: Richard Baker, Robin Megannity, Louise Giovanelli, Brian Mountford, Eilis Otway, Evie O’Connor, Tom Palin, Wayne Robinson, Alex Roberts, Edgar Soprans and Dylan Thomas

Painting fo’sho!

Painting Fo'Sho! explores what happens when an artist concerned with the shifting cultural signifiers between physical and online space is tasked with curating a show of five painters who share a preoccupation with framing their practice in contemporary parameters? The curatorial strategy seeks to foreground the idea of content, both physical and online. How is a work received? Here, through a series of curatorial games, Jack Fisher invites the audience to question the value of individual utterance and authenticity, challenging the painter to escape what he describes as the branded self. This is an exhibition about fiction, exchange and transformation. In Fisher’s words: ‘the expressions on their faces told the story. The paintings hung, drawn and quartered. A tired painter lay there waiting, tar’d and feathered. There was nothing left but a small reassembled pile of dust, or something to that description. They had been hung out to dry only; they never returned. They h’D been worrying for days and yet no one decided they wanted to eat anymore. They’d eaten to their heart’s content the night before; the paintings went flying. Tempers were high! No one knew what was going on at times. The Dead Professional Artist was NOWhere to be seen. Although they all knew in their eyes exactly what was going on, no one made their engagement public. They’d all got just a little bit fed up of being interested in the whole thing and realised they probably didn't wanna be ‘ere anyway. A figure enters the room and exclaims ‘You bastard! What have you done? Lady Beck presents Phoebe Ridgway, Rosie Vohra, Tom Palin, Richard Baker and James Quin. Curated and disrupted by Jack Fisher