Crack path and fracture analysis in FSW of small diameter 6082-T6 aluminium tubes under tension-torsion loading

This paper reports part of the work done in a research project aimed at developing an optimised process to join 38. mm diameter tubes of 6082-T6 aluminium alloy using friction stir welding (FSW), and then to determine the fatigue performance under tension, torsion and tension-torsion loading conditions. The final outcome of the project is intended to be guidance for fatigue design of small diameter aluminium tubes joined by FSW, and this paper presents information on crack path and defects under the various loading conditions. Crack path analysis was performed using both low magnification stereo microscopy and scanning electron microscopy, in order to identify crack initiation sites, the direction of crack propagation and the interrelated influence of microstructure and weld geometry on the crack initiation path

Fatigue performance of friction stir welded marine grade steel

An extensive study on the fatigue performance of friction stir welded DH36 steel was carried out. The main focus of this experimental testing programme was fatigue testing accompanied by tensile tests, geometry measurements, hardness and residual stress measurements, and fracture surface examination. The S-N curve for friction stir butt welded joints was generated and compared with the International Institute of Welding recommendations for conventional fusion butt welds. Friction stir welds of marine grade steel exceeded the relevant rules for fusion welding. This newly developed S-N curve is being proposed for use in the relevant fatigue assessment guidelines for friction stir welding of low alloy steel. Fracture surfaces were examined to investigate the fatigue failure mechanism, which was found to be affected by the processing features generated by the friction stir welding tool

Analysis of Residual Stresses in Laser-Shock-Peened and Shot-Peened Marine Steel Welds

Laser peening is now the preferred method of surface treatment in many applications. The magnitude and depth of the compressive residual stress induced by laser peening can be influenced strongly by the number of peen layers (the number of laser hits at each point) and by processing conditions including the use of a protective ablative layer. In this study, residual stresses have been characterized in laser and shot-peened marine butt welds with a particular focus at the fatigue crack initiation location at the weld toe. X-ray diffraction, synchrotron X-ray diffraction, incremental center-hole drilling, and the contour method were used for determination of residual stress. Results showed that the use of ablative tape increased the surface compressive stress, and the depth of compressive stress increased with an increase in number of peening layers. A key result is that variation of residual stress profile across laser peen spots was seen, and the residual stress magnitude varies between the center and edges of the spots

Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

FABLE AND “FABULOUS PRODUCTION” IN MODERN INTERNET-SPACE

The article considers successful examples of modern fabulous creativity (Vlad Malenko) and samples of “unfabulous” products from the Internet. For analysis, selected works by well-known and little-known authors, who posted their fables on copyright sites, as well as on the sites of Poetry.ru, WePishem.ru, Bizona.ru. Attention is drawn to the principles of creating a «modern fable» and its correspondence to the channels of the traditional fable as a genre. Аnalyzed the work of Vlad Malenko (actor and director of the Moscow Theater on Taganka, a member of the Union of Writers and the Union of Theater Workers of Russia, laureate of the literary prize named after AP Chekhov “For the revival of Russian satire”). Basically, Malenko’s book “Cheese fell out ...” and its individual fables “Glamorous Shrimp”, “Mole in the binge”, “Muskrat in the theater”, “Iron and meat grinder”, “Pops”, “Money Theater” were mainly analyzed. Samples of modern fable creativity are also analyzed, their authors do not belong to a recognized writer audience, but they are active participants in the “reanimation” of a modern fable. Vladimir Olishevsky (Alekbort. Online magazine) “Modern fable “Be polite on the roads”. “This author replaced the wellknown poetic form of the fable, replaced it with a prosaic version, expanded the plot, enriched it with details, added lyrical sarcasm as digressions. Vladimir’s fables were also analyzed. Shebzukhov’s “Scientific Work”, Boris Oznobishin`s “Elephant, Bison and Pug (political fable)”, “The Fable of the Invisible World” by Dudley Phoenix (“Bison.ru”), Svyatovit Kuzelnikov “The Demon Climbed”, Alexander Illarionov “Taught the Chicken, EggIgor Krasavin’s fable “Cabbage” covers the topic of business, which speaks about the politics, morality of modernity. Sergey Prilutsky’s fable “Just like a puddle,” Alexander Schneider “Menagerie” and others. Modern fables of the Internet space that adhere to the principles of building the old genre, They are amenable to modern trends. Their works have a different theme, the emphasis is on private events of today. In their style there is a lot of colloquial, everyday, and roughly reduced vocabulary. These fables have a lot of irony, sarcasm, allegory, hyperbole and morality. Morality, as always, mainly at the end of the text, sometimes there is even a separate word “morality”. On the Internet there are a huge number of fables that are not fables, but they are so named by the authors – “The Fable of the Invisible World” by Dudley Phoenix. I agree with this name if we take into account that the etymology of the very word “fable” is “bati”, which means “to speak”, “to buy”, it means “bike”, “tale”, “story”, “history”. Often, modern authors, creating worthy examples of poetic art, do not pay attention to the absence in their texts of the fundamental principles of a fable as a genre, replacing them with aphorism, metaphor, while not taking into account the obligatory allegory and didactics. Basically, Malenko’s book “Cheese fell out ...” with individual “Glamorous shrimp”, “Mole in a binge”, “Muskrat in the theater”, “Iron and meat grinder”, “Pops”), “Money Theater” was analyzed. Also analyzed are the samples of modern fable creative work, the authors of which are not classified as recognized writers but are active participants in the “reanimation” of the modern fable. Vladimir Olishevsky (Alekbort. Online magazine) “Modern fable Be polite on the roads”. V. Olishevsky replaced the wellknown poetic form of the fable with a prosaic one, he expanded the plot, enriched it with details, accompanied it with lyrical sarcasm in the form of digressions. Vladimir Shebzukhov’s fables are also analyzed “Scientific work”, Boris Oznobishin “Elephant, Bison and Pug (political fable)”, “Fable of the invisible world” by Dudley Phoenix (“Bison. ru”), Svyatovit Kuzelnikov “The Demon Climbed”, Alexander Illarionov “Taught the Egg Chicken”, Igor Krasavin “Ka mouth” covers the topic of business, correlated with the politics, morality of modernity. Sergey Prilutsky’s fable “Just like a puddle”, Alexander Schneider “Menagerie”and others. Modern fables of the Internet space, following the principles and instilled an old genre, are amenable to modern trends. their works change the theme, more emphasis is placed on specific private events of today, their style is full of colloquial, everyday sometimes rudely reduced vocabulary. A striking artistic feature of such fables was irony, sarcasm, allegory, hyperbole and the inherent presence of morality, mainly at the end of the text, which is sometimes accompanied separately by the word “morality”. There are also a huge number of fables that are not fables but are named by the authors as “The Fable of the Invisible World” by Dudley Phoenix. I agree with the author’s name of a philosophical poem only on the basis of the etymology of the very word “fable” – “bati”, which means “to say”, “to buy”, in fact, it is a “story”, “tale”, “story”, “story”

Principal axes for structural fatigue

Recent advances in the analysis of joint seakeeping processes are applied to the accumulation of spectral fatigue cycles. The methods of cross co-spectral moments and techniques adopted from the determination of principal angles for seakeeping processes are used to determine orientation of the most severe plane for the accumulation of spectral fatigue cycles and the distribution of stress cycles on that plane. The theory presented considers all aspects of the wave loads experienced over the life of the structure and uses linear theory to predict lifetime fatigue using more efficient techniques than equally comprehensive time-domain simulation. Three methods of determining the orientation of the principal plane and their theoretical differences are discussed. Quantitative comparisons are presented in the time, frequency and probability domains to illustrate differences and demonstrate consistency