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Erratum to Application of the 'structural stress' approach to a welded joint with complex geometry (Welding International, (2009), 12, (904-915))
No full textApplication of the 'structural stress' approach to a welded joint with complex geometry
No full textNowadays, local approaches for determining the fatigue strength of welded joints are commonly used in engineering
practices, and regulations describe their field of application and guide designers in the execution of the calculations with
numerical methods that are now extensively used.
The aim of this paper is to verify the application of the structural stress approach to a welded joint used in naval
construction and repair of particularly complex geometries. The structural detail is a butt weld between two bulb stiffeners,
strengthened by a plate (counterpiece) welded above the bevelled but unwelded bulbs. The study has been conducted by
following the guidelines of the method recommended by the International Institute of Welding (IIW), and the alternative
method proposed by Xiao and Yamada in 2004 has also been applied.
Large scale fatigue testing of the aforementioned joints and collapse testing on models, conducted at the DINAV Naval
Structure Laboratory, have allowed subsequent comparison: indeed, the numerical analyses have been conducted with no
knowledge of the experimental results.
The various calculations, carried out in accordance with the standards but with different interpretations, have shown a
significant spread of results, highlighting that, in the case of particularly complex geometries, this type of approach is not
simple to apply, and the IIW guidelines do not provide an unambiguous method for determining joint fatigue strength.
However, from the methods proposed, using those which best meet the general criteria of good FEM modelling and
considering other effects certainly present in heavy structures such as misalignments, estimates of joint fatigue lifespan may
be obtained which are in substantial agreement with the experimental results
Applicazione dell'approccio "structural stress" ad un giunto saldato di geometria complessa
No full textGli approcci locali per la determinazione della resistenza a fatica di giunti saldati sono ormai comunemente utilizzati nella pratica ingegneristica e le normative ne descrivono il campo di applicazione e guidano il progettista nell’esecuzione dei calcoli con metodi numerici ormai largamente diffusi.
Lo scopo di questo lavoro è l’applicazione del metodo della tensione strutturale (structural stress approach) ad un giunto saldato utilizzato nella costruzione e nella riparazione navale al fine di verificare l’applicabilità del metodo ad un caso di geometria particolarmente complessa. Il dettaglio è composto da una saldatura testa-testa tra due profilati a bulbo, rinforzata da un piatto (contropezza) saldato sopra i due profili cianfrinati ma senza saldatura tra le teste dei bulbi.
Lo studio è stato svolto seguendo le linee guida del metodo proposte dall’International Institute of Welding (IIW) ed inoltre è stato applicato il metodo alternativo proposto da Xiao e Yamada nel 2004.
Prove di fatica e di collasso su modelli in grande scala eseguite presso il laboratorio strutture navali del DINAV sui suddetti giunti hanno consentito un confronto a posteriori: infatti le analisi numeriche sono state svolte senza conoscere i risultati sperimentali.
I vari calcoli, eseguiti in accordo alla normativa ma utilizzando differenti approcci ed interpretazioni, hanno mostrato una significativa dispersione di risultati, evidenziando che, nel caso di geometrie particolarmente complesse, questo tipo di approccio non è di facile applicazione e le linee guida dell’IIW non forniscono un metodo univoco per la determinazione della resistenza a fatica del giunto.
Tuttavia, utilizzando, fra le metodologie proposte, quelle che meglio si sposano con i criteri generali di buona modellazione FEM e considerando altri effetti sicuramente presenti nella carpenteria pesante quali i disallineamenti fra i profilati, si possono ottenere stime della vita a fatica del giunto in sostanziale accordo con i risultati sperimentali
Computer aided evaluation of measurement uncertainty by convolution of probability distributions
No full textOptimal synthesis of an elastic suspension system for a marine reduction gear by multibody modelling
No full text
Metrology software for the expression of measurement results by direct calculation of probability distributions
No full textAn application of the hot spot stress approach to a complex structural detail
No full textNowadays, the hot spot stress approach is becoming a widespread and quite useful method for
fatigue strength estimates of welded structures and it has already been applied to plated structures successfully.
The aim of this paper is to review the application of the hot spot stress approach to a quite complex welded joint
widely used in ship structures, both for new buildings and for repairs, in order to check the method capabilities
for this challenging test case. The study has been carried out basically following the guidelines issued by the
International Institute of Welding, even if suggestions from papers found in open literature were taken into
account as well as advice from experimental tests. The different applications of the approach reveal some scatter
of the results, both in terms of stress concentration factors and, consequently, of fatigue lives
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