1,720,984 research outputs found
Propagazione di fratture longitudinali in gasdotti caratterizzati da bassa duttilità
No full textIl presente lavoro propone l’analisi di propagazione di una frattura fragile longitudinale di un gasdotto interrato basata sulla valutazione dell’energy release rate. Viene illustrata l’implementazione della suddetta metodologia all’interno di un codice proprietario agli elementi finiti con formulazione esplicita, illustrando gli interventi eseguiti sul preesistente algoritmo di propagazione stazionaria, e proponendo i risultati ottenuti a seguito di simulazioni dinamiche svolte su tubi in acciaio X80 e su provini SENB in pieno spessore sottoposti a prove DWTT
La resistenza a fatica di strutture in acciaio inossidabile saldate a punti: sintesi delle analisi teoriche, numeriche e sperimentali. Parte III: Prove di fatica, evoluzione del danno ed ERS equivalente
No full textAlcune considerazioni sull’implementazione numerica del modello di anneggiamento di Lemaitre-Bonora
No full textOn longitudinal propagation of a ductile fracture in a buried gas pipeline: numerical and experimental analysis
No full textNumerical Model of the Backfill Constraint Effect During Fracture Propagation on Buried Large Diameter Gas Pipelines
No full textAnalysis of CO2 dispersion in environment, Gaussian vs CFD modelling
No full textCO2 release and dispersion to the environment, as a consequence of leakage or fracture in onshore/offshore pipelines, is a matter of great concern. This interest is due to the expected future deployment of a pipeline network as essential element in Carbon Capture and Storage (CCS) projects or EOR applications. Hazards posed by accidental or intentional releases of CO2 from pipelines are often not easy due to a complex thermodynamics in the CO2 escaping related to phase change followed by cold heavy gas dispersion. As a consequence, a risk assessment based on the study of the atmospheric dispersion should be performed in the pipeline design.
An introduction to the CO2 release and dispersion occurrence is provided as a well as a review of the numerical models for dispersion prediction in the event of CO2 pipeline failure. Indeed, different mathematical models can be used for the simulation, mainly based on Gaussian codes or Computational Fluid Dynamics (CFD).
The main features of the two different numerical approaches have been reviewed focusing on their ability to simulate possible hazard scenarios of CO2 atmospheric dispersion and to account for different parameters, such as atmospheric conditions, orography, gas release mode, etc. The comparison between Gaussian and CFD models has allowed highlighting differences that impact directly on the accuracy of the results and affect the conservatism level of a numerically-based risk assessment.
The commercial CFD code Ansys Fluent and a freely available Gaussian code, ALOHA, have been used for the simulation of dispersion caused by the release from supercritical CO2 pipelines. The impact on the dispersion to the environment of different sources releasing CO2 has been studied and the results obtained have been processed for evaluating CO2 concentration evolution with respect to time and space
Sull’identificazione del comportamento plastico di un acciaio a partire da misure a campo intero ottenute tramite correlazione digitale di immagini
No full textIn the present work a method to obtain a true stress-true strain curve of an alloy by a full field digital image correlation measurement of the specimen surface kinematics, is presented. A preliminary set of parameters of a plasticity law is obtained to start up an automatized search algorithm, that includes, for each step a FE analysis in 3D. It’s also proposed a dual approach of the same search problem
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