Development of a Material Selection Procedure for Natural Gas Pipelines based on the Crack Tip Opening Angle
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Notice bibliographique
Résumé
In this thesis, extensive finite element simulations of ductile fracture propagation were analyzed using the cohesive zone model (CZM) and the constant CTOA model. The CZM was used to examine the effect of loading mode on the CTOA through comparing the results of a DWTT model to that of a pipe model. A novel constant CTOA model was proposed in which it was integrated into the explicit time integration solver for dynamic simulations. The proposed model was compared with previous published numerical data to serve as verification and then compared to recent experimental data for validation. The proposed model reduced the runtime from previous implementations by 94% while maintaining less than 2% difference. The analysis of the experimental data was the first use of the constant CTOA model to reproduce experimental fracture velocity data. Smoothed particle hydrodynamics was implemented to simulate the effect of backfill during fracture propagation simulations. Several aspects of the modelling techniques were investigated such as the effect of the backfill model size and particle size, as well as various backfill material properties. The effect of each of these parameters was quantified through the effect on the steady state fracture velocity of the model, and effect on the shape of the fracture resistance curve. The constant CTOA model was combined with the SPH model to calculate steady-state fracture velocities for an API X80 and X100 steel with various geometries. This was done to generate a database of fracture resistance data. The fracture resistance data was used to determine the arrest CTOA for various materials and geometries. Using the fracture resistance data, an equation was determined to calculate the arrest CTOA required for a given material, geometry, and operating pressure and backfill. This equation was compared with two other previous arrest CTOA models. The predictions were shown to agree well with X100 experimental data. The arrest methodology was further validated through examining a recent full scale burst test performed on a grade 550 pipe. The CTOA derived fracture resistance curves were shown to estimate the fracture velocity of each of the pipe sections better than the original TCM.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle