Bibliographic record
Abstract
Actuators are machines used to move valves in order to ensure the correct control of\nprocess fluid flows, in industrial and Oil&Gas application. To operate efficiently, valve actuators must be powerful but also reliable in order to guarantee the structural integrity of all its components under the service number of cycles required by the end-users, always more often greater than the minimum prescribed by the main standards of the sector. The fatigue assessment method currently adopted for the design of valve actuators produced by FLOWSERVE-Limitorque company, industrial partner of the research activities carried out in the present thesis is based on the nominal stress approach. Therefore, the current company design rules for the fatigue assessment of the components usually do not take into consideration local stress effects. An oversimplified design approach might be a particularly delicate issue when a structural failure could have safety and environmental related consequences. The present thesis focuses on the fatigue life assessment of the scotch yoke, which is the core component of a quarter turn valve actuator typically used in Oil&Gas sector. The thesis is arranged in five chapters. Chapter 1 introduces the valve actuation sector, explaining the different applications\nand describing the type of actuators. Furthermore, the main standards of the sector are described. Chapter 2 is devoted to a review of the technical literature on fatigue assessment and design of industrial components with particular attention to the fatigue strength evaluation of notched and welded components. Chapter 3 describes the experimental fatigue tests on scotch yokes. After a description of the testing set-up, the results of two different geometries of scotch yoke are presented. Chapter 4 describes the finite element analyses and the post-processing methods to predict fatigue life of the scotch yoke. The two geometries of the experimental campaign are considered in the simulations. Fatigue life assessment is performed according to some critical plane criteria based on local strain components. A dedicated post-processing software is used\nto obtain full-field maps of estimated fatigue life. In addition, fatigue life estimation is carried out by considering a strain energy method along with a so-called peak stress method. Finally, a comparison between the results of the different analyses carried out on the different geometries is described in Chapter 5, together with a comparison between the numerical and experimental results.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".