Revisiting creep test on polyethylene pipe—Data analysis and deformation mechanisms
Bibliographic record
Abstract
Abstract Creep tests have long been used to determine long‐term hydrostatic strength (LTHS) for polyethylene (PE) pipe. In view that current standard requires some long‐term creep tests of over 9000 h to determine LTHS, this paper explores the possibility of using relatively short‐term creep tests for the same purpose. The study found that trend line for applied stress versus failure time changes at the failure time around 10 h, and the data trend in the low‐stress regime is consistent with that from the standard test. The trend line change is believed to be caused by the change of the involvement of amorphous and crystalline phases in PE in the deformation process, that is, sequential involvement of the amorphous phase first and then the crystalline phase in the low‐stress regime, and simultaneous involvement of both phases from the beginning in the high‐stress regime. Activation energies based on the Eyring's model and the Norton power law are determined to examine the proposed concept. Both models suggest that additional activation energy is needed for deformation in the high‐stress regime, which provides some support to the proposed concept and the possibility of using short‐term creep tests to determine LTHS.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| 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".