Straight Tube Hydroforming of Dual Phase (DP780) Steel Tubes With End-Feed
Bibliographic record
Abstract
Dual phase (DP780) 76.2 mm (3”) diameter steel tubes were hydroformed with various levels of end‐feed (EF). The results of this study showed that when zero EF was applied during hydroforming, the average burst pressure was 70 MPa (10,075 psi) and the corner‐fill expansion (CFE), which is a measure of formability, was 6.4 mm. When an EF force of approximately 50% of the material yield strength was applied during hydroforming, the tube was able to support an internal pressure of 151.7 MPa (22,000 psi) without failure and achieved a CFE of 11.5 mm. Finite element (FE) models of the hydroforming process accurately predicted the CFE of the tubes for the various EF cases tested. Upper and lower bound strain‐based forming limit curves (εFLC) were determined from free‐expansion burst test data. These curves were then used to derive the upper and lower bound extended stress‐based forming limit curves (XSFLC), which were in turn used to predict the necking (failure) pressure in the FE models. For the two cases where burst was achieved in the experiments, the upper and lower XSFLC failure criteria curves bound the measured burst pressures. Also, two different friction coefficients were used in the FE models to evaluate their effect on predicting the failure pressure, CFE and end‐feed displacement.
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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 | 0.001 |
| 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".