Bibliographic record
Abstract
Determination of forming limit of tubes can be difficult when it involves many process related variables and the use of costly hydroforming equipment. Therefore, the industry currently relies on sheet or tube longitudinal properties to estimate tube hydroformability. This paper introduces a simple method for experimentally assessing formability of tubes as material intrinsic characteristics for tube hydroforming, and presents results on the correlation between mechanical properties and failure location as well as forming limit at a small negative minor strain state. One commercial hydroforming tube, and one aluminum trial tube, both made by a continuous tube mill and seam welded using high-frequency (HF) induction welding, were evaluated for their forming characteristics. It is found that during tube free expansion, the failure location of the tubes is affected by the nonuniformity of transverse tensile properties around the tube circumference, and failure initiates at lower strength/hardness location. Forming limit at -5.5% minor strain for the tubes studied here are also determined. It is found that the two tubes studied here have similar limit strain, which can be related to their similar level of n-value at their respective UTS, and similar uniform elongation, both obtained by uniaxial hoop tension test. The forming limit strain at free-expansion were obtained through the use of a newly developed test method using a ring specimen to simulate free expansion of tubes. The test method, referred here as the Zero-Gage Ring Hoop Tension Test (ZG-RHTT), is an extension of a recently developed method of uniaxial tube transverse tensile test.
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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 | 0.000 |
| 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) | 0.002 | 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".