Analysis of the effects of cold expansion of holes using thermoelasticity and image correlation
Bibliographic record
Abstract
ABSTRACT Although cold expansion has been shown to have a positive effect on fatigue life, little work to date has been performed to evaluate the evolution of the strain field surrounding the crack tip on the mandrel entry and exit faces in cold‐expanded coupons. Full‐field strain measurements using both digital image correlation (DIC) and thermoelastic stress analysis (TSA) were used to compare the strains during crack growth around holes that had and had not been cold‐expanded by 4%. Simple rectangular fatigue coupons were machined from 2024‐T3 aluminium sheet, half had simple open, unexpanded holes and half had cold‐expanded open holes. A DIC system was used to monitor the (mandrel) entry face of the coupon while a TSA system was used to monitor the (mandrel) exit face of the coupon during cyclic tensile loading (R‐ratio = 0.1). These two systems provide the first published measurements of the simultaneous mandrel entry and exit surface strains surrounding a crack initiating from a cold‐expanded hole. The cracks originating from the unexpanded hole exhibit a strain field around the crack tip which is characteristic of a mode I fatigue crack while those emanating from the cold‐expanded holes show a significantly lower distribution of strains around the crack tip. Crack opening displacements evaluated from the strain data obtained from DIC, are substantially reduced by the residual compressive stresses from cold expansion, while the overall fatigue data show the life improvement achieved at various applied stress levels.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.000 | 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 teacher head, 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".