Short/Small Crack Model Development for Aircraft Structural Life Assessment
Bibliographic record
Abstract
This paper presents the testing and modeling results from an NRC project on short/small1 crack model development for aircraft structures. Fatigue tests were conducted for 7075-T73 hand forging aluminium material using precracked compact tension (C(T)) and naturally cracked single edge-notch tension (SENT) coupons, under various stress ratios. The adjusted compliance ratio (ACR) method was used for the C(T) coupon tests aiming to quantify remote closure due to plasticity and forging-induced residual stresses. For the SENT coupons, three-dimensional StressCheck finite element (FE) models were developed to accurately calculate the stress intensity factors of surface and corner cracks. Both C(T) and SENT test data were combined to develop short-long fatigue crack growth rate models. These models were then used in crack growth life analyses for coupon and component cases, taken from transport aircraft under spectrum loadings. It was shown that the newly developed models resulted in more accurate fatigue life estimations.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".