A Probabilistic Study of Composite Impact Damage Design Strain Allowables
Why this work is in the frame
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Bibliographic record
Abstract
An investigation was made to assess the use of a probabilistic method to remove conservatism in the design of composite panels for impact damage. The baseline deterministic method used the barely visible impact damage (BVID) criterion. The probabilistic method accounts for variability of both the impact energy and applied loads with an allowable probability of failure of 10 -7 per flight as specified by the Joint Service Specification Guide (JSSG). A wing panel and a fuselage panel on an existing transport aircraft finite element model were selected for use in the analysis. Estimated impact energy variability was represented using normal distributions for multiple locations on the aircraft and multiple impact threat sources. Variability of the gust design load case was estimated using a discrete gust load analysis and Rice’s exceedance formula. The variability of the allowable panel loads was calculated using Lockheed Martin’s Composite Durability And Damage Tolerance (CDADT) program iteratively to find the zero margin of safety loads for a wide range of impact energies. Probability of failure per flight was calculated by integrating the product of the applied load cumulative probability and the allowable load probability density over the relevant range of loads. The probabilistic analysis method based on the JSSG criterion was found to offer a potential for modest (approximately 10%) weight savings for thick composite panels but no potential for weight savings for thin panels. It was concluded that the probabilistic analysis offers a potential for weight savings for thick panels, which have a high BVID impact energy threshold with a low probability of occurrence.
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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 | 0.004 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 it