Numerical Determination of Equivalent Reflected Blast Parameters Acting on Circular Cross Sections
Bibliographic record
Abstract
A number of experimenters observed that the blast shockwave loads experienced by circular cross sections were lower than the predicted loads. These observations revealed a gap in the understanding of the interaction between blasts and structures. The question of quantifying these reduced loads for purposes of analysis and design presented itself for investigation. This paper presents the numerical investigation of the blast reflection reduction due to diffraction around a circular cross section using the commercial software ANSYS Autodyn. The investigation focused on the effects of the cross section's diameter and the explosion's scaled distance on the reflected blast pressure and impulse. Nine numerical gauge points recorded pressure-time and impulse-time histories at regular radial intervals around the front quarter of the circular section. The model's results agreed with incident and reflected pressure and impulse design values. The results indicated that as the diameter of the section increased the peak reflected pressure and impulse at the point of incidence rapidly approached the design values. The results also indicated that both the pressure and the impulse varied sinusoidally between a maximum at the point of incidence and a minimum, approximately equal to the incident pressure and impulse, at the side of the section. Using a sinusoidal curve fit to obtain equivalent reflected pressure and impulse values showed that the actual pressure and impulse acting on a circular cross section were approximately half the recommended design values. The results supported the obvious advantages of designing circular members to resist blast loading. Simplified equations are proposed for calculating the equivalent pressure and impulse acting on circular sections from the standard design values.
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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".