Mass-spring model for a perforated periodic metamaterial in nonlinear regime
Bibliographic record
Abstract
This study is interested in the nonlinear acoustic response of a metamaterial composed of a periodic array of single-perforation plates spaced by thin air cavities. An equivalent mass-spring model is adapted to predict the metamaterial acoustic response under high sound pressure levels. The increase in losses induced by the high level is considered by a quadratic law for the airflow resistivity in an effective fluid model. The airflow resistivity coefficients are determined from predictions by the computational fluid dynamics method at different flow velocities. The model is validated with impedance tube measurements for samples with different numbers of periodic unit cells and perforation sizes. The results show that the acoustic resistance of the metamaterial increases with increasing sound pressure levels, while the reactance is almost unchanged. The absorption peaks at low frequencies are more impacted by high sound pressure levels. A criterion based on the viscous characteristic frequency is proposed to determine the limit of the beginnings of the nonlinear material response. This limit is given by an acoustic Reynolds number, which depends on the frequency and perforation size. Experimentally, an absorption peak is observed, shifting to lower frequencies with increasing sound levels. A preliminary explanation of underlying mechanisms is provided.
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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 | 0.000 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".