Humidity and Temperature Cycling Effects on Cracks and Delaminations in PEMFCs
Bibliographic record
Abstract
Abstract Temperature and relative humidity (hygrothermal) cycles during PEM fuel cell operation can lead to the introduction and exacerbation of micro‐scale mechanical defects. We developed a two‐dimensional finite element model based on cohesive zone theory to describe the delamination propagation at the cathodic membrane/catalyst layer interface due to temperature and hygrothermal duty cycles. Particularly, the effects of hygrothermal cycle amplitudes, relative humidity (RH) distribution profiles, and gas flow channel position were studied. It was found that doubling the hygrothermal cycle amplitude resulted in a 6‐fold increase in fatigue stresses, and a defect length growth to 0,1 mm before reaching the end of the fuel cell life (40,000 cycles). A counter intuitive result was also observed, whereby a crack located within the membrane was found to grow faster than a delamination located at the catalyst layer/membrane interface. When introducing an anode/cathode channel offset, a 2‐fold increase in the rate of delamination propagation was found compared to the case with the aligned anode and cathode channels.
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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) | 0.000 | 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".