Fracture toughness estimation of advaced ceramics materials by moleculardynamics methods
Bibliographic record
Abstract
Molecular dynamics simulation has been widely used for the research about the fracture behavior of brittle materials. The ceramics of alpha-alumina can also be explored based on this method for the atomic deformation changes under specific loadings. The alumina structures are constructed and validated with theoretical atomic structures first by some typical parameters such as the lattice parameters, and then the validated potential for this material is shown with some material constant such as Young's modulus, shear modulus and bulk modulus which are from experimental and simulation results. The stress intensity factor of the material is an important parameter to determine the fracture behavior for brittle materials which will be calculated in this paper under the typical loading conditions according to the fracture mechanics. The fracture surface energy of the single-crystal alumina models is also calculated and then used for the calculation of the fracture toughness (KIC) for comparison with the simulation results from theoretical equations and the experimental data. Along this routine, the ultimate fracture strength has been found to be increasing from 44.2 2.6 GPa to 49.5 3.1 GPa with the increase of tension loading rates from 10 9 /s to 10 11 /s along X-[100] crystal direction, and fracture toughness of alpha-alumina atomic models has been found to be decreasing from 4.22 0.16 MPa(m^1/2) to 3.26 0.18 MPa(m^1/2) with the increasing tension loading rate from 10 9 /s to 10 11 /s. Other parameters such as stiffness have the similar trends with the fracture strength and fracture toughness. These typical parameters of fracture trends of alpha-alumina models have been explored under the changes of tension loading rate, which can help bridge the microscale modelling of brittle material with the higher-scale experiments.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".