Investigating Thermal Gradient Cracking and Fracture Process Zone Development in Granitic Rocks
Bibliographic record
Abstract
Abstract Thermal stresses developed under disturbed temperature field induce thermal cracking when material’s strength is exceeded. In this paper, digital image correlation (DIC) and thermo-mechanical finite-discrete element method (FDEM-TM) simulations were adopted to investigate thermal gradient cracking and the evolution of its fracture process zone in Stanstead granite. DIC results showed that thermal gradient cracks initiated in a radial pattern from the heating source and the spatial density of the cracks was higher closer to the heating source than at the sample periphery. The macrocrack coalesced from the cooler portion of the sample inwards; however, smaller cracks initiated first from the hole before the coalescence. FDEM-TM simulations, supported by DIC experimental observations, revealed that thermal gradient cracks initiate as a result of an advancing tensile hoop stress front induced by the transient temperature diffusion in the rock. Therefore, the location of the thermal gradient crack initiation depends on both the local material tensile strength and the magnitude of the local induced tensile stress. Analysis of the thermal gradient fracture process zone (TG-FPZ) showed that maximum TG-FPZ length occurred at the onset of traction-free macrocrack propagation and decreased gradually until the macrocrack reached the heating hole. TG-FPZ width increased along the macrocrack length from the sample periphery towards the heating hole. This is attributed to the pronounced differential expansion mechanism in the hotter near-hole region and the induced tensile hoop stresses later in the heating stage when the macrocrack approached the hole.
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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".