An Experimental Study of Friction During Planar Elastic Impact
Bibliographic record
Abstract
Low-speed oblique elastic impacts frequently occur in heat exchangers and other equipment having loosely supported tubes or pipes. In order to experimentally study friction during such impacts, a pendulum-type impact apparatus was developed. A hardened steel sphere at the end of the pendulum collides with a flat steel surface for a range of approach velocities and angles. The present investigation examined eight velocities from 8 to 93 mm/s and impact angles (measured from the common normal) of 0 to 75 deg for each velocity. The normal and tangential contact force waveforms were measured using a triaxial piezoelectric force transducer which was dynamically calibrated. As expected, the results show that the tangential force is less than the limiting Amontons-Coulomb friction predictions at low impact angles. Two regimes of stick-slip and gross-slip friction are clearly distinguished by a new friction parameter called the specific traction ratio. Tangential force reversal was observed at low impact angles, indicating local tangential oscillations. The stick-slip results are consistent with a partial-slip model where the contact zone has a central sticking region surrounded by a ring area undergoing slip.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.000 | 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 teacher head, 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".