New Experiments Suggest that All Shear and Some Tensile Failure Processes are Inappropriate Subjects for ASTM Standards
Bibliographic record
Abstract
There are four ASTM standards which involve apparent shear failure of composites. These include the Iosipescu (D 5379), tube torsion (D 5448), the short beam test (D 2344), and two-rail and three-rail shear (D 4255). However, careful experiments in which polymers have been sheared show that failure is normally restricted to tensile failure with breaking of polymer chains and cross links. Moreover, it is already known that shear hackle is produced by a tensile process. In view of this, these standards should be reexamined to determine whether strengths should be reported at all. The same argument applies to the new standard being developed for mixed Mode I-Mode II interlaminar fracture toughness. Mode I is the only failure mode which is consistent with experimental observations. In addition, the D 3039 standard for tensile strength has been revised to include balanced and symmetric laminates. Experiments have shown that, with angle ply laminates, much greater strengths can be obtained just by making the specimen wider and shorter. These latter tests agree very well with tests on pressurized filament wound tubes, with structures equivalent to the angle ply structures. This strongly indicates that the ASTM test can severely underestimate the strength. The ASTM standard also seriously underestimates the stiffness. There appears to be an “edge softening” effect, so that apparent properties are very dependent on the aspect ratio of the test sample. Thus, true material properties are not measured. It is proposed that all ASTM D 30 mechanical tests be reexamined to determine (a) what purpose is served by having the test at all, and (b) whether it is measuring a true materials property.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.013 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.003 | 0.005 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.004 |
| Insufficient payload (model declined to judge) | 0.028 | 0.022 |
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".