Mechanical Behavior and Fatigue Responses of Hybrid Nanocomposite Laminates with Kinked Edge Cracks
Bibliographic record
Abstract
The aims of this research work were first to fabricate hybrid Ti/APC-2 neat and nanocomposite laminates.Then, the samples were cut with kinked single-and double-edged cracks by electrically discharged wire machine.The second part was to perform the static tensile tests to obtain their load-displacement diagrams, mechanical properties and failure mechanisms.According to the base-line data of mechanical properties the cyclic tests were conducted to receive the fatigue responses such as the load vs. cycles curves, fatigue life and the process of failure mechanisms.The work was mainly focused on experiments.The carbon fiber/polyetheretherketon (CF/PEEK) prepregs of 25.4 mm wide were cut and stacked into [0/90]s cross-ply layups.The cover sheets of Titanium were of 0.5 mm thick and treated optimally by chromic acid method of electroplating.As for nanoparticles of SiO2 were spread uniformly at the interfaces between 0 ∘ and 90 ∘ plies with the amount of 1% by weight of original sample [1-2].The modified diaphragm curing process was adopted [3][4].The cured panels were cut into samples of L×W×t: 240 mm×25 mm×1.55 mm.The single-and double-edged cracks were of 0.3 mm wide, and the kink angles were of 30 ∘ , 45 ∘ and 60 ∘ at the tips of horizontal main cracks.In conducting both the tension and fatigue tests an MTS-810 servohydraulic computer-controlled dynamic material testing machine was used.To do constant stress amplitude tension-tension cyclic tests the conditions such as stress ratio of 0.1, at frequency 5 Hz, and a sinusoidal wave form under load-controlled mode at room temperature.There were at least 3 specimens for tension tests in each set and listed in the average value with standard deviation; whilst , more than 6 specimens for fatigue tests by using staircase method, and tests stopped at one million cycles with the denotation of runouts as small arrows to the right.Until now, the received results were summarized as follows.The length of cracks increasing and kink angles decreasing, their mechanical properties were decreasing.The longer the crack lengths were, the more reduced the properties and life.With the adding of nanoparticles SiO2 in the interfaces of samples their mechanical properties and fatigue life were enhanced.Thus, the mechanical properties and fatigue life of nanocomposite laminates were improved slightly over those of neat laminates.It was attributed to uniformly spreading the nanoparticle, not concentrated at the tips of cracks and along the path of crack growth.The stress intensity factors (SIFs) at the tips of kinks were obtained for further applications [5].The complicated mechanisms of crack growth and path delayed the crack tips merged that were observed in double-edged cracks with kink angles.Although the interactive attraction did force both tips to move forwards, they did not head on together, i.e., they circled around to form a very small piece of ellipse.Simply, the two crack tips run around until they merge together with a small broken ellipse.Due to this phenomenon the life of symmetrically doubleedge crack with kink angles was longer than a half of life of the counterparts of single-edged cracks with kink angles.
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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) | 0.000 | 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 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".