Effects of impactor geometry and multiple impacts on low-velocity impact response and residual compressive strength of fiber-reinforced composite laminates
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Bibliographic record
Abstract
Fiber-reinforced composite panels used in aerospace applications often experience low-velocity impacts (LVI) during service and maintenance by objects of various shapes, sizes, and masses, which can significantly reduce the panel's residual compressive strength. This study provides a detailed numerical and experimental analysis of LVI and compression after impact (CAI) failure mechanisms of laminates impacted by different impactor sizes and masses, along with damage accumulation during multiple impacts, and presents an effective approach for modeling progressive damage in composite laminates. The experiments were conducted using three hemispherical impactors with diameters of 6.35 mm (sharp), 25.4 mm (standard), and 96 mm (blunt), at impact energy levels of 30 J and 75 J, corresponding to barely and clearly visible impact damage (BVID and CVID). Quasi-isotropic IM7/977-3 composite specimens, sized 254 mm × 304.8 mm, were used to better represent large composite panels and study a wider range of impact scenarios. A finite element modeling methodology was developed based on the integrated enhanced LaRC05 failure criteria and the cohesive zone modeling technique to predict various composite failure modes, such as fiber breakage, pull-out, kinking, crushing, and splitting, as well as matrix cracking and delamination. The LaRC05 fiber tensile failure criterion was revised based on experimental data, improving the accuracy of the model at higher impact energies. At the same energy level, the sharp impactor caused more concentrated and severe damage, leading to lower CAI strength. The blunt impactor caused less surface damage but similar internal delamination and CAI strength compared to the standard impactor. • Impactor geometry effects were studied on impact damage severity and residual compressive strength. • The blunt impactor caused significant internal delamination at higher impact energies despite minimal surface damage. • Damage area alone is not a reliable predictor of residual strength; failure modes play a key role. • Repeated impacts shifted the failure modes from matrix cracking and delamination to fiber breakage at higher energy levels. • The revised fiber tensile failure criterion improved model accuracy at high impact energies.
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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) | 0.001 | 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 it