Experimental characterization and phenomenological modeling of strainrate-dependent compressive mechanical responses of PVC foams up to 500s-1
Notice bibliographique
Résumé
Abstract: Polymeric foams have a ubiquitous presence in modern industrial design due to their unique combination of crucial advantages, including high strength-to-weight ratio, corrosion resistance and significant energy absorbing capacity. Proper understanding and characterization of the dynamic mechanical response of polymeric foams are crucial for safe and optimized engineering design. Therefore, significant research efforts have investigated the rate sensitivity of polymeric foams utilizing various experimental and simulation techniques. The Split Hopkinson Pressure Bar (SHPB) is the most frequently employed apparatus in the dynamic testing of polymeric foams. It is important to note that the SHPBs technique was originally developed for evaluating the mechanical properties of metallic materials with high impedance levels. However, applying this technique for testing soft materials presents a considerable challenge that requires further research and development to overcome. Furthermore, specimens with smaller dimensions (especially when comprised of testing soft materials) are more desirable for SHPB testing. The minimum specimen geometry in accordance with ASTM D1621, the standard test method for compressive properties of rigid cellular plastics, is typically not attainable when utilizing SHPBs. Therefore, in most previous experimental investigations, the specimen geometry requirements by ASTM D1621 were not fulfilled. Technical challenges associated with utilizing SHPBs (and other dynamic testing machines) in testing polymeric foams have resulted in a lack of reliable dynamic material characterization data at strain rates ranging from 50 s-1 to 500 s-1. In this research work, the strain rate sensitivity of PVC foams with nominal densities of 45 kg/m3 and 250 kg/m3 was experimentally investigated utilizing a pneumatic high strain rate testing machine in combination with a novel sacrificial energy absorber. The pneumatic machine was equipped with a bullet, having a mass of 11.5 kg, being massive compared to other pneumatic testing apparatuses considered by other research investigations. Therefore, testing larger foam specimens, enabling conformance to ASTM D1621 requirements at near-constant strain rates, was achieved by employing the described testing machine. The remaining amount of the bullet’s kinetic energy was dissipated by the novel energy absorber to prevent damaging the machine’s structure and the load transducers after foam compaction was achieved. Strain rates up to 500 s-1 were successfully achieved by using this apparatus. A phenomenological model based on the work of Avalle and a modified version of Nagy’s model was proposed to characterize the PVC foams’ rate-sensitive stress/strain response. The model accurately predicted the complete stress/strain response with an average accumulative error of 6.85%.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».