Nonlinear Instability and Reliability Analysis of Composite Laminated Beams
Notice bibliographique
Résumé
The wide range of high performance engineering applications of composite laminated structures demands a proper understanding of their dynamics performance. Due to the complexity and nonlinear behaviour of such structures, developing a mathematical model to determine the dynamic instability boundaries is indispensable and challenging. The aim of this research is to investigate the dynamic behaviour of shear deformable composite laminated beams subjected to varying time conservative and nonconservative loads. The dynamic instability behaviour of non-conservative and conservative system are dissimilar. In case of conservative loading, the instability region intersects the loading axis, but in case of non-conservative loads the region will be increased with loading increases. The extended Hamilton’s principle and the first order shear deformation theory are employed in this investigation to establish the integral form of the equation of motion of the beam. A five node beam model is presented to descritize the integral form of the governing equations. The model has the capability to capture the dynamic effects of the transverse shear stress, warping, and bending-twisting, bending-stretching, and stretching-twisting couplings. Also, the geometric and loading nonlinearities are included in the equation of system. The beam model incorporates, in full form, the non-classical effects of warping on stability and dynamic response of symmetrical and unsymmetrical composite beams. In case of nonlinear elasticity, the resonance curves are bent toward the increasing exciting frequencies. The response of the stable beam is pure periodic and follow the loading frequency. When the beam is asymptotically stable the response of the beam is aperiodic and does not follow the loading frequency. In unstable state of the beam response frequency increases with time and is higher than the loading frequency, also the amplitude of the beam will increases, end to beam failure. The amplitude of the beam subjected to substantial excitation loading parameters increases in a typical nonlinear manner and leads to the beats phenomena. The principal regions of dynamic instability are determined for various loading and boundary conditions using the Floquet’s theory. The beam response in the regions of instability is investigated. Axially loaded beam may be unstable not just in load equal to critical load and/or loading frequency equal to beam natural frequency. In fact there are infinite points in region of instability in plane load vs. frequency that the beam can be unstable. The region of instability of the shear deformable beams is wider compare to non-shear deformable beams. The lower bound of the instability region of the shear deformable beams changes faster than upper bound. Probabilistic stability analysis of the uncertain laminated beams subject to both conservative and nonconservative loads is studied. The effects of material and geometry uncertainties on dynamics instability of the beam, is investigated through a probabilistic finite element analysis and Monte Carlo Simulation methods. For non-conservative systems variations of uncertain material properties has a smaller influence than variations of geometric properties over the instability of the beam.
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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 | 0,001 |
| 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 ».