Linearized Frequencies and Damping in Composite Laminated Beams Subject to Buckling

Abstract

This paper considers the damped small-amplitude free-vibration of composite laminated strips subject to large in-plane forces and rotations. A theoretical framework is formulated for the prediction of the nonlinear damping of composite laminates subject to large Green-Lagrange axial strains and assuming a Kelvin viscoelastic solid. An extended beam finite element is developed capable of providing the nonlinear stiffness and damping matrices of the system. The linearized damped free-vibration equations associated with the deflected strip shape in the pre-and postbuckling region are presented. Numerical results quantify the strong geometric nonlinear effect of compressive in-plane loads on the modal damping and frequencies of composite strips. Measurements of the modal damping of a cross-ply glass/epoxy beam subject to buckling were also conducted and correlate well with the finite element predictions.

Dynamic Behavior of a Cracked Woven Composite Beam under Compression

“…These investigations conclude that the natural frequencies of a component tend to be reduced by crack and/or damage. Many experimental and numerical procedures are used to analysis the vibration characteristics of such those structures [1][2][3][4]. Due to the fact that first two natural frequencies of a cracked/damaged composite beam are particularly changed by boundary conditions, geometrical and material properties, stress field and strain energy density around the crack tip (SEC) with respect to natural frequency are of great importance [5][6][7][8].…”

Ανάλυση Και Σχεδιασμός Συστήματος Απορρόφησης Κραδασμών Με Αρνητικά Στοιχεία Δυσκαμψίας

“…Πολύ πρόσφατα, προτάθηκαν περιοδικές κατασκευές με εξελιγμένη δυναμική συμπεριφορά (Virk et al, 2013), (Baravelli and Ruzzene, 2013), (Michelis and Spitas, 2010), (Correa et al, 2015) που συνδυάζουν θετική και αρνητική δυσκαμψία. Αν και οι φυσικοί μηχανισμοί που δημιουργούν αυξημένη απόσβεση σε τέτοιες δομές δεν είναι εύκολα κατανοητοί, μπορούν να εξηγηθούν μέσω φαινομένων μικρολυγισμού ή ολίσθησης (Lakes et al, 1993), (Spitas et al, 2013) (Chortis et al, 2013).…”

Dynamic vibration absorbers in civil engineering structures

“…Quite recently, periodic cellular structures with advanced dynamic behavior have been also proposed (Baravelli and Ruzzene, 2013;Correa et al, 2015;Michelis and Spitas, 2010;Virk et al, 2013), combining high positive and negative stiffness. Although the physical mechanisms that generate increased damping in cellular structures are not well understood, micro-buckling or slip-stick phenomena (Lakes et al, 1993;Saravanos et al, 2013;Spitas et al, 2013), could be among the possible explanations. Parallel, quite interesting possibilities towards achieving significant damping have been demonstrated to exist also in materials comprising a negative stiffness phase (Lakes, 2001), not only at a material level (Jaglinski et al, 2007), but also at macroscopic devices (Dong and Lakes, 2013).…”

“…Quite recently, periodic cellular structures with advanced dynamic behavior have been also proposed (Baravelli and Ruzzene, 2013;Correa et al, 2015;Michelis and Spitas, 2010;Virk et al, 2013), combining high positive and negative stiffness. Although the physical mechanisms that generate increased damping in cellular structures are not well understood, micro-buckling or slip-stick phenomena (Lakes et al, 1993;Saravanos et al, 2013;Spitas et al, 2013), could be among the possible explanations.…”