(osama mohammed elmardi suleiman khayal) #1

In this study, the effects of both lamination
scheme and boundary conditions on the natural
frequencies of free vibration of laminated composite decks
beams were investigated. The problem is analyzed and
solved using the energy approach which is formulated by a
finite element model. Lamination schemes for symmetric
and non-symmetric laminated beams were studied. Six
boundary conditions are considered; clamped-free (CF),
hinged-hinged (HH), clamped-clamped (CC), hingedclamped
(HC), hinged-free (HF), free-free (FF). Each
beam has either movable ends or immovable ends. It is
found that both symmetrically and anti-symmetrically
laminated beams of similar size and end conditions have
equal natural frequencies which, generally, decrease as the
angle of orientation increases. Also, It is found that the
more constrained beams have the higher values of natural
frequencies of transverse vibration. However, the free-free
and hinged-free beams are found to have the highest
frequencies of transverse vibration amongst all beams
although they look less constrained. This behavior is due to
the fact that the first mode of the two beams is equal zero
(rigid body motion), and replaced by the second mode to
be the fundamental mode. The values of the natural
frequencies of longitudinal modes are found to be the same
for all beams with movable ends since they are generated
by longitudinal movements only. But for immovable ends,
the clamped-free and hinged-free beams have equal
frequencies in longitudinal vibration, and those of the
other beams are also the same.61-66,Tesma301,IJEAST.pdf (349.0% u)