VIBRATION OF LAMINATED COMPOSITE DECKS BEAMS

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