|
چکیده
|
The nonlinear vibrational characteristics and responses of sandwich beams
with graphene platelets reinforced composite face sheets and porous core
(GPLRC-FS-PC) subjected to a moving load is studied. Each individual layers
are manufactured by uniformly distributing and randomly orienting graphene
platelets (GPLs) in a metal matrix. The kinematic relations of face
sheets and core layer are developed separately based on the first-order
shear deformation theory (FSDT) and by employing the geometric continuity
at the interface of the face sheets and core layer. The Green’s strain
tensor under the von Karman nonlinear geometric assumptions is used.
The spatially discretized motion equations are derived using the Ritz
method with Chebyshev polynomials multiplied by suitable boundary functions
as its basis functions. The obtained nonlinear motion equations are
solved by employing the Newmark and Newton–Raphson methods. After
the approach is validated, parametric studies are conducted to investigate
the influences of the load velocity together with the geometric parameters
and material properties on the sandwich beam responses. The results indicate
that the porosities softening effects depend on their distribution patterns
and addition of a very small amount of GPLs, increases the overall
beam stiffness significantly. It is also found that the critical load velocities
may increase when increasing the porosity coefficient.
|