محمدرضا گل بهار حقیقی

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 K
arm
an 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.