Dynamic behavior of sandwich beam with agglomerated carbon nanotube reinforced face sheets under a moving mass

In this paper, the dynamic behavior of carbon nanotube (CNT) reinforced composite sandwich beams under a moving mass taking into account the influence of the CNT agglomeration is investigated by the finite element method. The sandwich beams composed of a homogeneous core and two face layers made from carbon nanotube–reinforced composite (CNTRC) material. The two-parameter micromechanical model is adopted to describe the agglomeration of the CNTs, and the Eshelby–Mori–Tanaka approach is used to estimate the effective material properties of the composite face layers. Based on a third-order shear deformation beam theory, a beam element in which the transverse shear rotation, not the conventional section rotation, is employed as an independent variable is formulated and used to establish the discretized equation of motion for the beams. Using an implicit Newmark method, dynamic characteristics such as the time histories for mid-span deflections and the dynamic magnification factors are obtained for a sandwich beam with simply supported ends. The accuracy of the derived beam element is confirmed by comparing the results obtained in the present work with the published data. The numerical result reveals that the CNT volume fraction and the CNT agglomeration have a significant influence on the dynamic response of the sandwich beams. The dynamic magnification factor is found to be decreased with an increase of the CNT volume fraction, but it is higher for the case of the severse CNT agglomeration. A parametric study carried out to highlight the effects of the CNT reinforcement and the mass velocity on the dynamic behavior of the sandwich beams. The influence of the layer thickness ratio on the dynamic response of the composite sandwich beams is also studied and discussed.