Nonlinear vibration model of sandwich beam with a shear thickening fluid core

Dynamic performance of sandwich beam with shear thickening fluid (STF) core subjected to a periodic excitation is investigated. The addition of STF enables the sandwich beam to have a tuning stiffness and damping capacity under dynamic deformation. Here, the constitutive model of STF is described by a complex shear modulus related to the shear rate. The transverse moving beam is modeled based on Newtonian law and derived nonlinear equations are solved by finite difference method. It is found that the resonant frequency of the beam increases with the amplitude of the external excitation by a power law. In addition, the initial damping ratio decreases first and then increases with the increase of the amplitude of the initial excitation for the STF with shear thinning zone. The minimum value of the initial damping ratio should be avoided, which is caused by initial shear thinning. This work can be used to guide the designing of structures with enhanced damping and the preparation of STF materials for application to such structures.