A study of damped free vibration characteristics on a metaconcrete unit cell

The research boom of functional concrete is aroused by the concept of metamaterials. In the paper, based on the one-dimensional spring-mass system model, a three-dimensional vibration model of a unit cell that was taken as the study object was established under linearelastic deformation. The soft coating and mortar were assumed as spring that have the equivalent stiffness, the equivalent length and the equivalent damping in the model. Analyzed the force of the system, the equation of damped free vibration was deduced using the D'Alembert law. The system of vibration solution and natural frequency was obtained. The influences of the initial conditions, aggregate geometry data, the elastic modulus of the soft coating on the natural frequency and the vibration characteristics were analyzed by using the MATLAB. Results show that: the relationship between the undamped natural frequency and the damped natural frequency of the nonlinear vibration system is not consistent with the linear vibration system, and the influence of damping on the natural frequency of nonlinear vibration system is greater than that of linear vibration system. The initial velocity has greater influence on the initial phase than the initial displacement. The initial conditions affect both the amplitude and the natural frequency, as well as the impact resistance of metaconcrete. The reduction factor η decreases with the initial velocity and the elastic modulus of the soft coating. The reduction factor η increases with the thickness of the soft coating. The influence of the reduction factor on metaconcrete structure can be reduced by reducing the initial speed, selecting the soft coating with a larger elastic modulus and increasing the size of the heavy core. © 2022, Editorial Office of Journal of Vibration and Shock. All right reserved.