Modelling and identifying a pressurised dilatant sand to be used as a smart damping material

Abstract

An experimental and modelling study of the properties of a prototype layered beam with a core made of a non-Newtonian sand mixture is presented. The non-typical dilatant sand was covered with an elastic envelope that restricted its movement, which allowed us to pressurise the grains by evacuating the air from within the cover. By applying controlled underpressure, the compressed sand grains become jammed, which resulted in an increased stiffness and damping. This gives the possibility to attenuate vibrations of a cantilever in an adaptive manner. The experiment was performed for free vibrations and prescribed sinusoidal base motion, to demonstrate the possibility of tuning material parameters in a vast range. The experimental amplitude, frequency and damping capacity of the kinetic sand are discussed. An analytical model is proposed to verify how many parameters are necessary to describe the material behaviour. Based on the experimental results, a parameter identification of a custom rheological model is performed and practical simplifications reducing complexity of the problem are elaborated. The performed parameter identification is indispensable for the further development of potential control strategies for effective vibration abatement of dynamic systems using such types of alternative smart materials.