Silo quake - measurements, a numerical polar approach and a way for its suppression

摘要

Silo quake can be observed in granular bodies during silo emptying in the form of pulsations or shocks. Dynamic measurements were performed in aluminium silos containing polymer granulates. During silo emptying, a noise similar to that of a truck horn was generated that greatly disturbed the neighbouring area. During experiments, wall accelerations, wall deformations and sound pressures were registered. Dynamic effects in granular bodies were analysed with a finite element method developed within a polar continuum, taking into account rotations, curvatures, couple stresses and a mean grain diameter. Two different polar constitutive models were used for numerical investigations, viz. a polar elastoplastic and a polar hypoplastic model. A reliable, practical method to significantly reduce dynamic and resonance effects in silos during mass flow was proposed. It was verified with model experiments, tests in full-scale silos, and numerical calculations.