Measurement of static and dynamic normal stress of granular materials in silos

Abstract

Accurate measurement of normal stress distribution on silo walls is essential for optimizing silo structural design and improving industrial silo safety. In this study, an embedded silo normal stress measurement system is designed to eliminate nonlinear system errors and prevent the influence of wall vibrations. By hydrostatic pressure experiments, the excellent accuracy and repeatability of the proposed measurement system are validated. Furthermore, the comparison of the stress measurement results with three different models reveals that the distribution of stress increase and stress saturation aligns with the Janssen model. Moreover, for the first time in the experiment, the trend of stress reduction is observed, which only obtained through the simulation. Notably, the dynamic response of the normal stress on the wall at different position is inconsistent, which will be influenced by both the granular packing structure and the distance from the outlet. Finally, a stabilized stress region is found in the hopper during the discharge process, which we hypothesize is caused by localized consistency in particle motion above the outlet, leading to a more stable packing structure of discrete particles. Accurate measurement of normal stress on silo walls not only helps to improve the silo stress distribution model, but also provides key data for silo design optimization and prevention of silo clogging and collapse.