Storage and handling of cohesive bulk solids such as powders and granules is integral to a wide range of industrial processes. Large quantities of these materials are often stored in solid silos and bunkers whilst smaller quantities are commonly transported in containers made of flexible fabric such as “buggies” and bulk bags (see Figure 1). Most studies conducted in the past have focused on rigid wall containers (silos), while the very few studies on flexible containers have shown that increased wall flexibility leads to large stress redistributions in the stored solid which are not predicted by the established theories [1, 2]. Consequently, there is a lack of understanding of the stress distribution in containers with flexible walls. Consistent with this, problems of non-uniform discharge, completely arrested discharge and incomplete emptying have been observed in flexible containers for the storage of cohesive powders, leading to loss of productivity in industrial processes.

The aim of this project is to understand the stress field and discharge flow modes in flexible-wall containers such as bulk bags and buggy systems through a combination of experiments and finite element analysis and then use that new insight to produce a design methodology for reliable discharge in such containers.

References

[1]R.J. Goodey, C.J. Brown, and J.M. Rotter. Predicted patterns of filling pressures in thinwalled square silos. Engineering Structures, 28(1):109 – 119, 2006.
[2]J.Y. Ooi and J.M. Rotter. Wall pressures in squat steel silos from simple finite element analysis. Computers & Structures, 37(4):361 – 374, 1990.