CALCULATION OF STRESS DISTRIBUTIONS IN A POWDER BED AS A PLANE-STRAIN FIELD AND VERIFICATION BY EXPERIMENT - THE EFFECT OF FRICTION FACTOR

It is important to predict the stress distribution in a powder bed for the design of storage vessels and unit operations with powder. Assuming a constant friction factor constant in the bed, we calculated the stress distributions in a storage vessel for various friction factors by using the incremental finite element method. The calculated results show that the stress distributions greatly depend upon the friction factor. However the friction factor in a powder bed varies with shear strain and packing ratio. In the present study we expressed the friction factors, which were obtained by a shearing tester, as a function of shear strain. Using them, we calculated the stress distributions and compared them with experimental results published in our previous paper. They are in fairly good agreement with each other in the horizontal stress distribution of the side wall as well as in the vertical stress of the bottom. Therefore, it would be possible to express the local changes of friction factors as a function of shear strain. Our calculated results also well describe the location of the arch at the side wall; thus the results would be useful in designing powder storage vessels.