The Stress-strain Rate Relationship for Flowing Coarse Particle Powder Beds Obtained by the 3-Dimensional Distinct Element Method and Experiments

• Published in: Funtai Kogakkaishi Vol. 34; no. 4; pp. 212 - 220
• Main Authors: YUU, Shinichi, HAYASHI, Akihisa, WAKI, Masahiro, UMEKAGE, Toshihiko
• Format: Journal Article
• Language: English
• Published: The Society of Powder Technology, Japan 1997
• Subjects: Constitutive Equation; Distinct Element Method; Powder Bed; Strain Rate; Stress
• ISSN: 0386-6157; 1883-7239
• DOI: 10.4164/sptj.34.212

The relationship between stresses and rates of the strains of flowing coarse particle powder beds (ceramic particles diameter Dp=5mm) were calculated by the 3-dimensional Distinct Element Method (D. E. M.). The experimental relationships were also obtained under the same conditions. The comparison of calculated and experimental stress-strain rate relationships shows that both the dynamic shear and the dynamic normal stresses, which are the values of the differences between measured and static stresses divided by the static normal stress, are expressed by the linear relationships of the strain rates of the flowing particulate beds over a fairly broad strain rate. The following equations show the stress-strain rate relationships in the results of the present investigation. τxy=-1/2A1(∂u/∂y)|σy0|+τxy0 σy=-A2(∂v/∂y)|σy0|+σy0 , where τxy and σy are the stresses of the flowing powder beds, τxy0 and σy0 are the static stresses, and u and v are the strain rates. These equations show that the product of the strain rate and the static stress indicates the importance of the constitution relationships in the particulate matter. Coefficient A1, and A2 in these equations in the present investigation show that A2 of the particulate matter is mush larger than A1. This means that shear deformation occurs more easily than normal deformation in the particulate matter.