Effect of granular shape on angle of internal friction of binary granular system

• Three regions have been divided based on the magnitude of granular aspect ratio.
• The effect of factors on angle of internal friction has been studied in detail.
• An integrated model has been proposed which agrees well with the measured results.

The study of angle of internal friction (ΦI) is widely prevalent due to its importance in science and engineering, and yet the quantitative description concerning the effect of granular shape on the ΦI is few. In our study, the influence of granular shape on the ΦI of various binary granular systems was investigated theoretically and experimentally with a Freeman FT4 Powder Rheometer. The results show that the variation amplitude of tangent ΦI (ΔtanΦI) exhibits a linear relation with the related particle physical properties. Our findings show that three regions have been divided for various binary granular systems based on their magnitude of aspect ratio, and there exists a powder function between ΔtanФI and granular shape factors. On this basis, an integrated model has been proposed to describe the quantitative relationship between angle of internal friction and granular shape factor, which agrees well with the experimental data.