A review on the angle of repose of granular materials ...
2018-5-1 · The box must contain at least one transparent side; the granular material is placed on the base of the box, and then the box is tilted gradually at a rate of 18°/min. The angle of repose is then measured as the tilting angle at which the material begins to slide [ 7, 35 ], as shown Fig. 2.