Design and fabrication of an angle of repose apparatus for granular material analysis

Abstract

The angle of repose (AOR) plays a crucial role in analyzing the flowability of granular materials, which are widely used in fields such as agriculture, pharmaceuticals, and civil engineering. This study outlines designing and constructing an affordable, user-friendly Apparatus for accurate AOR measurement. Built for both laboratory and field applications, the Apparatus was made from materials that are easily accessible and include an adjustable funnel, a central column, and a sturdy base to ensure consistent and precise measurements. Experimental tests using agricultural materials such as rice, beans, wheat, and millet yielded reliable results with low standard deviations. A paired t-test indicated significant statistical differences between the newly designed Apparatus and conventional methods (t-statistic of -2.98, p-value of 0.015), though these differences fell within an acceptable experimental range of ±0.5°. The mean difference of -0.26° and a 95% confidence interval of [-0.43°, -0.09°] illustrate a slight downward bias in the Apparatus while confirming its reliability and accuracy. This research provides a practical solution for measuring AOR, especially in resource-constrained environments, and suggests potential enhancements, like incorporating digital sensors for greater precision and changeable orifice opening sizes for the funnel ranging from 10 mm to 22 mm