Abstract
In this report, the analysis of the circumferential line of projected figure on a particle by using a stylus profilometer (graf-pen digitizer) is proposed for the shape characterization of particles.
The circumferential profile is digitized and converted to x, y values, so as to feed it to computer calculation, and then, the center of gravity is obtained by calculating the moment of a mass (area). Then, this circumferential line is unrolled around the center of gravity against angle θ.
From this unrolled line, the projected area diameter, Ds, the diameter of the circle of equal perimeter, Dl, and the average value of R, Rm, are calculated, where R is the distance between the center of gravity and the circumferential line. With these diameters, three circularities, ψ(=Ds/ Dl), ψs(=2Rm/Ds) and ψl(=2Rm/Dl), are defined as the characterization of the shape of a particle. As the examples, three models (roundness, concave, convex) and four materials are selected, and three circularities are calculated.
From these results, it can be found that when the shape of particles is characterized properly, the values of some circularities show very sharp distribution and consequently particle can be clearly identified from other particles. For example, iron powder can be identified more distinctly by ψl value, and limestone, by ψs value.
