The effect of particle orientation and/or position on two-dimensional shape measurements

Particle shapes were measured based on the random positioned (R) method, the stable positioned (S) method and the stable positioned/constant orientated (S /C) method. The mean values ϕ and ζ of two shape indices (circularity ϕ and smoothness ζ), previously defined, were calculated. It was found that smoothness ζ was little affected by shape measuring methods, while circularity ϕ differed according to methods. By analyzing the change in circularity using model ellipsoidal particles, it was confirmed that the R method could more effectively evaluate particle shapes than can the S method, based on the results of the S/C method.