Analysis of impact damage of agglomerates: effect of impact angle

The effect of impact angle on the breakage of two types of agglomerates of a synthetic detergent formulation is analysed. The agglomerates are in the same size range (0.60-0.71 and 1.00-1.18 mm)with the same formulation but have different structures arising from the processing method. In contrast to previous work reported in the literature for other materials, it is observed that for the types of agglomerates used in this work the extent of breakage increases as the impact angle is decreased from normal in the velocity range tested (15-35 m s(-1)). Furthermore, when the agglomerates break in the chipping regime, i.e. by surface damage at low impact velocities (less than 15 m s(-1)), the normal component of the impact velocity determines the extent of breakage independent of the impact angle. However, at higher impact velocities where fragmentation occurs, the role of the tangential component of the impact velocity becomes increasingly important. The difference in the failure mode of agglomerates tested here and those reported in the literature is thought to be the main reason for the dissimilarity. The granules examined here are sensitive to shearing because of the synthetic detergent formulation and their failure is predominantly due to ductile failure, whilst the previous materials fail mainly through brittle and semi-brittle mode of breakage. (C) 2004 Elsevier B.V. All rights reserved.