Erosion mechanisms due to impact of single angular particles

The trajectory of an angular particle as it cuts a ductile target is, in general, complicated because of its dependence not only on particle shape, but also on particle orientation at the initial instant of impact. This orientation dependence has also made experimental measurement of impact parameters of single angular particles very difficult, resulting in a relatively small amount of available experimental data in the literature. One of the present authors has previously developed a computer simulation, based on the rigid-plastic theory of single particle impact, which predicts the path of a single hard angular particle as it tumbles while cutting a ductile target, as a function of particle shape, orientation, angle of incidence, and incident velocity. This paper outlines recent progress in obtaining measurements of particle kinematics for comparison to this model. In particular, it describes a catapult apparatus capable of launching single angular particles of various shapes so that they arrive at the target in a known orientation. Fundamental mechanisms of material removal are identified, and measurements of incident and rebounding linear and angular velocity of single hardened steel particles launched against flat aluminum alloy targets, obtained via a high speed digital camera setup, are presented. When compared to the predictions of the rigid-plastic theory based computer simulation, good agreement is found.