FEM analysis of the dependency on impact angle during erosive wear

Abstract

The phenomenon of material surfaces being damaged and removed by particle-impact is called “erosion” and it is a serious problem in transportation by pneumatic conveyance. The erosive wear is complicated, and its behavior changes depending on factors including not only the kinds of material, hardness, shape, size and mechanical properties of the particles but the collision angles and velocity. In this study, mild steel was prepared and erosion wear tests were carried out using steel grits at different impact angles. It was found that the wear losses varied markedly by changing the impact angle and there appeared special angles that showed the maximum wear. They were 20 to 30° for mild steel, 60° for ductile iron, respectively. This suggested that harder the hardness of the alloy, the higher the value of the collision angle of the maximum wear. The dependency on impact angle during erosive wear was simulated by the Tabor [5] theory and FEM (MARC/MENTAT) that could analyze the plastic deformation of alloy surface as a single particle collision. In the case of mild steel and ductile cast iron, the impact angles to have maximum wear were explained successfully. In order to evaluate the plastic strain of the raised part quantitatively, the total corresponding plastic strain within the range of contact depth 0.3 mm and the length 0.6 mm is employed. The frictional coefficient μ is changed as 0.1, 0.3 and 0.7. The sum total of the corresponding plastic strain at this raised part reaches maximum at impact angles of 20 to 30° and appears the minimum value at impact angles of 60 to 90°. This dependency on impact angle agrees quite well with the results by experiments, namely, it can be explained by means of the total sum of corresponding plastic strain by unit particle impact that the reason for the appearance of a peak at impact angles of 60 to 90° for mild steel.