Effects of water-mixture film on impact contact in abrasive waterjet machining

The effects of a water-mixture film adhering to solid materials on the impact contact are examined by employing exact solutions for an inhomogeneous contact problem and the Hertz impact theory. The elastic modulus of the water on a surface is assumed to be zero and the modulus of the water-mixture between a water surface and a target material varies from zero to the modulus of the target material. Non-elastic deformation is considered based on an energy balance. A new expression of closed form for impact force is obtained. The film effect on the impact force is very significant for low impact energy and becomes stable and less influential once impact energy increases to a certain value. Experimental results for quasi-static force are in agreement with the theoretical analysis in which two unknown parameters are ascertained by experiments. The minimum effective velocity of garnet abrasives achieved in this work for waterjet machining is consistent with previous results.