Using the theory of perfect plasticity, upward cutting has been analyzed for very wide blades such as scrapers and for very thin plow blades. The results predict decreasing soil resistance with increasing blade roughness. The predicted reductions in soil-cutting resistance for a thin plow blade agreed well with observed reductions in forces with the upward-cutting vibratory plow in the Soil Mechanics Laboratory at Bell Telephone Laboratories, Chester, N. J.
