Automatic Control for Vibratory Tillage (II)

Deformation, Internal Stress and Characteristics of Failure in Soil Cutting

Abstract

In order to clarify the deformation, stress and failure pattern of the soil a small bin test device for Moirè method and soil stress meters were designed and constructed. From a series of experiments using these devices the following results were obtained.
1) The Moirè method made it possible to analyze the soil deformation under orthogonal cutting.
2) Neither the cutting conditions nor the soil conditions affected the direction of the principal strain. The cutting conditions gave effects on the soil deformation range, and soil conditions affected the magnitude of the principal strain of the soil.
3) Neither the cutting conditions nor the soil conditions affected the direction of the principal stress. Those conditions gave cosiderable effects on the magnitude of the principal stress as well as the stress distribution along the shear plane.
4) Vibratory tillage reduced the soil stress on the shear plane as compared to the non-vibratory tillage. This resulted in the smaller shearing force.
5) The shearing pitch increased proportionally to the cutting depth and soil hardness within the moisture range of 22%-27%.
6) Backward motion of the blade caused cracks near the edge point of the blade which reduced the shearing force.