Fundamental Studies on Tillage Machinery (II)

Development of the Micro Soil Stress Meters and Their Faculty and Performance

Abstract

In order to apply the theory of minimum stress in plane of soil failure in tillage, author tried to turn out micro soil stress meters which picked up the stress in soil cutting action.
Previous to the making of micro soil stress meters, author took consideration on the properties which the stress meters should possess; namely, scale of measurement, disturbance of stress field, accuracy of measuring direction, maximum and minimum measurable pressure, dynamic properties of, pressure plane, linearity of load and indicated value, allowable deflection of pressure plane and effect of temperature change.
Then, author thought out testing methods of these properties, and decided the type and dimension of stress meter and how to use it.
At first hand, author turned out cylindrical type micro soil stress meters which were of simple structure, but due to large distribution of measured value, as well as deficiency of direction accuracy and durability, it could be used only to measure the rough tendency of stress distribution in cutting fine soil. Then author made diaphragm type micro soil stress meter, which proved to have sufficient properties to be used in tillage of fine soil.