Methodological problems of friction force measurement of plant granular materials

Abstract

The methodology for measuring the frictional force of granular materials of plant origin is complex, since it requires taking into account both variable material factors and the use of available measurement methods in an appropriate way. This article deals with one of the important aspects of the application of a measurement methodology using bottomless containers. The effect of grain pressure on the side walls of the measuring container on the value of grain pressure on the measuring surface was studied. Five different granular materials (wheat, oat, beans, maize, peas) were used as the research material. To analyse the problem, the Janssen model was used as a basis, which describes the normal pressure of the granular material at the bottom of the container depending on certain factors. The tests were carried out for different heights of the material layer and different load values. After analysing the measurement values with calculated values, modifications of the base model were proposed. This modification allowed a high (close to 1) model fit to the measured values. The proposed approach can be useful in carrying out measurements of the friction force of granular materials, since it allows one to estimate the value of the actual pressure of the material on the contact surface. This provides an opportunity to make better use of the horizontal tribometer with a measuring container with support.