Deviation of resulting load of forestry vehicle from the normal to the bearing surface

Abstract

The purpose of the article is to develop and analyze relationships for calculating the ratio of the normal pressure of forestry vehicle on the bearing surface and the shear stress caused by the vehicle’s slipping. The study bases on provisions of off-the-road locomotion theory and soil mechanics. The study uses methods of mathematical analysis and applied mathematics for calculations and numeric data processing. The calculations were performed using Maple 2017 software. Calculations show that the ratio of shear stress caused by slipping of the vehicle to the normal pressure on strong forest soil is an average of 17%, reaching 22%; on bearing soil, the ratio averages 22%, reaching 25%; on a weaker forest soil, the ratio is on average 24%, reaching 29% when cutting of the soil layers occurs. It is established that the deviation of the resulting vehicle load from the normal to the bearing surface, at which the cut of the soil layers begins, is 12 - 16 °. The deviation of the resulting load caused by the vehicle slip results in a decrease in the bearing capacity of forest soil by 8.5-10.5%.