A mathematical model of tractor overturning and impact behaviour

Abstract

A mathematical model was developed based on the force and displacement equations of equilibrium at each point where the tractor or cab makes contact with the ground during overturning. This allowed incorporation of non-linear force-deflection characteristics describing deformation of the soil, cab and parts of the tractor, giving a more accurate representation than is possible if impacts are assumed to be pure plastic impulses. The model was used to cover the overturning phase, in addition to impact, by including tyre side force relationships and damping terms. A computer program based on the model was written in Fortran IV for the simulation of overturns down steep banks and multiple rolls on continuous slopes, the two most severe types found in a survey of overturning accidents. Validation of the model by a series of full scale experiments, and use of the simulation in predicting the effect of parameter changes are described in other papers (References (2) and (3)). A brief review of the literature is given.