ELASTIC-VISCOPLASTIC FINITE-ELEMENT PROGRAM FOR MODELING TIRE SOIL INTERACTION

The viscoplastic finite-element program for modeling tire/soil interaction is shown to be a powerful analytical tool that has a significant promise for improving the Air Force ability to predict aircraft ground operation. A brief review of the mathematical theory of viscoplasticity and the computational procedure used in the finiteelement program is first presented. Next, some of the capabilities of this powerful analytical tool are demonstrated. The first example considered is that of the effect of tire pressure on sinkage and rut depth produced on constant strength clay and sand soils. Then, the effect of layered soil on sinkage and rut depth is examined, considering the possibility of soft over hard as well as of hard over soft layers. This latest case is further studied investigating the effect of the variation of the top thickness layer on sinkage. In conclusion, tables are presented that provide an equivalent cone index for a two-layered clay soil of different strengths and thicknesses. To demonstrate the capability of the program to model contingency surfaces, the behavior of standard flexible and rigid pavements under a medium tire pressure were considered. © 1989 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.