Regularities of Contact Behavior of Small Supporting Elements (Feet) of Walking Machines and Robots with Weakly Bearing and Water-Saturated Soils

Abstract

The results of finite element modeling of the mechanics of contact interaction of small-sized supporting elements (feet) of walking machines with weak soils are discussed. A plane contact task is formulated for rigid feet interacting with an elastoplastic support surface. Nonlinear models of soil behavior under loading were used. The task was solved under conditions of large deformations of the supporting surface. The simulation results showed that when a small foot interacts with the supporting surface, a sufficiently large volume of soil is loaded. Under normal loading, the greatest stresses and deformations occur directly under the foot. In addition to vertical deformations, the soil is “squeezed out” to the right and left from under the foot. Under a shear load, the stress and strain fields lose their symmetrical character. The zones of the highest equivalent stresses and strains are displaced in the direction of the tangential load. The greatest ground stresses occur under the foot and on the lateral surface of the foot. It is shown that the use of feet with a small support surface leads to an undesirable increase in soil stresses in the contact zone. On the other hand, in small-sized feet, there is a decrease in the soil compaction zone and its upper layer is less loaded. Also, in small-sized feet, the support surface is used more efficiently — stresses along its length are distributed more evenly, and the lateral surface acts as a lug.