Tractive Performance of Wheels in Soft Soils
GRUMMAN AEROSPACE CORP BETHPAGE NY RESEARCH DEPT
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The traction developed by a wheel can be determined by appropriate integration of the soil wheel interface stresses. In soft soils these are governed by failure conditions in the soil brought about by the wheel load. The geometry of the two failure zones front and rear, as well as the associated stresses, are computed by solving the differential equations of plasticity by numerical techniques. A flow diagram shows the computation of failure zones and associated interface stresses that yield the load, torque and traction for a given wheel geometry and interface friction. Slip-shear stress equations are used to relate interface friction to slip. The solution of the practical problem of determining traction and slip for given soil conditions and applied wheel load and torque requires an iteration procedure that is shown in another flow diagram. Inputs for the computer program are soil properties, wheel load, and torque the end outputs are traction slip and sinkage. For the computation of traction exerted by tires, a soil-tire model has been developed that allows for the deflection of the tire and attendant restraint of the normal interface stresses.
- Soil Mechanics
- Surface Transportation and Equipment