A numerical study of tillage tool wear during plowing of sandy soil
1 online resource (93 pages) : PDF
University of North Carolina at Charlotte
Wear of tillage tools during tilling operations leads to increase in power requirements, frequent downtimes for tool replacement, loss of production and an increase in the equipment and operational costs. A large number of variables - such as the moisture content in the soil, soil particle sizes, plowing speed, plowing depth, tool material properties, etc. - influence the tool wear rates. In turn, the tool wear has an effect on the power requirements for the tilling operations since a worn out tool requires larger amounts of power. The purpose of the present work is to (a). develop finite element models for predicting tool wear and power requirements, (b). validate the finite element models with experiments, and (c). study the effect of the above-mentioned variables on tool wear and power requirements. The ultimate objective is to understand the primary mechanisms behind tool wear and devise new designs for tillage tools to mitigate tool wear rates.The tool wear process is treated as a two-body abrasion where a rigid sand particle scratches against the surface of the tillage tool at a prescribed speed. A finite element model is developed to model the scratching process. The deformations predicted by the finite element models are used in conjunction with the classical ploughing theory and the material removal factor to identify the mechanisms underlying the wear of the tillage tool. The predicted material removal factors are compared with experimental results and a parametric study is carried out to study the effect of various parameters on tool wear.A two-dimensional finite element model simulating the soil-tool interaction during tilling is also developed. The purpose of this model is to study the feasibility of using the finite element methods to predict power requirements during a tilling process. The tillage tool is modeled as a rigid body moving through soil at a prescribed speed. The constitutive behavior of the soil is assumed to be given by the Drucker-Prager model. The forces acting on the tillage tool as the tool moves through soil are calculated and the power required for the tilling operation is calculated using these forces.The computed values for tool material loss and power consumed during plowing operations are found to be in reasonable agreement with the experimental results. In addition, the parametric studies show that the primary wear mechanism is a combination of ploughing and cutting with cutting being dominant. More sophisticated models and analyses are needed to further understand the tillage tool wear process. The present work provides the foundation on which these advances can be made.
SMELSER, RONALDWEGGEL, DAVIDKAKAD, YOGENDRA
Thesis (Ph.D.)--University of North Carolina at Charlotte, 2013.
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