Comparison between the discrete and finite element methods for modelling an agricultural spray boom - Part 2: Automatic procedure for transforming the equations of motion from force to displacement input and validation

This paper validates the discrete element method for linear flexible multibody systems, elaborated in Part 1 of the paper, of which the flexible bodies are a composition of flexible beams. An automatic procedure is developed to convert the linear equations of motion of a multibody system from force to displacement input. By this procedure, support motions and displacements of actuators between the bodies can be employed as an input to the system. Furthermore, using this procedure, the methodology explained in Part 1, which was valid for tree structured systems can be extended to systems containing closed kinematic chains. The methodology of Part 1 is applied for the discrete and finite element approximations to model the horizontal behaviour of an agricultural spray boom. As the inputs to the spray boom are known under the form of positions, the equations of motions are converted from force to position inputs. The discrete and finite element approximations are compared based on accuracy and the complexity of the resulting models. (C) 2003 Elsevier Ltd. All rights reserved.