Comparison of two finite element models of bristles of gutter brushes for street sweeping

This paper models a bristle of a gutter brush for road sweeping, by means of two finite element models. In one of the models, displacement and rotation boundary conditions are applied to an end of the bristle, so that it follows a certain circular path under a given function of time. In the other model, the same end of the bristle is totally constrained, and inertia loads are applied so that they simulate the motion given by the path and function of the first model. The results of both models are validated, analysed, and compared. They indicate that their accuracy with respect to the degree of freedom results is acceptable. However, regarding force and moment results, the accuracy of the first model strongly depends on the number of straight lines used to approximate the circular path. The accuracy may be very low, mainly due to the modelling of damping. Appropriate values for the time step and integration time step are found so that both models produce reliable results. When these values are used, they provide practically the same results. It is concluded that the model that applies inertia loads may be more appropriate, because the modelling of damping may be more realistic and because much less computational resources are required.