Robot-Aided Rearrangement of Steel-Fibers in UHPFRC via Magnetic Forces (2015-08)¶

The undirected distribution of steel fibres in pre-fabricate concrete elements is of substantial nature. The goal of this investigation is to increase the local mechanical properties of specific concrete elements by controlling the alignment of the fibres according to the flow of forces using robots. The paper will present theoretical consideration and experimental research of the robot controlled interaction between magnetisms and the steel fibre orientation in a translucent gel as a substitut for freshly cast fibre reinforced concrete. The predefined path of the robot was controlled via movement parameters acceleration and velocity. The end effector of the robot arm was implemented with ultra-strong neodymium magnets of different dimensions and polarity. The repeatable path of the end-effector ensured reproducible interaction between the force fields and field lines of the different magnets, the geometry of the tested fibres and the geometry of the mould. The desired micro-overlap of parallel-orientated fibres in the tensile zones could be achieved by using sets of magnets mounted on the end-effector of the robot: They were aligned due to their specific characteristics and the particular choice of the fibres. Using the effect of moving these sets on the outside of the moulds in a rotary way, the concentration of fibres affected by the magnets could be increased drastically.