Evaluation of material behavior of wire strips under cyclic bending load and preparation of an experimental test method

Abstract

Steel fibers as concrete reinforcement improve the building material’s mechanical properties and enlarges its field of application. The production of steel fibers by the process chain notch rolling and cyclic bending promises energetic improvement compared to the conventional manufacturing process wire drawing. The innovative procedure is not yet researched extensively and modelling of the material behavior brings with it many challenges. Different stress states of both process steps require various material models and material failure must be considered. The study brings an appropriate modelling of the test sheet metal DP600 with a thickness of t0=0.8 mm for the second process step into focus. The wire strip’s notches are exposed to a cyclic tension-compression load for which high strength steel exhibits early yielding and a distinct transient region of the stress-strain curve after load reversal. For this reason, the isotropic-kinematic hardening model by Chaboche and Rousselier determined in tension-compression tests is validated by cyclic bending tests. For considering crack initiation, an appropriate ductile damage model for depicting material fatigue is identified. To allow practical realization of the process and validation of the material model, an experimental test method for manufacturing wire strip samples by notch stamping is introduced.