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

Alina Biallas,Marion Merklein

doi:10.25518/esaform21.3826

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.

Highlights

The reinforcement of concrete by steel fiber mainly increases the dissipated energy until total separation [1] and improves the post-failure behavior of the building material
The isotropic-kinematic hardening model according to Chaboche-Rousselier is validated by applying a cyclic bending
Compared to a pure isotropic hardening model, the simulation applying isotropic- kinematic parameters succeeds to improve the mapping of the force-displacement curve

Summary

Introduction

The reinforcement of concrete by steel fiber mainly increases the dissipated energy until total separation [1] and improves the post-failure behavior of the building material. The authors derive two general process methods: producing wires along or perpendicular to the rolling direction They emphasize the need for further analysis of the process through experimental and simulative trials for evaluating the suitability determining the process parameters. To enable a test phase of the cyclic bending process and a validation of the numerical model, the production of wire strip with comparable characteristics to the notch rolling process is desired. To meet this intention, a stamping process is designed and evaluated regarding the expenditure of force and the geometrical properties

Material Behavior under Cyclic Bending Load

Kinematic Hardening

Ductile Damage

Design and Trial of a Model Process for the Notch Rolling

Findings

Summary and Outlook