D1.1 Multi-scale approach to predict edge-fracture resistance – Abstract

In this deliverable, the development and optimization of multi-scale approaches to predict edge-fracture resistance are described. In particular, for the measurement of the edge-fracture resistance, two different approaches have been studied: (a) the optimization of a well-established method, Hole Expansion Test (HET); and (b) the development and adaptation of an alternative method to describe stretch-flangeability, Half-Specimen Dome Test (HSDT). These methodologies closely resemble industrial cases (punching and expanding a hole or bending an open edge). The variables affecting stretch-flangeability results (cutting clearance, tool radii and time between hole punching and hole expansion) have been identified for both tests aimed to propose a methodology to objectively measure this property for punched holes and sheared
edges.

On the other hand, the following micromechanical techniques have been used to assess the local damage and properties of sheared areas: Electron Back-Scatter Diffraction (EBSD) and nanoindentation tests. EBSD has been applied to evaluate the damage by the quantification of phase transformations, grain distributions and grain size variations, recrystallized grains and texture due to the cutting and forming processes. The extension of local damage in sheared areas have been evaluated measuring the Young`s modulus variation by a methodology developed using the nanoindentation technique. The XMT has been used to quantify different materials constituents, voids, micro cracks and imperfections in sheet materials.