This CWA provides information of interest about the fracture toughness evaluation of thin high strength metal sheets and its implication on sheet metal formability and crashworthiness. The document summarizes the most relevant findings obtained in previous research projects and academic works (PhD theses, post-doc works, scientific publications).
The main experimental methodologies to characterize the plane stress fracture toughness of thin ductile metal sheets are described and analysed in terms of complexity, accuracy and quickness. The most relevant fracture toughness parameters are defined, and a compilation of standard testing procedures is given.
Furthermore, the document includes recommendations to be applied during the different stages of AHSS manufacturing, from the microstructural design to the implementation in cold-formed components. Different examples are shown on how fracture toughness measurements can help to predict formability and part performance. Additionally, successful industrial case studies, where fracture toughness measurements have been used to solve cracking related issues in cold-formed components are reported to better exemplify the benefits of using a fracture mechanics approach in the design and implementation of AHSS sheets. The structure of the CWA is schematized in Figure 1.