%0 conference lecture (invited) %@ %A Heerens, J.,Schoedel, M.,Schwalbe, K.-H. %D 2005 %J 11th International Conference on Fracture, ICF 11 %N %P %T Experimental Determination of Critical Crack Tip Opening Angle (CTOA) using the CTOD Delta 5 Measurement Technique %U %X