Dynamic initiation toughness measu~ment using double Grooved discs

Among the multitude of test specimen geometries used for dynamic fiacture toughness evaluation, the most widely uscd specimen is lhc Chavpy specimen due its simple geomclry and availability of testing machines. The standard Chatpy specimen dimensions may llOl always give plane st~ain condilions and hence, it may be necessary Io coilduct lcs/s using specimens of dillEvcnt thicknesses to establish the plane strain K~a. An axisymmct/ic specimen, on the otlaev hand would always give flow constraints l~n a nominal specimen thickness i~rcspcctive of the test matctial. The notched disk specimen pVOl)oscd by Bcrn:ud ctal. [1] for static and dynamic initiation toughness measurement although p~ovicles plain-strain conditions, the crack plopagatcs at an angle to the direction of applied load. This makes inteq~retation of the test results difficult us it ~Ccluivcs ~actial slices to be cut fiom the fractured specimen to ascertain the angle o1 crack growth and a linite element model l~)r tl);t{ pa~ticulat ctack o~icntalion.