Volume 16, Issue 1 (January 1988)
A Cleavage Precracking Technique for Sheet Steel Fracture Specimens
A technique is described for the preparation of sheet steel fracture specimens containing a cleavage precrack instead of the usual fatigue precrack. Since the cleavage precrack can provide a high level of stress concentration and is free from cyclic-loading damage, such specimens are useful in the investigation of various fracture processes and mechanisms. The production technique involves low-temperature biaxial loading of a specimen blank to produce a cleavage crack extension, then separation of the specimen from the blank by electrical-discharge-machining (EDM). The stresses used to control the cracking are analyzed and discussed.