Dynamic Fracture Analysis of Notched Bend Specimens.
WASHINGTON UNIV SEATTLE DEPT OF MECHANICAL ENGINEERING
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A dynamic finite element code was used to determine dynamic initiation fracture toughness, K sub Id. in 25.4 mm 1 in. thick notched bend specimens of A533 B steel and a 15.9 mm 58 in. thick dynamic tear DT specimen of 6061 aluminum alloy. These specimen types can reflect varying dynamic fracture response due to differences in test temperature, specimen geometry and material as well as notch tip sharpness. Measured load-time histories were applied to the tup as modeled by finite elements and the dynamic stress intensity factor was computed by a calibrated COD procedure. Dynamic stress intensity factors were also computed by the ASTM E-399 procedure using a load based on local dynamic strain measurements and a static K-calibration. Reasonable agreements between measured and computed dynamic strains in the vicinity of the crack tip verified the accuracy of the dynamic finite element model. The attendant agreement between measured versus computed time-varying dynamic stress intensity factors also verified, for the first time, the applicability of the ASTM E-399 procedure for computing dynamic initiation fracture toughness, K sub Id on the basis of local dynamic strain measurements. Author