MECHANICAL TESTING

R-Curve Determination - ASTM E 561

ASTM E 561 covers the determination of resistance to fracturing of metallic materials by R-curves using either the center-cracked tension panel M(T), the compact specimen C(T), or the crack-line wedge-loaded specimen C(W), to deliver applied stress intensity factor, K, to the material. An R-curve is a continuous record of toughness development in terms of KR plotted against crack extension in the material as a crack is driven with a continuously increased stress intensity factor, K.

R-curves characterize the resistance to fracture of materials during incremental slow-stable crack extension and result from growth of the plastic zone as the crack extends from a sharp notch. They provide a record of the toughness development as a crack is driven stably under increasing applied K. They are dependent upon specimen thickness, temperature, and strain rate.

Index of Mechanical Testing