The development of a technique for the measurement of fracture toughness using computer-aided data collection and analysis has greatly reduced the computation time, increased accuracy, and enabled crack resistance curves to be determined from center-cracked panels of nonstandard geometries. The effective crack length is determined from compliance measurements and a geometric correction to stress intensity factor for nonstandard geometries derived from fatigue crack growth data and from energy release-rate calculations. Fracture toughness tests have been conducted on panels up to 2 m wide with a length-to-width ratio of 0.5.

The technique is illustrated using results showing the effect of panel size and geometry for the 2024-T3 aluminum alloy.