Volume 35, Issue 1 (January 2007)
Dynamic Fracture-Initiation Toughness ermination of Al 7075-T651 Aluminum Alloy
We present values of the static and dynamic fracture-initiation toughness at different loading rates of the aluminum alloy Al 7075-T651 obtained on three-point bend specimens with different thicknesses and initial crack lengths. In static conditions, the critical stress intensity factor was measured according to well known procedures. The methodology of dynamic fracture initiation toughness is not yet standardized, and the dynamic tests were done with a modified Hopkinson pressure bar coupled to high-speed cameras to measure the crack mouth opening displacement (CMOD) of the specimens. The critical stress intensity value was obtained from the CMOD at the time that crack starts to grow. This instant was detected by means of crack gauges at the crack tip.