Fracture Toughness & Precracking
Fatigue cracking loads are input by adjusting the crank stroke of the machine. As the specimen begins to crack, load decrease is detected by the SC-6 Shutdown Controller. (Fatigue cracks also may be observed visually or a predetermined number of fatigue cycles may be entered into the cycle counter to stop the machine to ascertain whether the desired crack length has been achieved.) Once the crack has propagated to the desired length, the specimen is installed in a universal test machine to complete the fracture test.
Equipment, Methods and Accessories:
The FDI-2000 and FDI-6000 Precrackers are designed to perform fatigue cracking of COMPACT TENSION specimens. FDI-2000 has a maximum tensile force capability of 2000 Ibs, and a speed of up to 2400 cycles/minute. FDI-6000 can provide up to 6000 lbs. of force and a max. of 2000 CPM. The load cell in each machine allows for static setup of the desired load as well as monitoring the load during the fatigue cracking process. Special specimen grips and alignment joints are available.
The FDI-4000 Precracker performs fatigue cracking of single-edged (3- point bend) notched specimens. Capacity up to 4000 lbs.; 200 to 2400 cycles/minute. The load cell can be repositioned to reduce the maximum capacity to 1500 lbs., increasing the low end load resolution for smaller specimens during setup and specimen cracking procedures. (Note use of the Fatigue Dynamics LFE Test Base; by installing other available test fixtures, a variety of fatigue tests can be performed.)