On the Experimental Calibration of a Potential Drop System for Crack Length Measurements in a Compact Tension Specimen

The present study was focused on the setup of a system for monitoring deep cracks in notched specimens in creep and fatigue laboratory tests. The test configuration features, the instrumentation requirements, and the important problems of the calibration for potential drop application to both fatigue and creep crack growth tests on compact tension specimens are discussed in detail. Experimental tests on the compact tension specimen geometry were carried out at ambient and high temperatures in order to define and validate an experimental calibration for this specimen geometry, to check the effect of temperature, and to compare the crack growth calibration curves under creep or fatigue conditions.