Measurement Method and Equipment of Fatigue Crack Length Based on Alternating Potential Method

The principles of measuring the fatigue crack length based on alternating potential method were interpreted and an equipment of measuring the fatigue crack length based on alternating potential method was developed.This equipment based on LabVIEW is a virtual instrument system which can acquire,analyze and process data and has functions of visualization operation,automatic measurement,curves displaying and data storage.The fatigue crack length of Ti1023 titanium alloy and Al7055 aluminum alloy was measured by this equipment.The results show that the resolution of this equipment is less than 1 μm,and the equipment can measure the relationship between the measuring voltage and fatigue cycles which can be translated into the relationship between fatigue crack length and fatigue cycles based on the calibration.