Infrared temperature mapping of ULTIMET alloy during high-cycle fatigue tests

Abstract

Fatigue analysis is an important aspect of understanding mechanical properties of metals and alloys. It is well known that the temperature of a specimen during cyclic fatigue testing increases as a result of internal friction. The temperature changes of a specimen are usually obtained using a thermocouple, but such measurements only provide temperature readings at a specific location. On the other hand, a detailed temperature distribution map of the specimen obtained during fatigue tests could be used as a new dynamic method of monitoring crack initiation and propagation behavior. Temperature changes during fatigue tests are expected to be local and in the form of thermal transients. Capturing thermal signatures associated with fatigue cracks requires a high-speed, high-sensitivity infrared imaging system. Relevant studies using a scanning infrared camera (IR) with temperature resolution of 0.1 K at 293 K can be found in the literature. In the present study, a state-of-the-art IR camera was employed to monitor temperature changes of ULTIMET* alloy during high-cycle fatigue tests. Using the snap-shot and the sequence modes of the IR camera, temperature distribution maps of the specimen as a function of time (cycles) have been obtained. This work reports temperature changes during high-cycle fatigue tests andmore » infrared imaging of fatigue cracks as a heat source before the final failure.« less