Application of thermoelastic stress analysis for the experimental evaluation of the effective stress intensity factor

Francisco A. Díaz, Eann A. Patterson, John R. Yates


In recent years, the advent of staring array detectors has made Thermoelastic Stress Analysis (TSA)
a technique with considerable potential for fatigue and fracture mechanics applications. The technique is noncontacting
and provides full field stress maps from the surface of cyclically loaded components. In addition, the
technique appears to have a great potential in the evaluation of the effective stress intensity factor range during
fatigue since fracture mechanics parameters are derived directly from the temperature changes in the vicinity of
the crack tip rather than from remote data. In the current work TSA is presented as a novel methodology for
measuring the effective stress intensity factor from the analysis of thermoelastic images. ?K values inferred
using TSA have been employed to estimate an equivalent opening/closing load at different R-ratios in a cracked
aluminium 2024 CT specimen. Results have been compared with those obtained using the strain-offset
technique showing a good level of agreement.

Full Text: