Residual stress evolution regularity in thermal barrier ceramic coatings(TBCs) under different cycles of thermal shock loading of 1 100℃ was investigated by the microscopic digital image correlation(DIC) and micro-Raman spectroscopy, respectively. The obtained results showed that, as the cycle number of the thermal shock loading increases, the evolution of the residual stress undergoes three distinct stages: a sharp increase, a gradual change, and a reduction.The extension stress near the TBC surface is fast transformed to compressive one through just one thermal cycle. After different thermal shock cycles with peak temperature of 1 100℃, phase transformation in TBC does not happen, whereas the generation, development, evolution of the thermally grown oxide(TGO) layer and micro-cracks are the main reasons causing the evolution regularity of the residual stress.
Residual stress measurement is of critical significance to in-service security and the reliability of engineering components,and has been an active area of scientific interest.This paper ofers a review of several prominent mechanical release methods for residual stress measurement and recent developments,focusing on the hole-drilling method combined with advanced optical sensing.Some promising trends for mechanical release methods are also analyzed.
