Investigation of D16ch Alloy Fracture Kinetics by Acoustic Emission, Digital Image Correlation, and Real Damage Analysis

Abstract—The mechanical and physical properties of a D16ch alloy, which is used as the fuselage skin of the IL-62M aircraft with a service life of more than 28 years, has been studied. The influence of the service life and preliminary cyclic loading on the acoustic emission (AE) characteristics, the strain characteristics during tension obtained by the digital image correlation (DIC) method, and the real damage determined using optical microscopy are estimated. The mechanical properties of the material during operation are found to remain almost unchanged as compared to the initial state. However, the AE study demonstrates a significant increase in the AE activity $${{\dot {N}}_{{{\text{AE}}}}}$$ and the accumulated number of AE signals ΣNAE, and the DIC investigation reveals an increase in the plastic zone area in specimens after operation. Preliminary cyclic loading of specimens both in the initial state and after operation leads to an increase in the relative damaged surface area. The results obtained indicate that the research methods used in this work give important information to estimate the degradation of the material and the effect of preliminary cyclic loading on it.