Optical nondestructive evaluation for minor debonding defects and interfacial adhesive strength of solid propellant

Abstract

Minor debonding defects and weak adhesion impair solid propellant integrity, which may cause rocket launch failure. However, it’s difficult to identify these interfacial bonding problems in-situ by the common temporal phase-shifting method due to its inaccurate phase calculation and background noises. In this work, a real-time phase processing method with high-frequency synchronizing trigger technology is proposed to improve phase map quality and anti-interference performance in the phase-shifting process. The method is applied to shearography/ESPI optical nondestructive measurement systems to detect minor debonding defects with minimum diameter of 2 mm and evaluate interfacial adhesive strengths of the bonding layers, respectively. The results show that stable and high-contrast phase maps are obtained in real-time from a large field of view, indicating that the detection capabilities of shearography/ESPI are enhanced via the application of the method. This work would contribute to the in-situ nondestructive evaluation of minor defects and weak adhesion in solid propellants.