Benchmarking the debonding resistance of large-scale thermal protection system composite panels under three-point bending using multi-camera digital image correlation

During prolonged atmospheric entry/re-entry of hyper Mach aircraft, maintaining the structural integrity of the thermal protection system (TPS) is of critical importance for safe flight. Large-scale TPSs are subjected to bending loads induced by fuselage flexure and pressure differentials, resulting in bending deformation. TPS debonding from the aircraft may occur when the interfacial stresses induced by structural deformation exceed the bonding load-bearing capacity, severely compromising flight safety. This study conducts a benchmarking experimental investigation on the debonding resistance of aerogel-based and phenolic impregnated carbon ablator (PICA)-based TPS. The debonding resistance of aerogel-based and PICA-based TPS composite panels was quantified and compared through three-point bending tests. Additionally, multi-camera digital image correlation (MC-DIC) was employed to investigate debonding mechanisms. The comprehensive experiments conclusively establish that aerogel-based TPS composite panels exhibit enhanced debonding resistance to PICA-based TPS composite panels, attributable to the higher bending compliance of aerogel-based TPS composite panels, which mitigates localized strain accumulation and effectively delays debonding initiation. These findings provide crucial insights for optimizing debonding resistance in advanced TPS.