Effects of overload-vibration coupling on combustion characteristics of aluminized propellant in solid rocket motors

Overload and vibration loads are typical load environments encountered by solid rocket motors (SRMs) during high-maneuverability flight, which may induce anomalies in propellant burning rate and interior ballistics, thereby posing a serious threat to motor reliability. To this end, a ground ignition test apparatus was designed and constructed to simulate coupled overload and vibration acceleration conditions. Using aluminized composite propellant as the research subject, the effects of coupled loads on motor acceleration response, interior ballistic characteristics, and microscopic morphology of combustion products were systematically investigated. The results indicate that under coupled loading, the motor acceleration amplitude decreases significantly and exhibits a regular variation pattern with frequency; the influence of overload on interior ballistic performance is far greater than that of vibration. Under low-frequency high-overload conditions (10 g/10 Hz), the burning rate enhancement ratio reaches up to 1.34, the average combustion chamber pressure increases by 11.6%, the combustion duration is shortened, and large-sized aluminum particle agglomerates tend to form in the combustion products; under high-frequency low-overload conditions (5 g/40 Hz), the burning rate enhancement ratio is only 1.019, the pressure oscillation frequency is consistent with the external excitation frequency, and the combustion products predominantly consist of medium-sized residues.