جستجوی مقالات مرتبط با کلیدواژه « پیشرانه دوپایه بهبود یافته » در نشریات گروه « مواد و متالورژی »

In the present work, the influence of formulation changes obtained by different compositions of double-base and modified double-base propellants, on the relaxation behavior was investigated using the dynamic-mechanical analysis techniques. In order to identify the dynamic-mechanical behavior and characterize the type of different relaxations and triple transition temperatures in double-base and composite modified double base (CMDB) propellants at the present work, DMTA test was used. According to the results, in spite of relaxation temperatures Tα and Tβ for the CMDB propellants, the other relaxation temperature T γ was not detected. By addition of energetics nitramines (RDX) to the modified double-base propellant, relaxation temperatures were increased. Decrease in values of nitroglycerine, also has the same effect on relaxation temperatures. The results were shown that for the samples containing RDX, the compression modulus was increased and for a more RDX content propellant sample, elongation at break was decreased.

In this study, the rheological parameters such as yield stress, viscosity coefficient, and power law index were obtained for double-base propellants and modified double-base propellants formulations using the Squeeze flow rheometric method. Squeeze flow test was used to investigate the rheological behavior without wall slip condition, and to determine the temperature dependency of fluidity in double-base propellants and modified double-base propellants formulations. The results showed that for double-base propellants and modified double-base propellants formulations, the initial elastic behavior is identical in terms of phenomenology, however, differs in term of the value. There are distinct structural differences and different rheological properties between double-base propellants and modified double-base propellants formulations. By increasing the percentage of energetics nitramines (RDX) in modified double-base, the average squeeze flow force moves to higher values. A similar behavior is observed by decreasing the percentage of nitroglycerin. The results show that the Sherwood’s model for the flow of double-base propellants is better than the curves of modified double-base propellants, which reflects the deviation of the rheological behavior of modified double-base propellants from Herschel-Bulkley fluids.