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Numerical Modelling of Effect of Heating Rate on Results of Dynamic Mechanical Analysis of a Rocket Propellant

Thermal methods play important role in the analysis of explosives. The most frequently these methods are used for the characterisations and determination of the thermal, thermomechanical, and thermokinetic properties of explosives. Due to dynamic nature of processes taking place during the experiment (chemical reaction and physical processes, heat flow, gas flow, etc.) results obtained by thermal methods may considerably depend on the conditions used during the experiment. Therefore, whenever results of thermal analysis are reported, the experimental conditions used should be stated. In this paper we have studied the heat transfer from the furnace to the sample, and through the sample, during dynamic mechanical analysis (DMA) measurements. Numerical modelling of the heat transfer was done using an own computer program based on the reactive heat conduction equation, solved numerically applying the finite difference methods. The calculated values of thermal lag between the furnace and sample were compared with values determined experimentally on samples of double-base rocket propellant at different heating rates. Also, the temperature distribution within the sample as a function of the heating rate was analysed using the same numerical model. It was shown that even at slow heating rates there is significant thermal lag between the furnace and sample, as well as significant thermal gradient within the sample.

thermal methods; dynamic mechanical analysis; heat conduction equation; double base rocket propellants; thermal lag; thermal gradient

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