Study on mechanical properties of solid propellant NEPE

Abstract Nitrate ester plasticized polyether (NEPE) propellants, are high energy solid propellants that are used widely in solid rocket motor. It is necessary to study the mechanical properties of NEPE propellants in order to ensure an accurate prediction of the performance of solid rocket motors and ensure the safety of launch platforms. We studied the viscoelastic hyperelastic constitutive model of NEPE propellants. The speckle defocusing method and digital image correlation(DIC) method are used to obtain the strain of solid propellant NEPE in three directions during unidirectional stretching, and the volume change rate, Poisson's ratio and true strain curves of NEPE under different stretching rates are obtained. With the increase of loading rate, the maximum stress that NEPE can encounter increases, and the modulus at the initial elastic stage also increases. At the initial stage of stretching, the volume change rate is close to 1, the Poisson's ratio fluctuates within a range close to 0.5. When the engineering principal strain in the tensile direction reaches a certain value, the volume change rate begins to increase and the Poisson's ratio begins to decrease. The strain of solid propellant NEPE in three directions during uniaxial tension was successfully measured by speckle defocus method and digital image correlation (DIC) method. NEPE is close to being a super elastic material at the initial stage of stretching. The change trend of the volume change rate curve of different loading rates is consistent, and the stretching rate has no effect on the volume change rate of NEPE.