Dynamic mechanical behavior of highly filled polymers: Energy balances and damage

Abstract Dynamic tests using the Naval Weapons Center torsion–tension tester and end‐bonded cylindrical propellant specimen were carried out to evaluate the effects of internal damage on propellants by subjecting samples to small tensile oscillations during low constantstrain rate tests. It is shown that microstructural damage in a propellant causes significant changes in mechanical properties. The mechanical property curves demonstrate that the response is markedly strain sensitive. So long as the maximum strain experienced by the sample during a test is not exceeded, the response of the propellant to small tensile oscillation during repeated strains below that maximum value remains relatively unchanged after the first initial dramatic change. The differences between mechanical energy balances of “undamaged” and “damaged” propellant samples were used to demonstrate microstructural damage and to estimate the extent of damage. For any one propellant, the total lost energy caused by microscopic failure of the propellant seems to be additive, constant, and independent of the mechanical path to failure.