Experimental Methods for Solid Propellant Mechanical Behavior Characterization (Project Title: Mechanical Properties of Solid Rocket Propellants at Shock Wave Rates)
[Technical Report, Final Report]
AIR FORCE RESEARCH LAB EDWARDS AFB CAIOWA STATE UNIV AMES
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Inert solid rocket propellant samples were subjected to dynamic inflation experiments, to characterize the high strain rate mechanistic response. During the experiments, an oxyacetylene-driven shock tube applied dynamic pressurization to the surface of the samples. Two high-speed cameras captured the deforming samples, which were speckled to measure the full-field surface displacements using the digital image correlation DIC algorithm. Concepts from both dynamic Kirchhoff plate bending theory and structural dynamics were used to mathematically derive the dynamic tensile elastic modulus, by considering both the initial transverse waves phase velocity transient response and the vibration frequency long-term response. An inverse finite element analysis iFEA was used to validate the mathematically derived tensile elastic modulus, by considering a linear elastic constitutive model. The calibrated tensile elastic modulus from the iFEA was comparable with the magnitude derived using the phase velocity. The iFEA was also used to characterize the linear viscoelastic i.e. Prony series having either one or two Maxwell branches behavior of the sample. The viscoelastic parameters calibrated using a Prony series with two Maxwell branches were in good agreement with the out-of-plane displacement data from DIC.
- Solid Rocket Propellants