Evaluation of the structural integrity of solid rocket propellant by means of the viscoelastic fracture mechanics approach at low and medium strain rates

This work analyzes the influence of displacement rate on tensile properties and fracture parameters, determined through a viscoelastic Fracture Mechanics approach, carboxyl-terminated polybutadiene (CTPB) based solid composite propellants. Low medium rates attained in an electromechanical testing machine were inspected. From true stress-true pseudo strain curves, Young’s modulus was not influenced by with value almost identical to instantaneous obtained from stress relaxation tests. The same trend achieved for Poisson’s ratio, behavior close incompressibility. On other hand, yield increased rise. Regarding behavior, strong dependency resistance curves terms both viscoelasic J-integral crack tip opening displacement, CTOD, proved, being greater as increases. Moreover, linear relationship between demonstrated. These results confirmed surfaces analysis. At low rate, damage nucleation propagation occurred matrix while at high rates, dewetting phenomena gave rise rougher initiation growth mainly – particle oxidizer interface.