The Mechanical Response of M30, XM39, and JA2 Propellants at Strain Rates from One One-hundredth to 250 per second
Final rept. Sep 1989-Feb 1990
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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The mechanical response of M30, XM39, and JA2 gun propellants at strain rates from .01 to 250sec is characterized using the BRLs new Hi-Rate Servohydraulic test apparatus. At axial strain rates of 250sec, there is good experimental agreement between the compressive moduli determined on the drop weight and servohydraulic apparatuses, yet the post-yield responses vary because of differing displacement history inputs. All three propellants deformed in a ductile fashion and sustained over 40 shortening. The M30 and XM39 propellants deformed by macroscopic fracture and work-softened after reaching maximum stress. The JA2 propellant deformed by macroscopic flow and work-hardened throughout the deformation history. The absorbed strain energy density per unit volume at 30 shortening and strain rate of 250sec, is 16 and 23 MPa for the XM39 and M30 propellants, respectively. In contrast, the absorbed strain energy density for the JA2 propellant is only 8 MPa and is due to the relatively low flow stress sustained by the material during deformation. A viscoelastic characterization reveals that the secant and relaxation moduli for these propellants can be represented by a power law in time with nonlinear behavior in the time range from .01 to .0001 millisecs.
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