Experimental Research on the Compressive Properties of Modified Double Base Propellant at Low and High Strain Rates

The compressive experiments from low to high strain rates have been performed on the material test machine and the split Hopkinson pressure bar(SHPB)apparatus at room temperature of 20 ℃.The availability of SHPB experimental data is examined,and the true stress-strain curves are obtained in the strain rate range from 1.1×10-4 s-1 to 4×103 s-1.The results show that the modified double base propellant behaves significant strain rate dependence.At low strain rate,the true stress-strain curves show initial elastic stage,yield and strain strengthening stage,and descend stage,in which the specimen fractures along the slope of 45°~55°,and the failure stress and failure strain increase with the strain rate.At high strain rate,the true stress-strain curve shows the effect of strain softening instead of strain strengthening.The initial modulus of elasticity and yield stress of modified double base propellant increases with the strain rate,what's more,they increase substantially at high strain rates compared with those in quasi-static.The relationship between yield strength and logarithm of strain rate is bilinear,which shows more strain rate sensitiveness at high strain rate than at low strain rate.