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| Johnson-Cook Constitutive Model and Failure Parameters of Al-based energetic structural material |
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Abstract The static and dynamic mechanical properties of Al-based energetic structural material at different temperatures were obtained by universal testing machine and Hopkinson bar. The validity of the dynamic experiment is verified by using the stress balance factor. Results show that the alloy is a brittle material with tension-compression symmetry. By analyzing the compression experimental results, the effects of temperature and strain rates on the mechanical properties were discussed, and the Johnson-Cook constitutive model of the alloy were established. The specimens with different notch sizes were designed, and the relationship of failure plastic strain with stress triaxiality were obtained by the two-dimensional digital image correlation (DIC) method. Based on the tensile experimental results and fracture morphology analysis, the parameters describing the relationship of failure plastic strain with strain rate and temperature in Johnson-Cook failure model were obtained. The empirical linear relationship between particle velocity and stress wave velocity of the material was acquired by planar impact experiments. Based on the constitutive model and the equation of state (EOS) of the alloy, impacts of the Al-based energetic structural material on multilayered thin steel targets were analyzed numerically. When the projectile made of Al-based energetic structural material impacts a multilayer steel target with 1800m/s, the central perforation diameter of the first, second and third target is 7.9mm, 24.5mm and 10mm, the error between numerical simulations and experiments is 1.3%, 5.8% and 5.3% respectively. The diameter of the spreading area of the crater on the second target is about 61mm, and the maximum dispersion diameter of fragments on the third target is 50mm, the error between numerical simulations and experiments is 7.0% and 8.7% respectively. The shallow pits with an average size of 8mm on the fourth target can be observed by numerical simulations, which is consistent with the experimental results. When the impact velocity increased to 2200m/s, the damage of the target in numerical simulation is similar to the experimental results. The Johnson-Cook constitutive model and failure parameters could be used in numerical simulation to study the hypervelocity impact mechanism of the Al-based energetic structural material.
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Received: 25 June 2023
Published: 27 December 2023
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2023, Vol. 44 
