Constitutive Model Constants for Al7075-T651 and Al7075-T6

Aluminum 7075-T651 and 7075-T6 are characterized at quasi-static and high strain rates to determine Johnson-Cook (J-C) strength and fracture model constants. Constitutive model constants are required as input to computer codes to simulate projectile (fragment) impact or similar impact events on structural components made of these material. J-C strength model constants (A, B, n, C, and m) for the two alloys are determined from tension stress-strain data at room and high temperature to 250$^{\circ}$C. J-C strength model constants for Al7075-T651 are: A=527 MPa, B=676 MPa, n=0.71, C=0.017, and m=1.61 and for Al7075-T6: A = 546 MPa, B = 674 MPa, n = 0.72, C = 0.059, and m =1.56. J-C fracture model constants are determined form quasi-static and high strain rate/high temperature tests on notched and smooth tension specimens. J-C fracture model constants for the two alloys are: Al7075-T651; D$_{1}$ = 0.110, D$_{2 }$= 0.573, D$_{3}$= -3.4446, D$_{4 }$= 0.016, and D $_{5}$= 1.099 and Al7075-T6;~D$_{1}$= 0.451 D$_{2}$= -0.952 D$_{3}$= -.068, D$_{4 }$=0.036, and D$_{5 }$= 0.697.