Influence of Stress State on the Mechanical Impact and Deformation Behaviors of Aluminum Alloys

Under impact loading conditions, the stress state derived from the contact between the projectile and the target, as well as from the subsequent mechanical waves, is a variable of great interest. The geometry of the projectile plays a dertermining role in the resulting stress state in the targeted structure. In this regard, different stress states lead to different failure modes. In this work, we analyze the influence of the stress state on the deformation and failure behaviors of three aluminum alloys that are commonly used in the aeronautical, naval, and automotive industries. To this purpose, tension-torsion tests are performed covering a wide range of stress triaxialities and Lode parameters. Secondly, the observations from these static tests are compared to failure mode of the same materials at high impact velocities tests with the aim of analysing the role of stress state and strain rate in the mechanical response of the aluminum plates. Experimental impacts are conducted with different projectile geometries to allow for the analysis of stress states influence. In addition, these experiments are simulated by using finite element models to evaluate the predictive capability of three failure criteria: critical plastic deformation, Johnson-Cook, and Bai-Wierzbicki.