High-Rate Material Modeling and Validation Using the Taylor Cylinder Impact Test

Taylor Cylinder impact testing is used to validate anisotropic elastoplastic constitutive modeling by comparing polycrystal simulated yield surface shapes (topography) to measured shapes from post-test Taylor impact specimens and quasistatic compression specimens. Measured yield surface shapes are extracted from the experimental post-test geometries using classical r-value definitions modified for arbitrary stress state and specimen orientation. Rolled tantalum (body-centered-cubic metal) plate and clock-rolled zirconium (hexagonal-close-packed metal) plate are both investigated. The results indicate that an assumption of topography invariance with respect to strain-rate is justifiable for tantalum. However, a strong sensitivity of topography with respect to strain-rate for zirconium was observed, implying that some accounting for a deformation mechanism rate-dependence associated with lower-symmetry materials should be included in the constitutive modeling. Discussion of the importance of this topography rate-dependence and texture evolution in formulating constitutive models appropriate for FEM applications is provided