Axisymmetric computation of Taylor cylinder impacts of ductile and brittle materials using original and dual domain material point methods

Although the Taylor cylinder impact itself has limited practical applications, the experiments are often conducted to infer the constitutive relations of materials under high strain rate through numerical calculations. Compared to other numerical methods, the material point method (MPM) has the accuracy advantage on severely deformed specimens. The MPM has been successfully applied in the study of ductile materials, but encounters significant difficulty because of stress noise in its application to brittle materials. The dual domain material point (DDMP) method has been recently developed to reduce the noise. In this paper we extend the DDMP method to axisymmetric cylindrical coordinates. Numerical characteristics of both methods are evaluated by performing computations of Taylor cylinder impacts for ductile and brittle materials. For ductile materials, there is no significant improvement in the results by using the DDMP method, because of the stress smoothing effect provided by the yield surface. For a brittle material, noise reduction is necessary because of the sudden and irreversible stress changes at material failure, and the transition from a continuous state to a granular state of the material. Although physical models for such a transition are still research topics, the newly developed DDMP method is shown to be numerically capable of simulating this transition of states. Dilation bands and formation of force chains in the resulting granular material are observed. The numerical results from the DDMP method compare well with experimental data for both ductile and brittle materials.

► Axisymmetric version of the Dual Domain Material Point method (DDMP) is studied.
► The DDMP method reduces numerical noises of original MPM method.
► This noise reduction is crucial for brittle material to prevent premature damage.
► Continuum to dust transition of a brittle material is studied using DDMP method.