Isale define code#

We first introduce an efficient method of simulating the inclusion of layers within the target. This thesis highlights additions to numerical models of impact crater formation so that the target sequence can be more accurately represented. Planetary bodies, such as Earth, the Moon, and Mars, are rarely so simple. In computer simulations of meteorite impacts, the target is often simplified by removing details such as layering that may be present. Stratigraphic uplift tends to increase with in thicker sedimentary targets, but the most uplifted material tends to be found at further radial distances from the point of impact. A thick sedimentary layer changes the cratering flow field the enhanced lateral motion of the weakened sedimentary material results in a crater that has a greater final diameter and reduced final depth relative to a crater formed in a purely crystalline target. An additional suite of ~60 simulations of impacts into mixed sedimentary-crystalline targets were created to further study the influence of the sedimentary layer on crater formation. Furthermore, several complex craters that formed in relatively thick sedimentary sequences (e.g., Haughton, Ries, Zhamanshin) do not have a central peak. In agreement with field observations at the Haughton and Ries impact structures, layering also appears to be partially responsible for suppressing central uplift formation during crater modification.Ĭomparisons of terrestrial impact structures suggest those that formed in sedimentary or mixed targets tend to have a smaller depth-diameter ratio relative to craters formed in purely crystalline targets.

Simulating layering via material anisotropy tends to increase the diameter and reduce the depth of the crater relative to a crater formed in an unlayered, isotropic target. A comparison of ~4000 impact simulations shows that this method reduces computational cost while replicating the morphology of the craters formed in the high-resolution simulations with multiple weak layers modelled in the target geometry. To address this limitation iSALE was modified to include an anisotropic yield criterion and rotation scheme to simulate the effect of thin, weak layers interspersed in the target. Meteorite impacts occur frequently in layered targets but resolving thin layers in the target sequence is computationally expensive and therefore not often considered in numerical simulations.

Isale define code#

This thesis describes modifications that were made to the impact Simplified Arbitrary Lagrangian Eulerian (iSALE) shock-physics code in order to more accurately simulate meteorite impacts into layered target sequences and details several applications that were investigated using this improved strength model. Numerical simulations of hypervelocity impact events provide a unique method of analyzing the mechanics that govern impact crater formation.