Modeling impact‐induced damage and debonding using level sets in a sharp interface Eulerian framework

Abstract

Summary This work presents a level‐set–based sharp interface technique to simulate the evolution of damage in ductile materials under high velocity impact conditions. The level‐set method is adopted to track all interfaces including damage zones within the materials. Two types of damage are considered, ie, the creation of spall zones due to damage accumulation in homogeneous ductile materials and interfacial debonding in heterogeneous materials. Spall is simulated using continuum damage models and a level‐set–based crack generation and evolution algorithm. Three continuum damage models are tested for metal targets subjected to flyer impact; the results from the current code (SCIMITAR3D) are compared with the two widely used computer codes EPIC and CTH, and to experimental data; it is found that the computer codes are in good agreement among each other, but agreement of all methods with experimental data is not uniform. At material interfaces, damage is handled using a cohesive zone model and evolving level sets to create void spaces because of material separation due to debonding. Finally, ductile damage combined with debonding is simulated in an Al‐Ni laminate impacted by a projectile. The results demonstrate the ability of the present approach to simulate various types of damage in materials with heterogeneities and inclusions.

A Flux-enriched Godunov Method for Multi-material Problems with Interface Slide and Void Opening

“…This work matches the oscillation frequency experimental velocity profile well, and matches the qualitative shape of the material separation between the flyerplate and the target and the damaged region found by Brauer et al [13] with their level set based approach.…”

“…No additional algorithm needs to be applied to initiate fracture. This approach also removes the need for the highly non-conservative approach of deleting critically damaged cells to form fracture, as is commonplace in finite element and level set based codes [15], [13], [4]. This also avoids the issue of potentially having to redistribute the conserved quantities such a mass and momentum to the neighbouring cells around the deleted cells.…”

“…To match experiment, the profile is taken at r = 0.5 mm. This test also compares against the Ghost Fluid method of Brauer et al [13], who performed the same test with a variety of damage models, using a level set based approach. The computational domain spans r = [0 : 20mm], z = [0 : 7mm], the test is run for 3 µs at a CFL of 0.6.…”

“…It is commonplace in many existing methods for simulating fracture to introduce cracks by eroding material from critically damaged cells [e.g. 15,13,4]. This approach is highly non-conservative and leads to issues if the conserved state of eroded material is simply redistributed to its neighbours.…”

The Modified Void Nucleation and Growth Model (MNAG) for Damage Evolution in BCC Ta

“…To derive the damage evolution from Equations ( 1)-( 12), it was necessary to measure the stress evolution as a function of time. Typically, the damage was modeled as a stressdependent quantity [63]. Here, instead, we treated stress as an independently varying state and proposed the following expression to simulate the stress evolution observed in MD simulations:…”