Multi-scale defect interactions in high-rate failure of brittle materials, Part II: Application to design of protection materials

Abstract

Micromechanics based damage models, such as the model presented in part I of this 2 part series [1], have the potential to suggest promising directions for materials design. However, to reach their full potential these models must demonstrate that they capture the relevant physical processes. In this work, we apply the multiscale material model described in [1] to ballistic impacts on the advanced ceramic boron carbide and suggest possible directions for improving the performance of boron carbide under impact conditions. We simulate both dynamic uniaxial compression and simplified ballistic loading geometries to demonstrate that the material model captures the relevant physics in these problems and to interrogate the sensitivity of the simulation results to some of the model input parameters. Under dynamic compression, we show that the simulated peak strength is sensitive to the maximum crack growth velocity and the flaw distribution, while the stress collapse portion of the test is partially influenced by the granular flow behavior of the fully damaged material. From simulations of simplified ballistic impact, we suggest that the total amount of granular flow (a possible performance metric) can be reduced by either a larger granular flow slope (more angular fragments) or a larger granular flow timescale (larger fragments). We then discuss the implications for materials design.

Field‐gradient partitioning for fracture and frictional contact in the material point method

“…The 2‐D computational examples in this work are all plane strain, but it is necessary to specify a material thickness to define the particle volume. While there is some evidence that a Weibull distribution may not be physically representative of flaw distributions in many engineering materials (cf., ), the need for physically motivated spatial heterogeneity is clear.…”

A micromechanical Sliding-Damage Model Under Dynamic Compressive Loading

“…The plastic multiplier, increment of wing-crack length and damage evolution are computed based on Eqs. (32), (29) and 4respectively. The increment of plastic strain tensor is calculated from Eq.…”

“…The developed model by Andrew and Ramesh (2016) showed that under dynamic compression, the simulated peak strength is sensitive to the maximum crack growth velocity [29].…”

“…31, the damage evolution and plastic flow rule have already been determined by Eqs. (4), (19) and (29). Application of the consistency condition to the frictional sliding criterion in Eq.…”

Steel spheres impact on alumina ceramic tiles: Experiments and finite element simulations

“…This constitutive model was implemented in the Abaqus finite element code by Lahiri and Ramachandra who simulated a projectile impact on ceramic metal composite back plate. Tonge and Ramesh also presented a micromechanics‐based model that captured the strength variability and strain rate sensitivity of brittle materials and provided qualitative validation by simulating a ballistic experiment of a 6.34‐mm tungsten sphere projectile impact a ceramic cylinder. More recently, Saucedo‐Mora and Marrow developed a novel method called FEMME (Finite Element Microstructure MEshfree) to account for the microstructure properties in the damaged zone while still computing at a larger scale.…”