Hierarchical multiscale simulations of crystalline β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (β-HMX): Generalized interpolation material point method simulations of brittle fracture using an elastodamage model derived from molecular dynamics

Abstract

A predictive constitutive model for single-crystal β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (β-HMX) under simple loading conditions was developed using a hierarchical multiscale approach based on molecular dynamics and the generalized interpolation material point method. Basic mechanical behaviors, such as elastic and damage responses to external loading conditions, were predicted at the molecular level using molecular dynamics. The molecular dynamics results were used to construct a preliminary elastodamage model for the generalized interpolation material point (GIMP) simulations. Anisotropy of the β-HMX crystal, which affects the secant elastodamage stiffness tensor in the constitutive model, was taken into account. The GIMP method was used to deal with large deformation and fracture. GIMP results predicted using the hierarchically obtained elastodamage model are shown to be in close agreement with the molecular dynamics predictions. Although the evolution of local damage surfaces from GIMP is not as detailed as that from molecular dynamics, the main features of nonlinear elastodamage in the stress–strain relationship are captured by GIMP at reduced computational expense. Thus, this preliminary hierarchical multiscale procedure can be considered as useful for simulations of elastodamage behaviors in brittle materials for engineering purposes.

Pressure‐dependent Elastic Coefficients of β‐HMX from Molecular Simulations

“…In the present study, we use the method of molecular statics, with sample preparation performed using molecular dynamics (MD), to calculate the second-order elastic tensor and derived isotropic moduli of b-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (b-HMX) on the 0 K isotherm for hydrostatic pressures between 10 À4 GPa (1 atm) and 30 GPa. The simulations are based on a fairly well-validated non-reactive force field that has been used in numerous previous studies [3][4][5][6][7][8][9][10]. Among the three pure crystal polymorphs of HMX, namely a [11], b [12], and d [13], b-HMX is the stable form at standard ambient conditions.…”

Energy-based assessment of brittle fracture in VO-notched polymer specimens under combined compression-shear loading conditions

“…Up to now, many researches have been performed dealing with fracture investigation in cracked engineering components under cyclic and monotonic loading conditions (Heydari-Meybodi et al, 2017Razavi et al, 2018aRazavi et al, , 2018b. Also, in recent years, some researches have been published dealing with fracture in engineering materials under dynamic loadings (Arbaoui et al, 2016;Dascalu, 2017;Djokovic´et al, 2016;Hu et al, 2016;Jiang et al, 2017;Xu et al, 2016).…”

A novel multi-scale model for predicting the thermal damage of hybrid fiber-reinforced concrete

“…À2.286 Â 10 À8 À2.040 Â 10 3 2.106 Â 10 À8.635 Â 10 À2 1.757 Â 10 À4 À1.774 Â 10 À7 7.107 Â 10 À11 At the level I, the equivalent C-S-H product matrix level contains C-S-H product and its thermal decomposed product. The characteristic length scale of this level is 10 À8 to 10 À6 m, which is currently the smallest material scale that can be accessible by nanoindentation test (Bernard et al, 2003;Constantinides and Ulm, 2004;Jiang et al, 2017). At this level, the C-S-H product is regarded as the matrix, the decomposition product is the inclusion.…”