Hydrodynamic Behavior

The material library in Abaqus/Explicit includes several equation of state models to describe the hydrodynamic behavior of materials. An equation of state is a constitutive equation that defines the pressure as a function of the density and the internal energy (Equation of State).

This page discusses:

The following equations of state are supported in Abaqus/Explicit:

Mie-Grüneisen equation of state

The Mie-Grüneisen equation of state (Mie-Grüneisen Equations of State) is used to model materials at high pressure. It is linear in energy and assumes a linear relationship between the shock velocity and the particle velocity.

Tabulated equation of state

The tabulated equation of state (Tabulated Equation of State) is used to model the hydrodynamic response of materials that exhibit sharp transitions in the pressure-density relationship, such as those induced by phase transformations. It is linear in energy.

P–alpha equation of state

The P-α equation of state (P–alpha Equation of State) is designed for modeling the compaction of ductile porous materials. The constitutive model captures the irreversible compaction behavior at low stresses and predicts the correct thermodynamic behavior at high pressures for the fully compacted solid material. It is used in combination with either the Mie-Grüneisen equation of state or the tabulated equation of state to describe the solid phase.

JWL high explosive equation of state

The Jones-Wilkins-Lee (or JWL) equation of state (JWL High Explosive Equation of State) models the pressure generated by the release of chemical energy in an explosive. This model is implemented in a form referred to as a programmed burn, which means that the reaction and initiation of the explosive is not determined by shock in the material. Instead, the initiation time is determined by a geometric construction using the detonation wave speed and the distance of the material point from the detonation points.

Ideal gas equation of state

The ideal gas equation of state (Ideal Gas Equation of State) is an idealization to real gas behavior and can be used to model any gases approximately under appropriate conditions (e.g., low pressure and high temperature).

Deviatoric Behavior

The material modeled by an equation of state may have no deviatoric strength or may have either isotropic elastic or viscous (both Newtonian and non-Newtonian) deviatoric behavior (Deviatoric Behavior). The elastic model can be used by itself or in conjunction with the Mises, the Johnson-Cook, or the extended Drucker-Prager plasticity models to model hydrodynamic materials with elastic-plastic deviatoric behavior.

Thermal Strain

Thermal expansion cannot be introduced for any of the equation of state models.