Elastic Behavior

Linear elasticity (Linear Elastic Behavior) is the simplest form of elasticity available in Abaqus. The linear elastic model can define isotropic, orthotropic, or anisotropic material behavior and is valid for small elastic strains.

Failure measures (Plane Stress Orthotropic Failure Measures) are provided for use with linear elasticity as indicators of material failure. They can be used to obtain postprocessed output requests based on the evaluation of common failure theories for fiber-reinforced composite materials.

The porous elastic model in Abaqus/Standard (Elastic Behavior of Porous Materials) is used to study porous materials with nonlinear pressure-dependent elastic behavior (including logarithmic or power laws). This form of nonlinear elasticity is valid for small elastic strains.

The hypoelastic model in Abaqus/Standard (Hypoelastic Behavior) is used for materials in which the rate of change of stress is defined by an elasticity matrix multiplying the rate of change of elastic strain, where the elasticity matrix is a function of the total elastic strain. This general, nonlinear elasticity is valid for small elastic strains.

The hyperelastic model for rubberlike materials (Hyperelastic Behavior of Rubberlike Materials) provides a general capability for modeling the behavior of nearly incompressible elastomers under large elastic deformations.

The hyperfoam model (Hyperelastic Behavior in Elastomeric Foams) provides a general capability for elastomeric compressible foams at finite strains. This nonlinear elasticity model is valid for large strains (especially large volumetric changes). The low-density foam model (Low-Density Foams) is a nonlinear viscoelastic model suitable for specifying strain-rate sensitive behavior of low-density elastomeric foams such as used in crash and impact applications. The crushable foam plasticity model (Crushable Foam Plasticity Models) is used to model compressible foam materials that undergo permanent deformation.

The anisotropic hyperelastic model (Anisotropic Hyperelastic Behavior) provides a general capability for modeling materials that exhibit highly anisotropic and nonlinear elastic behavior (such as biomedical soft tissues and fiber-reinforced elastomers). The model is valid for large elastic strains and captures the changes in the preferred material directions (or fiber directions) with deformation.

The fabric model in Abaqus/Explicit (Fabric Material Behavior) for woven fabrics captures the directional nature of the stiffness along the fill and the warp yarn directions. It also captures the shear response as the yarn directions rotate relative to each other. The model takes into account finite strains including large shear rotations. It captures the highly nonlinear elastic response of fabrics through the use of test data or a user subroutine, VFABRIC (see VFABRIC) for the material characterization. The test data based fabric behavior can include nonlinear elasticity, permanent deformation, rate-dependent response, and damage accumulation.

The viscoelastic model is used to specify time-dependent material behavior (Time Domain Viscoelasticity). In Abaqus/Standard it is also used to specify frequency-dependent material behavior (Frequency Domain Viscoelasticity). It must be combined with linear elasticity, rubberlike hyperelasticity, or foam hyperelasticity.

The parallel rheological framework (Parallel Rheological Framework) is intended for modeling nonlinear behavior for materials subjected to large strains, such as elastomers and polymers. The models defined within this framework consist of multiple parallel viscoelastic networks and, optionally, an elastoplastic network to allow modeling permanent set and material softening using the Mullins effect. The elastic response is defined using the hyperelastic material model; the plastic response is based on the theory of incompressible isotropic hardening plasticity; and the viscous response is specified using the flow rule derived from a creep potential.

The hysteresis model in Abaqus/Standard (Hysteresis in Elastomers) is used to specify rate-dependent behavior of elastomers. It is used in conjunction with hyperelasticity.

The Mullins effect model (Mullins Effect) is used to specify stress softening of filled rubber elastomers due to damage, a phenomenon referred to as Mullins effect. The model can also be used to include permanent energy dissipation and stress softening effects in elastomeric foams (Energy Dissipation in Elastomeric Foams). It is used in conjunction with rubberlike hyperelasticity or foam hyperelasticity.

The no compression and no tension models (No Compression or No Tension) can be used when compressive or tensile principal stresses should not be generated. These options can be used only with linear elasticity.